Different patterns of genetic structure of relict and isolated populations of endangered peat-bog pine (Pinus uliginosa Neumann)

Recent changes in environmental conditions in populations of peat-bog pine (Pinus uliginosa Neumann) caused rapid decline or even extinction of the species in several stands in Central Europe. Conservation strategies forP. uliginosa require information about the evolutionary history and genetic structure of its populations. Using isozymes we assessed the genetic structure ofP. uliginosa from four isolated stands in Poland and compared the results to genetic structures of other closely related pine species including eight populations ofPinus mugo, ten ofPinus sylvestris and one ofPinus uncinata. The level of genetic variability ofP. uliginosa measured by the mean number of alleles per locus and average heterozygosity was similar to others related toP. uliginosa taxa from the reference group but it differs among populations. High genetic similarity was found between two populations ofP. uliginosa from Low Silesian Pinewood. The populations were genetically distinct as compared to other populations includinglocus classicus of the species from the peat bog at Batorów Reserve. Very low genetic distance (D_n = 0.002) and small genetic differentiation (GST = 0.003) were found betweenP. uliginosa andP. mugo in the sympatric populations of the species from Zieleniec peat bog suggesting the ongoing natural hybridisation and genetic contamination of peat-bog pine from this area. Some evidence for skew in allele frequency distribution potentially due to recent bottleneck was found in population from Low Silesian Pinewood. The analysed open pollinated progeny derived from twoP. uliginosa stands from Low Silesian Pine-wood showed the excess of homozygotes as compared to the maternal trees indicating high level of inbreeding (F = 0.105,F = 0.081). The results are discussed in the context of evolution ofP. uliginosa populations, taxonomic relationships between the analysed species and conservation strategies for active protection of peat-bog pine.     

Genetic variability of Siberian fir <Emphasis Type="Italic">Abies sibirica</Emphasis> Ledeb. inferred from AFLP markers

Genetic variability of AFLP markers was studied in 20 populations of Siberian fir (Abies sibirica, Pinaceae) and in two populations of Far-Eastern species Manchurian fir A. nephrolepis and Sakhalin fir A. sachalinensis each. Four pairs of selective primers were used. In total, 168 samples from three fir species were genotyped for 117 polymorphic loci. According to the AMOVA results, the variability proportion characterizing the differences among three Abies species was several times higher (F _CT = 0.53) than that acounting for population differences within the species (F _SC = 0.125). Differentiation of the A. sibirica populations based on AFLP markers exceeded 14% (F _ST = 0.141). Significant correlation between the genetic distances calculated from the AFLP data and the geographic distances between populations was found. The results of AFLP variability analysis supported and supplemented the conclusions inferred previously from allozyme and cpSSR data: several genetically similar geographic groups of Siberian fir were identified. These groups differ both in allele frequencies and in the levels of genetic variation.     

High population differentiation and genetic variation in the endangered Mexican pine Pinus Rzedowskii (Pinaceae)

Pinus rzedowskii is an endangered pine species from Michoaca´n (central Me´xico), which has been previously reported from only three localities. Classified within the subgenus Strobus, it exhibits intermediate morphological characters between subgenera Strobus and Pinus. We analyzed genetic aspects that could shed light on the evolution and conservation of this species. The genetic structure of nine populations was examined using 14 isozyme loci. Pinus rzedowskii has a relatively high level of genetic variation with 46.8% of the loci assayed being polymorphic, a total of 35 alleles, and a mean heterozygosity per population of 0.219. We calculated Wright's F_ST statistic to estimate gene flow indirectly and to evaluate whether or not there was genetic structuring among populations. We found a marked differentiation among populations (F_ST = 0.175) and significant inbreeding (F_IS = 0.247). No pattern of isolation by distance was found. We also constructed a dendrogram based on a genetic distance matrix to obtain an overview of the possible historical relationships among populations. Finally, we found a convex relationship between the genetic distance among populations and the number of ancestral lineages, suggesting that demographically this species has not been at risk recently. Although endangered, with small and fragmented populations, P. rzedowskii shows higher levels of genetic variation than other conifer species with larger populations or similar conservation status.     

Diversity and genetic structure of three species of Dioon Lindl. (Zamiaceae, Cycadales) from the Pacific seaboard of Mexico

We have estimated levels of genetic diversity and partitioning in the Mexican endemic cycad species Dioon sonorense, Dioon tomasellii, and Dioon holmgrenii, whose populations are exclusively distributed along the Pacific seaboard. For the three species, the patterns of variation at 19 allozyme loci in a total of 11 populations were evaluated. The average number of alleles per locus was in the range 2.05–1.68, corresponding to the northernmost population of D. sonorense (Mazatán), and the southernmost population of Dioon holmgrenii (Loxicha), respectively. In turn, the percentage of polymorphic loci peaked (94.73) in the El Higueral and Altamirano populations of Dioon tomasellii, and was estimated to be lowest (57.89) in the Loxicha population of D. holmgrenii. The mean expected heterozygosis varied markedly between taxa, with relatively high indices for D. sonorense and D. tomasellii (H_E = 0.314 and 0.295, respectively) and substantially lower values for D. holmgrenii (H_E = 0.170). Comparison of the inferred genetic structure based on F‐statistics for the three species also indicated differences along the north‐south Pacific seaboard axis. For D. sonorense and D. tomasellii, local inbreeding (F_IS) was zero but global inbreeding (F_IT) values were positive and significantly different from zero (0.130 and 0.116, respectively). By contrast, values of both F_IT and F_IS were negative and significantly different from zero (?0.116 and ?0.201, respectively) for D. holmgrenii. The genetic differentiation between populations (F_ST) had positive values in all taxa and corresponded with their geographic location along the north‐south axis: according to this statistic, D. sonorense was the most differentiated species (F_ST = 0.151), D. tomasellii had intermediate values (F_ST = 0.145), and D. holmgrenii was the less differentiated taxon (F_ST = 0.069). Finally, a phenogram representing Nei's genetic distances among populations displayed three major groups, each one corresponding to each of the studied species. Within D. tomasellii (of intermediate geographic distribution), a further division into two clusters corresponded precisely to the pair of populations that are geographically divided by the Trans Mexican Neovolcanic Mountains. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94 , 765–776.     

Genetic structures of allopatric and sympatric populations in Pseudorasbora pumila pumila and Pseudorasbora parva

Pseudorasbora pumila pumila was collected to investigate its genetic relationships from 11 localities in Hokkaido and eastern Honshu of Japan with Pseudorasbora parva from 6 localities in Hokkaido, eastern Honshu, and Polovynka River (a tributary of the Amur River in eastern Russia) in 1996–1998. In Hokkaido and Akita prefectures (Honshu), three P. pumila pumila populations were distributed with P. parva sympatrically. Samples of P. pumila pumila and P. parva were analyzed based on 27 allozyme loci. Genetic differentiation between P. pumila pumila and P. parva (D = 0.522–0.622, average 0.601) was almost equal to or greater than that between other congeneric fish species previously reported. In the three sympatric populations of two species, which had arisen from artificial transplantation of the latter into localities of the former, the individual frequency composition of genetic types (P. pumila pumila, P. parva, F₁ hybrid, and later filial generation hybrid) were significantly different from each other. Differing from the previous studies, F₁ hybrids were fertile and coexisting populations of the two species included the F₁ hybrid and the later filial generation hybrid. These results suggest that genetic population dynamics of sympatric populations of the two species would be influenced not only by hybridization but also by ecological and environmental factors. Alternatively, the existence of populations that possessed both the alleles specific to P. pumila pumila and those specific to P. parva may indicate that introgressive hybridization, instead of species displacement, has occurred between the two species under a certain condition.     

Variation in the chloroplast DNA of Swiss stone pine (Pinus cembra L.) reflects contrasting post-glacial history of populations from the Carpathians and the Alps

Aim To characterize the genetic structure and diversity of Pinus cembra L. populations native to two disjunct geographical areas, the Alps and the Carpathians, and to evaluate the rate of genetic differentiation among populations. Location The Swiss Alps and the Carpathians. Methods We screened 28 populations at three paternally inherited chloroplast simple sequence repeats (cpSSRs) for length variation in their mononucleotide repeats. Statistical analysis assessed haplotypic variation and fixation indices. Hierarchical analysis of molecular variance (AMOVA), Mantel test, spatial analysis of molecular variance (SAMOVA) and barrier analyses were applied to evaluate the geographical partitioning of genetic diversity across the species’ range. Results Haplotypic diversity was generally high throughout the natural range of P. cembra, with the mean value substantially higher in the Carpathians (H = 0.53) than in the Alps (H = 0.35). The isolated Carpathian populations showed the highest haplotype diversity among the populations originating from the High Tatras (Velka Studena Dolina) and South Carpathians (Retezat Mountains). AMOVA revealed that only 3% of the total genetic variation derived from genetic differentiation between the two mountain ranges. Differentiation among Carpathian populations was higher (F_ST = 0.19) than among Alpine populations (F_ST = 0.04). Low, but significant, correlation was found between the geographical and genetic distances among pairs of populations (r = 0.286, P < 0.001). SAMOVA results revealed no evident geographical structure of populations. barrier analysis showed the strongest differentiation in the eastern part of the species’ range, i.e. in the Carpathians. Main conclusions The populations of P. cembra within the two parts of the species’ range still share many cpDNA haplotypes, suggesting a common gene pool conserved from a previously large, continuous distribution range. Carpathian populations have maintained high haplotypic variation, even higher than Alpine populations, despite their small population sizes and spatial isolation. Based on our results, we emphasize the importance of the Carpathian populations of Swiss stone pine for conservation. These populations comprise private haplotypes and they may represent a particular legacy of the species’ evolutionary history.     

Genetic structure of Polytrichum formosum in relation to the breeding system as revealed by microsatellites

Microsatellite variation was determined for three Danish and three Dutch populations of the haploid moss species Polytrichum formosum to gain insight into the relative importance of sexual vs. asexual reproduction for the amount and structure of genetic variation. In general, low levels of microsatellite variation were observed within this species. Even when estimated for polymorphic loci only, the levels of microsatellite variability (P=90.6, A=4.3 and H_S=0.468) within populations were on average lower than those reported for most other plant species. In contrast, genotypic diversity was high within each of the examined populations, indicating that sexual reproduction is a very important determinant of the genetic structure of P. formosum within populations. In agreement with previous findings for allozyme data, no significant genetic differentiation (F_ST=0.028, R_ST=0.015) was observed neither between populations nor between regions approximately 450 km apart (Denmark vs. the Netherlands). These low levels of population differentiation observed for both types of genetic markers are probably best explained by a high level of effective spore dispersal (gene flow) between populations. Therefore, also on a large geographical scale sexual reproduction is the most important determinant of the genetic structure of P. formosum, despite the high potential to reproduce clonally.     

Characterization of gene pools of three <Emphasis Type="Italic">Pinus pumila</Emphasis> (Pall.) Regel populations at the range margins

Genetic variation of Siberian dwarf pine Pinus pumila (Pall.) Regel was characterized in three marginal populations in southwestern, southern and eastern parts of the natural species range (Baikal Area, Primorye, Kamchatka) using isozyme analysis. Analysis involving 16 isozyme loci encoding ten enzyme systems was conducted. Our results confirm that P. pumila is one of the most polymorphic species in the genus Pinus. Three marginal populations exhibited high genetic variation (P ₉₅ = 68.8%, H _o = 0.247, H _e = 0.291). Populations heterogeneity and significantly high level of divergence in coniferous (F _ST = 0.050, D _N = 0.044) reflect their genetic originality. In summary, it was shown that the level of genetic variation characteristic for P. pumila in other parts of the not only is reproduced in the populations examined but even is close to maximum there.     

Population Genetic Structure of Two Columnar Cacti with a Patchy Distribution in Eastern Brazil

The genetic variability and population genetic structure of six populations of Praecereus euchlorus and Pilosocereus machrisii were investigated. The genetic variability in single populations of Pilosocereus vilaboensis, Pilosocereus aureispinus, and Facheiroa squamosa was also examined. All of these cacti species have a patchy geographic distribution in which they are restricted to small areas of xeric habitats in eastern Brazil. An analysis of genetic structure was used to gain insights into the historical mechanisms responsible for the patchy distribution of P. euchlorus and P. machrisii. High genetic variability was found at the populational level in all species (P=58.9–92.8%, A_p=2.34–3.33, H_e=0.266–0.401), and did not support our expectations of low variability based on the small population size. Substantial inbreeding was detected within populations (F_IS=0.370–0.623). In agreement with their insular distribution patterns, P. euchlorus and P. machrisii had a high genetic differentiation (F_ST=0.484 and F_ST=0.281, respectively), with no evidence of isolation by distance. Accordingly, estimates of gene flow (N_m) calculated from F_ST and private alleles were below the level of N_m=1 in P. machrisii and P. euchlorus. These results favored historical fragmentation as the mechanism responsible for the patchy distribution of these two species. The genetic distance between P. machrisii and P. vilaboensis was not compatible with their taxonomic distinction, indicating a possible local speciation event in this genus, or the occurrence of introgression events.     

Population Genetic structure ofPotentilla fragariodes var.major (Rosaceae) in Korea

The genetic diversity and population structure of eighteenPotentilla fragariodes var.major (Rosaceae) populations in Korea were determined using genetic variations at 22 allozyme loci. The percent of polymorphic loci within the enzymes was 66.7%. Genetic diversity at the species level and at the population level was high (Hes = 0.203; Hep = 0.185, respectively), whereas the extent of the population divergence was relatively low (G_ST = 0.069). F_IS, a measure of the deviation from random mating within the 18 populations, was 0.075. An indirect estimate of the number of migrants per generation (Nm = 3.36) indicated that gene flow was high among Korean populations of the species. In addition, analysis of fixation indices revealed a slight heterozygote deficiency in some populations and at some loci. Wide geographic ranges, perennial herbaceous nature and the persistence of multiple generations are associated with the high level of genetic variation. AlthoughP. fragariodes var.major usually propagated by asexually-produced ramets, we could not rule out the possibility that sexual reproduction occurred at a low rate because each ramet may produce terminal flowers. Mean genetic identity between populations was 0.983. It is highly probable that directional movement toward genetic uniformity in a relatively homogeneous habitat operates among Korean populations ofP. fragariodes var.major.     

Genetic diversity of nectar‐rewarding Platanthera chlorantha and nectarless Cephalanthera rubra

We examined the genetic diversity of two orchid species, the nectar‐rewarding Platanthera chlorantha and the nectarless Cephalanthera rubra, in north‐eastern Poland. We found lower differences in genetic diversity between the species than we expected. The level of genetic variation at species level was lower in C. rubra (P_POL = 14%, A = 1.14 and H_E = 0.060) than in P. chlorantha (P_POL = 25.5%, A = 1.35 and H_E = 0.078). In the majority of populations of both species a high proportion of unique genotypes was noted. The overall F_ST values for all populations were moderate and similar for both species (P. chlorantha: 0.251, P < 0.001; C. rubra: 0.267, P < 0.001). No relationship was found between genetic and geographical distances in either species (P > 0.05, Mantel test). We discuss the breeding systems, small population size and population subdivision as the most important factors affecting the genetic diversity of this species. We suggest that conservation programmes should be initiated to maintain or even increase the fitness and genetic variation of populations of both species. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013 , 171 , 751–763.     

Allozyme variation in the diploid (A genome) populations ofScilla scilloides (Hyacinthaceae)

Allozyme variation at eleven loci encoding seven enzyme systems were examined in 20 populations of diploid (genome AA, 2n = 16)Scilla scilloides in China. In comparison with the average species of seed plants studied, populations of this species display a high amount of genetic variation (A = 2.0, P = 58.6%, H_o = 0.172, and H_e = 0.185). Allozyme variation pattern revealed predominant outcrossing within populations and considerable differentiation (F_ST = 0.314) among populations as well as between the subtropic and temperate regions. The wide distribution, long existence and outcrossing are presumably the main factors responsible for the high genetic diversity within populations. But the gravity dispersal of seeds and pollination by small insects set limits to the increase of genetic variation within populations and promote differentiation between populations and regions. In addition, allozyme variation does not distinguishS. scilloides var.albo-viridis and suggests that subtropic populations may be considered as a genetic entity.     

Taxonomic and population differentiation of mitochondrial diversity inPinus banksiana andPinus conforta

We have studied two mitochondrial DNA polymorphisms in 741 individuals from 16 allopatric populations ofPinus banksiana Lamb. andPinus contorta Dougl. Restriction fragments of both polymorphisms distinguished the two species qualitatively, except in aP. Banksiana population whose ancestors were involved in hybridization withP. contorta.COXI-associated restriction fragments were monomorphic within species, whileCOXII-associated restriction fragments were highly variable inP. contorta (H_es=0.68). Population differentiation was substantial inP. contorta (F_st=0.31 among subspecies; mean F_st=0.66 within subspecies) and consistent with predictions for maternally inherited markers. Plant mitochondrial markers appear to be useful for the investigation of seed migration routes, hybridization and introgression, breeding zone designation, and the development of germ plasm conservation sampling strategies.     

Effects of concentrated carbon dioxide on the fruiting of several cultivated basidiomycetes (II)

Edible basidiomycetesFlammulia velutipes andPleurotus ostreatus were cultivated in the usual manner on media based on sawdust and rice bran, and the cultures were exposed to slowly flowing CO₂-enriched air (550 (control), 3,000, 6,000, and 9,000µl/l) for seven days at different stages of cultivation. When the cultures were exposed at the primordium stage (less than 10 mm in length), length and yield of fruit-bodies increased and pileus expansion was slightly inhibited inF. velutipes, while inP. ostreatus length increased, yield decreased, and pileus expansion was greatly inhibited. When the cultures with fruit-bodies larger than 10 mm were exposed, length and yield were insensitive and pileus expansion was greatly inhibited inF. velutipes, while inP. ostreatus length was insensitive, but pileus expansion was heavily damaged by trumpet-like deformation and yield decreased. The different action of CO₂ on the two species appeared to be due to the different anatomical structures of their fruit-bodies.     

Genetic diversity of insular natural populations of <Emphasis Type="Italic">Festuca pratensis</Emphasis> Huds.: RAPD analysis

In natural populations of Festuca pratensis Huds. from the islands of Onega Lake, the level of genetic diversity was evaluated. In three populations variability of 64 RAPD loci was tested. The level of genetic diversity (P _95% = 30.2; H _exp = 0.093) was low for a cross-pollinating plant species. Furthermore, genetic similarity between the plants from insular populations was found to be high (I _N = 0.887). It was demonstrated that genetic variation among the population accounted for at most 5.3% of total genetic diversity, which, however, was higher than the F _ST values for continental populations (F _ST = 0.022). It was suggested that specific features of the genetic structure of insular population, i.e., low gene diversity within the populations along with high differentiation among the populations, were caused by the gene flow attenuation, as a result of isolation, and intensification of inbreeding. These features had negative effect on total population adaptation.     

Genetic variability and individual assignment of Chinese indigenous sheep populations (Ovis aries) using microsatellites

The purpose of this study was to assess the genetic characteristics of six breeds of Chinese local sheep using 19 microsatellite loci and to effectively validate statistical methods for individual assignment based on informative microsatellites. All the six breeds deviated from Hardy–Weinberg equilibrium expectations, while the majority of markers complied. The polymorphism information content (PIC) of overall loci for the six populations ranged from 0.283 (SRCRSP5) to 0.852 (OarVH72). Tibetan sheep were the most diverse population with the highest mean allelic richness (6.895), while Ujmuqin (UQ) harboured the lowest allelic richness (6.000). The F‐statistics for the six populations were F_IS = ?0.172, F_IT = ?0.082 and F_ST = 0.077, respectively. Furthermore, the pair‐wise F_IS revealed a moderate genetic differentiation among populations (P < 0.01), indicating that all breeds can be considered genetically independent entities. The lowest genetic differentiation was between Tengchong (TC) and UQ (F_ST = 0.041), and the highest one was between TC and Fat‐tailed Han (F_ST = 0.111). In comparing the three statistical models, we note that the seven microsatellite loci (MAF65, OarJMP58, SRCRSP9, MCM140, OarAE129, BM8125 and SRCRSP5) commonly used for individual assignment will ensure a powerful detection of individual origin, with accuracy up to 91.87%, when the likelihood‐based method is used. Overall, these findings shed light onto the genetic characteristics of Chinese indigenous sheep and offer a set of microsatellite loci that is simple, economic and highly informative for individual assignment of Chinese sheep.     

Chilling and freezing stress in live oaks (Quercus section Virentes): intra- and inter-specific variation in PS II sensitivity corresponds to latitude of origin

Sensitivity to cold and freezing differs between populations within two species of live oaks (Quercus section Virentes Nixon) corresponding to the climates from which they originate. Two populations of Quercus virginiana (originating from North Carolina and north central Florida) and two populations of the sister species, Q. oleoides, (originating from Belize and Costa Rica) were grown under controlled climate regimes simulating tropical and temperate conditions. Three experiments were conducted in order to test for differentiation in cold and freezing tolerance between the two species and between the two populations within each species. In the first experiment, divergences in response to cold were tested for by examining photosystem II (PS II) photosynthetic yield (ΔF/F _m′) and non-photochemical quenching (NPQ) of plants in both growing conditions after short-term exposure to three temperatures (6, 15 and 30°C) under moderate light (400 μmol m⁻² s⁻¹). Without cold acclimation (tropical treatment), the North Carolina population showed the highest photosynthetic yield in response to chilling temperatures (6°C). Both ecotypes of both species showed maximum ΔF/F _m′ and minimum NPQ at their daytime growth temperatures (30°C and 15°C for the tropical and temperate treatments, respectively). Under the temperate treatment where plants were allowed to acclimate to cold, the Q. virginiana populations showed greater NPQ under chilling temperatures than Q. oleoides populations, suggesting enhanced mechanisms of photoprotective energy dissipation in the more temperate species. In the second and third experiments, inter- and intra-specific differentiation in response to freezing was tested for by examining dark-adapted F _v/F _m before and after overnight freezing cycles. Without cold acclimation, the extent of post-freezing declines in F _v/F _m were dependent on the minimum freezing temperature (0, −2, −5 or −10°C) for both populations in both species. The most marked declines in F _v/F _m occurred after freezing at −10°C, measured 24 h after freezing. These declines were continuous and irreversible over the time period. The North Carolina population, however, which represents the northern range limit of Q. virginiana, showed significantly less decline in F _v/F _m than the north central Florida population, which in turn showed a lower decline in Fv/F _m than the two Q. oleoides populations from Belize and Costa Rica. In contrast, after exposure to three months of chilling temperatures (temperate treatment), the two Q. virginiana populations showed no decline in F _v/F _m after freezing at −10°C, while the two Q. oleoides populations showed declines in F _v/F _m reaching 0.2 and 0.1 for Costa Rica and Belize, respectively. Under warm growth conditions, the two species showed different F ₀ dynamics directly after freezing. The two Q. oleoides populations showed an initial rise in F ₀ 30 min after freezing, followed by a subsequent decrease, while the Q. virginiana populations showed a continuous decrease in F ₀ after freezing. The North Carolina population of Q. virginiana showed a tendency toward deciduousness in response to winter temperatures, dropping 58% of its leaves over the three month winter period compared to only 6% in the tropical treatment. In contrast, the Florida population dropped 38% of its leaves during winter. The two populations of the tropical Q. oleoides showed no change in leaf drop during the 3-months winter (10% and 12%) relative to their leaf drop over the same timecourse in the tropical treatment. These results indicate important ecotypic differences in sensitivity to freezing and cold stress between the two populations of Q. virginiana as well as between the two species, corresponding to their climates of origin.     

The postglacial history of Scots pine (Pinus sylvestris L.) in western Europe: evidence from mitochondrial DNA variation

The geographical structure of mitochondrial (mt)DNA variants (mitotypes) was investigated in 38 western European populations of Scots pine Pinus sylvestris using restriction fragment length polymorphism (RFLP) analysis of total DNA and a homologous cox1 probe. Three major mitotypes (designated a, b and d ) were detected. Within Spain all three major mitotypes were found, gene diversity was high, H_T = 0.586, and this diversity was distributed predominantly among rather than within populations (F_ST(M) = 0.813 for the seven Spanish populations). Mitotype d was present only in the most southerly population from the Sierra Nevada . Elsewhere in Europe, populations showed little or no mtDNA diversity within regions, but there were marked differences between regions. Italian populations were fixed for mitotype b ; populations from northern France, Germany, Poland, Russia and southern Sweden were fixed for mitotype a ; while populations in northern Fennoscandia were fixed for mitotype b . The isolated Scottish populations were predominantly of mitotype a , but mitotype b was present in three of the 20 populations scored. In Scotland, UK gene diversity (H_T = 0.120) and genetic differentiation among populations (F_ST(M) = 0.37) was much lower than in Spain. When interpreted in the light of complementary data from pollen analysis and nuclear genetic markers, the results suggest that present-day populations of P. sylvestris in western Europe have been derived from at least three different sources after glaciation.     

Contemporary habitat loss reduces genetic diversity in an ecologically specialized butterfly

Aim This study investigated the influence of contemporary habitat loss on the genetic diversity and structure of animal species using a common, but ecologically specialized, butterfly, Theclinesthes albocincta (Lepidoptera: Lycaenidae), as a model. Location South Australia. Methods We used amplified fragment length polymorphism (AFLP) and allozyme datasets to investigate the genetic structure and genetic diversity among populations of T. albocincta in a fragmented landscape and compared this diversity and structure with that of populations in two nearby landscapes that have more continuous distributions of butterflies and their habitat. Butterflies were sampled from 15 sites and genotyped, first using 363 informative AFLP bands and then using 17 polymorphic allozyme loci (n = 248 and 254, respectively). We complemented these analyses with phylogeographic information based on mitochondrial DNA (mtDNA) haplotype information derived from a previous study in the same landscapes. Results Both datasets indicated a relatively high level of genetic structuring across the sampling range (AFLP, F_ST = 0.34; allozyme, F_ST = 0.13): structure was greatest among populations in the fragmented landscape (AFLP, F_ST = 0.15; allozyme, F_ST = 0.13). Populations in the fragmented landscape also had significantly lower genetic diversity than populations in the other two landscapes: there were no detectable differences in genetic diversity between the two continuous landscapes. There was also evidence (r² = 0.33) of an isolation by distance effect across the sampled range of the species. Main conclusions The multiple lines of evidence, presented within a phylogeographic context, support the hypothesis that contemporary habitat fragmentation has been a major driver of genetic erosion and differentiation in this species. Theclinesthes albocincta populations in the fragmented landscape are thus likely to be at greater risk of extinction because of reduced genetic diversity, their isolation from conspecific subpopulations in other landscapes, and other extrinsic forces acting on their small population sizes. Our study provides compelling evidence that habitat loss and fragmentation have significant rapid impacts on the genetic diversity and structure of butterfly populations, especially specialist species with particular habitat preferences and poor dispersal abilities.     

Molecular biogeography of the arctic-alpine disjunct burnet moth species Zygaena exulans (Zygaenidae, Lepidoptera) in the Pyrenees and Alps

Aim The phylogeography of ‘southern’ species is relatively well studied in Europe. However, there are few data about ‘northern’ species, and so we studied the population genetic structure of the arctic‐alpine distributed burnet moth Zygaena exulans as an exemplar. Location and methods The allozymes of 209 individuals from seven populations (two from the Pyrenees, five from the Alps) were studied by electrophoresis. Results All 15 analysed loci were polymorphic. The mean genetic diversities were moderately high (A: 1.99; H_e: 11.5; P: 65%). Mean genetic diversities were significantly higher in the Alps than in the Pyrenees in all cases. F_ST was 5.4% and F_IS was 10%. Genetic distances were generally low with a mean of 0.022 between large populations. About 62% of the variance between populations was between the Alps and the Pyrenees. The two samples from the Pyrenees had no significant differentiation, whereas significant differentiation was detected between the populations from the Alps (F_ST = 2.8%, P = 0.02). Main conclusion Zygaena exulans had a continuous distribution between the Alps and the Pyrenees during the last ice age. Most probably, the species was not present in Iberia, and the samples from the Pyrenees are derived from the southern edge of the glacial distribution area and thus became genetically impoverished. Post‐glacial isolation in Alps and Pyrenees has resulted in a weak genetic differentiation between these two disjunct high mountain systems.