Genetic and morphologic diversity of European fan palm (Chamaerops humilis L.) populations from different environments from Sicily

Chamaerops humilis is decreasing in abundance in Mediterranean Europe, which has induced the European community to call for its protection in Special Areas of Conservation. However, information about its genetic and morphological variability, which is crucial to the development of any conservation strategies, is insufficient. The present study aimed to investigate the genetic and morphological variability of C. humilis in Sicily, which was selected as a model because of the high number of dense populations. The relationships between morphological traits and climatic variables were studied to highlight patterns of adaptation to the environment, along with the genetic similarity among the populations. Ten natural populations were sampled, analyzed using 28 specifically designed SSR primers, and evaluated based on 29 morphological traits. The populations were clustered similarly based on genetic and morphological traits. Heterozygosity was high and inbreeding coefficients were low. These results, along with higher intra‐ than inter‐population differentiation, suggest that C. humilis populations in Sicily differentiated from a common ancestor and that inter‐population variation arose from secondary evolution processes induced by ecological adaptation. The correlations between climatic variables and morphological traits suggest that the morphological adaptation to arid environments depends more on summer temperatures than on evapotranspiration or rainfall and that autumn and winter temperatures are determinants of the species establishment at new sites. Considering the response of C. humilis to seasonal temperatures, the present results indicate this species as a candidate for tracking climatic changes in Europe. Further studies are needed to highlight the adaptation of C. humilis to cold environments. Palaeo‐climatological and ‐ecological studies could help clarify its strategies for the colonization of new sites. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 66–81.     

Allozyme diversity and systematics inAnnonaceae—a pilot project

Five species ofAnnona and one species fromArtabotrys, Cananga, Polyalthia, andRollinia were investigated in regard to 11 different allozyme loci. Preliminary studies on small population samples ofAnnona suggest genetic uniformity in three species and variability within and between populations in two other species. The allotetraploid origin ofA. glabra is clearly shown by its hybrid enzyme bands. The genetic distance between fiveAnnona species partly corresponds with their morphological relationships; onlyA. muricata appears more separated than is suggested by morphology. A comparison of the five genera demonstrates close relationship betweenAnnona andRollinia. Two enzyme loci are identical within all taxa investigated and possibly may serve as a genetic marker for the family.     

Genetic variability within and between the troops of toque macaque,Macaca sinica,in Sri Lanka

Genetic variability within and between the troops of toque macaque in Sri Lanka was studied from a population genetical perspective. Studies were made using electrophoretical blood protein variations as markers in order to clarify the genetic characteristics of the population of this species. A total of 256 samples from 20 troops which were collected in the field in 1981 to 1982 and 1983 to 1984 were examined for 32 blood protein loci. Eleven loci, that is, Tf, Alb, TBPA, Hb-α, PHI, PGM-II, CA-I, IDH, AK, ADA, and Ch-E showed the polymorphism in one or more troops. Of these 11 loci, 7 loci, that is, Tf, TBPA, Hb-α, PHI, PGM-II, CA-I, and IDH were highly polymorphic in most troops. The genetic variability within troops were quantified as H=0.0782 in average and this value was on higher level than other primates and comparable with that of continental macaques,Macaca fascicularis, in Thailand. The genetic differentiation between troops was quantified byG _ST andF _ST and these values were relatively smaller than those of other insular macaques.     

Genetic Relationships among Far Eastern Species of the Family Araliaceae Inferred by RAPD Analysis

A molecular genetic study of Far Eastern species of the family Araliaceae by means of RAPD analysis was conducted. Using 21 primers we assessed variability at 595 loci. Based on matrices of genetic distances D, dendrograms of genetic relationships among eleven species of this family were constructed. Our results suggest that Acanthopanax sessiliflorus and Eleutherococcus senticosus belong to different genera, Aralia cordata andA. continentalis are different species, and A. elata and A. mandshurica probably cannot be regarded as distinct species. Genetic similarity of Far Eastern A. cordata and American A. hispida is shown.     

Comparative analysis of genetic structure in natural populations of two <Emphasis Type="Italic">Arabidopsis</Emphasis> species with different degree of panmixia

Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P _99% = 62.50%; H _exp = 0.169) than the populations of A. thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P _99% = 42.27%; H _exp = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average D _N = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.     

Genetic diversity of the narrow endemic Allium aaseae (Alliaceae)

Low levels of genetic variability are common for a number of geographically restricted plants: these data are consistent with theoretical expectations that small populations should be genetically depauperate. However, in some species, high levels of variability have been found in rare species. Allium aaseae is a rare, narrow endemic in the foothills of the Boise Front of southwestern Idaho. Genetic variation in the rare endemic A. aaseae, and nearby populations of the more common species, A. simillimum, was examined with randomly amplified polymorphic DNA (RAPD) data. Eight populations of A. aaseae and six populations of A. simillimum (three near the range of A. aaseae, and three distant populations) of 25 individuals each were examined for this analysis. Genetic diversity as determined with RAPD markers of both species examined in this study is largely found within and not among populations. Levels of genetic diversity are high, especially for a narrow endemic species such as A. aaseae. Proportion of RAPD loci polymorphic was high in both species, although slightly higher in the more common A. simillimum. Because these higher levels of genetic variability run counter to theory, alternative explanations beyond population size must be invoked to explain the levels of genetic diversity found in this study. Possible explanations are (1) A. aaseae is only recently derived from A. simillimum, (2) hybridization between A. aaseae and A. simillimum is occurring, (3) multiple origins of A. aaseae, (4) populations of A. simillimum included in the analysis are all A. aaseae, (5) A. aaseae and A. simillimum are conspecific, and (6) an artifact of RAPD data.     

The phylogeny and biogeography of Gentiana L. sect. Ciminalis (Adans.) Dumort.: A historical interpretation of distribution ranges in the European high mountains

Gentiana sect. Ciminalis consists of seven mostly ecologically or geographically vicariant and closely related species which are distributed throughout the South and Central European high mountains. The analysis of a RAPD data set and trn L-intron and ITS sequences resulted in slightly different phylogenetic hypotheses. In the preferred hypothesis the group consists of two completely resolved main lineages: 1) G. clusii and G. alpina. 2) G. dinarica, G. acaulis, G. ligustica, G. angustifolia and G. occidentalis. The most important conclusions we have drawn from this phylogenetic hypothesis and from the observed patterns of molecular variation are: 1) The calcifuge ecology of G. acaulis and G. alpina evolved independently from calcicole ancestors. 2) Among the calcicole taxa speciation proceeded from East to West in a simple vicariant pattern. 3) The application of a provisional molecular clock indicates that speciation events in sect. Ciminalis probably occurred in the Quaternary. 4) Differences in infraspecific genetic variation among the widespread species suggest that G. alpina probably experienced more recent dispersal or gene flow than G. clusii and G. acaulis. 5) The large number of mutations in the lineage leading to G. angustifolia, compared to the few mutations in the lineage leading to G. dinarica, may be a result of their different population histories. While the extant range of G. angustifolia was strongly affected by Quaternary climatic fluctuations, that of G. dinarica has had a more stable climatic history. 6) The low number of mutations and the basal position in one clade of the preferred cladogram leads to the conclusion that G. dinarica is the species most similar to the last common ancestor of sect. Ciminalis.     

Genetic divergence between populations of two closely related troglobitic beetle species (Speonomus: Bathysciinae,Coleoptera)

Genetic variability and divergence at 13 enzyme loci were studied in two species of troglobitic beetles (Speonomus zophosinus andhydrophilus 12 populations) collected from the Pyrenees mountains. These allopatric species exhibit a high degree of specialization to underground life and a very small geographical range. Four diagnostic loci arePgi, Est-2, Pac-1, Phi. Within each species polymorphic loci exhibited marked spatial variation of allele frequencies, sometimes over short distances (5–10 km). The levels of genetic variability are comparable to those observed in non-cave invertebrates (frequency of polymorphic loci: 0.31; average expected heterozygosity: 0.112±0.015). Moreover, a single species showed variability in the average level of heterozygosity (0.06 to 0.172). Patterns of genetic differentiation among species were also studied; mean genetic distance (D: 0.263±0.010) between the twoSpeonomus species was of the same order of magnitude as most data reported in the literature between species. A significant heterozygote deficiency occurs in local populations and for all loci. This deficit does not vary from locus to locus. Several hypotheses were examined in an attempt to account for these observations in connection with the species biology. This deficit probably is due to the breeding structure of the population (inbreeding and assortative mating) coupled with limited dispersal ability.     

GENETIC ORGANIZATION AND EVOLUTIONARY HISTORY IN TWO NORTH AMERICAN SPECIES OF CIRSIUM

Relationships involving progenitor and derivative species pairs have been documented for a number of plant taxa. In this study, we used starch-gel electrophoresis to examine the probable relationship between Cirsium pitcheri, an endemic thistle restricted to the shorelines of the Great Lakes, and Cirsium canescens, a closely related species of the central Great Plains (U.S.A.). The species shared the same enzyme loci but differed greatly in levels of genetic diversity. C. pitcheri was genetically much less variable than its congener, with fewer polymorphic loci and significantly lower heterozygosity. The genetic variation in C. pitcheri represents a depauperate subset of the alleles present in C. canescens, consistent with the hypothesis that the two species represent a progenitor-derivative species pair. We suggest that C. pitcheri migrated into newly created dune habitats in the Great Lakes region near the end of the Wisconsin glaciation and that its low genetic variability results from repeated and probably prolonged population bottlenecks which accompanied its movement.     

Molecular diversity and derivations of populations of Silene acaulis and Saxifraga oppositifolia from the high Arctic and more southerly latitudes

A survey of allozyme diversity within and between populations of Silene acaulis from Spitsbergen, Norway, Iceland and Scotland, showed that populations from the high Arctic (Spitsbergen, > 76°N) contained high levels of diversity and were genetically similar to populations from more southern locations. Indirect measures of gene flow (Nm), calculated from Wrigh's F indicated that there had been extensive gene flow between Spitsbergen and some Norwegian populations. A restriction site analysis of chloroplast DNA (cpDNA) in S. acaulis revealed that all populations contained a single identical cpDNA haplotype, except one population from Norway which also contained a second haplotype. In contrast, five different cpDNA haplotypes were distinguished in a more limited survey of cpDNA variation in Saxifraga oppositifolia, with all five haplotypes present in one of two Spitsbergen populations surveyed. The contrasting cpDNA results for the two species suggest that whereas high-Arctic populations of Silene acaulis have most likely been derived from immigrants which arrived from the south after the last glacial period, high-Arctic populations of Saxifraga oppositifolia may be derived, in part, from ancient northern stocks which survived the last glaciation in high-Arctic refugia.     

Forest Fragmentation and Seed Germination of Native Species from the Chaco Serrano Forest

Habitat fragmentation is a widespread phenomenon that alters pollination and plant reproductive processes. These effects have demographic and genetic implications that determine offspring fitness and the long‐term viability of plant populations in fragmented systems. We evaluated fragmentation effects on early plant offspring fitness traits, individual seed mass, and percentage of seed germination in five native plant species (Acacia caven, Celtis ehrenbergiana, Croton lachnostachyus, Rivina humilis, Schinus fasciculatus) from the Chaco Serrano forest, a subtropical highly fragmented ecosystem. We found evidence of strong negative fragmentation effects on germination in the shrub C. lachnostachyus and the perennial herb R. humilis, after 30 d of controlled tests. No fragmentation effects were found in the studied traits on the remaining three tree species. We found significant maternal effects in offspring fitness traits in all five species. We discuss the relative magnitude of maternal vs. fragmentation effects taking into account both plant species' lifespan and the time elapsed in fragmentation conditions. We emphasize the need to increase the study of early and late plant offspring fitness produced in fragmented habitats coupled with analyses of genetic parameters and the pollination process in order to evaluate the conservation value of remnant forest fragments. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Small‐scale spatial associations between Artemisia frigida and Potentilla acaulis at different intensities of sheep grazing

Questions: The formerly overgrazed Inner Mongolia steppe was subject to retrogressive succession. Today, Artemisia frigida and Potentilla acaulis are two dominant species in different phases of successive degradation. To investigate the impact of grazing intensity on spatial community structure, we investigated the small‐scale spatial association between A. frigida and P. acaulis at zero, light, medium and heavy sheep grazing, and proposed factors involved in the spatial associations between these two species along a grazing intensity gradient. Location: The Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences. Methods: Four grazing intensities were selected: zero, light (1.33 sheep/ha), medium (4.0 sheep/ha) and heavy (6.7 sheep/ha). After 13 years of grazing three 2 m × 2 m quadrats with 100 × 100 cells of size 2 cm × 2 cm were randomly selected in each treatment in July and August 2002. The presence of A. frigida and P. acaulis in each cell was recorded and the positions of the individuals were mapped using Cartesian coordinates in each quadrat. The small‐scale spatial associations between A. frigida or P. acaulis were quantified with the L₁₂(d), J₁₂(d) functions (both derived from K₁₂(d), the former indicating the type of the spatial association, the latter indicating the strength of the spatial association), using Monte Carlo simulations. Results: A. frigida was negatively associated with P. acaulis at short distances (0–100 cm) under zero and light grazing, and negatively or independently under medium and heavy grazing. Increasing grazing intensities suppressed the peak negative associations. More intense grazing enhanced the tendency towards independent distribution of these two species. Conclusions: The small‐scale spatial associations between A. frigida and P. acaulis were significantly different at four different intensities of sheep grazing. Grazing disturbance, clonal growth habit of species, and interspecific competition are the main factors leading to a difference of spatial associations between these two species at different grazing intensities.     

Phylogenetic analysis of Altai osmans of the genus <Emphasis Type="Italic">Oreoleuciscus</Emphasis> (Pisces,Cyprinidae, Leuciscinae), based on the analysis of the cytochrome oxidase 1 gene (<Emphasis Type="Italic">Co-1</Emphasis>) sequence

Molecular genetic analysis of Altai osmans of the genus Oreoleuciscus from two different parts of the range was carried out. In this study, based on the mitochondrial Co-1 gene sequence, a total of 25 fish specimens belonging to four genera were examined: (1) O. humilis, 2 specimens; O. potanini, 13 specimens; (2) Pseudaspius leptocephalus, 1 specimen; (3) Tribolodon brandtii, T. hakonensis, and T. sachalinensis from the GanBank database, 9 speciens; and (4) Leuciscus waleckii, 1 specimen (used as an outgroup). The p-distances were very low both within and between the species: (1) 0.20 ± 0.03%; (2) 0.40 ± 0.12%; and (1–2) 0.80 ± 0.04%. To visualize the relationships among all of the species examined, the neighbor joining (NJ), maximum parsimony (MP), Bayesian (BA), and maximum likelihood (ML) trees were constructed. The results obtained using these methods were very similar. It was demonstrated that species assignment of the individuals (barcoding) with the help Co-1 gene was effective, despite of very low divergence of the two osman taxa, which was comparable with typical intraspecific values in other animal groups. Taxonomic status of O. potanini and O. humilis requires further investigation with paying attention to low genetic distances between these species along with the lack of material from sympatric parts of the ranges.     

Genetic variation and habitat conditions in Betula humilis Schrk. populations in Poland,Belarus and Latvia

A rapidly growing human population and the extirpation of numerous species make modern wetlands among the most threatened of ecosystems. One of the endangered wetland plants in central and eastern Europe is Betula humilis. B. humilis forms comparably abundant populations on both well-preserved and drained fens; thus, we aimed in this paper to investigate the relationships between habitat quality parameters (e.g. concentrations of calcium and magnesium, groundwater levels, pH and conductivity) and genetic diversity in 12 populations of B. humilis from Poland, Belarus and Latvia. For the purposes of this study, alcohol dehydrogenase (ADH) gene sequences and nuclear microsatellites were chosen as molecular markers. Analyses revealed that only the Ca²⁺ concentration was significantly negative relative to the observed heterozygosity of microsatellites, which suggests that calcium access is the only factor influencing genetic variation at B. humilis localities. No genetic differentiation was detected between populations occupying wet and dry habitats in different parts of the species range. A minimum spanning tree based on ADH gene haplotypes appears to confirm the B. humilis population history previously inferred from analyses of nuclear microsatellites and chloroplast markers.     

Comparison of genetic variability in remnant and wide-spread rainforest understorey species of Austromyrtus (Myrtaceae)

This study investigated the genetic variability, stand structure, and reproductive activity of four species of Austromyrtus which showed differing levels of rarity and patterns of distribution. The focus of the study was A. gonoclada which is extremely rare due to extensive urban expansion in Brisbane, Australia. The total number of known individuals in the species is only 27. Because nothing was known about the genetic structure of Austromyrtus comparison with other species was made to provide a context for studies on A. gonoclada. Population structure and levels of reproductive activity were not correlated to species rarity or distribution. A. gonoclada showed maximum genetic variability in comparison to the other species of Austromyrtus, despite the small population size. Three of six variable loci were in Hardy-Weinberg equilibrium in A. gonoclada populations, in contrast to populations of the other species which had few heterozygous genotypes. The higher variability of the remaining individuals is suggested to be a legacy of the relatively short time since they were part of a larger population. There were very few seedlings of A. gonoclada, in contrast to the other species of Austromyrtus and the seeds produced fell from the tree while still green and were unable to be germinated. A. gonoclada is under continuing threat from development and has low reproductive success. Active programmes for recovery of this species will be necessary as its continued survival is dependent on population increase. Management of the genetic resources of the species will enable survival with long-term evolutionary potential.     

Isolation and cross-amplification of the first set of polymorphic microsatellite markers of two high-Andean cushion plants

In the southern Andes mountains (27–\(39{^{\circ }}\hbox {S}\)) Azorella madreporica and Laretia acaulis, two Apiaceae cushion plant species commonly known as yaretas, conform a well-established altitudinal vegetation belt along the lower Andean zone. These species have been considered as fundamental components of several ecological dynamics within their communities; however, high-mountain ecosystems are increasingly threatened worldwide by natural and anthropogenic pressures and the southern Andes are not the exception. Recognizing that genetic information is crucial for the success of any conservation or restoration initiative in wild populations, we developed and cross-amplified 28 specifically designed microsatellite markers (14 in A. madreporica and 14 in L. acaulis), and also tested the cross amplification of 25 markers from the related species Azorella selago. In a region which is particularly vulnerable to global change trends, this new polymorphic microsatellite loci will be useful in the study of the genetic diversity of these high-mountain cushion plants, which are pivotal in the structuring of their native ecosystems.     

POPULATION GENETIC STRUCTURE OF CECROPIA OBTUSIFOLIA,A TROPICAL PIONEER TREE SPECIES

Theoretical analyses of the genetic organization of pioneer species have postulated two very different scenarios. Some models have predicted that such species would show strong population substructuring, whereas other models have suggested that extinction and recolonization can augment gene flow and reduce interpopulation differentiation. We tested these alternative scenarios by analyzing the genetic structure of eight loci from populations of the pioneer dioecious tree, Cecropia obtusifolia, in the tropical rain forest region of Los Tuxtlas, México. The populations studied exhibit low overall F_ST values, no clear pattern of isolation by distance, and high estimates of gene flow. These results suggest either that the species is not at a genetic equilibrium under present levels of gene flow with populations derived from each other in the recent past, or that pollen and seed dispersal in this species occur over long distances (up to more than 100 km). Mating among relatives appears higher than expected by chance based on significantly positive fixation indices (F) and F_IS values at some loci. However, no direct evidence for biparental inbreeding was found. The multilocus and single-locus outcrossing rates for C. obtusifolia were estimated at t_m = 0.974 (SE = 0.024) and t_s = 0.980 (SE = 0.035), respectively. These are not significantly different from 1, and the difference, t_m — t_s = — 0.006 (SE = 0.018), is not significantly different from 0. These estimates, however, could be biased because in all enzymes, except PGM-1, we found statistically significant departures from the mixed-mating model used to estimate them. Two rare alleles were found only in seeds collected from the soil, and the greatest number of different alleles were found also in soil seeds. It is hypothesized that the seed bank may play an important role in the genetic buffering of C. obtusifolia. Significantly positive or negative fixation indices in adults at some loci and significantly different heterozygosities among different life stages (from seeds to adults) suggest the action of selection at some loci.     

GENETIC POLYMORPHISM IN THE MORPHOLOGICALLY REDUCED DWARF MISTLETOES (ARCEUTHOBIUM,VISCACEAE): AN ELECTROPHORETIC STUDY

Arceuthobium is a well defined genus of obligate parasites of conifers. Assessment of taxonomic and phylogenetic relationships in this group is difficult owing to morphological reductions and complex host relationships. In the present study, genetic relationships within and among 19 taxa were examined using starch gel electrophoresis of triploid seed endosperm tissue. Allelic frequency data for eleven polymorphic loci were derived from analysis of 40 natural populations collected from the U.S. and Mexico. The genus showed remarkably high levels of genetic diversity: averaged across the 19 taxa, 66.7% of the loci were polymorphic with an average of 2.23 alleles per locus. This level of polymorphism is approximately double the average value reported for many dicotyledons and stands in contrast to the overall uniform morphology of these parasites. Unweighted pair group cluster analysis (UPGMA) of genetic similarity measures was conducted for all sampled populations and the results compared to a phenetic system of classification for the genus. Similarities between the two studies include the recognition of two subgenera based upon the segregation of the verticillately branched Arceuthobium americanum from the remainder of the taxa examined. Analysis of isozyme data supported a grouping of six taxa: A. vaginatum ssp. cryptopodum, A. vaginatum ssp. durangense, A. gillii, A. rubrum, A. divaricatum, and A. douglasii. The placement of the latter three taxa in other groups by phenetic criteria provides evidence for molecular divergence not seen using morphological features. The Campylopodum group of taxa comprised eleven members that were linked at similarity values of 80% or greater. Populations were not unambiguously grouped according to species as defined by the phenetic study or at similarity levels comparable to other well defined species in this study. This group is either not reproductively isolated or molecular differentiation is cryptic due to rapid adaptive radiation onto numerous host tree species.     

Species boundaries within the<Emphasis Type="Italic"> Acropora humilis</Emphasis> species group (Cnidaria; Scleractinia): a morphological and molecular interpretation of evolution

Species boundaries remain unresolved in many scleractinian corals. In this study, we examine evolutionary boundaries of species in the Acropora humilis species group. Five morphologically discrete units are recognized using principal components and hierarchical cluster analyses of quantitative and qualitative characters, respectively. Maximum parsimony and likelihood analyses of partial 28S rDNA sequences suggest that these morphological units diverged to form two evolutionarily distinct lineages, with A. humilis and A. gemmifera in one lineage and A. digitifera and two morphological types of A. monticulosa in the other. Low levels of sequence divergence but distinct morphologies of A. humilis and A. gemmifera within the former lineage suggest recent divergence or ongoing hybridization between these species. Substantially higher levels of divergence within and between A. digitifera and A. monticulosa suggest a more ancient divergence between these species, with sequence types being shared through occasional introgression without disrupting morphological boundaries. These results suggest that morphology has evolved more rapidly than the 28S rDNA marker, and demonstrate the utility of using morphological and molecular characters as complementary tools for interpreting species boundaries in corals.     

GENETIC STRUCTURE OF POPULATIONS OF GEOGRAPHICALLY RESTRICTED AND WIDESPREAD SPECIES OF ASTRAGALUS (FABACEAE)

Evolutionary theory predicts that species with small ranges and few individuals will exhibit low levels of genetic polymorphism. We investigated the population genetic structure of two locally endemic and two geographically widespread species of Astragalus. To facilitate direct comparisons among these congeners, three populations of each species were sampled in a consistent manner and scored for allozyme polymorphisms at 12 loci. Genetic polymorphism was lower in restricted A. linifolius and A. osterhouti than in widespread A. pectinatus. However, the restricted species do exhibit a moderate level of isozyme variation, comparable to that of widespread A. pattersoni and higher than has been detected in several other rare plant taxa. As measured by Wright's F statistics, there were no consistent differences between the restricted and widespread taxa with respect to the organization of genetic variation. F_ST values were low in all taxa, indicating little heterogeneity among populations.