Genetic differences in the response to landscape fragmentation by a habitat generalist,the bobcat,and a habitat specialist,the ocelot

The ecology of a species strongly influences genetic variation and population structure. This interaction has important conservation implications because taxa with low dispersal capability and inability to use different habitats are more susceptible to anthropogenic stressors. Ocelots (Leopardus pardalis albescens) and bobcats (Lynx rufus texensis) are sympatric in Texas and northeastern Mexico; however, their ecology and conservation status are markedly different. We used 10 microsatellite loci and a 397-bp segment of the mitochondrial control region to examine how historical and ecological differences in these two species have influenced current patterns of genetic diversity in a landscape heavily altered by anthropogenic activities. Substantially higher genetic diversity (heterozygosity and haplotype diversity) and population connectivity was observed for bobcats in comparison to ocelots. The level of divergence among proximate ocelot populations (<30 km) was greater than between bobcat populations separated by >100 km. Ocelot populations in the US have never recovered from reductions experienced during the twentieth century, and their low genetic variation and substantial isolation are exacerbated by strong preference for dense native thornshrub and avoidance of open habitat. In contrast, despite continued legal harvesting and frequent road-related mortality, bobcats have maintained wide distribution, high abundance, and population connectivity. Our study illustrates that sympatric species with a similar niche can still have sufficient ecological differences to alter their response to anthropogenic change. Sensitive species, such as the ocelot, require additional conservation actions to sustain populations. Ecological differences among species occupying a similar guild are important to consider when developing conservation plans.     

Population genetic analyses of the endangered alpine <Emphasis Type="Italic">Sinadoxa corydalifolia</Emphasis> (Adoxaceae) provide insights into future conservation

With increasing temperature and anthropogenic activity, endangered alpine species in the high altitudes of the Qinghai-Tibet Plateau face high risk of extinction; however, they have received little attention in the past. In this study, we used 12 nuclear and nine chloroplast microsatellites (simple sequence repeats, SSR) to assess genetic diversity within and among the only two populations of the highly endangered alpine species Sinadoxa corydalifolia (Adoxaceae). We identified only one individual exhibiting clonal reproduction across all 160 extant plants. The levels of genetic variability were estimated to be very low, with the allele number N_a = 3.2 and the expected heterozygosity H_e = 0.368. The genetic differentiation is extremely high between the two regional populations (F_ST = 0.214), with a limited rate of gene flow in the recent past. In addition, numerous endemic alleles were found for each subpopulation within each population. Our analyses suggest that it is critical not only to conserve all surviving individuals of the two populations in situ but also to mediate gene flow artificially between subpopulations within each population in this endangered species.     

Genetic diversity and structure of Lilium pumilum DC. in southeast of Qinghai–Tibet plateau

Lilium pumilum DC. is a valuable species not only for its showy flowers but also for its edible and medicinal values. As one of the distribution areas of L. pumilum, Qinghai–Tibet plateau has unique environmental features which have high impact on the evolution of the species. No population genetic studies have been done for L. pumilum so far. To provide the first reference data for evolutionary study and understanding the influence of eco-geographic factors on the distribution of genetic variation in L. pumilum, interspecific simple sequence repeat markers were used to investigate genetic diversity and population structure of 28 populations sampled from southeast of Qinghai–Tibet plateau. Fifteen selected primers generated a total of 147 polymorphic bands. The genetic diversity was low within populations (average He = 0.173), but higher at the species level (He = 0.392). A clear population structure and high level of genetic differentiation (F _ST = 0.518) were detected by unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. All clustering approaches supported a division of the 28 populations into 4 major groups for which analysis of molecular variance confirmed a significant variation among groups (34.3 %). These population genetic parameters suggest limited gene flow among populations and evidence for isolation by distance (r = 0.272, P < 0.0001) was found in this study. Altitude, AMT and AMP explained 9.5, 11.5 and 14.0 % of the total variance among populations indicating that eco-geographic factors have a significant effect. Considering the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve L. pumilum in Qinghai–Tibet plateau.     

Genetic diversity and genetic structure in wild populations of Mexican oregano (Lippia graveolens H.B.K.) and its relationship with the chemical composition of the essential oil

Mexican oregano is an aromatic plant traditionally harvested from wild populations by rural communities; however, there is little information about population genetics aspects of this species. Moreover, considering that the variation in essential oil production of aromatic plants has been attributed to several environmental as well as genetic factors, in this study we estimated the genetic diversity and genetic structure from 14 wild populations of L. graveolens located in four different bioclimatic regions in southeastern Mexico using AFLP markers. The overall genetic diversity of L. graveolens described as the percentage of polymorphic loci (PPL = 60.9 %) and Nei’s gene diversity (H _j  = 0.17) was moderate, but not associated with the bioclimatic conditions. Genetic variation was analyzed at chemotype and population levels. Regarding chemotypes, thymol had the highest genetic diversity (PPL = 82.8 % and H _j  = 0.22). PCoA revealed that chemotypes exhibit a certain level of genetic differentiation. Maximum parsimony dendrogram showed a grouping of individuals with a predominant chemotype. Bayesian analyses revealed a low, but significant differentiation among chemotypes (θ _ΙΙ = 0.008). Regarding populations, gene diversity showed significant differences (F _13,1204 = 22.8, P < 0.001); populations dominated by individuals from the thymol chemotype showed the highest gene diversity (H _j  = 0.31–0.25), while populations with exclusively sesquiterpene chemotype showed the lowest value (H _j  = 0.058). Cluster and Bayesian analyses (θ _ΙΙ = 0.027) revealed a low level of genetic differentiation among populations. Correlation analysis showed a significant association between the distance matrices based on the genetic markers (AFLP) and chemical compounds of essential oil (r = 0.06, P < 0.001). Our results suggest an important genetic influence on the observed chemical profiles. Nevertheless, other biotic and abiotic environmental pressures also play an important role in determining the chemotype and structure found in this aromatic species.     

Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Translocation is a strategy commonly used to maximize the persistence of threatened species, but it may sometimes lead to undesirable genetic consequences. The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that is critically endangered in Australia’s Northern Territory due to rapid population declines in areas recently colonized by the exotic cane toad Chaunus [Bufo] marinus. In 2003, 64 quolls were translocated to two offshore islands to establish insurance populations and reduce the species’ risk of extinction. In this study, we assessed genetic diversity at five microsatellite loci in the translocated populations, two endemic islands and three mainland populations. In the short-term (three generations), the translocated populations showed a slight but non-significant reduction in genetic diversity (A = 4.1–4.2; H _e = 0.56–0.59) compared to the mainland source populations (A = 5.0–8.4; H _e = 0.56–0.71). In comparison, high genetic erosion was observed in the endemic island populations (A = 1.5–2.9; H _e = 0.11–0.34). Genetic bottlenecks were detected on both endemic islands and in one mainland population, indicating recent reductions in population size. Our results are consistent with previous studies describing greater losses of genetic diversity on islands compared to mainland populations. Divergence from ancestral allele frequencies in the translocated populations also suggests effects due to founder events. This study, although short-term, highlights the importance of continued monitoring for detecting changes in genetic diversity over time and makes a significant contribution to our understanding of the effects of founder events on island populations.     

Rangewide Genetic Diversity in Natural Populations of Chinese Pine (Pinus tabulaeformis)

Thirteen natural populations from throughout the range of the Chinese pine (Pinus tabulaeformis Carr.) were examined using inter-simple sequence repeat markers to characterize the genetic structure at the species level and to compare the extent and distribution of genetic variation among central, intermediate, and marginal populations. Although the total genetic variation in the Chinese pine was mainly maintained within populations, the genetic differentiation among populations was significant (P < 0.001). The genetic divergence was significantly correlated with geographic distance (P < 0.05). Genetic diversity tended to decrease from the central to intermediate and marginal populations. The marginal populations had significantly lower intrapopulation genetic diversity than central populations (P < 0.05). Cluster analysis based on Nei’s unbiased genetic distances confirmed the difference among four central populations and the rest. Both historical and contemporary factors may have played key roles in shaping the spatial genetic structure of this species.     

Genetic structure and diversity of Coscinium fenestratum: a critically endangered liana of Western Ghats,India

Coscinium fenestratum is a critically endangered medicinal plant, well-known for its bioactive isoquinoline alkaloid berberine. The species has been over harvested from its natural habitats to meet the huge requirement of raw drug market and industrial consumption. This has lead to a rapid decline in the population size and has also led to local population extinction at few locations in the Western Ghats, India. In this study, inter-simple sequence repeat markers were used to investigate the genetic variation and population structure of seven extant populations of C. fenestratum from the central Western Ghats, India. Eight primer combination produced a total of 57 unambiguous bands, of which (47.1 %) were polymorphic. The species exhibited a moderate to low level of intra population genetic diversity (H _s = 0.347 ± 0.008; H _t = 0.378 ± 0.006 (POPGENE) and H _s = 0.262 ± 0.0028; H _t = 0.204 ± 0.020 (HICKORY)). The populations were low to moderately differentiated from one another (G _ST = 0.221) and geographical distance was not significantly correlated with genetic distance, suggesting that these long-lived, geographically distant remnant populations were once connected through gene flow. There was a significant amount of genetic variation among populations (19.85 %). The Bayesian software STRUCTURE and HICKORY were used to further reveal the genetic structure of C. fenestratum. The results revealed weak population structure (K = 2) with one single widespread gene pool, and indicated that gene flow and inbreeding are likely to be the major driving force in shaping current population genetic structure of C. fenestratum. Thus, an understanding of the genetic diversity and population structure of C. fenestratum can provide insight into the conservation and management of this species.     

Low levels of genetic variation within populations of the four rare orchids Gymnadenia cucullata, Gymnadenia camtschatica, Amitostigma gracile, and Pogonia minor in South Korea: indication of genetic drift and implications for conservation

Many terrestrial orchids are relatively rare, and their populations are small and spatially isolated. Population genetics theory predicts that populations of such species, affected historically by random genetic drift, would maintain low levels of genetic diversity and exhibit a high degree of among-population divergence. To test this prediction, I used enzyme electrophoresis. Genetic diversity within populations of the four rare, terrestrial orchids Gymnadenia cucullata (four populations) and its congener G. camtschatica (four populations), Amitostigma gracile (four populations in one region and three in another region), and Pogonia minor (three populations each in two regions) was investigated in South Korea at the landscape level. As predicted, populations of the four species harbor low levels of genetic diversity within populations: the mean percentage of polymorphic loci, %P, the mean number of alleles per locus, A, and the average expected heterozygosity, H _e, were 12.5%, 1.13, and 0.036 for G. cucullata, respectively; 18.2%, 1.18, and 0.067 for G. camtschatica; 3.0%, 1.04, and 0.009 for A. gracile; and 2.7%, 1.06, and 0.014 for P. minor. Except for G. camtschatica (F _ST = 0.000), a significantly high degree of genetic divergence between conspecific populations was detected in the other three species: F _ST = 0.081 for G. cucullata; 0.348 and 0.811 in two regions for A. gracile; and 0.469 and 0.758 in two regions for P. minor. In addition, individuals within populations are highly structured in the four species (overall F _IS = 0.276 for G. cucullata; 0.308 for G. camtschatica; 0.758 for A. gracile; and 0.469 for P. minor), suggesting that selfing, biparental inbreeding, and/or consanguineous mating have occurred in populations of the four species. With the exception of G. camtschatica, an allele at a locus is fixed in a population, whereas alternative alleles with low or high frequencies are detected in another population across the landscape. My results suggest that evolutionary histories of G. cucullata, A. gracile, and P. minor are different from G. camtschatica. Historical genetic drift would be an important force shaping the genetic structure of the Korean populations of G. cucullata, A. gracile, and P. minor. For G. camtschatica on Ulleung Island, relatively higher levels of genetic variation within populations compared to its congener G. cucullata (H _e = 0.067 vs. 0.036) and little evidence of population genetic structure among populations (F _ST = 0.000) suggest that individuals were, presumably, once continuously distributed on Ulleung Island, and populations have recently been isolated by habitat fragmentation through natural succession (e.g,. probably the encroachment of woody vegetation on grasslands) or human-mediated disturbances (e.g., collections). Thus, conservation strategies for the four species should be differently developed in order to preserve genetic diversity in South Korea.     

High level of genetic variation within clonal orchid Goodyera repens

Type of reproduction has an important effect on the maintenance of particular populations and species persistence in time and space. This trait significantly influences the ecological and genetic structure of populations, and in consequence the evolution of species. The primary objectives of this study were: to estimate genetic diversity within and among populations of clonal species Goodyera repens from different populations in northeastern Poland, and to amount factors shaping the genetic structure of this orchid. Based on 451 rosettes of G. repens from 11 localities in northeastern Poland, we conducted a genetic population analysis using allozymes. We included information on population size, flowering, fruit set and seed dispersal to elucidate their influences on genetic diversity of this species. Populations differed according to demographic properties. The majority of seeds (86.4–94.8 %) were found at a distance of 0.2 m. We observed a high level of genetic (P _PL = 50 %, A = 1.68, H _O = 0.210, H _E = 0.204) and genotypic diversity (G = 163, G/N _S = 0.66, G _U = 30.2 %), and low but statistically significant genetic differentiation among populations (F _ST = 0.060; P < 0.001). We suggest that the genetic diversity of G. repens is mainly an effect of the abundance of pine and spruce forest communities suitable for this species in NE Poland and the high level of sexual reproduction.     

Genetic structure in the paleoendemic and endangered Petagnaea gussonei (Spreng.) Rauschert (Saniculoideae, Apiaceae) and implications for its conservation

Our investigation aims to understand the genetic structure and evolutionary history of Petagnaea gussonei, an ancient and endangered species belonging to the Saniculoideae subfamily (Apiaceae). It is paleoendemic to Sicily, with a small number of populations in the Nebrodi Mountains. A total of seven chloroplast microsatellite repeat loci and 12 AFLP primer combinations were used to screen 115 individuals corresponding to 17 populations. The ratio of seed to pollen flow was also calculated using the modified Ennos equation. A relatively high level of genetic diversity was detected with AFLPs (e.g., 0.045 < H < 0.278), and a moderate variation was also found using cpSSRs (0 < Hk < 0.667). Two different haplotypes (B and W) were identified, with five populations being monomorphic for haplotype B. There was no genetic differentiation on the basis of haplotypic frequency (G _ST) and similarity (R _ST), and no phylogeographic structure was detected among the populations. AFLP values also confirmed that the populations are not very genetically differentiated. The principal component analysis based on pairwise genetic differences showed three groupings without a geographical correlation. The AMOVA analysis indicates that the amount of variation is higher within populations (82 %) than among populations (18 %). Results of the pollen flow/seed flow ratio indicated positive values for each population, indicating that gene flow by seed is not more efficient than by pollen. Instead, the total pollen/seed flow for all population presents a negative value, suggesting that pollen dispersal does not appear to be more effective over the long range for gene flow than seed dispersal. This differentiation level supports the hypothesis that the fragmentation and isolation of the residual populations is in progress. This phenomenon is due not only to post-ice age climate changes, but also to direct and indirect anthropic actions.     

The ‘paradigm of extremes’: extremely low genetic diversity in an extremely narrow endemic species, Coristospermum huteri (Umbelliferae)

Low levels of genetic diversity in endemic species are generally attributable to the small size of their populations. This lack of genetic variability will, predictably, be more evident in those species that occur in only one or a very few localities with a total population consisting of a few dozen individuals, or sometimes fewer (i.e. ‘extremely narrow endemics’, ENEs). We used allozyme electrophoresis to survey the genetic variability of Coristospermum huteri, an endemic species from the island of Majorca (Balearic Islands, W. Mediterranean Basin) with a single natural population of about 100 individuals. As expected, allozyme variability was virtually nil for this species (P = 8.3 %, A = 1.08, H _e = 0.022), which seems to be a general rule for ENEs (mean H _e = 0.057). A founder effect associated with a dispersal event from the continent is probably behind the lack of genetic diversity in this highly threatened species. Preservation of the mountain summit where the plant is found (Puig Major) is essential for the survival of C. huteri, and would also guarantee the conservation of other ENEs and rare and threatened species.     

Genetic Divergence and Signatures of Natural Selection in Marginal Populations of a Keystone,Long-Lived Conifer,Eastern White Pine (Pinus strobus) from Northern Ontario

Marginal populations are expected to provide the frontiers for adaptation, evolution and range shifts of plant species under the anticipated climate change conditions. Marginal populations are predicted to show genetic divergence from central populations due to their isolation, and divergent natural selection and genetic drift operating therein. Marginal populations are also expected to have lower genetic diversity and effective population size (N _e) and higher genetic differentiation than central populations. We tested these hypotheses using eastern white pine (Pinus strobus) as a model for keystone, long-lived widely-distributed plants. All 614 eastern white pine trees, in a complete census of two populations each of marginal old-growth, central old-growth, and central second-growth, were genotyped at 11 microsatellite loci. The central populations had significantly higher allelic and genotypic diversity, latent genetic potential (LGP) and N _e than the marginal populations. However, heterozygosity and fixation index were similar between them. The marginal populations were genetically diverged from the central populations. Model testing suggested predominant north to south gene flow in the study area with curtailed gene flow to northern marginal populations. Signatures of natural selection were detected at three loci in the marginal populations; two showing divergent selection with directional change in allele frequencies, and one balancing selection. Contrary to the general belief, no significant differences were observed in genetic diversity, differentiation, LGP, and N _e between old-growth and second-growth populations. Our study provides information on the dynamics of migration, genetic drift and selection in central versus marginal populations of a keystone long-lived plant species and has broad evolutionary, conservation and adaptation significance.     

Genetic variation and differentiation in Juniperus excelsa M. Bieb. populations in Turkey

Genetic variation within and among six populations of Juniperus excelsa M. Bieb., in a common garden in Lakes District of Turkey, was analyzed using four nuclear microsatellite primer pairs originally developed for J. communis. A total of five loci were observed as Jc037 amplified two distinct size ranges. The number of alleles observed for the species varied from 2 to 13, with an average of 4.5 alleles per locus. The mean expected heterozygosity (H _e) of populations was 0.584, after correction for null alleles. The mean F _IS value (?0.014) was close to zero showing no significant deviation from Hardy–Weinberg equilibrium. A low level of genetic differentiation was observed among populations (F _ST = 0.028; p < 0.001) and Nei’s genetic distance ranged from 0.014 to 0.120 between population pairs. Furthermore, there was no significant correlation between genetic distances on the one hand and geographic distances and trait differentiation on the other hand. However, the eastern populations Bey?ehir and Sorgun showed very similar genotypic structures and were differentiated from all other populations. A continuous monitoring of phenotypic traits and the association between nucleotide variation in functional genes and adaptive traits such as drought and frost tolerance of J. excelsa populations in common gardens will be useful to design effective conservation strategies in the future.     

Population genetic structure of wild daffodils (Narcissus pseudonarcissus L.) at different spatial scales

We studied the population genetic and clonal structure of the endangered long-lived perennial plant Narcissus pseudonarcissus using random amplified polymorphic markers. Estimates for mean gene diversity within 15 populations of N. pseudonarcissus of three neighbouring geographical regions were high in comparison to other long-lived perennials (H _eN = 0.33). The genetic diversity of the two smallest populations (<200 plants) was significantly reduced, indicating loss of genetic variability due to drift. The analysis of the population genetic structure revealed a significant genetic differentiation both between regions (Φ_ST = 0.06) and between populations within regions (Φ_ST = 0.20). However, there was incomplete correspondence between geographical regions and the population genetic structure. In order to preserve the overall genetic variation in wild populations of N. pseudonarcissus, management measures should thus aim to protect many populations in each region. The spatial genetic structure within populations of N. pseudonarcissus was in agreement with an isolation by distance model indicating limited gene flow due to pollinator behaviour and restricted seed dispersal. The very restricted spatial extent of clonal growth (<5 cm) and the high level of clonal diversity indicate that clonal growth in N. pseudonarcissus is not an important mode of propagation and that management measures should favour sexual reproduction in order to avoid further reductions in the size and number of populations.     

Effective Population Size,Genetic Variation,and Their Relevance for Conservation: The Bighorn Sheep in Tiburon Island and Comparisons with Managed Artiodactyls

The amount of genetic diversity in a finite biological population mostly depends on the interactions among evolutionary forces and the effective population size (N _e) as well as the time since population establishment. Because the N _e estimation helps to explore population demographic history, and allows one to predict the behavior of genetic diversity through time, N _e is a key parameter for the genetic management of small and isolated populations. Here, we explored an N _e-based approach using a bighorn sheep population on Tiburon Island, Mexico (TI) as a model. We estimated the current (N _crnt) and ancestral stable (N _stbl) inbreeding effective population sizes as well as summary statistics to assess genetic diversity and the demographic scenarios that could explain such diversity. Then, we evaluated the feasibility of using TI as a source population for reintroduction programs. We also included data from other bighorn sheep and artiodactyl populations in the analysis to compare their inbreeding effective size estimates. The TI population showed high levels of genetic diversity with respect to other managed populations. However, our analysis suggested that TI has been under a genetic bottleneck, indicating that using individuals from this population as the only source for reintroduction could lead to a severe genetic diversity reduction. Analyses of the published data did not show a strict correlation between H _E and N _crnt estimates. Moreover, we detected that ancient anthropogenic and climatic pressures affected all studied populations. We conclude that the estimation of N _crnt and N _stbl are informative genetic diversity estimators and should be used in addition to summary statistics for conservation and population management planning.     

Conservation genetics of the annual hemiparasitic plant <Emphasis Type="Italic">Melampyrum sylvaticum</Emphasis> (Orobanchaceae) in the UK and Scandinavia

Melampyrum sylvaticum is an endangered annual hemiparasitic plant that is found in only 19 small and isolated populations in the United Kingdom (UK). To evaluate the genetic consequences of this patchy distribution we compared levels of diversity, inbreeding and differentiation from ten populations from the UK with eight relatively large populations from Sweden and Norway where the species is more continuously distributed. We demonstrate that in both the UK and Scandinavia, the species is highly inbreeding (global F _IS = 0.899). Levels of population differentiation were high (F’_ST = 0.892) and significantly higher amongst UK populations (F’_ST = 0.949) than Scandinavian populations (F’_ST = 0.762; P < 0.01). The isolated populations in the UK have, on average, lower genetic diversity (allelic richness, proportion of loci that are polymorphic, gene diversity) than Scandinavian populations, and this diversity difference is associated with the smaller census size and population area of UK populations. From a conservation perspective, the naturally inbreeding nature of the species may buffer the species against immediate effects of inbreeding depression, but the markedly lower levels of genetic diversity in UK populations may represent a genetic constraint to evolutionary change. In addition, the high levels of population differentiation suggest that gene flow among populations will not be effective at replenishing lost variation. We thus recommend supporting in situ conservation management with ex situ populations and human-mediated seed dispersal among selected populations in the UK.     

Population genetic structure of the endangered Eastern Bristlebird, Dasyornis brachypterus; implications for conservation

For species that are habitat specialists or sedentary, population fragmentation may lead to genetic divergence between populations and reduced genetic diversity within populations, with frequent inbreeding. Hundreds of kilometres separate three geographical regions in which small populations of the endangered Eastern Bristlebird, Dasyornis brachypterus, a small, ground-dwelling passerine that occurs in fire-prone bushland in eastern Australia, are currently found. Here, we use mitochondrial and microsatellite DNA markers to: (i) assess the sub-specific taxonomy designated to northern range-edge, and central and southern range-edge D. brachypterus, respectively, and (ii) assess levels of standing genetic variation and the degree of genetic subdivision of remnant populations. The phylogenetic relationship among mtDNA haplotypes and their spatial distribution did not support the recognised subspecies boundaries. Populations in different regions were highly genetically differentiated, but in addition, the two largest, neighboring populations (located within the central region and separated by ~50 km) were moderately differentiated, and thus are likely closed to migration (microsatellites, F _ST = 0.06; mtDNA, F _ST = 0.12, ?? _ST = 0.08). Birds within these two populations were genotypically diverse and apparently randomly mating. A long-term plan for the conservation of D. brachypterus??s genetic diversity should consider individual populations as separate management units. Moreover, managers should avoid actively mixing birds from different populations or regions, to conserve the genetic integrity of local populations and avoid outbreeding depression, should further translocations be used as a recovery tool for this species.     

Genetic diversity and population genetic structure of wild banana Musa ornata (Musaceae) in Mexico

The wild banana Musa ornata is an inhabitant of the tropical regions of Mexico characterized by patches of tropical rainforest. The overexploitation of its habitat has caused the extinction of several populations affecting diversity and population genetic structure of remaining ones. We used microsatellite markers to determine the genetic diversity and the population’s genetic structure of all extant populations. The thirty-two microsatellite loci previously characterized for M. acuminata and M. balbisiana were tested in M. ornata. Only twelve amplified. From these seven were polymorphic and were used for genetic analyses. The Nei’s diversity estimator shows low levels of genetic diversity (H _e = 0.263) with a mean of 4.40 alleles per locus. Excess homozygosity was evident in all populations indicating high levels of inbreeding. F _ST pairwise analyses and AMOVA indicated low genetic differentiation. However, 28 % of private alleles were registered, suggesting limited gene flow. Genetic distances, Jaccard’s coefficient and principal component analysis showed a good correspondence to geographical locations. The Mantel test performed was not significant. The results support the hypothesis of recent fragmentation events; therefore, not enough time has passed to detect differences between populations. However, it is also likely that results are caused by factors such as bottleneck, decline in pollinator populations, self-pollination and/or a tendency towards clonal reproduction. It is proposed that the preservation strategy focuses on maintaining all the remaining populations and ensuring their connectivity, so as to maintain gene flow and increase the genetic diversity of this species.     

<Emphasis Type="Italic">Parnassius apollo nevadensis</Emphasis>: identification of recent population structure and source–sink dynamics

Population persistence depends in many cases on gene flow between local populations. Parnassius apollo nevadensis is an endemic subspecies of Apollo butterfly in the Sierra Nevada (southern Spain), whose populations are distributed in discrete patches at altitudes between 1850 and 2700 m. In this paper, we use 13 microsatellite loci to examine the genetic structure of this P. apollo subspecies. We revealed both a strong pattern of isolation by distance (which was stronger when calculated with realistic travel distances that accounted for topography) and source–sink dynamics. The observed population genetic structure is consistent with strongly asymmetrical gene flow, leading to constant directional migration and differential connectivity among the populations. The apparently contradictory results from the clustering algorithms (Structure and Geneland) are also consistent with a recent (<100 ya) reduction in the distribution range. The results point to global warming as a possible cause of this reduction, as in other populations of this species. We identify some natural and anthropogenic barriers to gene flow that may be the cause of the recent population structure and source–sink dynamics.     

Contrasting spatial genetic structure in Annona crassiflora populations from fragmented and pristine savannas

In continuous populations, fine-scale genetic structure tends to be stronger in species with restricted pollen and seed dispersal. However, habitat fragmentation and disturbances can affect genetic diversity and spatial genetic structure due to disruption in ecological processes, such as plant reproduction and seed dispersal. In this study, we compared the genetic diversity and fine-scale spatial genetic structure (SGS) in two populations of Annona crassiflora (Annonaceae) in a pristine savanna Reserve (ESECAE) and in a fragmented disturbed savanna area (PABE), both in Cerrado biome in Central Brazil. The analyses were based on the polymorphism at 10 microsatellite loci. Our working hypothesis was that SGS is stronger and genetic diversity is lower in population at fragmented area (PABE) than at pristine area (ESECAE). Both populations presented high levels of polymorphism and genetic diversity and showed no sign of bottleneck for both Wilcoxon sign-rank test for heterozygosity excess (p > 0.05) and coalescent analyses (growth parameter g not different from zero), but population at fragmented area showed higher fixation index and stronger SGS. Besides, populations are significantly differentiated (F _ST = 0.239, R _ST = 0.483, p < 0.001 for both). Coalescent analyses showed high historical effective population sizes for both populations, high gene flow between ESECAE and PABE and recent time to most recent common ancestor (~37 k year BP). Our results suggest that despite the high genetic diversity, fragmentation and disturbance may have been affecting populations of this species increasing mating between closely related individuals leading to high fixation index and strong SGS.