Population genetics and breeding system of Tupistra pingbianensis (Liliaceae), a naturally rare plant endemic to SW China

The levels and partitioning of genetic diversity and inbreeding depression were investigated in Tupistra pingbianensis, a narrow endemic of South-east Yunnan, China, characterized by a naturally fragmented distribution due to extreme specialization on a rare habitat type. Here genetic diversity and patterns of genetic variation within and among 11 populations were analyzed using AFLP markers with 97 individuals across its whole geographical range. High levels of genetic variation were revealed both at the species level (P₉₉ = 96.012%; H_t = 0.302) and at the population level (P₉₉ = 51.41%; H_s = 0.224). Strong genetic differentiation among populations was also detected (F_ST = 0.2961; ⍬^嘦= 0.281), which corresponded to results reported for typical animal-pollinated, mixed selfing and outcrossing plant species. This result was consistent with mating patterns detected by our pollination experiments. The indirect estimate of gene flow based on ⍬^嘦 was low (N_m = 0.64). Special habitat and its life history traits may play an important role in shaping the genetic diversity and the genetic structure of this species. A pollination experiment also fail to detect significant inbreeding depression upon F₁ fruit set, seed weight and germinate rate fitness-traits. Since naturally rare species T. pingbianensis is not seriously genetically impoverished and likely to have adapted to tolerating a high level of inbreeding early in its history, we propose this species need only periodic monitoring to ensure their continued persistence but not intervention to remain viable.     

Conservation genetics and breeding system of Penstemon debilis (Plantaginaceae), a rare beardtongue endemic to oil shale talus in western Colorado,USA

Rare species of plants are especially vulnerable to extinction when populations are few, have small numbers of individuals, and are fragmented. Such conditions lead to a reduction in gene flow and genetic diversity, and encourage inbreeding depression. We conducted a study of the reproductive biology and population genetics of Penstemon debilis (Plantaginaceae), a Federally Threatened species endemic to a small region of oil shale extraction in western Colorado, USA. Most of the habitat area is privately owned and undergoing natural gas extraction activities. Penstemon debilis reproduces both vegetatively and as an outcrosser that requires a pollen vector. Moderate levels of inbreeding, but no inbreeding depression, were found within populations of P. debilis. Genetic divergence among the extant populations surveyed was moderate (F_ST values = 0.069–0.231; Nm = 0.831–3.385) with levels of genetic diversity within populations relatively low compared to congeners with similar modes of pollination and reproductive biology. STRUCTURE analysis revealed three population clusters with some admixture among all extant populations. Genetic diversity within and among P. debilis populations is similar to genetic diversity found for other rare and endemic outcrossing plant species. Our results are consistent with a pattern of recent population fragmentation or low levels of pollen‐mediated gene flow among populations in close proximity to one another. Conservation of P. debilis will require cooperative management strategies between private landowners, government agencies, and concerned NGOs to preserve habitat for this rare species.     

濒危植物矮沙冬青的等位酶多样性及居群分化

采用超薄平板微型聚丙烯酰胺等电聚焦技术,对珍稀濒危植物矮沙冬青(Ammopiptanthus nanus)6个自然居群的等位酶遗传多样性进行了初步研究。8个酶系统、l9个酶位点的检测结果表明,矮沙冬青具有较低的遗传变异水平。物种水平上的遗传多样性参数为：P=21．05％,A=1．21,Ht=0．040;居群水平上的平均遗传多样性为：P=14．04％,A=1．14(0．04),Ht=0．036(0．018),比长寿命多年生木本的狭域分布种和特有种的多样性水平都低。F-统计量分析显示,矮沙冬青在居群水平(F15=0．129)和总居群水平(FIT=0．202)上都表现为杂合子缺乏;Fsr=0．085表明居群问遗传分化较小,这与居群间较高的遗传一致度(I=0．997)的结果一致。据研究结果推测矮沙冬青进化历史上经历过遗传瓶颈,是造成遗传多样性水平偏低的重要原因。基于研究结果,提出应当重点保护遗传变异相对丰富的何依儿佣克尔(KE)居群,并且可将其作为引种的种源地。     

Microsatellite variation and structure of 28 populations of the common wetland plant, Lychnis flos-cuculi L., in a fragmented landscape

Habitat fragmentation is known to cause genetic differentiation between small populations of rare species and decrease genetic variation within such populations. However, common species with recently fragmented populations have rarely been studied in this context. We investigated genetic variation and its relationship to population size and geographical isolation of populations of the common plant species, Lychnis flos-cuculi L., in fragmented fen grasslands. We analysed 467 plants from 28 L. flos-cuculi populations of different sizes (60 000-54 000 flowering individuals) in northeastern Switzerland using seven polymorphic microsatellite loci. Genetic differentiation between populations is small (F(ST) = 0.022; amova; P < 0.001), suggesting that gene flow among populations is still high or that habitat fragmentation is too recent to result in pronounced differentiation. Observed heterozygosity (H(O) = 0.44) significantly deviates from Hardy-Weinberg equilibrium, and within-population inbreeding coefficient F(IS) is high (0.30-0.59), indicating a mixed mating breeding system with substantial inbreeding in L. flos-cuculi. Gene diversity is the only measure of genetic variation which decreased with decreasing population size (R = 0.42; P < 0.05). While our results do not indicate pronounced effects of habitat fragmentation on genetic variation in the still common L. flos-cuculi, the lower gene diversity of smaller populations suggests that the species is not entirely unaffected.     

栓皮栎天然群体SSR遗传多样性研究

利用微卫星(SSR)标记对我国4个省内的5个栓皮栎（Quercus variabilis Bl.）天然群体的遗传多样性进行了研究。16对SSR标记揭示了栓皮栎丰富的遗传多样性：等位基因数（A）平均8.4375个,有效等位基因数(Ne)平均为5.9512个,平均期望杂合度(He)0.8059,Nei多样性指数(h)为0.8041。栓皮栎自然分布区中心地带的群体具有较高的遗传多样性,而人为对森林的破坏将降低林木群体的遗传多样性。栓皮栎群体的变异主要来源于群体内,群体间分化较小,遗传分化系数仅为0.0455。此外,栓皮栎群体间的遗传距离与地理距离之间存在显著的正相关。这些遗传信息为栓皮栎遗传多样性的保护和利用提供了一定依据。Abstract: Genetic diversity of five Quercus variabilis natural populations in four provinces of China was studied with microsatellite (SSR) markers. A relatively high level of genetic diversity was detected in Q. variabilis species with 16 polymorphic microsatellite loci. Average number of alleles (A) and effective number of alleles (Ne) were 8.4375 and 5.9512 respectively. The mean expected heterozygosity (He) was 0.8059 and Nei diversity index (h) was 0.8041. Higher diversity was found with the populations from the central range of the species in contrast to those from peripheral areas and human activities might decrease the genetic diversity of populations. The majority of genetic variation occurred within populations, which could be concluded from the low coefficient of genetic differentiation (Fst=0.0455). In addition, significant correlation was found between geographical distance and genetic distance. All these results present a basis to the conservation and utilization of genetic diversity of Quercus variabilis.     

Back from the brink: potential for genetic rescue in a critically endangered tree

Rare plant species are vulnerable to genetic erosion and inbreeding associated with small population size and isolation due to increasing habitat fragmentation. The degree to which these problems undermine population viability remains debated. We explore genetic and reproductive processes in the critically endangered long-lived tropical tree Medusagyne oppositifolia, an endemic to the Seychelles with a naturally patchy distribution. This species is failing to recruit in three of its four populations. We evaluate whether recruitment failure is linked to genetic problems associated with fragmentation, and if genetic rescue can mitigate such problems. Medusagyne oppositifolia comprises 90 extant trees in four populations, with only the largest (78 trees) having successful recruitment. Using 10 microsatellite loci, we demonstrated that genetic diversity is high (H(E) : 0.48-0.63; H(O) : 0.56-0.78) in three populations, with only the smallest population having relatively low diversity (H(E) : 0.26 and H(O) : 0.30). All populations have unique alleles, high genetic differentiation, and significant within population structure. Pollen and seed dispersal distances were mostly less than 100 m. Individuals in small populations were more related than individuals in the large population, thus inbreeding might explain recruitment failure in small populations. Indeed, inter-population pollination crosses from the large donor population to a small recipient population resulted in higher reproductive success relative to within-population crosses. Our study highlights the importance of maintaining gene flow between populations even in species that have naturally patchy distributions. We demonstrate the potential for genetic and ecological rescue to support conservation of plant species with limited gene flow.     

Genetic variation and the mating system in the rare Acacia sciophanes compared with its common sister species Acacia anfractuosa (Mimosaceae)

Acacia sciophanes is an extremely rare and Critically Endangered species known from two small populations separated by less than 7 km. Specifically we aimed to investigate whether rarity in A. sciophanes is associated with decreased levels of genetic variation and increased levels of selfing by comparing patterns of genetic variation and mating system parameters with its widespread and common sister species A. anfractuosa. Fourteen polymorphic allozyme loci were used to assess genetic diversity with four of these used in the estimation of mating system parameters. At the species level A. sciophanes has lower allelic richness, polymorphism, observed heterozygosity and gene diversity than A. anfractuosa and significantly lower levels of gene diversity at the population level. Both species have a mixed mating system but the largest population of A. sciophanes has lower levels of outcrossing, higher correlated paternity and increased bi-parental inbreeding compared with two A. anfractuosa populations. However, both correlated paternity and bi-parental inbreeding appear to be at least partly influenced by population size regardless of the species. We suggest that A. sciophanes is likely to be an intrinsically rare species and that in particular the lower levels of genetic diversity and increased selfing are a feature of a species that has the ability to persist in a few localised small populations. Despite recent extensive habitat destruction our comparative study provided no clear evidence that such events have contributed to the lower genetic diversity and increased selfing in A. sciophanes and we believe its ability to exist in small populations may not only be an important factor in its survival as a rare species but also indicates that it may be less susceptible to the impacts of habitat loss and fragmentation. The key to this species conservation will be the maintenance of suitable habitat, particularly through improved fire regimes and control of invasive weeds, that will allow the two small populations to continue to persist in extremely restricted areas of remnant vegetation.     

ISSR variation in the endemic and endangered plant Cycas guizhouensis (Cycadaceae)

BACKGROUND AND AIMS: Cycas guizhouensis (Cycadaceae) is a rare and endangered species endemic to the southwest of China. An investigation was undertaken into the genetic variation of wild populations. METHODS: ISSR markers were used to determine the genetic variation within and between 12 extant populations of this species. KEY RESULTS: Low genetic diversity (at population level, P = 14.21 %, H(E) = 0.0597; at species level, P = 35.90 %, H(T) = 0.1082) and a high degree of differentiation among populations (G(ST) = 0.4321) were detected. CONCLUSIONS: This genetic structure is considered to be due to the combined effects of slow biochemical evolution, genetic drift, inbreeding and limited gene flow between populations. Based on these findings, strategies are proposed for the genetic conservation and management of the species.     

Population structure and inbreeding in a rare and declining bumblebee, Bombus muscorum (Hymenoptera: Apidae)

Owing to habitat loss populations of many organisms have declined and become fragmented. Vertebrate conservation strategies routinely consider genetic factors, but their importance in invertebrate populations is poorly understood. Bumblebees are important pollinators, and many species have undergone dramatic declines. As monoandrous social hymenopterans they may be particularly susceptible to inbreeding due to low effective population sizes. We study fragmented populations of a bumblebee species, on a model island system, and on mainland Great Britain where it is rare and declining. We use microsatellites to study: population genetic structuring and gene flow; the relationships between genetic diversity, population size and isolation; and frequencies of (sterile) diploid males - an indicator of inbreeding. We find significant genetic structuring (theta = 0.12) and isolation by distance. Populations > 10 km apart are all significantly differentiated, both on oceanic islands and on the mainland. Genetic diversity is reduced relative to closely related common species, and isolated populations exhibit further reductions. Of 16 populations, 10 show recent bottlenecking, and 3 show diploid male production. These results suggest that surviving populations of this rare insect suffer from inbreeding as a result of geographical isolation. Implications for the conservation of social hymenopterans are discussed.     

Small population size and extremely low levels of genetic diversity in island populations of the platypus, Ornithorhynchus anatinus

Genetic diversity generally underpins population resilience and persistence. Reductions in population size and absence of gene flow can lead to reductions in genetic diversity, reproductive fitness, and a limited ability to adapt to environmental change increasing the risk of extinction. Island populations are typically small and isolated, and as a result, inbreeding and reduced genetic diversity elevate their extinction risk. Two island populations of the platypus, Ornithorhynchus anatinus, exist; a naturally occurring population on King Island in Bass Strait and a recently introduced population on Kangaroo Island off the coast of South Australia. Here we assessed the genetic diversity within these two island populations and contrasted these patterns with genetic diversity estimates in areas from which the populations are likely to have been founded. On Kangaroo Island, we also modeled live capture data to determine estimates of population size. Levels of genetic diversity in King Island platypuses are perilously low, with eight of 13 microsatellite loci fixed, likely reflecting their small population size and prolonged isolation. Estimates of heterozygosity detected by microsatellites (H(E)= 0.032) are among the lowest level of genetic diversity recorded by this method in a naturally outbreeding vertebrate population. In contrast, estimates of genetic diversity on Kangaroo Island are somewhat higher. However, estimates of small population size and the limited founders combined with genetic isolation are likely to lead to further losses of genetic diversity through time for the Kangaroo Island platypus population. Implications for the future of these and similarly isolated or genetically depauperate populations are discussed.     

High genetic diversity vs. low genetic differentiation in Nouelia insignis (Asteraceae), a narrowly distributed and endemic species in China, revealed by ISSR fingerprinting

BACKGROUND AND AIMS: Nouelia insignis Franch., a monotypic genus of the Asteraceae, is an endangered species endemic in Yunnan and Sichuan Provinces of China. Most of the populations are seriously threatened. Some of them are even at the brink of extinction. In this study, the genetic diversity and differentiation between populations of this species were examined in two drainage areas. METHODS: DNA fingerprinting based on inter-simple sequence repeat polymorphisms was employed to detect the genetic variation and population structure in the species. KEY RESULTS: Genetic diversity at species level was high with P=65.05% (percentage of polymorphic loci) and Ht=0.2248 (total genetic diversity). The coefficient of genetic differentiation among populations, Gst, which was estimated by partitioning the total gene diversity, was 0.2529; whereas, the genetic differentiation between populations in the Jinsha and Nanpan drainage areas was unexpectedly low (Gst=0.0702). CONCLUSIONS: Based on the genetic analyses of the DNA fingerprinting, recent habitat fragmentation may not have led to genetic differentiation or the loss of genetic diversity in the rare species. Spatial apportionment of fingerprinting polymorphisms provides a footprint of historical migration across geographical barriers. The high diversity detected in this study holds promise for conservation and restoration efforts to save the endangered species from extinction.     

Reproductive biology and population genetic structure of Kandelia candel (Rhizophoraceae), a viviparous mangrove species

The pollination biology, mating system, and population genetic structure of Kandelia candel were investigated. Field observations on its pollination and reproductive biology suggested that this species is pollinator dependent for fruit set, and bee activities can lead to substantial geitonogamous selfing. Quantitative analysis of the mating system parameters was performed using progeny arrays assayed for allozyme markers. Multilocus outcrossing rates (t(m)) were estimated to be 0.697 ± 0.091 and 0.797 ± 0.062 in two populations. In comparison to other plant species with mixed-mating system, the level of allozyme variation was very low in the 13 populations sampled along the coastlines of Hong Kong. At the species level, the proportion of polymorphic loci was 20%, number of alleles per locus was 1.2, and heterozygosity was 0.0362. The total gene diversity was primarily distributed within populations (H(S )= 0.0339), and the coefficient of genetic differentiation among populations was low (G(ST )= 0.064). This pattern of population genetic structure suggests that gene flow, primarily in the form of water-dispersed seedlings in viviparous mangrove species, is not as limited as previously thought. However, microgeographic pattern in allele frequency at the marker loci could still be detected between the western and eastern coastal populations.     

Genetic Connectivity of the Moth Pollinated Tree Glionnetia sericea in a Highly Fragmented Habitat

Long-distance gene flow is thought to be one prerequisite for the persistence of plant species in fragmented environments. Human influences have led to severe fragmentation of native habitats in the Seychelles islands, with many species surviving only in small and isolated populations. The endangered Seychelles endemic tree Glionnetia sericea is restricted to altitudes between 450 m and 900 m where the native forest vegetation has been largely lost and replaced with exotic invasives over the last 200 years. This study explores the genetic and ecological consequences of population fragmentation in this species by analysing patterns of genetic diversity in a sample of adults, juveniles and seeds, and by using controlled pollination experiments. Our results show no decrease in genetic diversity and no increase in genetic structuring from adult to juvenile cohorts. Despite significant inbreeding in some populations, there is no evidence of higher inbreeding in juvenile cohorts relative to adults. A Bayesian structure analysis and a tentative paternity analysis indicate extensive historical and contemporary gene flow among remnant populations. Pollination experiments and a paternity analysis show that Glionnetia sericea is self-compatible. Nevertheless, outcrossing is present with 7% of mating events resulting from pollen transfer between populations. Artificial pollination provided no evidence for pollen limitation in isolated populations. The highly mobile and specialized hawkmoth pollinators (Agrius convolvuli and Cenophodes tamsi; Sphingidae) appear to promote extensive gene flow, thus mitigating the potential negative ecological and genetic effects of habitat fragmentation in this species. We conclude that contemporary gene flow is sufficient to maintain genetic connectivity in this rare and restricted Seychelles endemic, in contrast to other island endemic tree species with limited contemporary gene flow.     

Assessing genetic diversity and structure of fragmented populations of eastern white pine (Pinus strobus) and western white pine (P. monticola) for conservation management

Aims Many pine populations in Canada have fragmented distributions resulting from the effects of glaciations, overharvesting and white pine blister rust infections. Forest fragmentation can modify gene flow and reduce genetic diversity. Selective logging can reduce the density of trees, thereby altering mating patterns and increasing inbreeding. The hypothesis of the present study is that forest fragmentation will not increase inbreeding and will have no effect on genetic diversity parameters in the Canadian Pinus moniticola and P. strobus populations targeted because of (i) the long life span of the pine species, (ii) outbreeding and self-incompatibility of P. monticola and P. strobus and (iii) wind pollination resulting in high gene flow among populations. We studied the genetic diversity of P. strobus across its range in Canada, and we completed a detailed analysis of the genetic structure of P. monticola populations from western Canada using microsatellites genetic markers.Methods Seed samples from 10 P. monticola populations and 10 P. strobus populations were collected from western and eastern Canada, respectively. The mother trees included in seed lots were representative of each stand. Genomic DNA extracted from each sample was amplified with microsatellite primers. The intra- and interpopulation genetic diversity parameters were assessed using Popgene and Genepop softwares and the genetic distances among populations within each species using the PowerMarker software.Important findings Pinus monticola and P. strobus exhibited moderate to high genetic diversity. Also, both species showed low levels of inbreeding despite the geographic isolation and small stand size. Gene flow estimates were high and population differentiation values were relatively low for these fragmented forest sites.     

Low genetic variability and strong differentiation among isolated populations of the rare steppe grass Stipa capillata L. in Central Europe

Stipa capillata L. (Poaceae) is a rare grassland species in Central Europe that is thought to have once been widespread in post‐glacial times. Such relict species are expected to show low genetic diversity within populations and high genetic differentiation between populations due to bottlenecks, long‐term isolation and ongoing habitat fragmentation. These patterns should be particularly pronounced in selfing species. We analysed patterns of random amplified polymorphic DNA (RAPD) variation in the facultatively cleistogamous S. capillata to examine whether genetic diversity is associated with population size, and to draw initial conclusions on the migration history of this species in Central Europe. We analysed 31 S. capillata populations distributed in northeastern, central and western Germany, Switzerland and Slovakia. Estimates of genetic diversity at the population level were low and not related to population size. Among all populations, extraordinarily high levels of genetic differentiation (amova : φ_ST = 0.86; Bayesian analysis: θ^B = 0.758) and isolation‐by‐distance were detected. Hierarchical amova indicated that most of the variability was partitioned among geographic regions (59%), or among populations between regions when the genetically distinct Slovakian populations were excluded. These findings are supported by results of a multivariate ordination analysis. We also found two different groups in an UPGMA cluster analysis: one that contained the populations from Slovakia, and the other that combined the populations from Germany and Switzerland. Our findings imply that S. capillata is indeed a relict species that experienced strong bottlenecks in Central Europe, enhanced by isolation and selfing. Most likely, populations in Slovakia were not the main genetic source for the post‐glacial colonization of Central Europe.     

Differential threshold effects of habitat fragmentation on gene flow in two widespread species of bush crickets

Effects of habitat fragmentation on genetic diversity vary among species. This may be attributed to the interacting effects of species traits and landscape structure. While widely distributed and abundant species are often considered less susceptible to fragmentation, this may be different if they are small sized and show limited dispersal. Under intensive land use, habitat fragmentation may reach thresholds at which gene flow among populations of small-sized and dispersal-limited species becomes disrupted. Here, we studied the genetic diversity of two abundant and widespread bush crickets along a gradient of habitat fragmentation in an agricultural landscape. We applied traditional (G(ST), θ) and recently developed (G'ST', D) estimators of genetic differentiation on microsatellite data from each of twelve populations of the grassland species Metrioptera roeselii and the forest-edge species Pholidoptera griseoaptera to identify thresholds of habitat fragmentation below which genetic population structure is affected. Whereas the grassland species exhibited a uniform genetic structuring (G(ST) = 0.020-0.033; D = 0.085-0.149) along the whole fragmentation gradient, the forest-edge species' genetic differentiation increased significantly from D < 0.063 (G(ST) < 0.018) to D = 0.166 (G(ST) = 0.074), once the amount of suitable habitat dropped below a threshold of 20% and its proximity decreased substantially at the landscape scale. The influence of fragmentation on genetic differentiation was qualitatively unaffected by the choice of estimators of genetic differentiation but quantitatively underestimated by the traditional estimators. These results indicate that even for widespread species in modern agricultural landscapes fragmentation thresholds exist at which gene flow among suitable habitat patches becomes restricted.     

西鄂尔多斯特有种四合木种群遗传多样性及遗传分化研究

利用垂直板聚丙烯酰胺凝胶电泳技术,对西鄂尔多斯高原特有种四合木（Tetraena mogolica）4个种群遗传多样性和遗传分化进行了初步研究。电泳结果表明,四合木在种和种群水平维持较高的遗传多样性,1多态位点百分率P＝60％,等位基因平均数A＝1.6,平均期望杂合度He=0.245。4个种群之间遗传分化很小,基因分化系数GST只有0.052,明不同于其它濒危物种。四合木种较高的遗传多样性和极低的种群间分化,说明不同的种群可能有共同的起源,随机遗传漂变和近交衰退不是影响遗传多样性的主要过程。     

The cost of inbreeding in Platanthera leucophaea (Orchidaceae)

Fragmentation and isolation are expected to have a considerable impact on viability and recruitment in populations of rare species. Platanthera leucophaea (Orchidaceae), a rare orchid, currently exists in a fragmented landscape of its natural habitat. Floral morphology suggests this species is predominantly outcrossing, but surveys of allozyme diversity suggest high, variable levels of inbreeding in populations (F(IS) = -0.078 to 1.0). This study examines the potential cost of inbreeding and the extent to which inbreeding depression can vary temporally and in populations of different size and genetic structure. Flowers were pollinated by hand in one large population and one small population over three seasons. Seed set, seed mass, and seed viability were compared among self-, outcross-, and open-pollinated fruits. Seed set was greater than 50% in both populations for all years of study. High levels of inbreeding depression were detected in seed viability but not in seed mass in both populations. However, the magnitude of inbreeding depression differed over years and between populations, a pattern that reflects differing environmental conditions and variable evolutionary and demographic histories. Consequently, conservation of this species will be most successful if outcrossing is promoted in populations by maximizing population size and genetic variability.     

遗传多样性与濒危植物保护生物学研究进展

尽管对于濒危物种的遗传学人们已经进行了大量研究,但是种群遗传学在植物保护中的实际地位尚存在很大争议。濒危物种的遗传多样性可能会由于遗传漂变、近交的作用而丧失;但这种丧失更可能是濒危的结果而不是濒危的起因。遗传多样性水平与物种生存力之间没有任何必然的联系。但植物种群遗传结构如果由于自交不亲和等位基因的丧失和与亲缘种杂交造成的遗传同化而发生改变,那么它对物种生存力会产生明显负作用。     

Contemporary pollen-mediated gene immigration reflects the historical isolation of a rare,animal-pollinated shrub in a fragmented landscape

Fragmentation is generally considered to have negative impacts on widespread outbreeders but impacts on gene flow and diversity in patchy, naturally rare, self-compatible plant species remain unclear. We investigated diversity, gene flow and contemporary pollen-mediated gene immigration in the rare, narrowly distributed endemic shrub Calothamnus quadrifidus ssp. teretifolius. This taxon occurs in an internationally recognized biodiversity hotspot subjected to recent human-induced fragmentation and the condition of the remnants ranges from intact to highly degraded. Using microsatellites, we found that inbreeding, historically low gene flow and significant population differentiation have characterized the genetic system of C. quadrifidus ssp. teretifolius. Inbreeding arises from self-pollination, a small amount of biparental inbreeding and significant correlation of outcross paternity but fecundity was high suggesting populations might have purged their lethals. Paternity analyses show that pollinators can move pollen over degraded and intact habitat but populations in both intact and degraded remnants had few pollen parents per seed parent and low pollen immigration. Genetic diversity did not differ significantly between intact and degraded remnants but there were signs of genetic bottlenecks and reduced diversity in some degraded remnants. Overall, our study suggests human-induced fragmentation has not significantly changed the mating system, or pollen immigration to, remnant populations and therefore genetic connectivity need not be the highest conservation priority. Rather, for rare species adapted to higher levels of inbreeding, conservation efforts may be best directed to managing intact habitats and ecosystem processes.