Wild Source Populations Research Articles

Gene body methylation evolves during the sustained loss of parental care in the burying beetle

Epigenetic modifications, such as 5-methylcytosine (5mC), can sometimes be transmitted between generations, provoking speculation that epigenetic changes could play a role in adaptation and evolution. Here, we use experimental evolution to investigate how 5mC levels evolve in populations of biparental insect (Nicrophorus vespilloides) derived from a wild source population and maintained independently under different regimes of parental care in the lab. We show that 5mC levels in the transcribed regions of genes (gene bodies) diverge between populations that have been exposed to different levels of care for 30 generations. These changes in 5mC do not reflect changes in the levels of gene expression. However, the accumulation of 5mC within genes between populations is associated with reduced variability in gene expression within populations. Our results suggest that evolved change in 5mC could contribute to phenotypic evolution by influencing variability in gene expression in invertebrates.

Small translocations of endangered Gallinula galeata sandvicensis (Hawaiian Common Gallinule) may be sufficient to generate a viable reintroduced population

Abstract Where stable source populations of at-risk species exist, translocation may be a reasonable strategy for re-establishing extirpated populations. However, the success rates of such efforts are mixed, necessitating thorough preliminary investigation. Stochastic population modeling can be a useful method of assessing the potential success of translocations. Here, we report on the results of modeling translocation success for the Gallinula galeata sandvicensis or ‘alae ‘ula (Hawaiian Common Gallinule), an endangered waterbird endemic to the Hawaiian Islands. Using updated vital rates, we constructed a model simulating 3 existing extant (wild) source populations and a hypothetical recipient site on another island. We then projected the effects of 6 different translocation scenarios and sensitivity of the results to variation of three important demographic parameters on the probability of extinction (PE) of the reintroduced and donor populations. Larger translocations, of at least 30 birds, had low probability of extinction in the reintroduced population, but raised extinction risk of the smallest source population. Spacing out translocations in time (e.g., 10 birds translocated in total in 3 installments over 9 years), led to lower PE than translocating all individuals at once (i.e., bulk translocations) for both the source and reintroduced populations. Brood size and hatch-year juvenile survival had a disproportionate impact on reintroduced population viability. Importantly, the reported juvenile survival rate is very near the threshold for population failure. This suggests that post-introduction and subsequent management of wetlands, particularly predator control, could be critical to reintroduction success. We recommend that individuals should be translocated from multiple, genetically distinct subpopulations to reduce the possibility of inbreeding depression. Based on this analysis, the recipient wetland should be sufficiently large that it can support at least 25 pairs of gallinules. Based on recent estimates of population densities on O‘ahu, such a wetland would need to be between 3.75 and 74.6 ha.

Ex situ conservation of two rare oak species using microsatellite and SNP markers.

Plant collections held by botanic gardens and arboreta are key components of ex situ conservation. Maintaining genetic diversity in such collections allows them to be used as resources for supplementing wild populations. However, most recommended minimum sample sizes for sufficient ex situ genetic diversity are based on microsatellite markers, and it remains unknown whether these sample sizes remain valid in light of more recently developed next-generation sequencing (NGS) approaches. To address this knowledge gap, we examine how ex situ conservation status and sampling recommendations differ when derived from microsatellites and single nucleotide polymorphisms (SNPs) in garden and wild samples of two threatened oak species. For Quercus acerifolia, SNPs show lower ex situ representation of wild allelic diversity and slightly lower minimum sample size estimates than microsatellites, while results for each marker are largely similar for Q. boyntonii. The application of missing data filters tends to lead to higher ex situ representation, while the impact of different SNP calling approaches is dependent on the species being analyzed. Measures of population differentiation within species are broadly similar between markers, but larger numbers of SNP loci allow for greater resolution of population structure and clearer assignment of ex situ individuals to wild source populations. Our results offer guidance for future ex situ conservation assessments utilizing SNP data, such as the application of missing data filters and the usage of a reference genome, and illustrate that both microsatellites and SNPs remain viable options for botanic gardens and arboreta seeking to ensure the genetic diversity of their collections.

San Diego Thornmint (Acanthomintha ilicifolia) Populations Differ in Growth and Reproductive Responses to Differential Water Availability: Evidence from a Common Garden Experiment.

The responses of rare plants to environmental stressors will determine their potential to adapt to a rapidly changing climate. We used a common garden approach to evaluate how six populations of the annual San Diego thornmint (Acanthomintha ilicifolia Lamiaceae; listed as endangered in the state of California and as threatened by the US Fish and Wildlife Service) from across the species range respond in terms of growth (biomass, height, and width) and reproduction (seed production, floral production, and next generation seed viability) to experimental differences in water availability. We found a significant irrigation-by-population interaction on the aboveground growth, wherein the differences in the magnitude and direction of treatment did not correlate directly with climate variables in natural populations. With respect to reproduction, the low-irrigation treatment produced more seeds per plant, more reproductive individuals, and a larger proportion of viable seed in most, but not all, populations. The seed production and the effect of irrigation on seed production correlated positively with rainfall at wild source populations. These results suggest that Acanthomintha ilicifolia responds to water limitation by creating more and higher-quality seed, and that plants locally adapted to a higher annual rainfall show a greater plasticity to differences in water availability than plants adapted to a lower annual rainfall, a finding that can inform the in situ demographic management and ex situ collection strategy for Acanthomintha ilicifolia and other rare California annuals.

Do leaf functional traits differ between 20–35-year-old transplanted and wild source populations? A case study involving five endangered tree species

Conservation of threatened species through translocation has become an effective way to combat species extinction worldwide. Plant functional traits are good predictors of plant performance and can reflect the adaptation strategies of plants to the environment. However, it is still unclear whether transplanted populations have comparable levels of leaf functional traits to their wild source populations. To assess the effectiveness of conservation-based translocation of long-living endangered tree species, we investigated the long-term (20–35 years) population dynamics of five co-existing endangered tree species (Davidia involucrata, Dipteronia sinensis, Pterostyrax psilophyllus, Tapiscia sinensis, and Tetracentron sinense) in transplanted populations, and compared the leaf functional traits between the transplanted and their wild source populations. We found that the survival rates of the five species in the transplanted populations ranged from 42.86% to 73.81%, and most of these species could blossom and yield fruit. All species had significant differences in some leaf functional traits between transplanted and wild populations. The intraspecific traits variation of some species in the transplanted populations was decreased compared with that in the wild populations on the whole. We conclude that after a long period of translocation, these species in transplanted populations were able to grow normally and most species become more efficient in resource acquisition or utilisation and more resources were available for growth. However, the intraspecific traits variation of some species in transplanted populations may lead to competitive exclusion, affect species coexistence, and thus affect their performance.

Exploring the origin and genetic representation of ex situ living collections of five endangered tree species established for 20–35 years

How well ex situ living collections capture the genetic variation of their wild-source populations, is an efficient indicator for assessing the success of ex situ conservation. Here, we explore the origins and genetic representation of multiple species' ex situ living collections that have been established for 20–35 years. We only sampled the potential wild-source populations, which cover parts of the focal species’ natural distribution ranges. Using microsatellite loci, we compared the genetic diversity between ex situ and wild populations, and verified the wild-source populations of ex situ living collections for five endangered tree species (i.e., Davidia involucrata , Dipteronia sinensis , Tetracentron sinense , Cercidiphyllum japonicum , and Tapiscia sinensis ). We found that the genetic diversity of ex situ populations is comparable to their wild-source populations for all five plant species. We detected weak genetic structure among ex situ and wild-source populations for each species. Our results suggested that ex situ living plant collections may have comparable genetic diversity compared with their corresponding wild-source populations. We recommend that additional ex situ collections from different maternal lines across ex situ institutions or the distribution range of the target species would contribute to high level of genetic representation of ex situ populations, and (2) complete collection records and optimal sampling strategies are required for effective ex situ plant conservation.

Eight generations of native seed cultivation reduces plant fitness relative to the wild progenitor population.

Native seed for restoration is in high demand, but widespread habitat degradation will likely prevent enough seed from being sustainably harvested from wild populations to meet this need. While propagation of native species has emerged in recent decades to address this resource gap, few studies have tested whether the processes of sampling from wild populations, followed by generations of farm cultivation, reduce plant fitness tolerance to stress over time. To test this, we grew the eighth generation of farm‐propagated Clarkia pulchella Pursh (Onagraceae) alongside seeds from two of the three original wild source populations that established the native seed farm. To detect differences in stress tolerance, half of plants were subjected to a low‐water treatment in the greenhouse. At the outset, farmed seeds were 4.1% heavier and had 4% greater germination compared to wild‐collected seed. At maturity, farmed plants were 22% taller and had 20% larger stigmatic surfaces, even after accounting for differences in initial seed size. Importantly, the mortality of farmed plants was extremely high (75%), especially in the low‐water treatment (80%). Moreover, farmed plants under the high‐water treatment had 90% lower relative fitness than wild plants due to the 1.3 times greater weekly mortality and a 3‐fold reduction in flowering likelihood. Together, these data suggest that bottlenecks during initial sampling and/or unconscious selection during propagation severely reduced genetic diversity and promoted inbreeding. This may undermine restoration success, especially under stressful conditions. These results indicate that more data must be collected on the effects of cultivation to determine whether it is a suitable source of restoration seed.

Meta-analysis of genetic representativeness of plant populations under ex situ conservation in contrast to wild source populations.

Ex-situ conservation is widely used to protect wild plant species from extinction. However, it remains unclear how genetic variation of ex-situ plant collections reflects wild source population diversity. Here, we conduct a global meta-analysis of the genetic representativeness of ex-situ populations by comparing genetic diversity (i.e. AR, allelic richness; HE , expected heterozygosity; PPB, percentage polymorphic bands; and SWI, Shannon-Winner index), inbreeding coefficient (FIS ), and genetic differentiation between ex-situ plant collections and their wild source populations. Genetic diversity (i.e., HE , PPB, and SWI) was significantly lower in ex-situ populations than their wild source populations, while genetic differentiation between ex-situ and wild populations (ex-situ-wild FST ), but not that among ex-situ populations, was significantly higher than among wild populations. Outcrossing species, but not those with mixed mating system, had significantly lower genetic diversity in ex-situ populations, and significantly higher ex-situ-wild FST . When the collection size for ex-situ conservation was ≥30 or 50, PPB, HE , and ex-situ-wild FST were not significantly different between ex-situ and wild populations, indicating a relatively high genetic representativeness. Collecting from the entire natural distribution range and mixing collections from different sources could significantly increase the genetic representativeness of ex-situ populations. Type of ex-situ conservation (i.e., planting or seed bank) had no effect on genetic representativeness. The effect size of HE decreased and the effect size of ex-situ-wild FST increased with the duration of ex-situ conservation. Our results suggest that current ex-situ plant collections do not effectively capture the genetic variation of wild populations. Low genetic representativeness of ex-situ populations was caused by both initial incomplete sampling from wild populations and genetic erosion during ex-situ conservation. We emphasize that it is necessary to employ more thorough sampling strategies in future collecting efforts and to add new individuals where needed. Article impact statement: Low genetic representativeness of living plant collections is a worldwide problem in ex situ conservation. This article is protected by copyright. All rights reserved.

Genetic impacts of conservation management actions in a critically endangered parrot species

Establishing populations of endangered species in captivity is becoming an increasingly common component of species recovery programs for insurance against extinction, and/or for reintroductions. It is important for the success of these efforts that captive populations are genetically representative of wild source populations, and that genetic diversity is maintained over time. Our study presents SNP data from wild and captive populations of the critically endangered Australian orange-bellied parrot (Neophema chrysogaster). We examine the genetic effects of a decision made in the 2010/2011 breeding season to recruit half of the juvenile cohort (n = 21), from a wild population in decline, to supplement an existing captive program. We report that heterozygosity among wild birds decreased in the years after this action. Following multiple releases of captive-reared birds back into the wild (occurring annually since 2013), captive and wild populations have attained similar overall levels of heterozygosity, and genetic differentiation between these populations is low. Parentage analyses confirm that captive-bred released individuals have successfully paired with wild birds and produced offspring. Our study suggests that translocation of wild individuals into captivity, from wild populations in decline, can potentially have deleterious lasting impacts on genetic diversity levels in these populations. However, our data also confirm that in captivity, founder diversity can be successfully preserved over time, and addition of wild founders can improve captive population health. The genetic diversity retained in captive populations can also be reintroduced to wild populations at a later date, provided that captive-release individuals are able to reproductively contribute to their recipient population.

Ex situ cultivation impacts on plant traits and drought stress response in a multi-species experiment

Ex situ collections of wild plants of conservation value are supposed to preserve the phenotypic variability of their wild source populations as well as their plastic responses to environmental stress. However, genetic erosion and adaptive evolutionary changes during cultivation are likely to impose strong constraints to those aims. To date, is it not known whether cultivation affects plant trait variability and stress response of species in botanic garden collections. We studied the effects of cultivation on the trait expression, genetic trait variability, and drought stress response in 12 plant species cultivated in Meise Botanic Garden, Belgium. We found that cultivation increased germination rate and leaf length across all species, while it decreased flowering and delayed the beginning of the flowering period in six drought-tolerant species. We furthermore found indications that plant response to drought was reduced by cultivation in some performance variables, while mortality due to drought slightly increased with cultivation. In three out of 10 traits measured, genetic variability decreased with increasing cultivation time in the botanic garden indicating a loss of evolutionary potential. Our results suggest that the preservation of the phenotypic status and evolutionary potential in ex situ collections is a challenging task and that the application of up-to-date protocols is decisive to achieve meaningful conservation collections.

A Novel RNA Virus in the Parasitoid Wasp Lysiphlebus fabarum: Genomic Structure, Prevalence, and Transmission.

We report on a novel RNA virus infecting the wasp Lysiphlebus fabarum, a parasitoid of aphids. This virus, tentatively named “Lysiphlebus fabarum virus” (LysV), was discovered in transcriptome sequences of wasps from an experimental evolution study in which the parasitoids were allowed to adapt to aphid hosts (Aphis fabae) with or without resistance-conferring endosymbionts. Based on phylogenetic analyses of the viral RNA-dependent RNA polymerase (RdRp), LysV belongs to the Iflaviridae family in the order of the Picornavirales, with the closest known relatives all being parasitoid wasp-infecting viruses. We developed an endpoint PCR and a more sensitive qPCR assay to screen for LysV in field samples and laboratory lines. These screens verified the occurrence of LysV in wild parasitoids and identified the likely wild-source population for lab infections in Western Switzerland. Three viral haplotypes could be distinguished in wild populations, of which two were found in the laboratory. Both vertical and horizontal transmission of LysV were demonstrated experimentally, and repeated sampling of laboratory populations suggests that the virus can form persistent infections without obvious symptoms in infected wasps.

Tracking genetic diversity in a large-scale oyster restoration program: effects of hatchery propagation and initial characterization of diversity on restored vs. wild reefs.

The release of hatchery-propagated fish and shellfish is occurring on a global scale, but the genetic impacts of these practices are often not fully understood and rarely monitored. Slow recovery of depleted eastern oyster populations in the Chesapeake Bay, USA has prompted a hatchery-based restoration program focused in the Choptank River, Maryland consisting of the mass release of hatchery-produced juveniles from local, wild broodstock. To evaluate potential genetic effects of this program, we (1) examined changes in genetic diversity (allelic richness, heterozygosity) and the effective number of breeders (Nb) over the hatchery production cycle with microsatellite-based parentage of natural, mass- and controlled-spawned cohorts, and (2) compared genetic diversity and effective population size (Ne) of a restored reef to wild source populations. Mass-spawned cohorts showed high variance in reproductive contribution, particularly among males, leading to a 45% average reduction in Nb from spawning adult numbers and higher relatedness-lower magnitude reductions in heterozygosity and significant reductions in allelic richness were also observed. While controlled-spawns (single-male fertilizations of pooled eggs) reduced male variance, overall reproductive variance (Vk) remained high. Finally, oysters sampled from a restored reef displayed comparable Ne, genetic diversity, and relatedness to samples from wild populations, with no significant genetic differentiation among them. Overall, the hatchery-based results and initial field-based population genetic analyses suggest that despite reductions in diversity from parents to offspring owing to high Vk, enhancement with rotated, wild broodstock appears to have maintained genetic diversity in a restored reef population compared to proximal wild populations.

The role of ecotype-environment interactions in intraspecific trophic niche partitioning subsequent to stocking.

Worldwide, stocking of fish represents a valuable tool for conservation and maintenance of species exploited by recreational fishing. Releases of hatchery-reared fish are more and more recognized to have numerous demographic, ecological, and genetic impacts on wild populations. However, consequences on intraspecific trophic relationships have rarely been investigated. In this study, we assessed the impacts of supplementation stocking and resulting introgressive hybridization on the trophic niches occupied by stocked, local, and hybrid lake trout (Salvelinus namaycush) within populations of piscivorous and planktivorous ecotypes stocked from a wild piscivorous source population. We compared trophic niches using stable isotope analysis (δ13 C and δ15 N) and trophic position among the three genetic origins. Putative genetic effects were tested with phenotype-genotype association of "life history" ecological traits (body size, growth rate, condition index, and trophic niche) and genotypes (RADseq SNP markers) using redundant discriminant analysis (RDA). Results showed that sympatry resulting from the stocking of contrasting ecotypes is a risk factor for niche partitioning. Planktivorous populations are more susceptible to niche partitioning, by competitive exclusion of the local fish from a littoral niche to an alternative pelagic/profundal niche. Observed niche partitioning is probably a manifestation of competitive interactions between ecotypes. Our results emphasize that ecotypic variation should be considered for more efficient management and conservation practices and in order to mitigate negative impact of supplementation stocking.

Egg size and lipid content of lake trout (Salvelinus namaycush) in the wild and in captivity

Egg quality influences early life survival in fishes, but drivers of egg quality variation remain poorly understood. I examined egg quality of a long-lived, iteroparous salmonid (lake trout (Salvelinus namaycush)) with respect to maternal traits and environmental conditions in wild and captively reared populations. Variation was stronger and more consistent for egg size than for lipid content. Among females, egg size was most strongly related to maternal age, in both wild and captive populations, and faster-growing females tended to produce larger eggs. Among wild populations, maternal growth was more strongly associated with indices of ecosystem size or productivity than climate, whereas the opposite was observed for egg size. Egg size and, to a lesser extent, maternal growth in captive populations were positively correlated with egg size and growth, respectively, in their wild source populations. However, captive females grew faster and produced larger eggs at age, but smaller eggs at length, than their wild counterparts. Lake trout egg quality variation has both maternal and environmental components, and captive rearing appears to alter the ontogenetic progression of egg size.

Looking back to go forward: genetics informs future management of captive and reintroduced populations of the black-footed rock-wallaby Petrogale lateralis

Active management is essential to the survival of many threatened species globally. Captive breeding programmes can play an important role in facilitating the supplementation, translocation and reintroduction of wild populations. However, understanding the genetic dynamics within and among wild and captive populations is crucial to the planning and implementation of ex situ management, as adaptive potential is, in part, driven by genetic diversity. Here, we use 14 microsatellite loci and mitochondrial Control Region sequence to examine the population genetics of both wild populations and captive colonies of the endangered warru (the MacDonnell Ranges race of the black-footed rock-wallaby Petrogale lateralis) in central Australia, to understand how historical evolutionary processes have shaped current diversity and ensure effective ex situ management. Whilst microsatellite data reveal significant contemporary differentiation amongst remnant warru populations, evidence of contemporary dispersal and relatively weak isolation by distance, as well as a lack of phylogeographic structure suggests historical connectivity. Genetic diversity within current captive populations is lower than in the wild source populations. Based on our genetic data and ecological observations, we predict outbreeding depression is unlikely and hence make the recommendation that captive populations be managed as one genetic group. This will increase genetic diversity within the captive population and as a result increase the adaptive potential of reintroduced populations. We also identify a new site in the Musgrave Ranges which contains unique alleles but also connectivity with a population 6 km away. This novel genetic diversity could be used as a future source for supplementation.

An empirical test of the role of learning in translocation

AbstractTranslocation centers on the introducing, reintroducing, or augmenting populations by moving individuals from existing wild source populations to different locations with purportedly suitable habitat. Despite much research in and application of translocation, this technique is often marred by low success rates. While many possible factors could contribute to low translocation success, outcomes are often improved when researchers engage in a soft release, which provides the animals with the opportunity for extra time to acclimate to their release site, indicating that aspects of learning may play an important role in translocation success. To test the importance of the time available for learning in translocation success, we performed hard and soft releases into an existing population of Eastern painted turtles Chrysemys picta that has experienced seasonal ephemeral water sources and in which resident turtles navigate to new permanent sources of water with extreme precision (±3.5 m) using specific routes known to be facilitated by learning. Translocated adult turtles in both hard‐ and soft‐release groups failed to successfully negotiate upland habitat, even when given 3 months to prospect and learn (the maximum time possible in our system). Likewise, turtles in both groups moved more slowly, stopped more frequently, and were slower to restart movement than resident adults. Finally, both translocated groups exhibited significant drops in body mass and elevated rates of predation. In contrast, juveniles from the same donor population navigated to alternative water successfully, with movements and mortality rates not different from resident animals. These results indicate that complex aspects of cognition beyond time to learn can influence translocation success and highlight the importance of considering how and when animals learn.

Half a century of genetic interaction between farmed and wild Atlantic salmon: Status of knowledge and unanswered questions

AbstractAtlantic salmon (Salmo salar) is one of the best researched fishes, and its aquaculture plays a global role in the blue revolution. However, since the 1970s, tens of millions of farmed salmon have escaped into the wild. We review current knowledge of genetic interactions and identify the unanswered questions. Native salmon populations are typically genetically distinct from each other and potentially locally adapted. Farmed salmon represent a limited number of wild source populations that have been exposed to ≥12 generations of domestication. Consequently, farmed and wild salmon differ in many traits including molecular‐genetic polymorphisms, growth, morphology, life history, behaviour, physiology and gene transcription. Field experiments have demonstrated that the offspring of farmed salmon display lower lifetime fitness in the wild than wild salmon and that following introgression, there is a reduced production of genetically wild salmon and, potentially, of total salmon production. It is a formidable task to estimate introgression of farmed salmon in wild populations where they are not exotic. New methods have revealed introgression in half of ~150 Norwegian populations, with point estimates as high as 47%, and an unweighted average of 6.4% across 109 populations. Outside Norway, introgression remains unquantified, and in all regions, biological changes and the mechanisms driving population‐specific impacts remain poorly documented. Nevertheless, existing knowledge shows that the long‐term consequences of introgression is expected to lead to changes in life‐history traits, reduced population productivity and decreased resilience to future challenges. Only a major reduction in the number of escapees and/or sterility of farmed salmon can eliminate further impacts.

Performance of Juvenile Cutthroat Trout Translocated as Embryos from Five Populations into a Common Habitat

AbstractThe distributions of most native trout species in western North America have been severely reduced, and conservation of many of these species will require translocation into vacant habitats following removal of nonnative species. A critical question managers have is “Does it matter which donor sources are used for these translocations?” We present a case study that addressed this question for a large native trout translocation project in Montana. We introduced embryos from five source populations of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi to a large, fishless watershed in Montana following removal of nonnative fish with piscicides. Source populations providing embryos for translocations were three nearby (<120 km) wild populations, the state of Montana's captive Westslope Cutthroat Trout hatchery conservation population (initiated 32 years ago using fish from wild populations located >350 km from the translocation site), and a population in captivity for one generation comprised of individuals from the three wild populations used as single sources for this project, which were variably crossed (59% within populations and 41% between populations) to provide embryos. We used remote‐site incubators at six different sites to introduce approximately 35,000 embryos from 400 genotyped parents. We later resampled and genotyped 1,450 of these individuals at age 1 and age 2. Juvenile survival for the more genetically diverse Montana Westslope Cutthroat Trout conservation population was twice as high as for other source populations, even though these other source populations were geographically closer to the translocation site than populations used to make the Montana Westslope Cutthroat Trout conservation population. Body weight for progeny from the two captive populations was higher than for progeny from wild source populations, and some differences were observed in body condition among source populations. Continued monitoring over several generations will be necessary to determine the eventual contributions of each source population and the relevance of these initial findings.Received October 9, 2015; accepted February 27, 2016 Published online July 20, 2016

Population genetic analysis of a medicinally significant Australian rainforest tree, Fontainea picrosperma C.T. White (Euphorbiaceae): biogeographic patterns and implications for species domestication and plantation establishment.

BackgroundFontainea picrosperma, a subcanopy tree endemic to the rainforests of northeastern Australia, is of medicinal significance following the discovery of the novel anti-cancer natural product, EBC-46. Laboratory synthesis of EBC-46 is unlikely to be commercially feasible and consequently production of the molecule is via isolation from F. picrosperma grown in plantations.Successful domestication and plantation production requires an intimate knowledge of a taxon’s life-history attributes and genetic architecture, not only to ensure the maximum capture of genetic diversity from wild source populations, but also to minimise the risk of a detrimental loss in genetic diversity via founder effects during subsequent breeding programs designed to enhance commercially significant agronomic traits.ResultsHere we report the use of eleven microsatellite loci (PIC = 0.429; PID = 1.72 × 10−6) to investigate the partitioning of genetic diversity within and among seven natural populations of F. picrosperma. Genetic variation among individuals and within populations was found to be relatively low (A = 2.831; HE = 0.407), although there was marked differentiation among populations (PhiPT = 0.248). Bayesian, UPGMA and principal coordinates analyses detected three main genotypic clusters (K = 3), which were present at all seven populations. Despite low levels of historical gene flow (Nm = 1.382), inbreeding was negligible (F = -0.003); presumably due to the taxon’s dioecious breeding system.ConclusionThe data suggests that F. picrosperma was previously more continuously distributed, but that rainforest contraction and expansion in response to glacial-interglacial cycles, together with significant anthropogenic effects have resulted in significant fragmentation. This research provides important tools to support plantation establishment, selection and genetic improvement of this medicinally significant Australian rainforest species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0743-2) contains supplementary material, which is available to authorized users.

Inside-out flowers of Lacandonia brasiliana (Triuridaceae) provide new insights into fundamental aspects of floral patterning.

Background and Aims. A recently described Brazilian species, Lacandonia brasiliana, shares with its longer established putative sister species from Mexico, L. schismatica, inverted floral patterning (carpels surrounding stamens) that is almost unique among angiosperms. We present a detailed ontogenetic study of L. brasiliana for comparison with other members of the tribe Triurideae (Triuridaceae) to explore the possible evolutionary origins of “inside-out” flowers.Methods. Wild-source populations of L. brasiliana were compared morphologically and ontogenetically with related species of Triurideae, using light and scanning electron microscopy.Key Results. Relatively few morphological differences separate flowers of L. brasiliana and L. schismatica. Both species have tepals with late-developing subapical appendages. In both species, the three central (almost sessile) anthers develop precociously with respect to the carpels; the anthers remain closed, and fertilization is achieved via pollen-tube growth from germinating pollen grains of the same cleistogamous flower. Carpels are initiated on fascicles.Conclusions. The close similarity between the two Lacandonia species makes it unlikely that they arose independently from two separate homeotic transformation events; they could either represent sister species or two populations of a single disjunct species. Our study underlines the problematic generic and species boundaries within Triurideae. We present an evolutionary scenario of character evolution in Triuridaceae. The inside-out Lacandonia flower could have resulted from a stabilized homeotic transformation; this hypothesis is not in conflict with constrasting theories of the origin of the Triuridaceae flower, which coincided with a shift to unisexuality. The unisexual yet highly plastic flowers that are typical of Triuridaceae could have pre-adapted the origin of the extraordinary Lacandonia morphology.