DOCSLIB.ORG

High Genetic Load in an Old Isolated Butterfly Population

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
High Genetic Load in an Old Isolated Butterfly Population High genetic load in an old isolated butterfly population Anniina L. K. Mattila1, Anne Duplouy, Malla Kirjokangas, Rainer Lehtonen, Pasi Rastas, and Ilkka Hanski1 Metapopulation Research Group, Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland Edited by Wyatt W. Anderson, University of Georgia, Athens, GA, and approved July 2, 2012 (received for review April 11, 2012) We investigated inbreeding depression and genetic load in a small reversible way. Theoretical models have been constructed to ana- (Ne ∼ 100) population of the Glanville fritillary butterfly(Melitaea lyze the factors influencing the likelihood of mutational meltdown. cinxia), which has been completely isolated on a small island These models have addressed the effects of effective population [Pikku Tytärsaari (PT)] in the Baltic Sea for at least 75 y. As a refer- size (5) and the rate of appearance of new deleterious mutations ence, we studied conspecific populations from the well-studied and their effects (5), as well as compensatory beneficial mutations metapopulation in the Åland Islands (ÅL), 400 km away. A large (20) and epistatic interactions (21). What is in short supply are population in Saaremaa, Estonia, was used as a reference for es- empirical studies of genetic load and its consequences in natural N timating genetic diversity and e. We investigated 58 traits related populations. Previous studies have rarely documented the history to behavior, development, morphology, reproductive perfor- of isolation and past population sizes. In the absence of this in- mance, and metabolism. The PT population exhibited high genetic formation, researchers have merely assumed that small current load (L=1 − WPT/WÅL) in a range of fitness-related traits including L= fl L population size combined with reduced genetic variation is indic- adult weight ( 0.12), ight metabolic rate ( = 0.53), egg viability ative of long-term isolation and that such populations potentially (L = 0.37), and lifetime production of eggs in an outdoor popula- suffer from the accumulation of deleterious mutations (22). In the tion cage (L = 0.70). These results imply extensive fixation of case of naturally isolated insect populations, the focus of research deleterious recessive mutations, supported by greatly reduced di- has been on reduced genetic diversity (23–27). Strong support for versity in microsatellite markers and immediate recovery (hetero- fi sis) of egg viability and flight metabolic rate in crosses with other genetic load due to drift is provided by demonstration of tness populations. There was no significant inbreeding depression in recovery (heterosis) in crosses between isolated populations (28, fi most traits due to one generation of full-sib mating. Resting met- 29). Studies of natural populations have demonstrated tness re- abolic rate was significantly elevated in PT males, which may be covery due to a small number of unrelated immigrants entering an – related to their short lifespan (L=0.25). The demographic history isolated population (14, 30 32) and leading to genetic rescue (33, and the effective size of the PT population place it in the part of 34), regardless of whether reduced fitness was due to inbreeding the parameter space in which models predict mutation accumula- depression (segregation load) or drift (fixation load) (35, 36). tion. This population exemplifies the increasingly common situa- Here, we report on inbreeding depression, genetic load (fit- tion in fragmented landscapes, in which small and completely ness), and local adaptation in a population of the Glanville frit- isolated populations are vulnerable to extinction due to high ge- illary butterfly(Melitaea cinxia) on the small island of Pikku netic load. Tytärsaari (PT) in the northern Baltic Sea. This small population has been completely isolated for at least 75 y. As a reference, we fixation load | segregation load | hybrid vigor | persisting population | use the large conspecific metapopulation in the Åland Islands inbreeding avoidance (ÅL), located 400 km away, which has been intensively studied for the past 20 y (37, 38). The amount of neutral genetic variation lost ampant loss and fragmentation of natural habitats is a prime by the small isolated population is consistent with model pre- Rcause of population and species extinctions. At their final dictions, given its demographic history. We found no convincing stage, extinctions are typically ascribed to ecological processes evidence for local adaptation and only limited inbreeding de- (1), especially to demographic and environmental stochasticities, pression due to one generation of full-sib mating, supporting which increase the risk of extinction for remaining small pop- a high degree of relatedness between individuals and purging of ulations (2–4). However, in the absence of gene flow, the viability strongly deleterious alleles. In contrast, the isolated PT population of isolated remnant populations may be compromised also by exhibits large fitness reduction in comparison with the reference genetic processes, such as inbreeding depression due to segre- population in a range of traits including body size, flight metabolic gation of deleterious recessive mutations and overdominant rate, egg viability, adult longevity, and lifetime production of eggs alleles and mutational meltdown due to fixation of old and new and larvae. Finally, we observed complete fitness recovery (het- deleterious mutations of smaller effect by random genetic drift erosis) in crosses between PT and other regional populations, (5–7). On the other hand, increased homozygosity due to in- implying high genetic load in this isolated population, which may breeding and drift may expose strongly deleterious recessive be undergoing a genetic meltdown to extinction. mutations to selection (8), thereby increasing mean fitness (9, 10), and local adaptation may further enhance fitness in the fl – absence of disruptive gene ow (11 13). Complete isolation and Author contributions: A.L.M. and I.H. designed research; A.L.M., A.D., M.K., and R.L. reduction in population size, which are increasingly common performed research; P.R. contributed new reagents/analytic tools; A.L.M., A.D., M.K., predicaments for populations in human-dominated landscapes R.L., and P.R. analyzed data; and A.L.M., A.D., M.K., R.L., P.R., and I.H. wrote the paper. (14–16), can thus have contrasting effects on population viability. The authors declare no conflict of interest. There are scores of studies focusing on the effects of drift or This article is a PNAS Direct Submission. inbreeding or local adaptation (7, 17, 18), but their joint effects Freely available online through the PNAS open access option. remain little studied and therefore poorly understood (19). 1To whom correspondence may be addressed. E-mail: anniina.mattila@helsinki.fi or ilkka. Increasing frequency and fixation of deleterious recessive mu- hanski@helsinki.fi. tations in isolated populations via inbreeding and drift are a par- See Author Summary on page 14744 (volume 109, number 37). ticularly serious concern for conservation as they may erode This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. population viability gradually, in an initially imperceptible but ir- 1073/pnas.1205789109/-/DCSupplemental. E2496–E2505 | PNAS | Published online August 20, 2012 www.pnas.org/cgi/doi/10.1073/pnas.1205789109 Downloaded by guest on September 29, 2021 PNAS PLUS Results 1+1 founders Population Origin and Genetic Diversity. The Glanville fritillary 0.8 2+2 founders fi 3+3 founders was rst recorded on the small uninhabited island of PT in the 4+4 founders middle of the Gulf of Finland in 1936. The island has a single 5+5 founders meadow of ca. 10 ha with the larval host plant Veronica spicata 0.7 50+50 founders along the shore. The nearest mainland (Estonia) is ca.30km away. The Glanville fritillary was most likely unintentionally in- 0.6 troduced from the Estonian coast by people who used the island as a base for fishing and travel. It is practically certain that there 0.5 has been no further gene flow to the island because it has been Heterozygosity visited very seldom by anyone since World War II (WWII) and the butterfly is a poor disperser (39). Exhaustive surveys of the 0.4 entire habitat area on the island revealed 111 and 198 larval family groups (full siblings) in 2009 and 2011, respectively. Using the formula in Hartl and Clark 2007 (40) and assuming that the 0.3 expected heterozygosities in the initial and current populations 0 20 40 60 80 100 120 are 0.73 and 0.43, respectively (Table 1) and that the age of the Time since colonization population is 100 y (=100 generations), we obtain Ne = 95, Fig. 1. Model-predicted reduction in expected heterozygosity in the PT which is consistent with the above-cited numbers of larval family population with time since the colonization. The results are shown for six groups (some females produce two or even more larval groups different propagule sizes, from a single mated female to 50 females mated that survive until the autumn) (41). with 50 males. Bars giving 1 SD are shown for the propagule size 3+3 and are Data for seven microsatellites indicate closer similarity of the very similar to all other propagule sizes. The propagule is assumed to have PT population to the Estonian population from Saaremaa (SA) the genetic parameters of the Estonian population on the island of Saar- than to the Finnish population from the ÅL (Table 1). The PT emaa (Table 1). The horizontal line gives the expected heterozygosity in the population shares seven alleles in the seven microsatellites with PT population. only the Estonian population, but only one allele with only the < ÅL population (P 0.05). The pairwise Fst values between PT quenced the mitochondrial DNA gene COI, which had only one and Estonia and between PT and ÅL are 0.28 and 0.41, re- haplotype in PT, but this is not informative because the same F spectively, whereas st between Estonia and ÅL is 0.22 (all values haplotype is common in both SA and ÅL, which had five and fi P < statistically signi cant, 0.05).
Load more

Recommended publications
  • E D I T O R I a L
    E D I T O R I A L A MECHANISM FOR RAPID CHANGE? In a highly recommended book1 Del Ratzsch notes that creationists and evolutionists often criticize each other for positions that are more imagined than real. One of the most common misconceptions is the alleged creationist belief in fixity of species.2 One may read dogmatic statements that creation theory cannot be true because Noah’s ark could not hold all the species of beetles, etc. Such arguments seem misguided to many creationists. I doubt any creationist believes that the ark needed to hold 250,000 or more species of beetles. One reason this criticism seems misguided is that creation theory includes the expectation of change in species. Whether every species of beetle depended on the ark for survival is an interesting question that will not be pursued here. The Bible includes several statements that indicate that change in species is to be expected. Genesis 3 records the story of the sin of Adam and Eve, followed by the curses pronounced on nature. As a result of those curses, the serpent was to crawl on its belly, and thorns and thistles would be produced. If these conditions already existed, they could not be attributed to the curses resulting from sin. Thus, these species would change. Another suggestion that plants would change is found in Genesis 2:5, which states that certain types of plants had not yet appeared.3 The text seems to be referring to the spiny xerophytic plants now common in Israel, but the changes that produced this type of plant had not yet occurred at the time Adam was created.
    [Show full text]
  • Spike Protein Mutational Landscape in India: Could Muller’S Ratchet Be a Future Game
    bioRxiv preprint doi: https://doi.org/10.1101/2020.08.18.255570; this version posted August 18, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Spike protein mutational landscape in India: Could Muller’s ratchet be a future game- changer for COVID-19? Rachana Banerjeea, Kausik Basaka, Anamika Ghoshb, Vyshakh Rajachandranc, Kamakshi Surekaa, Debabani Gangulya,1, Sujay Chattopadhyaya,1 aCentre for Health Science and Technology, JIS Institute of Advanced Studies and Research Kolkata, JIS University, 700091, West Bengal, India. bDepartment of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, 711103, West Bengal, India. cSchool of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690525, Kerala, India. 1To whom correspondence may be addressed. Email: [email protected] or [email protected] Classification Major: Biological Sciences, Minor: Evolution Keywords: SARS-CoV-2, Muller's ratchet, mutational meltdown, molecular docking, viral evolutionary dynamics 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.08.18.255570; this version posted August 18, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract The dire need of effective preventive measures and treatment approaches against SARS-CoV-2 virus, causing COVID-19 pandemic, calls for an in-depth understanding of its evolutionary dynamics with attention to specific geographic locations, since lockdown and social distancing to prevent the virus spread could lead to distinct localized dynamics of virus evolution within and between countries owing to different environmental and host-specific selection pressures.
    [Show full text]
  • Genetic and Demographic Dynamics of Small Populations of Silene Latifolia
    Heredity (2003) 90, 181–186 & 2003 Nature Publishing Group All rights reserved 0018-067X/03 $25.00 www.nature.com/hdy Genetic and demographic dynamics of small populations of Silene latifolia CM Richards, SN Emery and DE McCauley Department of Biological Sciences, Vanderbilt University, PO Box 1812, Station B, Nashville, TN 37235, USA Small local populations of Silene alba, a short-lived herbac- populations doubled in size between samples, while others eous plant, were sampled in 1994 and again in 1999. shrank by more than 75%. Similarly, expected heterozygosity Sampling included estimates of population size and genetic and allele number increased by more than two-fold in diversity, as measured at six polymorphic allozyme loci. individual populations and decreased by more than three- When averaged across populations, there was very little fold in others. When population-specific change in number change between samples (about three generations) in and change in measures of genetic diversity were considered population size, measures of within-population genetic together, significant positive correlations were found be- diversity such as number of alleles or expected hetero- tween the demographic and genetic variables. It is specu- zygosity, or in the apportionment of genetic diversity within lated that some populations were released from the and among populations as measured by Fst. However, demographic consequences of inbreeding depression by individual populations changed considerably, both in terms gene flow. of numbers of individuals and genetic composition. Some Heredity (2003) 90, 181–186. doi:10.1038/sj.hdy.6800214 Keywords: genetic diversity; demography; inbreeding depression; gene flow Introduction 1986; Lynch et al, 1995), the interaction of genetics and demography could also influence population persistence How genetics and demography interact to influence in common species, because it is generally accepted that population viability has been a long-standing question in even many abundant species are not uniformly distrib- conservation biology.
    [Show full text]
  • Révision Taxinomique Et Nomenclaturale Des Rhopalocera Et Des Zygaenidae De France Métropolitaine
    Direction de la Recherche, de l’Expertise et de la Valorisation Direction Déléguée au Développement Durable, à la Conservation de la Nature et à l’Expertise Service du Patrimoine Naturel Dupont P, Luquet G. Chr., Demerges D., Drouet E. Révision taxinomique et nomenclaturale des Rhopalocera et des Zygaenidae de France métropolitaine. Conséquences sur l’acquisition et la gestion des données d’inventaire. Rapport SPN 2013 - 19 (Septembre 2013) Dupont (Pascal), Demerges (David), Drouet (Eric) et Luquet (Gérard Chr.). 2013. Révision systématique, taxinomique et nomenclaturale des Rhopalocera et des Zygaenidae de France métropolitaine. Conséquences sur l’acquisition et la gestion des données d’inventaire. Rapport MMNHN-SPN 2013 - 19, 201 p. Résumé : Les études de phylogénie moléculaire sur les Lépidoptères Rhopalocères et Zygènes sont de plus en plus nombreuses ces dernières années modifiant la systématique et la taxinomie de ces deux groupes. Une mise à jour complète est réalisée dans ce travail. Un cadre décisionnel a été élaboré pour les niveaux spécifiques et infra-spécifique avec une approche intégrative de la taxinomie. Ce cadre intégre notamment un aspect biogéographique en tenant compte des zones-refuges potentielles pour les espèces au cours du dernier maximum glaciaire. Cette démarche permet d’avoir une approche homogène pour le classement des taxa aux niveaux spécifiques et infra-spécifiques. Les conséquences pour l’acquisition des données dans le cadre d’un inventaire national sont développées. Summary : Studies on molecular phylogenies of Butterflies and Burnets have been increasingly frequent in the recent years, changing the systematics and taxonomy of these two groups. A full update has been performed in this work.
    [Show full text]
  • Land-Use Changes, Farm Management and the Decline of Butterflies Associated with Semi-Natural Grasslands in Southern Sweden
    A peer-reviewed open-access journal Nature Conservation Land-use6: 31–48 (2013) changes, farm management and the decline of butterflies.... 31 doi: 10.3897/natureconservation.6.5205 APPLIED ECOLOGY http://www.pensoft.net/natureconservation Launched to accelerate biodiversity conservation Land-use changes, farm management and the decline of butterflies associated with semi-natural grasslands in southern Sweden Sven G. Nilsson1, Markus Franzén1,2, Lars B. Pettersson1,3 1 Biodiversity Unit, Department of Biology, Lund University, Ecology Building, SE-223 62 Lund, Sweden 2 UFZ Helmholtz Centre for Environmental Research, Department of Community Ecology, Theodor-Lieser- Straße 4, D-06120 Halle, Germany 3 Swedish Butterfly Monitoring Scheme, Lund University, Ecology Buil- ding, SE-223 62 Lund, Sweden Corresponding author: Lars B. Pettersson ([email protected]) Academic editor: L. Penev | Received 26 March 2013 | Accepted 30 October 2013 | Published 18 November 2013 Citation: Nilsson SG, Franzén M, Pettersson LB (2013) Land-use changes, farm management and the decline of butterflies associated with semi-natural grasslands in southern Sweden. Nature Conservation 18: 31–48. doi: 10.3897/ natureconservation.6.5205 Abstract Currently, we are experiencing biodiversity loss on different spatial scales. One of the best studied taxo- nomic groups in decline is the butterflies. Here, we review evidence for such declines using five systematic studies from southern Sweden that compare old butterfly surveys with the current situation. Additionally, we provide data on butterfly and burnet moth extinctions in the region’s counties. In some local areas, half of the butterfly fauna has been lost during the last 60–100 years.
    [Show full text]
  • Genetic Threats to Population Persistence
    Ann. Zool. Fennici 40: 155–168 ISSN 0003-455X Helsinki 30 April 2003 © Finnish Zoological and Botanical Publishing Board 2003 Genetic threats to population persistence Oscar E. Gaggiotti Metapopulation Research Group, Department of Ecology and Systematics, P.O. Box 65, FIN-00014 University of Helsinki, Finland (e-mail: oscar.gaggiotti@helsinki.fi ) Received 27 Nov. 2002, revised version received 20 Jan. 2003, accepted 20 Jan. 2003 Gaggiotti, O. E. 2003: Genetic threats to population persistence. — Ann. Zool. Fennici 40: 155–168. Human activities are having a devastating effect on the survival of natural popula- tions. The reduction in population size and changes in the connectivity of populations due to human disturbances enhance the effect of demographic and genetic factors that can lead to population extinction. This article provides an overview of our current understanding of the role of genetic factors in the extinction of populations. The three primary genetic factors are loss of genetic variability, inbreeding depression, and accu- mulation of mildly deleterious mutations. The effects of these factors are discussed in the context of three different scenarios: isolated populations, local populations with immigration, and metapopulations. Introduction demographic and genetic factors (Lande 1988). However, the last decade has witnessed much Although the extinction of populations is a natu- progress in this area and there is a general agree- ral phenomenon, human induced habitat loss, ment that, although the most immediate causes pollution and overexploitation have increased of extinction are human predation, introduction extinction rates well above background levels of exotic species and habitat loss, genetic factors and have lead to the mass extinction that we are can still play an important role.
    [Show full text]
  • Fixation of New Mutations in Small Populations
    Whitlock MC & Bürger R (2004). Fixation of New Mutations in Small Populations. In: Evolutionary Conservation Biology, eds. Ferrière R, Dieckmann U & Couvet D, pp. 155–170. Cambridge University Press. c International Institute for Applied Systems Analysis 9 Fixation of New Mutations in Small Populations Michael C. Whitlock and Reinhard Bürger 9.1 Introduction Evolution proceeds as the result of a balance between a few basic processes: mu- tation, selection, migration, genetic drift, and recombination. Mutation is the ulti- mate source of all the genetic variation on which selection may act; it is therefore essential to evolution. Mutations carry a large cost, though; almost all are delete- rious, reducing the fitness of the organisms in which they occur (see Chapter 7). Mutation is therefore both a source of good and ill for a population (Lande 1995). The overall effect of mutation on a population is strongly dependent on the pop- ulation size. A large population has many new mutations in each generation, and therefore the probability is high that it will obtain new favorable mutations. This large population also has effective selection against the bad mutations that occur; deleterious mutations in a large population are kept at a low frequency within a balance between the forces of selection and those of mutation. A population with relatively fewer individuals, however, will have lower fitness on average, not only because fewer beneficial mutations arise, but also because deleterious mutations are more likely to reach high frequencies through random genetic drift. This shift in the balance between fixation of beneficial and deleterious mutations can result in a decline in the fitness of individuals in a small population and, ultimately, may lead to the extinction of that population.
    [Show full text]
  • Die Gattung Coenonympha HÜBNER, 1819, in Europa: Systematik, Ökologie Und Schutz (Lepidoptera: Papilionoidea: Nymphalidae: Satyrinae)
    Oedippus 25:1-42 30.IX.2007 Die Gattung Coenonympha HÜBNER, 1819, in Europa: Systematik, Ökologie und Schutz (Lepidoptera: Papilionoidea: Nymphalidae: Satyrinae) MARTIN WIEMERS Key words: Europe; allozyme electrophoresis; systematics; identification; ecology; conservation. Abstract: A review of the systematics, ecology and conservation of the 13 species of the genus Coenonympha which are currently recognized from Europe is presented. The paper comprises results from allozyme electrophoretic studies in several Coenonympha species with a focus on C. glycerion. These prove that populations of the latter species from the Iberian Peninsula are genetically differentiated from Central European populations, but freely interbreed in the Pyrenees. Therefore the taxon iphioides should be regarded as a subspecies of C. glycerion. Authors’ address: Dr. Martin Wiemers, Department für Populationsökologie, Universität Wien, Althanstr. 14, A-1090 Wien, [email protected]. Price: 12,-- € Inhaltsverzeichnis: 1. Einleitung 2 2. Die Gattung Coenonympha 4 3. Enzymelektrophoretische Untersuchungen 7 3.1 Einleitung 7 3.2 Material und Methoden 7 3.3 Ergebnisse 9 3.4 Diskussion 13 4. Bestimmungsschlüssel der europäischen Coenonympha-Arten 14 5. Die europäischen Coenonympha-Arten 15 C. tullia 15 C. rhodopensis 17 C. glycerion 18 C. hero 19 C. arcania 20 C. gardetta 21 C. leander 23 C. dorus 24 C. corinna 25 C. pamphilus 26 C. lyllus 28 C. thyrsis 28 C. oedippus 29 6. Gefährdung und Schutz 30 7. Summary 33 8. Zitierte Literatur 34 9. Anhang 40 1 1. Einleitung Die Wiesenvögelchen der Gattung Coenonympha sind jedem europäischen Schmet- terlingskundler ein Begriff, denn in den meisten grasigen Habitaten sind Vertreter dieser Augenfalter oft zahlreich anzutreffen.
    [Show full text]
  • Lecture on Positive and Negative Selection
    POSITIVE AND NEGATIVE SELECTION (AND RELATED PROBLEMS) CLAUDIA BANK Evolutionary Dynamics @ IGC: ➤ How do populations adapt to challenging environments? E.g., how does drug resistance evolve? ➤ Which processes drive speciation & diversification? ➤ What is the role of interactions in evolution? Mutation Genetic drift Migration Selection What we do ➤ Study evolutionary processes using simple models ➤ Evaluate these models using empirical and simulated data ➤ Use modeling to inform experimental design a priori Evolutionary Dynamics @ IGC: ➤ How do populations adapt to challenging environments? E.g., how does drug resistance evolve? ➤ Which processes drive speciation & diversification? ➤ What is the role of interactions in evolution? Mutation Genetic drift Migration Selection What we do ➤ Study evolutionary processes using simple models ➤ Evaluate these models using empirical and simulated data ➤ Use modeling to inform experimental design a priori It may be said that natural selection is daily and hourly scutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working , whenever and “ wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages. - Darwin, 1859 It may be said that natural selection is daily and hourly scutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working , whenever and “ wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life.
    [Show full text]
  • Genome Size and the Extinction of Small Populations
    bioRxiv preprint doi: https://doi.org/10.1101/173690; this version posted August 8, 2017. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Genome size and the extinction of small populations Thomas LaBar1;2;3, Christoph Adami1;2;3;4 1 Department of Microbiology & Molecular Genetics 2 BEACON Center for the Study of Evolution in Action 3 Program in Ecology, Evolutionary Biology, and Behavior 4 Department of Physics and Astronomy Michigan State University, East Lansing, MI 48824 Abstract Species extinction is ubiquitous throughout the history of life. Understanding the factors that cause some species to go extinct while others survive will help us manage Earth's present-day biodiversity. Most studies of extinction focus on inferring causal factors from past extinction events, but these studies are constrained by our inability to observe extinction events as they occur. Here, we use digital experimental evolution to avoid these constraints and study \extinction in action". Previous digital evolution experiments have shown that strong genetic drift in small populations led to larger genomes, greater phenotypic complexity, and high extinction rates. Here we show that this elevated extinction rate is a consequence of genome expansions and a con- current increase in the genomic mutation rate. High genomic mutation rates increase the lethal mutation rate, leading to an increase the likelihood of a mutational melt- down. Genome expansions contribute to this lethal mutational load because genome expansions increase the likelihood of lethal mutations.
    [Show full text]
  • The Inflated Significance of Neutral Genetic Diversity in Conservation Genetics PERSPECTIVE Jo~Ao C
    PERSPECTIVE The inflated significance of neutral genetic diversity in conservation genetics PERSPECTIVE Jo~ao C. Teixeiraa,b,1 and Christian D. Hubera,1 Edited by Andrew G. Clark, Cornell University, Ithaca, NY, and approved December 30, 2020 (received for review July 22, 2020) The current rate of species extinction is rapidly approaching unprecedented highs, and life on Earth presently faces a sixth mass extinction event driven by anthropogenic activity, climate change, and ecological collapse. The field of conservation genetics aims at preserving species by using their levels of genetic diversity, usually measured as neutral genome-wide diversity, as a barometer for evaluating pop- ulation health and extinction risk. A fundamental assumption is that higher levels of genetic diversity lead to an increase in fitness and long-term survival of a species. Here, we argue against the perceived impor- tance of neutral genetic diversity for the conservation of wild populations and species. We demonstrate that no simple general relationship exists between neutral genetic diversity and the risk of species extinc- tion. Instead, a better understanding of the properties of functional genetic diversity, demographic his- tory, and ecological relationships is necessary for developing and implementing effective conservation genetic strategies. conservation genetics | adaptive potential | inbreeding depression | genetic load | species extinction Are Species with Little Genetic Diversity Moreover, low genetic diversity is related to reduced Endangered? individual life span and health, along with a depleted Climate change caused by human activity is currently capacity for population growth (9). In contrast, high responsible for widespread ecological disruption and levels of genetic diversity are often seen as key to habitat destruction, with an ensuing unprecedented promoting population survival and guaranteeing the rate of species loss known as the Anthropocene Mass adaptive potential of natural populations in the face of Extinction (1–4).
    [Show full text]
  • Evolutionary Conservation Biology
    Cambridge Studies in Adaptive Dynamics Evolutionary Conservation Biology Edited by R. Ferrière, U. Dieckmann, and D. Couvet Evolutionary Conservation Biology Edited by Régis Ferrière, Ulf Dieckmann, and Denis Couvet PUBLISHED BY THE PRESS SYNDICATE OF THE UNIVERSITY OF CAMBRIDGE The Pitt Building, Trumpington Street, Cambridge, United Kingdom CAMBRIDGE UNIVERSITY PRESS The Edinburgh Building, Cambridge CB2 2RU, UK http://www.cup.cam.ac.uk 40 West 20th Street, New York, NY 10011-4211, USA http://www.cup.org 477 Williamstown Road, Port Melbourne, VIC 3207, Australia Ruiz de Alarcón 13, 28014 Madrid, Spain c International Institute for Applied Systems Analysis 2004 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of the International Institute for Applied Systems Analysis. http://www.iiasa.ac.at First published 2004 Printed in the United Kingdom at the University Press, Cambridge Typefaces Times; Zapf Humanist 601 (Bitstream Inc.) System LATEX A catalogue record for this book is available from the British Library ISBN 0 521 82700 0 hardback Contents Contributing Authors xii Acknowledgments xiv Notational Standards xv 1 Introduction 1 Régis Ferrière, Ulf Dieckmann, and Denis Couvet 1.1 Demography, Genetics, and Ecology in Conservation Biology . 1 1.2 Toward an Evolutionary Conservation Biology . 3 1.3 Environmental Challenges and Evolutionary Responses . 6 1.4 Evolutionary Conservation Biology in Practice . 10 1.5 StructureofthisBook....................... 12 A Theory of Extinction 15 Introduction to Part A . 16 2 From Individual Interactions to Population Viability 19 Wilfried Gabriel and Régis Ferrière 2.1 Introduction .
    [Show full text]