Southern Gerenuk

Population Biologist Nicole Clausen, (Litocranius walleri) [email protected] AZA Animal Program AZA SSP Coordinator/ Studbook Keeper Christina Seely, Population Viability [email protected] Analysis Report AZA SSP Vice-C oordinator Manda Butler [email protected]

AZA Antelope & Giraffe TAG Vice-Chair Sharon Joseph, [email protected]

AZA Antelope & Giraffe TAG Chair Martha Fischer, [email protected]

Photo by: Deidre Lantz

December 20th, 2013

TABLE OF CONTENTS Table of Contents ...... 1 Executive Summary ...... 2 Population Viability Analysis (PVA) Model Description ...... 3 Population’s Demographic Background ...... 4 PVA Model Setup ...... 5 Starting Population: ...... 5 Age Structure: ...... 5 Current Demographics and Genetics: ...... 6 Reproduction: ...... 6 Mortality: ...... 6 Genetic Management: ...... 7 Inbreeding Depression: ...... 7 MODEL SCENARIOS ...... 9 BASELINE MODELS ...... 10 If Conditions Remain the Same ...... 10 ALTERNATE MODEL SCENARIOS ...... 13 Alternate Mortality Rates ...... 13 ALTERNATE MODEL SCENARIOS ...... 14 Increased Female Probability of Breeding [p(B)] ...... 14 ALTERNATE MODEL SCENARIOS ...... 16 Importing Individuals ...... 16 ALTERNATE MODEL SCENARIOS ...... 17 Import for Artificial Insemination...... 17 ALTERNATE MODEL SCENARIOS ...... 18 Varying Space ...... 18 ALTERNATE MODEL SCENARIOS ...... 19 No Genetic Management ...... 19 ALTERNATE MODEL SCENARIOS ...... 20 Combining Multiple Management Actions – Space and Increased Female p(B) – AZA only ...... 20 Genetic Results Across Scenarios ...... 22 Risk Results ...... 23 Management Actions ...... 24 Conclusions ...... 24 Acknowledgements ...... 25 Appendix A. Literature Cited ...... 26 Appendix B. Studbook Data Exports ...... 27 Appendix C. ZooRisk PVA Model Setup ...... 27 Appendix D. Risk Categories And Results ...... 28 Appendix e. Overall Results Table ...... 29 Appendix F. Included Individuals ...... 29 Appendix G. Male and Female Mortality Rates (Qx) ...... 32 Appendix H. Inbreeding...... 33 Appendix I. Definitions ...... 34

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 1 EXECUTIVE SUMMARY Southern Gerenuk AZA Animal Program Population Viability Analysis Population Viability Analysis (PVA) model scenarios were developed with members of the Association of Zoos and Aquariums (AZA) Antelope and Giraffe Taxon Advisory Group (TAG) and Southern Gerenuk Animal Program during meetings in 2013. In 2011 Lincoln Park Zoo researchers received a two-year grant from the Institute of Museum and Library Services (IMLS) to analyze AZA population’s long-term viability. The project team is using ZooRisk 3.80 (Earnhardt et al. 2008), a PVA modeling software, to examine what would happen to AZA populations if current conditions remained the same (the baseline scenario), and then assess the impact of changes in reproduction, altering mortality rates, increasing space, and not utilizing genetic management (alternative scenarios). The current gerenuk AZA total population size is 82 (27 males, 55 females) individuals and the gerenuk potential space is 92.

MODEL RESULTS Model results indicate that if conditions remain the same, the AZA gerenuk (Litocranius walleri) population will face approximately an annual 2% decline over the next 25 years. The most demographically sustainable model scenarios require an increase in reproduction to 25 total births per year over the next decade. To increase to 92 individuals in the next 100 years, there would need to be approximately 25 births per year over the next decade combined with decreased mortality rates and space of 150 animals to allow the increase in births to have space to grow. It may be challenging to increase reproduction to these levels as they are higher than recently observed birth rates and, at this time, there is not high institutional interest in the species. Currently there are 15 holding institutions in the program; under the declining baseline scenario, the population would have approximately 3 gerenuk per holding institution (45 total individuals) in 25 years.

Model scenarios with increased reproductive rates and space could help meet the AZA Southern Gerenuk Animal Program’s demographic goals. However, the population will only be capable of retaining low levels of gene diversity (lower than current levels) and high inbreeding levels under most realistic scenarios. The explicit effects of inbreeding were not included in the model scenarios explored, thus, if this population is susceptible to inbreeding depression, the predictions presented are likely optimistic. To reach the potential spaces and maintain maximum gene diversity, the population would need to increase reproduction to at least 45% (25 offspring per year), decrease mortality rates, and increase the number of partnering institutions. In the best case scenario, the population can retain 77% gene diversity for 100 years.

MANAGEMENT ACTIONS The AZA Southern Gerenuk Animal Program should apply several management strategies in concert to avoid a strong demographic decline and high inbreeding levels in the future.

 Increase reproduction: The Animal Program should focus on breeding reproductively females to increase the number of offspring produced, with the goal of increasing from the current level (average of ~21 births per year) to 25 births per year. All breeding recommendations received are important to the long-term future of this population; institutions should work hard to get recommended pairs into appropriate breeding situations quickly and work on husbandry to improve breeding success.

 Decrease mortality rates: Historic mortality rates for this population are considerably high; management should take every precaution to decrease this rate, especially focusing infant mortality rates.

 Recruit new institutions and allocate additional spaces: If reproduction is successful (also in combination with imports) in improving the population’s trajectory, it may be hampered by its small number of potential spaces. An increased number of spaces will allow for increased reproduction, a healthier age structure, a more stable population size, and somewhat improved long-term genetic health.

 Import individuals: In certain cases, importation (in accordance with federal agencies and international regulations) could offset the decline the population is facing in the next several years and increase the long-term gene diversity (if the imported individuals are founders). Modeled levels of imports did not assist the population demographically. Imports must be coupled with increased reproduction and decreased mortality rates to successfully grow the population in the long-term and increase gene diversity. Ultimately this population, under all model scenarios, is predicted to retain very low levels of gene diversity over the next 100 years. To provide the biggest genetic impact, imported individuals should be unrelated to the AZA population.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 2 FULL REPORT Southern Gerenuk AZA Animal Program Population Viability Analysis

POPULATION VIABILITY ANALYSIS (PVA) MODEL DESCRIPTION A Population Viability Analysis (PVA) is a computer model that projects the likely future status of a population. PVAs are used for evaluating long-term sustainability, setting population goals, and comparing alternative management strategies. PVAs are tools that can be used to determine the extinction risk of a population, forecast the population’s future trajectory, and identify key factors impacting the population’s future.

ZooRisk is a PVA software package that can be used to model the dynamics of an individual population (Earnhardt et al. 2008). Full documentation on ZooRisk can be found in the software’s manual (Faust et al. 2008). In this analysis, we use it to integrate the complex factors impacting a population – its age and sex structure, demographic rates, stochasticity (random chance due to variation in mortality, fecundity, and sex ratios among individuals), genetic management, and potential management actions. ZooRisk is an individual-based, stochastic model.

Since stochastic models have inherent variation, each model run (or iteration) will produce a slightly different population trajectory, and the model is run hundreds of times to reflect the full potential variation a population could experience. For example, there may be a wide range in population trajectories (Fig. 1). For clarity, most figures in this report show the mean population size (Fig. 1). Model results such as mean population sizes, levels of gene diversity (GD), and inbreeding (F) are averaged across 1000 model iterations. Where relevant, results are reported on medium-term (25 year), and long-term (100 year) time frames. Results such as the probability of reaching the TPS or quasi-extinction (10 individuals) are based on the percentage of iterations that hit that target at least once over the 100 years. Where applicable, ± 1 standard deviation is included; large values represent wider variability in model results.

70 70

60 60 50 50 40 40 30 30 20 20

10 10

NumberofIndividuals NumberofIndividuals 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Model Year Model Year

Figure 1. An example of 30 iterations of a stochastic model (left) and what the mean population size averaged across 500 iterations of the same model would look like (right).

The most powerful use of PVAs is to compare a baseline scenario, reflecting the population’s future trajectory if no management changes are made, to alternate scenarios reflecting potential changes. These comparisons can help evaluate the relative costs and benefits of possible management changes. Note that for easy comparison, model results across all scenarios are included in Appendix D.

The future can be uncertain and difficult to predict. Model results are most appropriately used to compare between scenarios (e.g. relative to each other) rather than as absolute predictions of what will happen.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 3 POPULATION’S DEMOGRAPHIC BACKGROUND

Demography: Based on the AZA Gerenuk Studbook, the first record of gerenuk in zoos was in 1977 at the St. Louis Zoo and the first zoo birth occurred in the same year at the Los Angeles Zoo. The gerenuk AZA population has primarily grown since its introduction to captivity from zoo births, reaching a peak of 92 individuals in 2008 (Fig. 2). Intensive management in this population did not begin until 1990, when gene diversity was already decreasing and mortality had reached unordinary rates. A management decision driven by a decline in numbers (mostly males) was made to breed all reproductively viable females in 2004 in order to reach the TAG population goal of 150 individuals. However, this goal has not yet been met.

Over the last 10 years, the population size has ranged between 62 and 92 individuals, with an average population size of 80. The average population growth rate of the last decade was λ =1.011 with an average of 22 births and 20 deaths per year. The high rate of mortalities has been a major factor limiting the growth of the population.

100 Total 90 Females 80 70 Males 60 50 40

Number of Individuals of Number 30 20 10 0 1977 1982 1987 1992 1997 2002 2007 2012 Year

Figure 2. Number of gerenuks in AZA institutions.

40 Births Deaths Entering AZA Institutions Exiting AZA Institutions

-10

Number of Births/Deaths of Number -20

-30

-40 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 Year Figure 3. Number of births, deaths, enters and exits to and from the AZA population over the last 20 years.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 4 PVA MODEL SETUP Starting Population: ZooRisk uses a starting population to initiate each model scenario, and it incorporates data on each individual’s pedigree, age, sex, and reproductive status. Any animals unable to breed due to age, medical issues, or sterilizations can be designated as non-reproductive in the model, which removes them from the potentially breeding population. The model assumes that any new animals (either births or imports) are potentially reproductively viable; this may be an optimistic assumption.

At the time of analyses the AZA population consisted of 82 animals (27 males, 55 females) at 15 AZA institutions (Fig. 4). In addition, 6 animals (1 male, 5 females) were designated as non-reproductive, based on being beyond the reproductive age classes, sterilized, or having medical issues that prevent them from breeding. Non-reproductive animals hold space in the model projections for the remainder of their lives but are not eligible to breed. With these exclusions, this leaves a potentially breeding population of 76 (26.50) individuals. For scenarios B and H, we incorporated the Larry Johnson institution (JOHNSONTX) that works with the AZA population. By including their 5 individuals, the population consists of 87 individuals (27 males, 60 females) and a potentially breeding population of 81 (26.55) individuals. See Appendix F for a complete list of the individuals included in the model and their reproductive statuses.

Given that there is an even birth sex ratio in gerenuk (see “Reproduction” section below), the sex bias present in the population is likely reflective of higher mortality rates among males (see Appendix G) or higher export rates among males (exports were male-biased over the last 20 years, with 30 males and only seven females exported). However, the biased sex ratio may not be a large concern for the population given that breeding groups are typically structured as 1 male with multiple females (current mean and median of females per male is 3).

Age Structure: The age pyramids for the total population and the potentially breeding portion of the population both show a very female- biased sex ratio (Fig. 4). In addition, the female half of the population displays a healthy age distribution, while the male half of the population has a bi-modal age distribution: many males are ages one and six, but few are ages two through five (Fig. 14).

Total Population Potentially Breeding Population

a) b)

a) Figure 4. Gerenuk age distribution within AZA institutions, divided into (a) total gerenuk population 82 (27 males, 55 females and (b) Potentially breeding population 76 (26.50).

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 5 Current Demographics and Genetics: All ZooRisk scenarios started with the population’s current demographics and genetics (Table 1).

Table 1. Starting demographic and genetic statistics for the AZA gerenuk population. Population AZA only AZA + non-AZA Starting population size (Males.Females.Unknown Sex) 82 (27.55.0) 87 (27.60.0) Potentially breeding population size 76 (26.50.0) 81 (26.55.0) Percentage of pedigree known (after exclusions and assumptions) 100% 100% Gene diversity (GD) 85.35% 85.55% Population mean kinship (MK) 0.1465 0.1445 Mean inbreeding (F) 0.1021 0.1017 Mean generation time (T) (years) 5.2 5.2 Number of generations in 100 model years 19.2 19.2

Reproduction: ZooRisk uses the following parameters to determine how offspring are produced in each model year:

 Female Reproductive Age Classes: ages 1 – 13. The oldest female to produce offspring was 13 years old (SB# 44, who was captive born in 1979). The modeling team and program managers felt that realistically, female gerenuk in zoos are only reproductively viable until 13 years of age.

 Male Reproductive Age Classes: ages 1 – 13. According to the studbook, the oldest male gerenuk to reproduce was 14 years old, though most can only breed till age 13. The modeling team and program managers felt that realistically, male gerenuk in zoos are only reproductively viable until 13 years of age.

 Female Probability of Breeding [p(B)]: Female p(B) is the age-specific probability that a female will have at least one offspring in a given year. Since it is difficult to determine from the studbook what a population could do if all animals were in breeding situations, model scenarios utilize simplified hypothetical levels of p(B) to illustrate the impact of potential changes in birth rates. All female p(B) were set at a constant value across all the reproductively viable age classes. This constant p(B) corresponds with an interbirth interval (e.g. p(B) = 25% = an offspring every 4 years on average), which varies depending on the model scenario. Using a constant value means that all reproductively viable females have the same chance of reproduction regardless of age. This probability of breeding is used in the model to stochastically determine whether a paired female produces offspring in any given model year.

 Annual Number of Offspring (ANO): Gerenuks typically produce one offspring per litter, twins are not likely though it is possible for a female to have a second offspring in one year. Based on studbook data, the annual frequency of producing one offspring was 78% and two offspring was 22% (Appendix C). When a female within the model is selected to reproduce in a given model year, ZooRisk uses these frequencies to stochastically determine the number of offspring she produces.

 Birth Sex Ratio (BSR): Based on studbook data, the birth sex ratio is not significantly different than the expected equal 2 BSR (50 males: 50 females, Χ df=1 = 0.55, p > 0.05). For this population, all model scenarios were given a BSR of 0.5 (no bias).

Mortality:  Male and Female Age-Specific Mortality Rates (Qx): Mortality rates for age classes 0 – 16 for males and 0 – 17 for females were based on studbook data from individuals living within North America from 01 January 1980 to present. For scenarios C and K, we used mortality rates based on the studbook data from 01 January 1995 to present. These more

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 6 recent mortality estimates were often, but not always, lower than the 1980-present estimates. See Appendix G for both sets of male and female mortality rates used in the model.

 Infant Mortality Rates (Qx): male = 41%, female = 39% for all scenarios except C and K. For scenarios C and K, male = 39%, female = 34%.

 Maximum Longevity: Male longevity is 16 years old, and female longevity is 17. These maximums were based on studbook records and the knowledge on animal managers for animals in North American institutions.

Space: There is limited space available in AZA institutions and in many cases populations can compete for similar spaces. Viability of some species may be limited if too little space is allocated, while others may exceed the space needed to maintain sustainable populations. PVAs can identify the number of spaces needed to attain a population’s long-term sustainability. ZooRisk has the option of including a space limitation on population growth. This limitation reduces breeding in the model population as it approaches the potential space limit, mimicking zoo management. For example, a Program Leader may begin to recommend fewer breeding pairs if available spaces for a population become limited.

To determine an appropriate space limitation for the models, the PVA team, in consultation with the AZA Wildlife Conservation and Management Committee (WCMC), developed the approach of using the number of projected spaces in 5 years based on a Taxon Advisory Group’s (TAG) Regional Collection Plan (RCP). If that number is unavailable or unsuitable (i.e. if the population is already larger than that space), the team will use the current population size + 10% or 10 individuals, whichever is greater.

Projected spaces for the gerenuk population for most scenarios were set at 92 individuals for the AZA population and 97 for the non-AZA population (+5 individuals). The 2009 Antelope and Giraffe TAG RCP set the gerenuk long-term target population size at 150, thus for scenarios which explored increased potential space this number was used.

Genetic Management: ZooRisk can model genetic management by mean kinship pairings and other genetic criteria, mimicking the way that AZA populations are managed to maintain gene diversity (GD) (Ballou and Lacy, 1995). Therefore, ZooRisk can more accurately project the amount of gene diversity retained through genetic management. Unless otherwise noted, we used mean kinship genetic management in all scenarios. We also modeled alternate scenarios with no genetic management.

Inbreeding Depression: One of the largest genetic threats to small populations is the potential detrimental effects of inbreeding, where breeding between close relatives results in decreased short-term and long-term fitness via reductions in fecundity or litter size, increases in infant mortality, and other detrimental effects (DeRose and Roff, 1999; Koeninger, Ryan, et al., 2002; Ballou and Foose, 1996; Reed and Frankham, 2003). This phenomenon, called inbreeding depression, has been observed in several ex situ species (Ralls and Ballou, 1982; Olech, 1987; Laikre and Ryman, 1991; Lacy et al., 1993), although effects vary between species (Lacy et al., 1993; Kalinowski et al., 1999). However, inbreeding depression is a concern in the zoo community as many populations have a limited number of founders, small population sizes, and a low chance of receiving additional founders in the future (i.e. they are closed populations) Lacy 1997. In other words, inbreeding depression could put this population at higher risk of extinction, particularly if the population size decreases further (Gilpin and Soulé, 1986; Lacy, 1997). At this time there is no evidence that inbreeding depression is potentially affecting this population (see Appendix H for more details).

There are several strategies that can delay the effects or lower the probability of inbreeding depression including; pairing based on mean kinship and importing and breeding unrelated individuals (Ballou and Lacy, 1995). These strategies were modeled for all scenarios except those without genetic management.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 7

Inbreeding depression can be challenging to incorporate into PVA models because of uncertainty about which populations and life history traits will be affected, and at what inbreeding level they will be detected. Our analyses do not indicate that inbreeding depression influences infant mortality (Appendix H), but other important life history parameters could be negatively effects. Due to this uncertainty and since modeling inbreeding depression adds an additional layer of complexity to interpretation of results; we have not included a “standard” inbreeding depression effect in the gerenuk PVA models. Readers should therefore consider that model results may be optimistic.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 8 MODEL SCENARIOS Model scenarios for AZA Southern Gerenuk Animal Program were created to reflect what would happen if current management approaches continued (baseline) and to address potential alternate management strategies (Table 2); scenarios are described in more detail in their results sections below.

Table 2. ZooRisk model scenarios. Scenario Name Scenario Description p(B) Space Baseline Scenarios: Baseline Reproduction to match past 10 years (2003 - 2012) for AZA A. AZA Baseline; p(B) = 39% 39% 92 institutions Reproduction to match past 10 years (2003 - 2012) for AZA B. AZA + non-AZA; p(B) = 37% 37% 97 institutions plus JOHNSONTX Alternate Scenarios: Alternate Mortality Rates – AZA only C. Alternate mortality; p(B) = 36%; AZA Mortality data altered to match rates since 1995. Reproduction to 36% 92 only match past 10 years in AZA only (2003 - 2012) Alternate Scenarios: Increased Female Probability of Breeding [p(B)] – AZA only D. p(B) = 45%; AZA only Increase p(B) to 45% (1 offspring every 1.5 years for each female) 45% 92 Alternate Scenario: Importing Individuals – AZA only E. Import 2.2 every 5 years for 20yrs; Import 2 males, 2 females (ages 1 – 3) in model years 5, 10, 15, and 39% 92 p(B) = 39%; AZA only 20; 16 individuals total Alternate Scenarios: Import for Artificial Insemination – AZA only Import 20 males (end of reproductive age class to represent low F. Import 20 individuals in year 1; p(B) = probability of success) in year one - as a representation of 1 39% 92 39%; AZA only importation of semen Alternate Scenarios: Increase Space G. Increase space to 150; p(B) = 39%; Increase space to RCP allotted space of 150 animals; p(B) = 39% 39% 150 AZA only H. Increase space to 150; p(B) = 39%; Increase space to RCP allotted space of 150 animals; p(B) = 37% 37% 150 AZA + non-AZA Alternate Scenarios: No Genetic Management – AZA only I. No Genetic Management; p(B) = 39%; Turned genetic management off (mean kinship pairing) for baseline 39% 92 AZA only model Alternate Scenarios: Combining Multiple Management Actions – AZA only J. Increase space to 150 + p(B) = 45%; Increase space to RCP allotted space of 150 animals; increased p(B) = 45% 150 AZA only 45% Mortality data altered to match rates since 1995. Increase space to K. Alternate mortality + Increase space RCP allotted space of 150 animals; increased p(B) = 45%. 45% 150 to 150 + p(B) = 45%; AZA only Reproduction to match past 10 years in AZA only (2003 - 2012)

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 9 BASELINE MODELS If Conditions Remain the Same – All populations The gerenuk baseline scenario describes what is likely to happen to the gerenuk population if the population were closed (no imports), experiences the mortality patterns observed in the studbook and maintains a birth rate equivalent to that observed over the last decade (from 2003 – 2012, the AZA population produced an average of ~22 births per year, which is approximately equal to a p(B) of 39%). For detailed model results, see Figure 5, 6, 7 and Table 3 below.

100

30 Number of Individuals of Number 20

0 0 10 20 30 40 50 60 70 80 90 100 Model Year

Figure 5. Projected total population size for the AZA baseline model scenario (p(B) = 39%). Solid lines are mean results across the 1000 iterations, and dashed lines are ± 1 standard deviation.

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80 A. AZA Baseline; 60 p(B) = 39%

B. AZA + Number of Individuals of Number non-AZA 20 Baseline; p(B) = 37%

0 0 10 20 30 40 50 60 70 80 90 100 Model Year

Figure 6. Projected mean total population size for AZA baseline, scenario A (p(B) = 39%) and AZA + non-AZA baseline, scenario B (p(B) = 37%). The solid black line represents the AZA potential space of 92 individuals, and the dashed black line represents the AZA + JOHNSONTX space of 97 individuals.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 10 The projected population decline occurs because deaths are predicted to exceed births. The baseline model scenario produces, on average, ~22 births and ~23 deaths per year in the first 10 years of the model.

Under this scenario, the population’s age structure is predicted to change over the next 25 years as the population ages and new births fail to compensate for the deaths that are expected (Fig. 7). The baseline scenario produces a stable age distribution in model year 25 with approximately 45 individuals in the population (Fig. 7c). This small population size will make reproduction goals and meeting institutional needs difficult.

Starting Age Structure Model Year 10 Model Year 25

a. b. c. a

Figure 7. Gerenuk population age structures under AZA baseline scenario, p(B) = 39%: (a) starting age structure; (b) mean age structure at model year 10; (c) mean age structure at model year 25. Results are averaged across 1000 iterations. Starting population = 82 (27 males and 55 females).

Table 3. Baseline model results. AZA starting population = 82 (27 males, 55 females), starting GD = 85.35%, starting F = 0.1021. AZA + non- AZA starting population = 87 (27 males, 60 females), starting GD = 85.55%, starting F = 0.1017. Probability Mean Mean Median Mean GD of Probability Median Mean F Population Population Time to Retained1 Reaching of Time to Retained1 SCENARIO Size1 in Size1 in Potential in Year Potential Reaching Extinction in Year 100 Year 25 ± Year 100 ± Space 100 ± 1 Space of Extinction (years) ± 1 SD2 1 SD2 1 SD2 (years)3 SD2 92 or 97 44% ± A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 0.46 ± 0.11 15% 47% ± B. AZA + non-AZA Baseline; p(B) = 39% 50 ± 20 16 ± 14 35% 5 76% 71 0.44 ± 0.12 15% 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 11 Results for baseline scenarios: 1. If no management changes are made, the AZA population will decline strongly throughout the next 100 years and will not retain healthy levels of gene diversity. a. The projected population size in 100 years is very small; there will be only an average of 15 animals remaining in the population. b. The AZA population has a high probability of extinction- 80% probability of reaching extinction with a median time to reaching of 70 years. Some simulations did reach potential space early in their projections, but none remained near this population size for the duration of the projection (only 1% of simulations had population sizes above 45 individuals at the end of the 100 years). c. Mean gene diversity for the AZA population in 100 years is only 44% with an average inbreeding level of 0.46. Under this scenario (scenario A), the population cannot retain healthy levels of gene diversity. Given the level of GD retained and the projected mean final inbreeding coefficient, it is likely that the demographic projections are optimistic, due to potential effects of inbreeding depression (lowered fecundity, increased mortality). The level of inbreeding projected in 100 years is almost equal to full sibling or parent-offspring mating.

2. The model projects a similar trajectory for the population under the projected baseline scenario for the AZA + non-AZA population. The addition of 5 animals to the population will not have a significant effect on the population size and will not contribute a significant amount of gene diversity in the population.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 12 ALTERNATE MODEL SCENARIOS Alternate Mortality Rates - AZA only Mortality rates have generally decreased over time in the AZA gerenuk population (see Appendix G), due to changes in captive management. The PVA team was interested in determining the effect of these changes in mortality rates on the populations projected future. We therefore conducted simulations using mortality rates estimated with data from 1995 to the present only (mortality in the baseline scenario was estimated using data from 1980 to present). The combination of this alternate set of mortality data with a birth rate equivalent to that observed over the last decade (an average of ~22 births per year), adjusted the p(B) equal to 36%. For detailed model results, see Figure 8 and Table 4 below.

100 90

70 C. Alternate 60 mortality; p(B) 50 = 36%; AZA only 40 30 Number of Individuals of Number A. AZA 20 Baseline; p(B) = 39% 10 0 0 10 20 30 40 50 60 70 80 90 Model Year

Figure 8. Projected mean total population size under 1980 historic mortality rates and 1995 altered mortality rates. The black line represents the potential space of 92 individuals.

Table 4. Model results under varying mortality rates. Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Mean Mean Median Probability Median Mean GD Mean F Population Population Time to Probability of Reaching Time to Retained1 in Retained1 SCENARIO Size1 in Size1 in Potential of Reaching Potential Extinction Year 100 ± 1 in Year 100 Year 25 ± 1 Year 100 ± Space Extinction Space of 92 (years) SD2 ± 1 SD2 SD2 1 SD2 (years)3 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 44% ± 15% 0.46 ± 0.11 C. Alternate mortality; p(B) = 36%; 60 ± 20 29 ± 23 64% 5 46% 79 55% ± 13% 0.4 ± 0.1 AZA only 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenario with alternate mortality rates: 1. Using the more contemporary mortality rates (scenario C) still resulted in a decline. However, the decline is less steep than that predicted when using the more historic mortality rates. a. The change in mortality rates reduced the probability of extinction within 100 years from 80% to 46% and delayed the median extinction time from 70 to 79 years. b. This change in mortality rates is also predicted to lead to higher gene diversity retention, although it remains very low at the end of the 100 model years (GD = 55%). Additionally, the inbreeding coefficient in 100 years is predicted to be lower in this scenario, but is still high at 0.4.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 13 ALTERNATE MODEL SCENARIOS Increased Female Probability of Breeding [p(B)] - AZA only We modeled the impact of increasing the current p(B) of 39% to a p(B) of 45% (for reproductive-aged females 1 – 13 years) to illustrate what may happen to the population if reproduction can increase to the population’s full potential. A p(B) of 45% is equivalent to each reproductive-aged female reproducing approximately every 2.25 years, whereas a p(B) of 39% corresponds to a female reproducing every 2.5 years. For detailed model results, see Figure 9, 10, and Table 5 below.

100 90

70 60 D. p(B) = 45%; AZA only 50 40 A. AZA Baseline;

30 p(B) = 39% Number of Individuals of Number 20 10 0 0 10 20 30 40 50 60 70 80 90 100 Model Year

Figure 9. Projected mean total population varying p(B) levels. The black line represents the potential space of 92 individuals.

30 39% = 1 offspring every 2.5 years 45% = 1 offspring every 2.25 years 25 25

10 Number of Births of Number

0 A. AZA Baseline; p(B) = 39% D. p(B) = 45%; AZA only Scenario

Figure 10. Projected mean total number of offspring per year over the first 10 years of the model based on varying levels of female probability of breeding (p(B)). Note that this is the total number of offspring produced before any infant mortality occurs – these would not have to be surviving births.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 14

Table 5. Model results under varying p(B) levels. Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Mean Mean Median Probability Median Mean GD Mean F Population Population Time to Probability of Reaching Time to Retained1 in Retained1 SCENARIO Size1 in Size1 in Potential of Reaching Potential Extinction Year 100 ± 1 in Year 100 Year 25 ± 1 Year 100 ± Space Extinction Space of 92 (years) SD2 ± 1 SD2 SD2 1 SD2 (years)3 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 44% ± 15% 0.46 ± 0.11 D. p(B) = 45%; AZA only 73 ± 18 56 ± 27 90% 6 11% 80 65% ± 9% 0.32 ± 0.06 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenario with increased female probability of breeding [p(B)]: 1. With an increase of approximately 3 additional births per year (scenario D), the population is still predicted to decrease over time, but at a much less steep rate. a. The probability of extinction during the next 100 years is reduced considerably to only 11%, and those populations that persist to year 100 have an average size of 56 animals. Although 90% of the simulations reach the potential space over the next 100 years (and do so rapidly, with a mean time of 6 years), only 20% of simulations have a population size over 80 individuals in year 100. b. At this level of breeding, gene diversity is retained at a much higher rate (GD = 65%) and inbreeding in only increases to 0.32 (although this level is still quite high, this is reflective of an average mating being more related than half-siblings). The low levels of gene diversity and high levels of inbreeding are still a concern.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 15 ALTERNATE MODEL SCENARIOS Importing Individuals - AZA only The AZA Southern Gerenuk Animal Program is currently investigating private sources for potential importations to assist the population with maintaining a healthy GD. We simulated the impact of importing 2 males and 2 females every 5 years for the next 20 years for a total of 16 imported individuals. All imported individuals were between the ages of 1 and 3 (age is randomly assigned within this range). Imported individuals are assumed to be reproductively viable and unrelated (potential founders) to the current population. All results include only the AZA population. This scenario’s p(B) was consistent with the baseline scenario of 39% in order to represent only the addition of imports to the population. Results are presented in Figure 11 and Table 6.

100 90

80 70 E. Import 2.2 60 every 5 years for 50 20yrs; p(B) = 39%; 40 AZA only 30 A. AZA Baseline; Number of Individuals of Number 20 p(B) = 39% 10 0 0 10 20 30 40 50 60 70 80 90 100 Model Year Figure 11. Projected mean total gerenuk population size under varying import scenario. Results are averaged across 1000 iterations. The solid black line represents the potential space for the baseline scenario.

Table 6. Gerenuk results under import scenario. Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Mean Mean Median Probability Median Mean GD Mean F Population Population Time to Probability of Reaching Time to Retained1 in Retained1 SCENARIO Size1 in Size1 in Potential of Reaching Potential Extinction Year 100 ± 1 in Year 100 Year 25 ± 1 Year 100 ± Space Extinction Space of 92 (years) SD2 ± 1 SD2 SD2 1 SD2 (years)3 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 44% ± 15% 0.46 ± 0.11 E. Import 2.2 every 5 years for 56 ± 19 15 ± 15 47% 5 73% 74 55% ± 15% 0.34 ± 0.11 20yrs; p(B) = 39%; AZA only 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenario importing individuals: 1. Imports alone cannot substantially improve the population’s demographic trajectory over the next 100 years. a. This scenario produces the same small mean population size at year 100 as the baseline scenario with no imports. There is a slight reduction in the probability of reaching extinction within 100 years (80% to 73%). However, the population is still quite extinction prone, and virtually all of the trajectories are declining over time. b. However, imports are predicted to have relatively positive genetic impacts on the population due to the addition of new founders to the population. These imports lead to a higher GD and lower F at 100 years compared to the baseline. However both metrics are still at problematic levels even with the imports.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 16 ALTERNATE MODEL SCENARIOS Import for Artificial Insemination - AZA only The AZA Animal Program is currently investigating sources for potential importations of semen for artificial insemination (A.I.) to assist the population with maintaining gene diversity and maintaining the current population size. We simulated the impact of A.I. by importing 20 males of age 13 (the last reproductive age class) in year 1. Using age 13 males represents the assumption that A.I. will have a low probability of success (these males only get one opportunity to breed). The animals introduced into the population for this scenario are considered unrelated to the population. This scenario’s p(B) was consistent with the baseline scenario of 39% in order to represent only the addition of an A.I. import to the population. Results are presented in Figure 12 and Table 7.

120

100

80 F. Import 20 individuals in year 60 1; p(B) = 39%; AZA only

Number of Individuals of Number A. AZA Baseline; p(B) = 39% 20

0 0 10 20 30 40 50 60 70 80 90 100 Model Year Figure 12. Projected mean total gerenuk population size after artificial insemination in year 1. Results are averaged across 1000 iterations.

Table 7. Gerenuk results under artificial insemination scenario. Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Mean Mean Probability Median Mean GD Mean F Population Population of Time to Retained1 in Retained1 SCENARIO Size1 in Size1 in Reaching Extinction Year 100 ± 1 in Year 100 Year 25 ± 1 Year 100 ± Extinction (years) SD2 ± 1 SD2 SD2 1 SD2 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 80% 70 44% ± 15% 0.46 ± 0.11 F. Import 20 individuals in year 1; 47 ± 21 16 ± 14 79% 70 49% ± 15% 0.41 ± 0.11 p(B) = 39%; AZA only 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenarios with an import of artificial insemination: 1. The A.I. import model scenario suggests that whether or not the import occurs, the population will still decline over the next 100 years. The use of A.I.it will not significantly alter the population’s demographic trajectory. a. Using A.I. will lead to a modest increase in GD retained and decrease in F in 100 years, but less than the predicted effect of importing individuals (see scenario E).

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 17 ALTERNATE MODEL SCENARIOS Varying Space The most recent space survey reported that there is a potential for 150 spaces for gerenuk in AZA institutions, thus we created scenarios to demonstrate how additional spaces could assist the population. A scenario for the AZA population and a separate scenario for the AZA + non-AZA population were modeled to see if the populations could fill the exhibit space if it were available to them. Results are presented in Figure 13 and Table 8.

160 G. Increase space to 140 150; p(B) = 39%; AZA 120 only A. AZA Baseline; p(B) 100 = 39% 80

60 H. Increase space to 150; p(B) = 39%; AZA

Number of Individuals of Number 40 + non-AZA

20 B. AZA + non-AZA Baseline; p(B) = 37% 0 0 10 20 30 40 50 60 70 80 90 100 Model Year Figure 13. Projected mean total gerenuk population size under increased space scenarios. Results are averaged across 1000 iterations. The solid black line represents the increased space of 150 individuals. The dashed black line represents the potential space for AZA + JOHNSONTX population. The dotted black line represents the potential space for scenario AZA population.

Table 8. Gerenuk results under varying space scenarios. Starting AZA population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Starting AZA + non-AZA population = 87 (27 males and 60 females). Starting GD = 85.55%. Starting F = 0.1017. Probability Mean Mean of Median Median Mean GD Mean F Population Population Reaching Time to Probability Time to Retained1 Retained1 SCENARIO Size1 in Size1 in Potential Potential of Reaching Extinction in Year 100 in Year 100 Year 25 ± 1 Year 100 ± Space of Space Extinction (years) ± 1 SD2 ± 1 SD2 SD2 1 SD2 92, 97, or (years)3 150 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 44% ± 15% 0.46 ± 0.11 B. AZA + non-AZA Baseline; p(B) = 50 ± 20 16 ± 14 35% 5 76% 71 47% ± 15% 0.44 ± 0.12 39% G. Increase space to 150; p(B) = 48 ± 21 16 ± 14 0.2% 37 78% 69 46% ± 15% 0.46 ± 0.12 39%; AZA only H. Increase space to 150; p(B) = 50 ± 21 15 ± 14 0.1% 25 77% 73 46% ± 16% 0.44 ± 0.13 37%; AZA + non-AZA 1 All population sizes are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenarios with varying space: 1. These results suggest that providing additional spaces alone or in concert with the additional animals from JOHNSONTX is not enough to alter the future trajectory of the population. a. The population sizes at 100 years, probability of extinction, and time to extinction are all virtually the same for the two increased space scenarios as they are for the baselines. b. Under these additional space scenarios, there is also no difference from the baselines in terms of the mean GD results or the mean inbreeding coefficient results in 100 years.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 18 ALTERNATE MODEL SCENARIOS No Genetic Management - AZA only All previous scenarios were run simulating genetic management by creating breeding groups by ranked mean kinship, the typical strategy used to manage zoo populations. To illustrate the impact of genetic management, we created an alternate scenario, which is modeled after the baseline scenario but without any genetic management. For this comparison scenario, animals in the model were randomly paired for the 100 years of the model as opposed to all other scenarios where animals were paired by mean kinship. The results from these scenarios are presented in Table 9.

Table 9. Mean gene diversity retained across the population in 100 years and average inbreeding level in 100 years in scenarios with and without genetic management (pairing by mean kinship). Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021.

Mean Population Size1 in Mean GD Retained1 Mean F Retained1 SCENARIO Year 100 ± 1 SD2 in Year 100 ± 1 SD2 in Year 100 ± 1 SD2

A. AZA Baseline; p(B) = 39% 15 ± 15 44% ± 15% 0.46 ± 0.11 I. No Genetic Management; p(B) = 39%; AZA only 15 ± 15 41% ± 17% 0.52 ± 0.14 1Averaged across 1000 iterations, only calculated for iterations where the population size at year 100 is greater than 0 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

Results for scenario with no genetic management: 1. The population retains more gene diversity in 100 years when managed with mean kinship pairing than without any genetic management. Scenario I illustrates that the mean gene diversity will decrease more strongly when the population isn’t managed genetically by mean kinship. However, the levels of inbreeding in 100 years are still very high in the baseline scenario, higher than sibling relatedness. Managers should strategically match breeding groups to avoid higher mean inbreeding coefficients.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 19 ALTERNATE MODEL SCENARIOS Combining Multiple Management Actions – Increased Space, Increased Female p(B), and Altered Mortality Rates - AZA only Scenarios were created to demonstrate how the combination of management techniques could assist the population in increasing demographically and retain more gene diversity over the long-term. Scenario J illustrates the combination of additional spaces and increased female p(B), while scenario K combines additional space, increased p(B), and alternate mortality rates (other scenarios are included in the figures for reference). Both scenarios included only the AZA population, potential space was increased to 150 individuals, female p(B) was increased to 45%, and only for scenario K mortality rates were altered. Results are presented in Figure 14 and Table 10.

160 K. Alternate mortality, Increase space to 150; 140 p(B) = 45%; AZA only

120 J. Increase space to 150; 100 p(B) = 45%; AZA only

80 G. Increase space to 150; 60 p(B) = 39%; AZA only

NumberofIndividuals 40 A. AZA Baseline; p(B) = 20 39% 0 0 10 20 30 40 50 60 70 80 90 100 Model Year Figure 14. Projected mean total gerenuk population size under various increased space scenarios, including previous scenarios for reference. Results are averaged across 1000 iterations. The solid black line represents the potential space for the baseline scenario. The dashed black lines represent the increased space of 150.

Table 10. Results under varying p(B) and space scenarios. Starting population = 82 (27 males and 55 females). Starting GD = 85.35%. Starting F = 0.1021. Probability Mean Mean Median of Median Mean GD Mean F Population Population Time to Probability Reaching Time to Retained1 in Retained1 SCENARIO Size1 in Size1 in Potential of Reaching Potential Extinction Year 100 ± 1 in Year 100 Year 25 ± 1 Year 100 ± Space Extinction Space of 92 (years) 3 SD2 ± 1 SD2 SD2 1 SD2 (years) or 150 A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 32% 5 80% 70 44% ± 15% 0.46 ± 0.11 G. Increase space to 150; p(B) 48 ± 21 16 ± 14 0.2% 37 78% 69 46% ± 15% 0.46 ± 0.12 = 39%; AZA only J. Increase space to 150 + 95 ± 32 90 ± 45 46% 41 5% 83 70% ± 9% 0.28 ± 0.07 p(B) = 45%; AZA only K. Alternate mortality + Increase space to 150 + 144 ± 13 146 ± 10 100% 15 0% - 77% ± 1% 0.22 ± 0.01 p(B) = 45%; AZA only 1 All population sizes, GD, and F are the mean value across 1000 iterations. 2 One standard deviation. 3Inbreeding levels: parent/offspring or siblings: 0.25, half-siblings: 0.125, first cousins: 0.0625

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 20

Results for scenarios with varying female probability of breeding [p(B)], mortality, and space: 1. With additional space and increased reproduction (scenario J), the population is able to increase and maintain a population size of approximately 90 individuals over the next 100 years. Although the probability of reaching potential space (150 individuals) in Scenario J is only 46%, the probability of the population going extinct within 100 years is just 5% (compared to 11% extinction probability without the additional spaces), indicating that the additional spaces provide a potentially important buffer for the population even if they aren’t filled. a. Increasing reproduction and space would allow the population to retain a much higher GD and lower inbreeding at the end of 100 years. However, both values are still indicative of a population with problematic genetics.

2. If the population can be managed with more contemporary mortality rates over the long term as well as having an increased breeding rate and more available spaces (scenario K), its demographic and genetic future will be improved further. Under these conditions, the population can increase to fill potential space, and is predicted to do so in 15 years. Importantly, unlike in other scenarios where the population is projected to fill potential space and then decline (for example, scenario D), the population is predicted to remain near the total number of potential spaces throughout the next 100 years (Fig. 14). Indeed, only 1% of simulations had final population sizes below 120 individuals, and no simulations went extinct. a. In addition, the genetic future of the population is predicted to be the best under these conditions, as 77% of GD is predicted to be retained and the final inbreeding level is predicted to be 0.22. However, both of these values are still worse than benchmarks, indicating that alleviating the demographic concerns with this population will lessen, but not remove, the genetic issues.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 21 GENETIC RESULTS ACROSS SCENARIOS

Some of the risks inherent to small populations are related to the potential impacts of inbreeding depression. Inbreeding depression can result in higher mortality or lower reproduction rates throughout a population and can increase over time as inbreeding in the population increases. Although explicit effects of inbreeding depression were not included in model scenarios, if this population is susceptible to inbreeding depression, it would mean that the model scenarios presented are likely optimistic (i.e. if we included inbreeding depression, the model’s demographic projections over time would be worse). Our initial analyses indicated that inbreeding does not negatively affect infant mortality rates (Appendix H), but it is still possible for inbreeding to influence other important life history traits.

The gerenuk population is descended from 16 potential founders that were assumed to be unrelated, and the living population is estimated to have retained ~85% of the gene diversity of the source population. However, current mean inbreeding levels are at 0.1021. If no additional importations occur and the population remains closed in the future, gene diversity will decrease and inbreeding levels will increase through genetic drift. Scenarios representing current breeding rates are predicted to reach inbreeding levels (F) near 0.5, which is the value representing sibling-sibling or parent-offspring mating (Fig. 15b). In particular, if the population is not managed genetically, the predicted F value in 100 years is above 0.5.

Increased space, increased reproduction, or managing for more contemporary mortality rates will all help mitigate the genetic situation, but not entirely alleviate the problems faced by this population. The best genetic conditions for the population were seen under the full combination of management changes (scenario K), but even under that scenario, inbreeding levels are still above half-sibling mating and the amount of GD retained is still below 80%.

90% 0.60 b) Sibling a) Half-sibling 80% First cousin 0.50

70%

60% 0.40 50% 0.30

40% %Retianed GD 30% 0.20

20% Coefficient (F) Inbreeding 0.10 10%

0% 0.00 A B C D E F G H I J K A B C D E F G H I J K Scenario Scenario Figure 15. a) The mean genetic statistics at year 100 across 1000 iterations for each model scenario in Table 11, including a) gene diversity (GD) retained and b) inbreeding coefficient (F). The black horizontal lines indicate the levels of F equivalent to first cousins (0.0625) and half siblings (0.125) mating. Starting GD for the population is 85%, starting F is 0.1021.

Table 11. Scenarios in figures 15a and 15b above. A AZA Baseline; p(B) = 39% G Increase space to 150; p(B) = 39%; AZA only B AZA + non-AZA Baseline; p(B) = 37% H Increase space to 150; p(B) = 37%; AZA + non-AZA C Alternate mortality; p(B) = 39%; AZA only I No Genetic Management; p(B) = 39%; AZA only D p(B) = 45%; AZA only J Increase space to 150 + p(B) = 45%; AZA only E Import 2.2 every 5 years for 20yrs; p(B) = 39%; AZA only K Alternate mortality + Increase space to 150 + p(B) = 45%; AZA only F Import 20 individuals in year 1; p(B) = 39%; AZA only

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 22 RISK RESULTS ZooRisk also uses a standardized set of five risk tests which evaluate different aspects of a population’s demography, genetics, and management that might put the population at risk, and summarizes them into a single Risk Score for each model scenario. A population under a given model scenario can be: Low Risk in captivity, Vulnerable in captivity, Critical in captivity, or Endangered in captivity (for a detailed description of risk categories see ZooRisk manual, Faust and Earnhardt, 2005). This approach standardizes assessments across species and allows managers to compare species programs using the same framework. For more details on what makes a scenario fall into a particular category, see Appendix X.

For the gerenuk scenarios, the risk levels varied from Vulnerable to Critical in zoos depending on the model scenario (Table 12). The goal for managers should be to move the population from Critical/Endangered towards Vulnerable/Low Risk, utilizing some of the management tactics highlighted in the model results. The Gerenuk Animal Program has the ability to move its population’s risk level from Critical to Vulnerable with a combination of management changes; decrease mortality rates, increase space to 150, and increase breeding.

Table 12. Overall risk results for each gerenuk scenario (Low Risk is the most secure category, Critical the least secure). Baseline Scenario Scenario’s Risk Category (highlighted category = score) A. AZA Baseline; p(B) = 39% LOW RISK VULNERABLE ENDANGERED CRITICAL B. AZA + non-AZA Baseline; p(B) = 37% LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: Alternate Mortality C. Alternate mortality; p(B) = 39%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: Varying Female Probability of Breeding [p(B)] D. p(B) = 45%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenario: Importing Individuals E. Import 2.2 every 5 years for 20yrs; p(B) = 39%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: Import for Artificial Insemination F. Import 20 individuals in year 1; p(B) = 39%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: Increase Space G. Increase space to 150; p(B) = 39%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL H. Increase space to 150; p(B) = 37%; AZA + non-AZA LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: No Genetic Management I. No GM; p(B) = 39%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL Alternate Scenarios: Combining Multiple Management Actions J. Increase space to 150; p(B) = 45%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL K. Alternate mortality, Increase space to 150; p(B) = 45%; AZA only LOW RISK VULNERABLE ENDANGERED CRITICAL

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 23 MANAGEMENT ACTIONS The AZA Southern Gerenuk Animal Program should apply several management strategies in concert to avoid a strong demographic decline and high inbreeding levels in the future.

CONCLUSIONS This model is a scientifically-sound comprehensive tool to be used by population managers for assessing future directions for the animal program. This PVA report is provided to the AZA community and others to integrate into management of the important species within our care. The PVA model results are intended to provide the necessary data to make science-based decisions.

These model results illustrate that if the AZA gerenuk population continues on its current trajectory, it will drastically decline over the next 100 years with an 80% chance of reaching extinction. If the population continues on this current path, it will be most difficult to continue a genetically healthy population. In 100 years, there will only be approximately 44% gene diversity retained throughout the population.

Several management actions, such as a combination of increased reproduction, decreased mortality rates, and increased space could help reverse this declining trend and will allow for a larger population and detrimentally improve the population’s long –term demographic and very importantly genetic health. All efforts should be made to explore these possibilities as a way to set the gerenuk population on the path towards long-term sustainability within AZA institutions.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 24 ACKNOWLEDGEMENTS

On July 16, and October 3, 2013, the following attended a Go-To-Meeting to discuss the AZA Southern Gerenuk Animal Program Population Viability Analysis:  Nicole Clausen, Population Biologist o Lincoln Park Zoo, [email protected]  Lisa Faust, Vice President of Conservation and Science o Lincoln Park Zoo, [email protected]  Christina Seely, SSP Coordinator/ Studbook Keeper o Denver Zoo, [email protected]  Manda Butler, SSP Vice-Coordinator o Cameron Park Zoo, [email protected]  Sharon Joseph, TAG Vice-Chair o Houston Zoo, [email protected]  Martha Fischer, TAG Chair o St. Louis Zoo, [email protected]

This report was also reviewed by:  Joseph Simonis, Postdoctoral Fellow in the Alexander Center for Applied Population Biology o Lincoln Park Zoo, [email protected]

If you have any questions about the report, please contact Lisa Faust at [email protected].

Analyses in this report utilized the North American Regional Gerenuk Studbook current to 6 March 2013 (citation) and were performed using PopLink 2.4 and ZooRisk 3.8.

Funding provided by Institute of Museum and Library Services (IMLS) LG-25-11-0185

Cover photo courtesy of Deidre Lantz, Dee Otter Photography (photo taken at Denver Zoo). 2013.

Citation: Clausen, N, Seely, C, Butler, M, Joseph, S, Fischer, M. 2013. Southern Gerenuk (Litocranius walleri) AZA Animal Program Population Viability Analysis Report. Lincoln Park Zoo, Chicago, IL.

The contents of this report including opinions and interpretation of results are based on discussions between the project team and do not necessarily reflect the opinion or position of Lincoln Park Zoo, Association of Zoos and Aquariums, and other collaborating institutions. The population model and results are based on the project team’s best understanding of the current biology and management of this population. They should not be regarded as absolute predictions of the population’s future, as many factors may impact its future status.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 25 APPENDIX A. LITERATURE CITED

AZA Antelope & Giraffe Taxon Advisory Group (TAG). 2008. Felid Taxon Advisory Group Regional Collection Plan (RCP) – 5th Edition.

Ballou, J. D., and R. C. Lacy. 1995. Identifying genetically important individuals for management of genetic variation in pedigreed populations. Pages 76-111 in J. D. Ballou, M. Gilpin, and T. J. Foose, eds. Population Management for Survival and Recovery: Analytical Methods and Strategies in Small Population Conservation. Columbia University Press, New York.

Ballou, J. D., and T. J. Foose. 1996. Demographic and genetic management of captive populations. Pages 263-283 in S. Lumpkin, ed. Wild Mammals in Captivity. University of Chicago Press, Chicago.

Barnes, B, and Cox, C. 2010-2011. Breeding and Transfer Reccommendations for Gerenuk (Litocranius walleri) Population Management Plan.

Seely,C. 2013. North American Gerenuk Studbook. Denver Zoo.

DeRose, M. A., and D. A. Roff. 1999. A comparison of inbreeding depression in life-history and morphological traits in animals. Evolution 53: 1288-1292.

Earnhardt, JM, Bergstrom, YM, Lin, A, Faust, LJ, Schloss, CA, and Thompson, SD. 2008. ZooRisk: A Risk Assessment Tool. Version 3.8. Lincoln Park Zoo. Chicago, IL.

Faust, LJ, Earnhardt, JM, Schloss, CA, and Bergstrom, YM. 2008. ZooRisk: A Risk Assessment Tool. Version 3.8 User’s Manual. Lincoln Park Zoo. Chicago, IL.

Gilpin, M., and M. Soulé. 1986. Minimum viable populations: Processes of species extinction. Pages 19-34 in M. Soulé, ed. Conservation Biology: The Science of Scarcity and Diversity. Sinauer Associates Inc., Sunderland, MA. Kalinowski, S. T., P. W. Hedrick, and P. S. Miller. 1999. No inbreeding depression observed in Mexican and red wolf captive breeding programs. Conservation Biology 13: 1371-1377.

Koeninger Ryan, K., Lacy, R.C., and Margulis, S.W. 2002. Impacts of kinship and inbreeding on components of fitness. Reproduction and Integrated Conservation Science.

Lacy, R. C., Petric, A., and Warneke, M. The Natural History of Inbreeding and Outbreeding : University of Chicago Press; 1993.

Lacy, R. C. 1997. Importance of genetic variation to the viability of mammalian populations. Journal of Mammalogy 78: 320- 335.

Laikre, L. and Ryman, N. Inbreeding Depression in a Captive Wolf (Canis Lupus) Population. Conservation Biology. 1991 Mar; 5(1):33-40

Olech, A. Analysis of inbreeding in European bison. Acta Theriologica. 1987; 32(22):373-387.

Ralls, Katherine., Ballou, J. D., and Templeton, A. Estimates of Lethal Equivalents and the Cost of Inbreeding in Mammals. Conservation Biology. 1988 Jun; 2(2):185-193.

Reed, D. H., and R. Frankham. 2003. Correlation between fitness and genetic diversity. Conservation Biology 17: 230-237.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 26 APPENDIX B. STUDBOOK DATA EXPORTS

Studbook Information Studbook Currentness Date 31 December 2012 Studbook Keeper Christina Seely

Studbook Extractions: Start Date End Date Institution Filter Fecundity Window 01 January 1980* 03 July 2013 N.AMERICA Mortality Window 01 January 1980* 03 July 2013 N.AMERICA Living Population 09 July 2013 - N.AMERICA *Unless otherwise stated in methods.

APPENDIX C. ZOORISK PVA MODEL SETUP

Name of ZooRisk Project = SGerenuk2013

Model Parameter Parameter Value Additional Setup Notes Species Biology Number of Males per Breeding Group 1 Number of Females per Breeding Group 3 Number of Years Between Pairing 7 Model Settings Number of Years 100 Number of Iterations 1000 Extinction Threshold 0 Gene Diversity Threshold 0.90 Potential Space 92 or 97 Reach TPS over 5 years Genetic Management Mean kinship pairing Used in all scenarios except “No Genetic Management” Annual Number of Offspring Model Frequency Actual number of offspring (calculated by ZR) 1 offspring 0.7806 0.7806 (427) 2 offspring 0.2194 0.2194 (120) Birth Sex Ratio Birth Sex Ratio 0.4798 Is not significantly different from 0.5 (chi-square value = 0.6265, p>0.05)

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 27 APPENDIX D. RISK CATEGORIES AND RESULTS

ZooRisk uses five, standardized tests to determine a scenario’s risk level. The ZooRisk development team and members of the AZA Small Population Management Advisory Group (SPMAG) worked to develop the cutoffs for each category level during the development of ZooRisk.

The 5 tests and the cutoffs for each level are: # Risk Tests Low Risk Vulnerable Endangered Critical Probability of extinction (P(E)) in 100 years, 0-9% P(E) within 10-19% P(E) 20-49% P(E) 50-100% P(E) 1 based on ZooRisk model 100 years within 100 years within 100 years within 100 years Distribution of breeding-aged, mixed-sex 2 >3 Zoos 3 Zoos 2 Zoos 1 Zoo groups, based on current population Current number of breeding-aged animals 3 More than 10.10 7.7 to 10.10 4.4 to 6.6 0.0 to 3.3 (m.f), based on current population Consistent Inconsistent Sporadic success: Reproduction in the last generation, based on Little success: 0-2 4 success: >9 pairs success: 6-9 pairs 3-5 pairs historic studbook data pairs reproducing reproducing reproducing reproducing Gene diversity of starting population or Starting GD >0.9 Starting GD <0.9 Starting GD <0.8 Starting GD <0.75 5 modeled population in 100 years, based on and modeled GD or modeled GD or modeled GD or modeled GD current population and ZooRisk model >0.9at 100 years <0.9at 100 years <0.75at 100 years <0.5at 100 years

For a given scenario, the overall risk level is based on the most severe score it achieved for any of the five tests. Tests 2-4 are based on the population’s history, and are the same across all model scenarios:

Test 3 - Test 5 - Test 1 - Test 2 - Current Test 4 - GD of starting Probability of Distribution number of Reproduction population or Overall extinction of breeding- breeding- in the last modeled (P(E)) in 100 aged, mixed- aged animals generation population in years sex groups (m.f) 100 years

Baseline Scenarios A. AZA Baseline; p(B) = 39% CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL B. AZA + non-AZA Baseline; p(B) = 37% CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL Alternate Scenarios: Alternate Mortality C. Alternate mortality; p(B) = 39%; AZA CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK ENDANGERED only Alternate Scenarios: Varying Female Probability of Breeding [p(B)] D. p(B) = 45%; AZA only ENDANGERED VULNERABLE LOW RISK LOW RISK LOW RISK ENDANGERED Alternate Scenario: Importing Individuals E. Import 2.2 every 5 years for 20yrs; p(B) CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK ENDANGERED = 39%; AZA only Alternate Scenarios: Import for Artificial Insemination F. Import 20 individuals in year 1; p(B) = CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL 39%; AZA only Alternate Scenarios: Increase Space G. Increase space to 150; p(B) = 39%; AZA CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL only H. Increase space to 150; p(B) = 37%; AZA CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL + non-AZA Alternate Scenarios: No Genetic Management I. No GM; p(B) = 39%; AZA only CRITICAL CRITICAL LOW RISK LOW RISK LOW RISK CRITICAL Alternate Scenarios: Combining Multiple Management Actions J. Increase space to 150; p(B) = 45%; AZA ENDANGERED LOW RISK LOW RISK LOW RISK LOW RISK ENDANGERED only K. Alternate mortality, Increase space to VULNERABLE LOW RISK LOW RISK LOW RISK LOW RISK VULNERABLE 150; p(B) = 45%; AZA only

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 28 APPENDIX E. OVERALL RESULTS TABLE Southern Gerenuk AZA starting population = 82 (27 males, 55 females). Starting GD = 85.35%. Starting F = 0.1021. Southern Gerenuk AZA + non-AZA starting population = 87 (27 males, 60 females). Starting GD = 85.55%. Starting F = 0.1017. Mean # Probability Mean Mean of Mean GD Mean F of reaching Median Median Population Population Offspring Probability Retained1 Retained1 Potential time to time to SCENARIO Size1 in Size1 in in the of reaching in Year in Year Space of TPS Extinction Year 25 ± Year 100 ± first 10 Extinction 100 ± 1 100 ± 1 92 or 97 (years)3 (years) 1 SD2 1 SD2 model SD2 SD3 Individuals years Baseline Scenarios: 44% ± 0.46 ± A. AZA Baseline; p(B) = 39% 45 ± 19 15 ± 15 21.4 32% 5 80% 70 15% 0.11 B. AZA + non-AZA Baseline; 47% ± 0.44 ± 50 ± 20 16 ± 14 21.5 35% 5 76% 71 p(B) = 37% 15% 0.12 Alternate Scenarios: Alternate Mortality Rates C. Alternate mortality; p(B) = 55% ± 60 ± 20 29 ± 23 21.3 64% 5 46% 79 0.40 ± 0.1 39%; AZA only 13% Alternate Scenario: Increased Female Probability of Breeding [p(B)] 0.32 ± D. p(B) = 45%; AZA only 73 ± 18 56 ± 27 25 90% 6 11% 80 65% ± 9% 0.06 Alternate Scenario: Importing Individuals E. Import 2.2 every 5 years for 55% ± 0.34 ± 56 ± 19 15 ± 15 21.8 47% 5 73% 74 20yrs; p(B) = 39%; AZA only 15% 0.11 Alternate Scenarios: Import for Artificial Insemination F. Import 20 individuals in year 49% ± 0.41 ± 47 ± 21 16 ± 14 21.9 0% 0 79% 70 1; p(B) = 39%; AZA only 15% 0.11 Alternate Scenarios: Increase Space G. Increase space to 150; p(B) = 46% ± 0.46 ± 48 ± 21 16 ± 14 21.9 0.2% 37 78% 69 39%; AZA only 15% 0.12 H. Increase space to 150; p(B) = 46% ± 0.44 ± 50 ± 21 15 ± 14 23.5 0.1% 25 77% 73 37%; AZA + non-AZA 16% 0.13 Alternate Scenarios: No Genetic Management 41% ± 0.52 ± I. No GM; p(B) = 39%; AZA only 45 ± 19 15 ± 15 21.4 32% 5 80% 69 17% 0.14 Alternate Scenarios: Combining Multiple Management Actions J. Increase space to 150 + p(B) 0.28 ± 95 ± 32 90 ± 45 28.3 46% 41 5% 83 70% ± 9% = 45%; AZA only 0.07 K. Alternate mortality + 0.22 ± Increase space to 150 + p(B) = 144 ± 13 146 ± 10 33.8 100% 15 0% 0 77% ± 1% 0.01 45%; AZA only 1 All population sizes and GD retained are the mean value across 1000 iterations. 2 One standard deviation. 3 A dash (-) indicates that TPS can never be reached.

APPENDIX F. INCLUDED INDIVIDUALS These individuals were included as the starting population in all scenarios in the ZooRisk. Individuals excluded from breeding, marked as “neutered” designated as non-breeders (see list below) and were excluded from the breeding population. Those animals with Allow Breed = NO hold space but are never eligible for reproduction.

ID Allow Breed Sex % Known Age Institution Reason for Exclusion

396 NO Contracepted Female 100 15 FORTWORTH Age/ neutered 414 NO Male 100 14 METROZOO 476 YES Female 100 12 METROZOO 486 YES Female 100 11 YULEE

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 29 *503 YES Female 100 11 JOHNSONTX *Non-AZA institution 516 YES Female 100 10 SD-WAP 519 YES Male 100 9 PHOENIX 522 YES Female 100 9 LOSANGELE 530 YES Female 100 9 YULEE 540 NO Female 100 9 FORTWORTH Medical issues *542 YES Female 100 9 JOHNSONTX *Non-AZA institution 547 YES Female 100 8 METROZOO 548 NO Contracepted Female 100 8 DENVER Neutered 557 YES Male 100 8 YULEE 560 YES Female 100 7 DALLAS 563 YES Female 100 7 WACO 571 YES Female 100 7 YULEE 577 YES Male 100 7 DENVER 578 YES Female 100 7 PORTLAND 579 YES Female 100 7 PORTLAND 581 YES Male 100 7 PORTLAND 583 YES Female 100 7 YULEE 585 YES Male 100 6 ST LOUIS 588 YES Male 100 6 YULEE 589 YES Male 100 6 SANDIEGOZ 590 YES Female 100 6 YULEE 593 YES Male 100 6 SANDIEGOZ 598 YES Female 100 6 LOSANGELE 600 YES Male 100 6 LOSANGELE *611 YES Female 100 5 JOHNSONTX *Non-AZA institution 617 NO Female 100 5 METROZOO Broken legs 619 YES Female 100 5 METROZOO 620 YES Female 100 5 LOSANGELE 621 YES Male 100 5 PHOENIX 624 YES Female 100 5 SD-WAP 626 YES Female 100 5 WACO *627 YES Female 100 5 JOHNSONTX *Non-AZA institution 628 YES Male 100 5 GLEN OAK 629 YES Male 100 5 SANDIEGOZ 630 YES Female 100 5 YULEE 634 YES Female 100 5 YULEE 637 YES Female 100 4 SANDIEGOZ 639 YES Female 100 4 DENVER 644 YES Female 100 4 SANDIEGOZ 646 YES Female 100 4 LOSANGELE 650 YES Female 100 4 SANDIEGOZ 655 YES Female 100 3 PHOENIX 657 YES Male 100 3 SD-WAP 658 YES Female 100 3 PHOENIX 659 NO Female 100 3 DISNEY AK Medical issues 661 YES Female 100 3 PHOENIX 665 YES Female 100 3 YULEE *667 YES Female 100 3 JOHNSONTX *Non-AZA institution 668 YES Female 100 3 YULEE 670 YES Female 100 3 MEMPHIS

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 30 674 YES Male 100 3 ST LOUIS 676 YES Female 100 2 DALLAS 677 YES Female 100 2 LOSANGELE 678 YES Female 100 2 SD-WAP 680 YES Male 100 2 WACO 684 YES Female 100 2 PHOENIX 691 YES Male 100 1 LOSANGELE 694 YES Female 100 2 YULEE 695 YES Female 100 2 YULEE 696 YES Female 100 1 YULEE 697 YES Male 100 1 YULEE 698 YES Male 100 1 YULEE 699 YES Male 100 1 YULEE 700 YES Female 100 1 YULEE 701 YES Female 100 2 DALLAS 702 YES Female 100 1 SD-WAP 705 YES Female 100 1 PHOENIX 708 YES Male 100 1 METROZOO 709 YES Female 100 1 METROZOO 710 YES Male 100 1 METROZOO 711 YES Female 100 1 HOUSTON 713 YES Male 100 1 LOSANGELE 717 YES Male 100 0 METROZOO 718 YES Female 100 1 YULEE 719 YES Male 100 0 LOSANGELE 720 YES Female 100 0 LOSANGELE 724 YES Female 100 0 WACO 725 YES Male 100 1 SD-WAP 726 YES Female 100 0 SD-WAP 727 YES Female 100 0 SD-WAP 728 YES Male 100 0 SD-WAP 730 YES Female 100 0 DENVER

**Animals 621, 705, 713, and 720 were sent outside the AZA population after studbook update

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 31 APPENDIX G. MALE AND FEMALE MORTALITY RATES (QX) Male and female mortality rates used in scenarios A, B, and D through J of the ZooRisk model are listed below. Each year, the model determines whether each individual lives or dies stochastically based on that individual’s age- and sex-specific mortality rate.

Male Female Age(x) Qx Number at Risk Age(x) Qx Number at Risk

0 0.4133 331.5 0 0.3876 353.5

1 0.2448 192 1 0.1449 214

2 0.2086 139 2 0.0843 178

3 0.1574 108 3 0.1346 156 4 0.0968 93 4 0.1029 136 5 0.2262 84 5 0.161 118

6 0.2381 63 6 0.1556 90

7 0.1667 42 7 0.1081 74

8 0.1613 31 8 0.2667 60

9 0.24 25 9 0.2857 42 10 0.3889 18 10 0.3462 26 11 0.4545 11 11 0.1875 16

12 0.3333 6 12 0.4545 11

13 0.25 4 13 0.4 5

14 0 3 14 0.3333 3

15 0.5 2 15 0 2 16 1 1 16 0 1 17 1 1

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 32 Male and female mortality rates used in scenarios C and K of the ZooRisk model are listed below - these rates were extracted from 1995 to present.

Male Female Age(x) Qx Number at Risk Age(x) Qx Number at Risk

0 0.3871 201.5 0 0.3385 224.5

1 0.1811 127 1 0.1409 149 2 0.2233 103 2 0.0472 127 3 0.1625 80 3 0.1017 118

4 0.0746 67 4 0.098 102

5 0.2615 65 5 0.1538 91

6 0.2609 46 6 0.1765 68

7 0.2069 29 7 0.1091 55 8 0.1818 22 8 0.2 45 9 0.2222 18 9 0.2647 34

10 0.4615 13 10 0.2857 21

11 0.5714 7 11 0.2143 14

12 0.3333 3 12 0.5556 9

13 0.3333 3 13 0.5 4 14 0 3 14 0 2 15 0.5 2 15 0 2

16 1 1 16 0 1

17 1 1

APPENDIX H. INBREEDING All individuals within the studbook born in AZA zoos after 1/1/1980 and before 12/31/2011 (one year before the currentness date of the studbook) were included in the analyses. Total number of offspring included = 652 (309.327.16).

Infant Mortality There is no significant effect of inbreeding level of offspring on infant mortality (logistic regression, all p > 0.4). Overall, the rate of infant mortality was 41.0% (267 mortalities out of 652 individuals).

Litter Size Gerenuk almost always have one offspring per reproduction (even if they reproduce more than once per year), so there is no ability for anything to affect litter size.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 33 APPENDIX I. DEFINITIONS

Age Structure: A two-way classification showing the numbers or percentages of individuals in various age and sex classes.

Current Gene Diversity (GD): The proportional gene diversity (as a proportion of the source population) is the probability that two alleles from the same locus sampled at random from the population will not be identical by descent. Gene diversity is calculated from allele frequencies, and is the heterozygosity expected in progeny produced by random mating, and if the population were in Hardy-Weinberg equilibrium.

Founder: An individual obtained from a source population (often the wild) that has no known relationship to any individuals in the derived population (except for its own descendants).

Inbreeding Coefficient (F): Probability that the two alleles at a genetic locus are identical by descent from an ancestor common to both parents. The mean inbreeding coefficient of a population will be the proportional decrease in observed heterozygosity relative to the expected heterozygosity of the founder population.

Mean Kinship (MK): The mean kinship coefficient between an animal and all animals (including itself) in the living, zoo born population. The mean kinship of a population is equal to the proportional loss of gene diversity of the descendant (zoo born) population relative to the founders and is also the mean inbreeding coefficient of progeny produced by random mating. Mean kinship is also the reciprocal of two times the founder genome equivalents: MK = 1 / (2 * FGE). MK = 1 - GD.

Mean Generation Time (T): The average time elapsing from reproduction in one generation to the time the next generation reproduces. Also, the average age at which a female (or male) produces offspring. It is not the age of first reproduction. Males and females often have different generation times.

Percent Known: Percent of an animal's genome that is traceable to known Founders. Thus, if an animal has an UNK sire, the % Known = 50. If it has an UNK grandparent, % Known = 75%

Population Viability Analysis (PVA): A PVA is a computer model that projects the likely future status of a population. PVAs are used for evaluating long-term sustainability, setting population goals, and comparing alternative management strategies. Several quantitative parameters are used in a PVA to calculate the extinction risk of a population, forecast the population’s future trajectory, and identify key factors impacting the population’s future.

Probability of Breeding [p(B)]: Female p(B) is the age-specific probability that a female will have at least one offspring in a year. For example, p(B) = 25% is equivalent to females producing an offspring once every 4 years. Within the reproductively viable age classes, all p(B) were set at a hypothetical constant value corresponding with an interbirth interval, which varied depending on the model scenario. Using a constant value means that all reproductively viable females would have the same chance of reproduction regardless of age.

Qx, Mortality: Probability that an individual of age x dies during time period.

Regional Collection Plan (RCP): document developed by Taxon Advisory Group (TAG) to describe species managed under their TAG, level of management with explanations, and evaluation of Target Population Sizes for each managed species.

Risk (Qx or Mx): The number of individuals that have lived during an age class. The number at risk is used to calculate Mx and Qx by dividing the number of births and deaths that occurred during an age class by the number of animals at risk of dying and reproducing during that age class. The proportion of individuals that die during an age class is calculated from the number of animals that die during an age class divided by the number of animals that were alive at the beginning of the age class (i.e.-"at risk").

Stochastic Model: A model that includes random chance and variation in model parameters (e.g. randomly select if an individual will breed). Stochastic models will produce many different outcomes each time the model is run due to this variation. Models are typically run for many iterations to fully explore the trajectory a population might take. ZooRisk is a stochastic model.

Target Population Size (TPS): In the context of a Regional Collection Plan, the ‘target’ size selected for each Program within the RCP, which may be based on available spaces for that species, desired spaces the TAG wishes to allocate, the size needed to maintain a viable population, or some combination of those factors. In the context of the ZooRisk modeling work, the TPS is a model parameter that can be set at any level, including the size listed in the RCP or a higher or lower size based on other criteria.

Taxon Advisory Group (TAG): There are several different TAGs and each oversees a broad group of animals (e.g. Antelope TAG, Small Carnivore TAG). Each TAG consists of several programs. The TAG contains experts including studbook keepers, program leaders, the TAG chair, and other advisors. TAGs evaluate the present conditions surrounding a broad group of animals (e.g., marine mammals) and then prioritize the different species in the group for possible captive programs.

2013 Population Viability Analyses for AZA Southern Gerenuk Animal Program 34