Science for Saving Species Research findings factsheet Project 4.3

Evaluating persistence in threatened translocations: Genetic diversity and mating systems as measures of success

In brief Background For the many long-lived threatened plant species targeted Many threatened plant species However, alternative approaches for translocation in Australia, targeted for translocation in such as benchmarking genetic measuring success is challenging. Australia are relatively long-lived. variation and patterns of pollination New approaches to measuring The timeframes over which they in translocated populations can translocation success include may reproduce and recruit can allow for assessments of long- benchmarking genetic variation and provide significant challenges for term persistence and ultimately patterns of pollination. We applied evaluating translocation success. translocation success that are these methods to translocated and Flowering and fruiting may take more timely. years, or even decades for some wild populations of five woody Successful plant translocation species. Translocation success shrubs native to south-west Western requires the establishment of has been measured in many ways, Australia that have a range of populations with: (1) adequate with practitioners commonly using pollinator types. levels of genetic diversity; and demographic measures such as: We found that the genetic diversity (2) in animal pollinated a • vegetative growth of individuals of all translocated populations was functional mating system where comparable to or surpassed that • survival of individuals over time pollination tends to occur more of the wild reference populations. • survival of individuals to between different plants, rather Our findings for pollination patterns flowering than self-pollination. were, however, mixed, with • presence of reproductive Evaluating how successfully higher levels of self-pollination structures genetic diversity has been and significantly higher inbreeding • presence/abundance of seeds captured in translocations has estimates in both adults and progeny • presence/abundance of a been recommended for some found for two animal-pollinated second generation time, but not widely undertaken. species. This indicates that while Similarly, assessing patterns of • capacity to successfully genetic diversity can be maintained mating (pollination) in animal- respond to future disturbances or even increased in translocated pollinated plants that will reflect such as fire. populations, long-term persistence pollinator presence, abundance of some translocated species No single measure of translocation and behaviour have generally not may be hampered by increased success will provide certainty to been considered when evaluating inbreeding and genetic erosion declare a population viable and self- translocation success. Both genetic over time if required pollinators are sustaining or provide the foundation variation and patterns of pollination not present in sufficient numbers. for recommending the down-listing can be readily assessed using DNA- We recommend further monitoring, or de-listing of a threatened species; based genetic marker or genomic and that caution be applied when rather, a combination of measures techniques by comparing genetic using only demographic and/or will generally be needed. diversity and mating systems in genetic diversity measures to Traditional approaches using translocated populations to assess translocation success demographic measures remain wild reference populations. of animal-pollinated species. important and necessary. BELOW LEFT (top left, middle, bottom): Acacia cochlocarpa. Image: Andrew Crawford; orbifolia SRP. Image: Andrew Crawford; anatona. Image: Andrew Crawford: RIGHT: . Image: Anne Cochrane

Research aims We aimed to benchmark genetic • Round leaf honeysuckle equivalent to wild populations, and diversity and mating systems Narrikup subspecies whether mating systems or patterns (patterns of pollination) within () – of pollination in translocations are translocated and wild populations bird-pollinated equivalent to wild populations. of five long-lived threatened woody • Round leaf honeysuckle Affirmative answers would provide shrub species from south-west evidence of translocation success Scott River Plains subspecies that have a range and indicate that sourcing and/or (Lambertia orbifolia) – of pollinator types (see Figure 1). mixing of propagule sources had bird-pollinated These include: been effective when establishing • Cactus dryandra (Banksia • Spiral fruited wattle translocations, and the development anatona) – primarily bird (Acacia cochlocarpa subsp. of functioning mating systems and mammal-pollinated Cochlocarpa) – insect-pollinated and pollinator assemblages. • Feather-leaved banksia (Banksia Specifically, we wanted to know brownii) – primarily bird and whether levels of genetic diversity mammal-pollinated within translocated populations are What we did We investigated genetic diversity and Scientists and management staff of were used either to augment mating systems in six translocated the Western Australian Department current translocations or, in the populations of the four primarily of Biodiversity, Conservation and case of cactus dryandra, feather- bird/mammal pollinated plants Attractions (DBCA) and researchers leaved banksia and both round and genetic diversity in three from Murdoch University and The leaf honeysuckle subspecies, to translocated populations of the University of Western Australia did establish new translocations. insect-pollinated spiral fruited the sampling of leaf material and We genotyped (characterised wattle, and compared these seed from translocations and wild genetically) adult plants with wild reference populations. populations. Some seed material and seedling progeny from that had been collected some translocations and wild populations The translocated populations were years earlier from both wild and of all five species and subspecies established in areas in south-west translocated populations was stored using highly variable DNA markers Western Australia with similar soil, ex-situ under standard gene-bank called Simple Sequence Repeats habitat and climate to the wild conditions in the DBCA Threatened (SSRs) or microsatellites. These populations, but were outside the Flora Seed Centre. All seed was markers allow the accurate current range of each species/ germinated and then propagated assessment of levels and patterns subspecies. Significantly, a number of under nursery conditions for of genetic diversity within and translocations had been established approximately six months at the between translocated and wild with seed from now-extinct DBCA Botanic Gardens and Parks populations, and also patterns of populations. All translocations Authority nursery. We extracted pollination via paternity analysis had been established for at least DNA from both adult leaf material (mating system analysis), based five years before sampling was and seedlings. Importantly, once on genetic variation in the carried out from 2012 to 2017. sampled for DNA, seedlings seedling progeny.

Lambertia orbifolia SRP. Image: Andrew Crawford Key findings Genetic assessment of translocated Alternatively, where the translocated positive outcome for persistence of populations of all five plants found population was established by all the translocations, our findings that their genetic diversity was mixing seed from multiple source for the mating system and patterns comparable to or surpassed that populations (feather-leaved banksia, of pollination were varied. All four of the wild reference populations. Narrikup subspecies of round leaf species we investigated had mating honeysuckle), genetic diversity systems combining outcrossing Two propagule sourcing strategies was comparable to or higher (pollination between different plants) had been used when establishing than that of source populations and “selfing” (self-pollination) in the different translocations: taking of known high diversity and, as varied proportions among species seed from a single large source expected, higher than that of and among populations. population; or mixing seed from smaller source populations. In this two or more usually smaller case, strategic mixing of source The mating system in four of populations. Our findings indicated populations to maximise genetic the species is predominantly by that in those cases where the diversity was seen to be effective. bird pollination and, in the case translocation was established For example, genetic analysis of the two Banksia species from a single source population demonstrates that the mixing of (cactus dryandra and feather- (spiral fruited wattle, cactus two different source populations to leaved banksia) also pollination dryandra and the Scott River establish two translocations in the by honey possums and other Plains subspecies of round leaf Narrikup subspecies of round leaf mammal species, and probably honeysuckle) the seed sourcing honeysuckle has resulted in genetic insects. If mating systems were strategies captured adequate representation from both source comparable between translocated genetic diversity. Our results populations, with an overall increase and wild populations, we could also indicated that the source in genetic variation compared to the be confident that the translocation populations themselves for these individual populations (see Figure 2). is functioning effectively in plants were genetically diverse and In contrast to our assessment of terms of the mating system and appropriate single sources for seed. genetic diversity, which shows a associated pollinator services.

Figure 2. Genetic analysis of all translocated and wild populations of both subspecies Lambertia orbifolia subsp. Scott River Plains Lambertia orbifolia subsp. orbifolia of round leaf honeysuckle (Lambertia orbifolia). 1 The colours represent different genetic groups as defined by a STRUCTURE analysis, and each bar represents a single plant. Upper tier: showing two clearly distinct 0.5 groupings confirming the current subspecies. Lower tier: wild and translocated populations of the Scott River Plains and Narrikup subspecies. Arrows indicate source 0 populations for translocated populations. Note the second source population for the Chorkerup translocation is now extinct.

Chorkerup Redmond Jolly Rd South East Spencer West Beenup West Dennis Rd Adelaide Beenup Dennis Rd translocation translocation Springs translocation Spencer Rd Sleeman Rd Rd Narrikup 1 1

0.5 0.5

0 0

Second source population now extinct. Represented by yellow genetic group Key findings(continued) In two species, cactus dryanda and established by the mixing of While our findings indicate the Narrikup subspecies of round seed from two or more source that genetic diversity has been leaf honeysuckle, this was the case. populations (see Figure 2). While maintained or even increased In both, we found that mating increased selfing is potentially an in all translocated populations system estimates for translocated ongoing concern, the increased investigated in the five species/ populations largely reflected inbreeding estimates may be due subspecies and that seed sourcing those in wild populations. to the survival of less-fit (inbred/ strategies have been effective, selfed) individuals during ex-situ patterns of mating also need to However, in the feather-leaved propagation of seedlings or may be be considered when evaluating banksia and the Scott River associated with a genetic sampling the long-term persistence of Plains subspecies of round leaf effect known to occur in admixed animal-pollinated translocated honeysuckle, there were higher populations known as the Wahlund plant populations. Higher levels of levels of selfing and significantly effect. The effect of the latter would inbreeding in some translocated higher inbreeding estimates in be expected to lessen over time populations are of concern and, both adults and progeny at both but the survival of inbred individuals although possibly only temporary, sites. Although we have no direct during ex-situ propagation and require further monitoring. It is observations of pollinators in these their subsequent establishment also important to note that plant translocated populations, the in the population is of concern. mating systems may vary over higher levels of selfing suggests It seems likely that less-fit seedlings both time and space and, as such, that pollinator activity is suboptimal survived to adulthood because these studies represent only a and could ultimately result in they were nurtured through the snapshot in time. Nevertheless, reduced seed set or seedling vulnerable seed germination and if the mating patterns in the fitness associated with inbreeding. plant establishment phase in the translocation populations revealed Interestingly, these translocated laboratory and nursery, where so far continue on a similar populations with higher levels of selective pressures are likely to trajectory, there is a likelihood selfing and significantly higher be far less than those in the wild. of increased inbreeding and inbreeding estimates were all This requires further investigation. genetic erosion \over time.

Acacia cochlocarpa. Image: Andrew Crawford BELOW: seed collections. Image: Sarah Barrett

Implications and recommendations Our findings provide an optimistic if the translocated populations are assessment of translocation success to avoid inbreeding effects and in capturing sufficient genetic to have the genetic resources to diversity in all five plants through adapt to changing environmental careful seed sourcing strategies conditions. However, there is also and/or where strategic mixing of the need to avoid longer-term seed sources to maximise genetic erosion of genetic diversity through variation is implemented. unfavourable patterns of mating in animal-pollinated plants, especially While common features of in the case of long-lived species. We threatened plant translocations, therefore recommend that caution such as small population size, be applied to such species when genetically limited sources of using only demographic and/or propagules and novel habitat, genetic diversity measures to assess can render them vulnerable to translocation success. Ensuring the negative effects associated with presence of pollinators and their reduced genetic diversity, these abundance – in the case of our effects can be largely negated by planning, assessing and predicting examples, birds and mammals – appropriate strategies for sourcing translocation success, it is is an important first step. Further, and admixing seed and other unlikely to be available for most understanding how the pollinators propagules. Detailed guidelines plant translocations in Australia. may disperse pollen and influence are now available that outline seed However, it is possible to ensure mating events such as outcrossing collection methodologies and adequate levels of genetic diversity and selfing will be important for strategies for maximising genetic in translocated populations by assessing the risk of undesirable variation in translocated plant carefully following seed sourcing levels of inbreeding and longer- populations. Approaches set out and seedling establishment term loss of genetic diversity. in these guidelines were followed protocols and using sufficient when planning the translocations In this study we have highlighted numbers of founders, as detailed of all five threatened plants the use of molecular genetic in current guidelines. investigated in this study, and we techniques to benchmark genetic It is also possible to at least have been able to confirm their diversity and mating system indirectly assess effective pollinator suitability for creating genetically variation in the translocated performance and mating system populations as valuable approaches diverse translocations. outcomes by evaluating seed to assessing translocation success. The initial establishment of production, and pollinator sufficient genetic diversity is While the genetic data we used abundance and behaviour, important and likely to be critical can be extremely useful in in the translocated populations.

Cited material Further Information Monks L, Standish R., McArthur S., Dillon R., Byrne M. and Coates D. Genetic and mating system assessment of translocation success of David Coates the long-lived perennial shrub Lambertia orbifolia (). [email protected] Restoration Ecology (in press). doi.org/10.1111/rec.13369

Cite this publication as NESP Threatened Species Recovery Hub. 2021. Evaluating persistence in threatened plant translocations: Genetic diversity and mating systems as measures of success, Project 4.3 research findings factsheet.

This project is supported through funding from the Australian Government’s National Environmental Science Program.