Cryptic invasion of Italian pool frogs (<Emphasis Type="Italic">Pelophylax bergeri</Emphasis>) across Western Europe unraveled by multilocus phylogeography

Human introductions of exotic amphibians can have catastrophic effects on native species. However, they usually remain unnoticed without genetic tools when species are difficult to distinguish morphologically. In Western Europe, pool frogs (Pelophylax sp.) make a worrisome case: recent genetic data showed the presence of Italian (Pelophylax bergeri) mtDNA haplotypes within the range of the threatened European Pelophylax lessonae, two morphologically similar taxa. Here we conduct a multilocus phylogeographic and population genetic survey of European and Italian pool frogs (combining present and historic samples), to investigate the origin(s) and consequences of potential introductions. Results are unequivocal: we show that the alien P. bergeri have extensively invaded France and north-Alpine Switzerland, and have also deeply introgressed with P. lessonae, which has led to the complete replacement of most populations. Alien specimens have probably been translocated multiple times from Central Italy at least prior to the 1960s. Based on our dense sampling, only two areas, north and south of the Alps still host native pool frogs in Switzerland, the Joux Valley near the French border and the canton of Ticino, respectively. Importantly, we show that these last P. lessonae populations are remnants of a private genetic diversity specific to Western Europe, which vanished during the P. bergeri’s invasion. Our study emphasizes the risk of genetic pollution during invasion by human-introduced taxa and brings alarming concern regarding uncontrolled amphibian translocations. Moreover, it demonstrates the necessity for genetic surveys to detect and monitor these invasions, especially where species determination is problematic.     

The endangered white-clawed crayfish <Emphasis Type="Italic">Austropotamobius pallipes</Emphasis> (Decapoda,Astacidae) east and west of the Maritime Alps: a result of human translocation?

The genetic variability among Italian populations of the white-clawed crayfish (Austropotamobius pallipes) was examined to determine their phylogeography and to assess their conservation status as a management unit. A fragment of the mitochondrial DNA COI gene of 107 specimens from ten populations was sequenced, and the phylogenetic relationships were established. Two out of three haplotypes sampled in two French populations from the Rhône basin were shared with Italian populations. Despite a moderate level of genetic variability within the Italian populations of A. pallipes, no genetic structure was revealed. It has been suggested that there have been translocation events throughout the Alpine barrier between the North-Western Italian basins and the Rhône basin. Genetic exchangeability of the French and Italian populations was demonstrated in this study, and a shift of conservation efforts towards the native, congeneric Austropotamobius italicus is recommended.     

Genetic diversity and population structure identify the potential source of the invasive red clover casebearer moth, <Emphasis Type="Italic">Coleophora deauratella</Emphasis>, in North America

The red clover casebearer, Coleophora deauratella, is an invasive pest of red clover grown for seed in North America. In 2006, an outbreak in Alberta, Canada was discovered that resulted in significant seed losses, while further invasion threatens the world’s largest red clover forage seed production region in Oregon, USA. Prior to the recent outbreak, C. deauratella was thought to be restricted to eastern North America in its invasive range. We sequenced a 615-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene, and developed three microsatellite markers to assess the genetic diversity and population structure of C. deauratella in North America and its native range in Europe. We observed signatures of a founder effect in North American populations and a further loss of genetic diversity within Alberta populations. Most genetic differentiation was found between continents, with no evidence of isolation-by-distance within each continent. From the limited number of European populations sampled, a single introduction from Switzerland is the most probable source of North American populations based on similar mitochondrial diversity and lack of population differentiation. Within North America, based on increased genetic diversity compared to the rest of the continent, the first North American record from Ithaca, NY, and the first documented outbreak in southern Ontario in 1989, the initial C. deauratella invasion most likely occurred in southern Ontario, Canada or adjacent states in the USA, followed by transport throughout the continent. This study provides insight into the phylogeographic history of C. deauratella in North America and Europe and may help to identify a regional source of future classical biological control agents.     

Phylogeographic-based conservation implications for the New Zealand long-tailed bat, (<Emphasis Type="Italic">Chalinolobus tuberculatus</Emphasis>): identification of a single ESU and a candidate population for genetic rescue

The New Zealand long-tailed bat (Chalinolobus tuberculatus) is an endemic species threatened with extinction. Since the arrival of humans, massive deforestation has occurred and invasive mammalian predators were introduced. As a result, C. tuberculatus’ distribution shrank dramatically and became fragmented. To aid the management of the remaining populations, two Evolutionary Significant Units (ESUs) were designated: one on each of New Zealand’s main islands. We utilised mitochondrial sequence data (cytb, 703 bp) and 10 nuclear DNA microsatellite loci to reconstruct the demographic history of this species, to characterise the level of genetic diversity in remaining populations, and to assess the current connectivity between them. Our results indicate that the North Island, with the highest genetic diversity, served as a glacial refuge, with a loss of diversity following the path recolonization to the south of the South Island. However, our data are also consistent with continued, or at least very recent, genetic exchange between colonies across the species distribution. The only exception is the Hanging Rock colony on the east coast of the South Island, which appears to be isolated. Thus, there was no support for the previously designated ESUs. Signatures of past population declines were found in three colonies, the most extreme of which was found in Hanging Rock. Consequently, we recommend that it be genetically rescued via translocation from a donor population. In general, future management priorities should treat Chalinolobus tuberculatus as a single unit, focusing on maintaining connectivity between remaining populations, together with continued roost protection and pest control.     

Evidence of multiple introductions and genetic admixture of the Asian brush-clawed shore crab <Emphasis Type="Italic">Hemigrapsus takanoi</Emphasis> (Decapoda: Brachyura: Varunidae) along the Northern European coast

The Asian brush-clawed shore crab Hemigrapsus takanoi is a non-indigenous species along the Northern European coast. Although the history of range expansion of European H. takanoi has been well-documented, little is known about the genetic compositions of either the introduced European populations or the native Asian ones. We therefore collected H. takanoi broadly from their native Asian sites and introduced European ranges, and genotyped them by sequencing the mitochondrial 16S RNA gene and by analyzing nuclear microsatellite loci. Our results revealed that the H. takanoi Bay of Seine (France) populations consisted of a genetic admixture between populations in Japan and those in the Yellow Sea region. These French populations should be carefully monitored in the future, since the genetic admixture of multiple source populations may accelerate range expansion in non-indigenous organisms. Our results also suggested that shipping lines from East Asia were more probable vectors than historical juvenile oyster transportations from Japan for the foundation of present European H. takanoi populations. Interestingly, gene flow between populations in Japan and those in the Yellow Sea region (i.e., domestic invasion) was not observed despite the higher potential for artificial translocations via shipping lines in the native Asian range compared with those from Asia to Europe. The lack of domestic invasions implied that intra-specific priority effects of the resident H. takanoi populations played an important role in preventing the successful colonization of artificially-transferred individuals.     

Consequences of the arms race between <Emphasis Type="Italic">Maculinea teleius</Emphasis> social parasite and <Emphasis Type="Italic">Myrmica</Emphasis> host ants for myrmecophilous butterfly conservation

The arms race between Maculinea butterflies and Myrmica host ants leads to local host-parasite adaptations. In our study, we assessed whether sympatric and allopatric Myrmica scabrinodis populations exhibit behavioural differences towards Maculinea teleius larvae during the adoption-period when butterfly larvae need to be taken inside the Myrmica nest. The second aim was to assess the butterfly survival rate inside ant colonies from different populations. We used one sympatric host population and three allopatric populations: one infested by M. teleius and two uninfested populations. We found that ants from the sympatric population showed a higher number of positive behaviours toward M. teleius larvae during adoption than ants from the allopatric populations. There were no differences in the number of inspection or negative behaviour events. The survival of butterfly larvae was highest inside sympatric host colonies and differed from the survival of M. teleius reared by ants from the allopatric, uninfested populations. No difference was found for the survival rate of M. teleius raised by infested, allopatric host colonies compared to sympatric host populations. Our results suggest the lack of behavioural counter-adaptations of local hosts of M. teleius that more easily adopt and rear butterfly caterpillars compared to naive M. scabrinodis colonies. Our results may also have implications for Maculinea butterfly conservation, especially for reintroduction programmes. We suggest that the existence of behavioural host defences should be checked for the source host population, as well as for the Myrmica population from the reintroduction site. It may also be reasonable to introduce several Myrmica host colonies from the source butterfly host population.     

Development and characterization of twelve microsatellite markers for <Emphasis Type="Italic">Porphyra linearis</Emphasis> Greville

The genus Porphyra (and its sister genus Pyropia) contains important red algal species that are cultivated and/or harvested for human consumption, sustaining a billion-dollar aquaculture industry. A vast amount of research has been focused on species of this genus, including studies on genetics and genomics among other areas. Twelve novel microsatellite markers were developed here for Porphyra linearis. Markers were characterized using 32 individuals collected from four natural populations of P. linearis with total heterozygosity varying from 0.098 to 0.916. The number of alleles per locus ranged from 2 to 18. All markers showed cross amplification with Porphyra umbilicalis and/or Porphyra dioica. These polymorphic microsatellite markers are useful for investigating population genetic diversity and differentiation in P. linearis and may become useful for other genetic research on the reproductive biology of this important species.     

Long-term population fluctuations of the exotic New Zealand mudsnail <Emphasis Type="Italic">Potamopyrgus antipodarum</Emphasis> and its introduced aporocotylid trematode in northwestern France

Long-term studies of invasive populations are rare, which is unfortunate because important aspects of their dynamics may only be detected over long term. For instance, invasive populations can experience substantial population declines, or even crashes, sometime after their introduction and invasion. Potamopyrgus antipodarum (Caenogastropoda) is a successful invader, and is rarely parasitized in introduced areas. In France, the snail is parasitized as first intermediate host by only one trematode species (Aporocotylid sp. I), native to the snail’s home range, New Zealand. Here, we examined the dynamics of the molluscan assemblage in a French stream on a 14-year interval (2000–2004 and 2009–2013), focusing on this introduced host-parasite association. Overall, P. antipodarum was numerically dominant (90.80%) among molluscs, also including sphaeriid clams (9.12%) and pulmonate snails (0.08%). However, during the last monitoring period, we found a substantial population decline of P. antipodarum, potentially driven by environmental change, such as decreased water temperature and depth, and possibly competitive interactions with sphaeriids, which became numerically dominant (56.34%). P. antipodarum was the only mollusc found infected and only by Aporocotylid sp. I. Interestingly, despite low monthly prevalence (from 0 to 1.52%) and snail host population decline, the P. antipodarum-aporocotylid relationship appeared to be persistent over time.     

Conservation genetics of the highly endangered Azorean endemics <Emphasis Type="Italic">Euphrasia azorica</Emphasis> and <Emphasis Type="Italic">Euphrasia grandiflora</Emphasis> using new SSR data

In the Azores Islands, two Euphrasia L. (Orobanchaceae) endemic species are recognized: Euphrasia azorica H.C.Watson, an annual herb, in Flores and Corvo, and Euphrasia grandiflora Hochst. ex Seub., a semi-shrub, in Pico, São Jorge and Terceira. Both species are highly endangered and protected by the Bern Convention and Habitats Directive. A population genetics study was conducted with new microsatellite primer pairs in 159 individuals of E. azorica and E. grandifolia, sampled from populations in Flores, Corvo, Pico and São Jorge. Allele sizing suggested that E. azorica is a diploid while E. grandiflora is a tetraploid. Euphrasia grandiflora revealed higher genetic diversity then E. azorica. The E. grandiflora population of Morro Pelado in São Jorge, displayed higher genetic diversity when compared with all others, while the E. azorica population of Madeira Seca in Corvo, showed the lowest. Private and less common bands were also overall higher in E. grandiflora populations. Population genetic structure analysis confirmed a distinctiveness between the two Azorean endemic Euphrasia, in addition to island-specific genetic patterns in E. azorica. The genetic structure obtained for E. grandiflora was complex with the populations of Cabeço do Mistério in Pico Island and of Pico da Esperança in São Jorge sharing the same genetic group, while a putative spatial barrier to gene flow was still retrieved between both islands. Although some populations of both species might benefit from propagation actions, studies are needed on plant host species and translocations between islands or between some populations of a same island should be avoided, due to the occurrence of putative ESUs. Eradication of invasive species and control of grazing will be fundamental to promote in situ restauration.     

Molecular and morphological insights into the origin of the invasive greater white-toothed shrew (<Emphasis Type="Italic">Crocidura russula</Emphasis>) in Ireland

Identifying routes of invasion is a critical management strategy in controlling the spread of invasive species. This is challenging however in the absence of direct evidence. Therefore, indirect methodologies are used to infer possible invasion sources and routes, such as comparisons of genetic and morphological data from populations from invasive ranges and putative source areas. The greater white-toothed shrew (Crocidura russula) was first discovered in Ireland from skeletal remains in the pellets of birds of prey collected in 2007 and is it is now sufficiently established that the species has a detrimental impact on Ireland’s small mammal community. In this study, we address the uncertain origin(s) of the Irish population of C. russula. The cytochrome b gene of mitochondrial DNA was analysed from 143 individuals from throughout its range within a phylogenetic and approximate Bayesian computation framework. These analyses revealed that the Irish population stemmed from Europe as opposed to North Africa. Additionally, mandibles from 523 individuals from Ireland and 28 other European populations were subjected to multivariate and distance-based analyses, which demonstrated an association between the Irish population and those in France, Switzerland and Belgium. When the genetic and morphological analyses were considered together, an origin stemming from France was deemed the most likely scenario for the source of the invasive Irish population. This study has demonstrated the importance of utilising a multidisciplinary approach when attempting to identify the origins and invasion routes of invasive species.     

Polyploid speciation across a suture zone: phylogeography and species delimitation in S French <Emphasis Type="Italic">Leucanthemum</Emphasis> Mill. representatives (Compositae–Anthemideae)

Chromosome counts suggest that the three varieties of the SE French and NW Italian Leucanthemum vulgare subsp. glaucophyllum (var. glaucophyllum: decaploid; var. esterellense: octoploid; var. subglaucum: hexaploid) deserve acknowledgement as independent species. Here we use AFLP fingerprinting and sequence information from two chloroplast regions (psbA-trnH, rpl16) to gain insight into the evolutionary relationships among those species, along with those with the co-occurring and ecologically similar L. pallens (hexaploid) and the closely related L. ircutianum subsp. leucolepis (tetraploid). Both genetic marker systems reveal a geographical differentiation pattern in L. pallens with the Rhône valley forming a suture zone between the western (SW France, Spain) and eastern (SE France, NW Italy) populations, arguing for the existence of two lineages in the species that may have survived the Last Glacial Maximum (LGM) in refugia on the Iberian and Apennine Peninsulas. Transgressions of this suture zone are observable in the case of the hexaploid L. subglaucum from the Massif Central, which shows genetic relationships to the more eastern decaploid L. glaucophyllum from the Alps Maritimes, and the octoploid L. esterellense from the Esterel Massif (Côte d´Azur), for which relationships to the more western populations of the hexaploids L. pallens and L. subglaucum are observable. The genetic and cytological survey of a mixed stand of L. pallens and L. glaucophyllum on Monte Bignone (Liguria, NW Italy) reveals patterns of recent hybridisation of these two species with intermediate octoploid and nonaploid cytotypes that are, however, genetically distinct from L. esterellense.     

On the Trail of Date-Plum (<Emphasis Type="Italic">Diospyros lotus</Emphasis> L.) in Italy and Its First Archaeobotanical Evidence

Diospyros lotus L. is an arboreal species native to the Balkans and Caucasus and ranging to the Far East. In Italy, it has been cultivated for centuries and has reverted to the wild state in some regions. During archaeological excavations carried out in the historical center of Modena (northern Italy), two floral calyxes of D. lotus were discovered in a layer dating from the first century ce. These are the first and only remains of D. lotus found in an archaeological context in Italy thus far. The first historical mention of this species as an arboreal plant in Italy occurs in the 1565 edition of Dioscorides’ Commentarii de Medica materia by Pietro Andrea Mattioli. Our research allowed us to establish that the first three Italian herbaria containing samples of D. lotus, dating to the 1551–1570 period, are the Erbario B of the Biblioteca Angelica of Rome, the Erbario Aldrovandi (Bologna) and the Erbario Cesalpino (Florence). However, archaeobotanical remains reveal that the fruits of this species were known during the Roman period, probably arriving in northern Italy as a luxury food owing to their exceptional flavor.     

De novo development and characterization of polymorphic microsatellite markers in a schilbid catfish, <Emphasis Type="Italic">Silonia silondia</Emphasis> (Hamilton, 1822) and their validation for population genetic studies

The stock characterization of wild populations of Silonia silondia is important for its scientific management. At present, the information on genetic parameters of S. silondia is very limited. The species-specific microsatellite markers were developed in current study. The validated markers were used to genotype individuals from four distant rivers. To develop de novo microsatellite loci, an enriched genomic library was constructed for S. silondia using affinity–capture approach. The markers were validated for utility in population genetics. A total number of 76 individuals from four natural riverine populations were used to generate data for population analysis. The screening of isolated repeat sequences yielded eleven novel polymorphic microsatellite loci. The microsatellite loci exhibited high level of polymorphism, with 6–24 alleles per locus and the PIC value ranged from 0.604 to 0.927. The observed (Ho) and expected (He) heterozygosities ranged from 0.081 to 0.84 and 0.66 to 0.938, respectively. The AMOVA analysis indicated significant genetic differentiation among riverine populations (overall F_ST = 0.075; P < 0.0001) with maximum variation (92.5 %) within populations. Cross-priming assessment revealed successful amplification (35–38 %) of heterologous loci in four related species viz. Clupisoma garua, C. taakree, Ailia coila and Eutropiichthys vacha. The results demonstrated that these de novo polymorphic microsatellite loci are promising for population genetic variation and diversity studies in S. silondia. Cross-priming results indicated that these primers can help to get polymorphic microsatellite loci in the related catfish species of family Schilbidae.     

Successful worldwide invasion of the veined rapa whelk, <Emphasis Type="Italic">Rapana venosa</Emphasis>, despite a dramatic genetic bottleneck

Biological invasions represent an important component of global change, with potentially huge detrimental effects on native biological biodiversity and ecosystems. Knowledge about invasion history provides information about the invasion process and the origin and genetic composition of invading populations. To clarify the source and invasive routes of a successful world-wide invader, the veined rapa whelk, Rapana venosa, genetic variability of samples from five representative native populations from coasts of Japan and China and 13 worldwide invasive populations was analyzed using 11 nuclear microsatellite loci. A dramatic decrease of genetic variation was detected in the invasive populations compared with the native populations. The results demonstrated that R. venosa was capable of establishing itself in many areas despite a dramatic genetic bottleneck, suggesting that a remarkable reduction of genetic diversity is not a limiting factor for short-term success of this invasive species. Considering the lack of mitochondrial variation previously observed in the invasive populations, the dramatic genetic bottleneck and the allele distribution detected using microsatellites suggested that the original introduced Black Sea population could have been founded by very few individuals, perhaps only a single female and a single male. The initial invasive Black Sea population was likely an accidental introduction from Japan, and then invaded the Adriatic Sea by range expansion, which served as a source for subsequent invasive populations in Europe and America by various transport vectors. In addition, microsatellite alleles in the invasive populations showed a tendency to mutate with the addition or deletion of a single repeat, which is consistent with the stepwise mutation model. Our findings provide a good example of how an aquatic invader with a drastic genetic bottleneck and very low genetic diversity rapidly expands its geographical range.     

The secret of Pianosa island: an Italian native population of European brown hare (<Emphasis Type="Italic">Lepus europaeus meridiei</Emphasis> Hilzheimer, 1906)

Given its relevance as a game species, the brown hare (Lepus europaeus Pallas, 1778) is one of the most managed and translocated mammals in Europe. In Italy, the species shows a genepool consisting of a mix of native and exotic lineages, due to translocations and introductions for hunting purposes. Some authors argued that the introduction of exotic brown hares could have caused the extinction of an endemic subspecies, L. e. meridiei Hilzheimer 1906, once present in central and northern Italy. Here we genetically characterized for the first time the brown hare population living in Pianosa island (part of the Tuscan Archipelago National Park) using 13 STR loci and a fragment of the mtDNA control region. All individuals analyzed share a unique haplotype, the L. europaeus haplotype Leu2, recognized as the ancestral mitochondrial lineage corresponding to the subspecies L. e. meridiei. Furthermore, considering autosomal markers, Pianosa brown hare population and current Italian peninsular population are genetically distinct. The discovery of this ancient population in a protected area, isolated and not affected by recent translocation/restocking events, has a great relevance in conservation and confirms the current presence of the endemic subspecies L. e. meridiei in Italy.     

Isolation and Characterization of Microsatellite Markers for <Emphasis Type="Italic">Viola websteri</Emphasis> (Violaceae) and Cross-Species Amplification within the Genus <Emphasis Type="Italic">Viola</Emphasis>

We isolated and characterized microsatellite loci in Viola websteri (Violaceae), an endangered species from Korea and endemic to Northeast Asia. A total of 27 microsatellite loci were developed and tested in Korean and Chinese populations. The number of alleles per locus varied from two to eight. The observed and expected heterozygosities within two populations were 0.000 to 1.000 and 0.080 to 0.816, respectively. Korean and Chinese populations were clearly distinguished by the private alleles from 16 loci. A total of 21 loci out of the 27 developed loci were successfully cross-amplified in 39 other Viola species. We believe that these microsatellite loci will be useful for future studies on genetic diversity and population structure of V. websteri, as well as other Viola species.     

Phylogeography and founder effect of the endangered Corsican red deer (<Emphasis Type="Italic">Cervus elaphus corsicanus</Emphasis>)

Red deer (n = 149) from eight geographical locations, including the endangered endemic populations from the Tyrrhenian islands (Sardinia and Corsica), were analysed at eight polymorphic microsatellite loci. Two questions were addressed: (1) Is there a founder effect in the Corsican population, which was reintroduced to the island using Sardinian deer after the species’ extinction on Corsica? (2) What is the origin of the Tyrrhenian or Corsican red deer (Cervus elaphus corsicanus)? Our results showed signs of a founder effect for the red deer on Corsica in that these deer showed differentiation from the Sardinian population as measured by F_ST values, assignment tests (with and without a priori definition of populations) and individual-based dendrograms. Genetic variability, however, did not differ significantly between the two populations. With respect to the phylogeography of C. e. corsicanus we found that both deer from North-Africa and Mesola on the Italian mainland were genetically close to the Corsican red deer, but phylogenetic trees based on genetic distances were only poorly supported statistically. Among all populations studied the Mesola red deer showed the lowest distance values from Corsican red deer and yielded allele frequencies that were more similar to those of C. e. corsicanus than were those of North-African red deer. These results are in line with recent palaeontological and archaeozoological findings which suggest that the Corsican red deer is derived from small Italian red deer introduced from the mainland to Sardinia and Corsica during the Late Neolithic and just before the beginning of Classical Antiquity, respectively. They also suggest a possible recent introduction of Tyrrhenian red deer to North-Africa (rather than the other way around), thus accounting for the close genetic relationship (especially based on mitochondrial DNA) that has repeatedly been found between C. e. corsicanus and C. e. barbarus.     

Genetic Analysis of the <Emphasis Type="Italic">Indri</Emphasis> Reveals No Evidence of Distinct Subspecies

Subspecies were traditionally defined by identifying gaps between phenotypes across the geographic range of a species, and may represent important units in the development of conservation strategies focused on preserving genetic diversity. Previous taxonomic research proposed that phenotypic variation between scattered Indri indri populations warranted the naming of two distinct subspecies, I. i. indri and I. i. variegatus. We tested these subspecific designations using mitochondrial sequence data generated from the control region or D-loop (569 bp) and a large section (2362 bp) of multiple genes and tRNAs known as Pastorini’s fragment and nuclear microsatellite markers. This study used 114 samples of I. indri from 12 rainforest sites in eastern Madagascar, encompassing the entire range of the species. These genetic samples represent multiple populations from low- and high-elevation forests from both putative subspecies. Molecular analyses of the mitochondrial sequence data did not support the two proposed subspecies. Furthermore, the microsatellite analyses showed no significant differences across the range beyond population level differentiation. This study demonstrates the utility of incorporating multiple lines of evidence in addition to phenotypic traits to define species or subspecies.     

Breeding system,gene dispersal and small-scale spatial genetic structure of a threatened food tree species, <Emphasis Type="Italic">Pentadesma butyracea</Emphasis> (Clusiaceae) in Benin

Pentadesma butyracea Sabine, a rain forest food tree species, plays a vital role in the socio-economic livelihood of some West African rural communities due to its various products. However, its scattered populations are threatened in Benin. Defining appropriate conservation strategies requires a good knowledge of mating patterns and their consequences for population genetics. The outcrossing rate, levels of correlated paternity and fine-scale spatial genetic structure of adults and maternal sibships were estimated for one small population and three large populations in Benin using microsatellite markers. Similar outcrossing rates (88–95%) were found in all populations, showing that P. butyracea is mainly an outbreeding species. We found no evidence of inbreeding depression from a decay of inbreeding with age. The spatial genetic structure within the large populations (Sp statistic?=?0.003–0.038) was consistent with isolation-by-distance expectations, showing that gene dispersal is spatially limited. Limited pollen dispersal is highlighted by the decay of the degree of correlated paternity between sibships with spatial distance. The mean pollen dispersal distance was estimated between 50 m and 450 m, but up to 21% pollen may migrate from external sources. The smallest population displayed slightly higher correlated paternity than the large populations (r _p ?=?0.37 vs. r _p ?=?0.17–0.30). In conclusion, our results suggest that small populations may show a reduction in sire numbers in seed, while the fragmented populations, large and small, are connected through gene flow. There is little inbreeding and no evidence of inbreeding depression.