Phylogeography of the Atlanto-Mediterranean sea cucumber Holothuria (Holothuria) mammata: the combined effects of historical processes and current oceanographical pattern

We assessed the genetic structure of populations of the widely distributed sea cucumber Holothuria (Holothuria) mammata Grube, 1840, and investigated the effects of marine barriers to gene flow and historical processes. Several potential genetic breaks were considered, which would separate the Atlantic and Mediterranean basins, the isolated Macaronesian Islands from the other locations analysed, and the Western Mediterranean and Aegean Sea (Eastern Mediterranean). We analysed mitochondrial 16S and COI gene sequences from 177 individuals from four Atlantic locations and four Mediterranean locations. Haplotype diversity was high (H=0.9307 for 16S and 0.9203 for COI), and the haplotypes were closely related (π=0.0058 for 16S and 0.0071 for COI). The lowest genetic diversities were found in the Aegean Sea population. Our results showed that the COI gene was more variable and more useful for the detection of population structure than the 16S gene. The distribution of mtDNA haplotypes, the pairwise F(ST) values and the results of exact tests and amova revealed: (i) a significant genetic break between the population in the Aegean Sea and those in the other locations, as supported by both mitochondrial genes, and (ii) weak differentiation of the Canary and Azores Islands from the other populations; however, the populations from the Macaronesian Islands, Algarve and West Mediterranean could be considered to be a panmictic metapopulation. Isolation by distance was not identified in H. (H.) mammata. Historical events behind the observed findings, together with the current oceanographic patterns, were proposed and discussed as the main factors that determine the population structure and genetic signature of H. (H.) mammata.     

Glossina swynnertoni (Diptera: Glossinidae): effective population size and breeding structure estimated by mitochondrial diversity

Nucleotide diversity was examined at mitochondrial COI and r16S2 loci in eight Glossina swynnertoni Austen collections from northern Tanzania and from a culture maintained by the International Atomic Energy Agency. Eighteen composite haplotypes were observed among 149 flies, two of which were common to all samples and 10 were private. Mean haplotype diversity was 0.59 and nucleotide diversity was 0.0013. There were excess singular haplotypes and mutation-drift disequilibrium suggesting that populations had experienced an earlier bottleneck and subsequent expansion. Factorial correspondence analysis showed that haplotype frequencies varied much more temporally (G ST=0.18) than spatially (G ST=0.04). The estimate of effective population size N e in Tarangire was a harmonic mean approximately 50 reproductive flies averaged over approximately 47 generations. The mean rate of gene flow was estimated to be approximately 5+/-1 reproducing females per generation but inflated because of mutation-drift disequilibrium arising from likely earlier bottlenecks.     

Gene flow among geographically diverse housefly populations (Musca domestica L.): a worldwide survey of mitochondrial diversity

Single-strand conformation polymorphisms at 16S2 and COII mitochondrial genes were surveyed in 111 housefly samples from North, Central, and South America, Europe, Asia, Africa, and the Western Pacific. Forty-eight phenotypes were detected, of which none were ubiquitous, and 21 (44%) were confined to a single zoogeographical region. Nei's gene diversity index (H(S)) was 0.27 and was heterogeneous among zoogeographical regions. Phenotypes were the most diverse in the Ethiopian region and least diverse in the Palearctic and Nearctic regions. Hierarchical partitioning of the total diversity among regions (Nei's G(RT) = 0.49) indicated only a small proportion was shared. The differentiation of populations within regions (G(SR)) was 0.32. All pairwise estimates of gene flow between zoogeographical regions were less than 0.31 reproducing females per generation (mean 0.19). We conclude that housefly populations are highly structured even though the flies are mobile and easily capable of passive transport by ship and air.     

Population genetics and recent colonization history of the invasive drosophilid Zaprionus indianus in Mexico and Central America

Zaprionus indianus, also known as the African fig fly, is an invasive pest of a variety of commercial and native fruit. The species was first reported in Brazil in 1999, but has established itself in much of the New World within the last 10–15 years. We used nucleotide sequences from a segment of the mitochondrial cytochrome c oxidase subunit I (COI) gene to examine haplotype relationships, population structure, and infer the colonization history of Z. indianus in Mexico and Panama. Construction of a haplotype network showed that six COI haplotypes, obtained from flies collected at six localities in Mexico and one in Panama, clustered into three distinct clades. Clade composition was generally consistent in flies from Panama to northwestern Mexico, and analysis of molecular variance indicated no significant structure among populations. Three of the six haplotypes from Mexico and Panama were identical to previously reported haplotypes from Brazil. None of the six haplotypes, however, were shared with previously reported haplotypes from potential source populations in the Old World. The results of our genetic analysis suggest that the invasion of Z. indianus into Central America and Mexico most probably includes a northward migration of individuals from Brazil, with the possibility of at least one additional introduction of Z. indianus to the New World. Additional sequence data from potential source populations in the Old World will be required to confidently determine the number of introductions of Z. indianus into the New World, and to identify the geographic source.     

基于线粒体COI基因的中国西南地区木领针蓟马地理种群的遗传分化分析

【目的】木领针蓟马Helionothrips mube近年来成为芋头Colocasia esculenta上的一种常见害虫。本研究旨在探讨其中国西南地区地理种群间的遗传变异。【方法】通过Sanger法测定了21个地理种群132头木领针蓟马的线粒体COI基因序列,利用MEGA, DnaSP, Arlequin和Network等软件对木领针蓟马种群间的遗传多样性、遗传分化、分子变异等进行分析。【结果】获得的木领针蓟马132条线粒体COI序列(643 bp)中共发现34个变异位点、16种单倍型,其中单倍型H1出现频率最高、分布最广。木领针蓟马总群体的遗传多样性较高(Hd=0.712, Pi=0.00413, K=2.655),遗传分化程度极大(Fst=0.3443),基因交流水平不高(Nm=0.96)。分子方差分析(AMOVA)表明,木领针蓟马的遗传分化主要来自种群内部,Mantel检测出种群地理距离与遗传距离呈正相关。总群体中性检验Tajima’s D值显著负值,Fu’s Fs值不显著,错配分布曲线呈多峰。综合种群间遗传距离、单倍型系统发育树及中介网络图结果,表明四川成都(CHD)、云南昌宁(CHN)和贵州遵义(ZY)3个种群的遗传分化程度均高于其他种群。【结论】中国西南地区木领针蓟马总群体的遗传多样性较高,遗传分化明显,种群间的基因交流受到地理距离的影响,总群体在较近的历史时期内没有出现扩张现象。     

中国甜菜夜蛾地理种群的遗传分化与基因流

【目的】为了明确我国甜菜夜蛾Spodoptera exigua地理种群间的遗传分化及基因流,阐明该种害虫在我国的种群历史动态。【方法】本研究对采自我国20个地理种群的529头甜菜夜蛾样品进行线粒体COI基因序列测定与分析,利用DnaSP 5.0和Arlequin 3.11软件分析种群间遗传多样性、遗传分化、基因流水平及分子变异,构建了单倍型系统发育树与单倍型网络图。【结果】在所分析的所有529个序列样本中,共检测出10个单倍型,其中Hap_1为所有种群所共享。总群体遗传多样性较低（Hd=0.257±0.025,Pi=0.0007±0.0001,Kxy=0.323）,群体间遗传分化较小（F_ST=0.211）,基因流水平较高（N_m=1.870）。AMOVA分析表明,甜菜夜蛾遗传变异主要来自种群内,种群间变异水平较低。各种群间遗传分化程度与地理距离无显著相关性（R²=0.005,P>0.05）。各单倍型相互散布在不同种群中,未形成明显系统地理结构。中性检验（Tajima’s D=-2.177, P<0.05; Fu’s F_S=-8.629, P<0.05)与错配分布分析表明,我国甜菜夜蛾种群曾经历种群近期扩张。【结论】研究结果揭示,甜菜夜蛾各种群间的基因交流并未受到地理距离的影响,验证了甜菜夜蛾具有高度的迁飞能力。     

Genetic diversity of <Emphasis Type="Italic">Haemaphysalis qinghaiensis</Emphasis> (Acari: Ixodidae) in western China

Haemaphysalis qinghaiensis as an endemic species in China mainly infests domestic animals and causes great harm to animals and humans in Northwestern plateau. However, there is no information about genetic diversity within the recently established populations of this tick species. Therefore, the present study analyzed the fragments of mitochondrial 16S rDNA, COI and the nuclear gene ITS1 of 56 H. qinghaiensis ticks across four regions of China which are main endemic areas of this species. Analysis showed 98.1–100% (16S rDNA), 97.9–100% (COI), 99.7–100% (ITS1) identity within individuals. For these sequences, 9, 15 and 8 haplotypes were found for 16S rDNA, COI and ITS1, respectively. Ticks from Yongjing were the most variable group, followed by Lintan, Huangyuan, and Tianzhu. Based on parallel analysis of the mitochondrial and nuclear genetic diversity of H. qinghaiensis, our results indicated that mitochondrial markers (especially COI) were much more useful than nuclear ITS for intraspecific genetic variability analysis.     

Genetic and taxonomic diversity of the house mouse Mus musculus from the asian part of the former Soviet Union

Genetic diversity of the house mouse Mus musculus from 12 local populations (n = 65) of the central and eastern parts of the former Soviet Union was examined using RAPD-PCR. About 400 loci were identified, encompassing approximately 500 kb of the mouse genome. Genetic diversity was assessed using NTSYS, POPGENE, TFPGA, and TREECON software programs. In general, the house mouse sample from the regions examined was characterized by moderate genetic variation: polymorphism P = 95.6%, P99 = 60.7%, P95 = 24.2%; heterozygosity H = 0.089; the mean observed number of alleles n(a) = 1.97; effective number of alleles n = 1.13; intrapopulation differentiation deltaS = 0.387; gene diversity h = 0.09. Individual local populations displayed different levels of genetic isolation: the genetic subdivision index G(st) varied from 0.086 to 0.324 at gene flow Nm varying from 5.3 to 1.05, while the interpopulation genetic distance D(N) ranged from 0.059 to 0.186. Most of the genetic diversity of the total sample resided within the local populations: H(S) = 0.6, total gene diversity H(T) = 0.09. The exact test for differentiation, however, did not confirm the affiliation of all the mice examined to one population: chi2 = 1446, d.f. = 724, P = 0.000. Molecular markers specific to four subspecies (musculus, castaneus, gansuensis, and wagneri) were identified. Moreover, in some cases the populations and individual animals exhibited traits of different subspecies, suggesting their introgressive hybridization. It was demonstrated that the house mouse fauna on the territories investigated was characterized by the prevalence of musculus-specific markers, while gansuensis-specific markers ranked second. The castaneus-specific markers were highly frequent in the Far East, but almost absent in Central Asia, where wagneri-specific markers were detected. It was suggested that house mice from Turkmenistan could belong to one of the southern subspecies, which had not deeply penetrated into the Asian fauna of the former Soviet Union. In phenogenetic (UPGMA) and phylogenetic (NJ) reconstructions this form with the high bootstrap support was placed at the tree base, while the isolation of other clusters was not statistically significant. It is thus likely that the house mice from Turkmenistan are closest to the ancestral form of the genus Mus on the territory of the former Soviet Union.     

基于mtDNA COI基因序列的中国柑橘果实蝇的分子鉴定及柑橘大实蝇种群的遗传多样性分析

【目的】探明危害我国柑橘的实蝇种类以及柑橘大实蝇Bactrocera minax不同地理种群和不同寄主种群的遗传多样性。【方法】利用mtDNA COI基因对危害柑橘的果实蝇进行种类鉴定,采用MEGA软件对其中28个地理种群的535头果实蝇COI基因片段(约505 bp)序列进行比对,分析种间及种内遗传距离,构建系统发育树。使用DnaSP软件分析柑橘大实蝇不同地理种群和不同寄主种群的遗传多样性。【结果】从柑橘虫果内共鉴定出4种实蝇,分别为柑橘大实蝇B.minax、桔小实蝇B.dorsalis、蜜柑大实蝇B.tsuneonis和瑞丽果实蝇B.ruiliensis。这4种实蝇的种间遗传距离为0.0264～0.2410,种内遗传距离为0.0000～0.0140,种间与种内遗传距离没有重叠区域。单个柑橘虫果内一般仅有1种实蝇,极个别柑橘果实可同时被两种实蝇危害(4/43);在这些为害柑橘的实蝇种类中,以柑橘大实蝇的个体数量比例最大,占90.70%。柑橘大实蝇地理种群遗传多样性高,28个种群共有17个单倍型。【结论】柑橘大实蝇是所调查地区柑橘实蝇的绝对优势种,其种群遗传分化程度较高,扩散危害风险大。本研究结果对柑橘果实蝇类的监测和防控具有重要意义。     

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.     

Genetic diversity of the house mouse Mus musculus and geographic distribution of its subspecies-specific RAPD markers on the territory of Russia

Genetic diversity and geographic distribution of taxon-specific RAPD markers was examined in ten local populations of the house mouse Mus musculus (n = 42). The house mice were generally characterized by moderate genetic variation: polymorphism P99 = 60%, P95 = 32.57%; heterozygosity H = 0.12; the observed allele number n(a) = 1.6; the effective allele number n(e) = 1.18; the within-population differentiation Theta = 0.388; and Shannon index I = 0.19. The degree of genetic isolation of individual local populations was greatly variable. The genetic subdivision index G(st) varied from 0.162 to 0.770 at the gene flow of Nm = 2.58-0.149, while the among-population distances D(N) varied from 0.026 to 0.178. of the largest part of the genetic diversity was found among the populations (H(T) = 0.125), while the within-population diversity was twice lower (H(S) = 0.06). The samples examined were well discriminated relative to the sets of RAPD markers. The character distribution pattern provided conditional subdivision of the mice into the "western" and the "eastern" groups with the putative boarder along the Baikal Lake. The first group was characterized by the prevalence of the markers typical of M. m. musculus and M. m. domesticus. The second group was characterized by the prevalence of the markers typical of M. m. musculus, M. m. gansuensis, M. m. castaneus, M. m. domesticus, and m. m. wagneri. The genotype of the nominative subspecies M. m. musculus was background for all populations. In the populations examined some of earlier described subspecies-specific molecular markers were found at different frequencies, pointing to the involvement of several subspecies of M. musculus in the process of hybridization.     

A Brave New World for an Old World Pest: Helicoverpa armigera (Lepidoptera: Noctuidae) in Brazil

The highly polyphagous Old World cotton bollworm Helicoverpa armigera is a quarantine agricultural pest for the American continents. Historically H. armigera is thought to have colonised the American continents around 1.5 to 2 million years ago, leading to the current H. zea populations on the American continents. The relatively recent species divergence history is evident in mating compatibility between H. zea and H. armigera under laboratory conditions. Despite periodic interceptions of H. armigera into North America, this pest species is not believed to have successfully established significant populations on either continent. In this study, we provide molecular evidence via mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) partial gene sequences for the successful recent incursion of H. armigera into the New World, with individuals being detected at two sites (Primavera do Leste, Pedra Preta) within the State of Mato Grosso in Brazil. The mtDNA COI and Cyt b haplotypes detected in the Brazilian H. armigera individuals are common throughout the Old World, thus precluding identification of the founder populations. Combining the two partial mtDNA gene sequences showed that at least two matrilines are present in Brazil, while the inclusion of three nuclear DNA Exon-Primed Intron-Crossing (EPIC) markers identified a further two possible matrilines in our samples. The economic, biosecurity, resistance management, ecological and evolutionary implications of this incursion are discussed in relation to the current agricultural practices in the Americas.     

中国东南沿海弹涂鱼科常见鱼类的遗传多样性和DNA条形码

为了探究中国东南沿海海岸线经济开发、海水污染等对该区域生物遗传多样性的潜在影响,本文使用COI基因作为DNA条形码,对从中国东南沿海广东汕头、福建东山、福建云霄、福建泉州、福建霞浦、上海崇明6个地点采集的大弹涂鱼(Boleophthalmus pectinirostris)、弹涂鱼(Periophthalmus modestus)和青弹涂鱼(Scartelaos histophorus)进行种间和种内的遗传学分析。遗传多样性分析显示,青弹涂鱼的核苷酸多样性(0.0018)在3个种中最低;青弹涂鱼广东汕头种群的核苷酸多样性(0.0018)比福建云霄种群低;大弹涂鱼的上海崇明种群核苷酸多样性(0.0021)低于其他5个地理种群。物种水平分析表明,3个物种间分化明显,种间与种内遗传距离有明显差异;不同种的单倍型在系统发育树上聚成3个高度支持的独立分支。种群水平分析显示,大弹涂鱼的6个不同地理种群之间有共享单倍型,地理种群间与地理种群内的遗传距离重叠;各地理种群之间的基因流较频繁(Nm>4);青弹涂鱼的分析情况与大弹涂鱼基本一致。大弹涂鱼和青弹涂鱼的单倍型在系统发育树上均呈现多系或并系分布格局,并未按地理位置分成不同的单系群。本研究表明,应及时加强3种鱼类及其野生种群遗传多样性的保护,且COI基因对种一级的识别明确可靠,而在地理种群水平的识别则比较困难,有待进一步深入研究。     

Genetic diversity and population connectivity of the Asian green mussel Perna viridis in South China Sea,inferred from mitochondria DNA markers

The Asian green mussel Perna viridis is ecologically and economically important in the coastal regions of China. In order to characterize the genetic diversity and population connectivity of P. viridis in South China Sea, a 664 bp region of mitochondrial COI gene and a 293 bp region of 16S rRNA gene were sequenced and analyzed for 78 and 92 individuals from four populations in South China Sea, respectively. A total of 15 haplotypes were defined by 14 variable nucleotide sites in COI gene, and 7 haplotypes by 6 variable nucleotide sites in 16S rRNA gene. High haplotype diversity and low nucleotide diversity were observed in COI gene, while moderate haplotype diversity and low nucleotide diversity were observed in 16S rRNA gene. Pairwise F_ST values of COI gene were all negative and those of 16S rRNA gene ranged from −0.01409 to 0.10289. The results showed that no significant genetic divergence (or shallow genetic structure) and high levels of population connectivity among the four populations of P. viridis in South China Sea.     

A worldwide perspective on the population structure and genetic diversity of bottlenose dolphins (Tursiops truncatus) in New Zealand

Bottlenose dolphins (Tursiops truncatus) occupy a wide range of coastal and pelagic habitats throughout tropical and temperate waters worldwide. In some regions, "inshore" and "offshore" forms or ecotypes differ genetically and morphologically, despite no obvious boundaries to interchange. Around New Zealand, bottlenose dolphins inhabit 3 coastal regions: Northland, Marlborough Sounds, and Fiordland. Previous demographic studies showed no interchange of individuals among these populations. Here, we describe the genetic structure and diversity of these populations using skin samples collected with a remote biopsy dart. Analysis of the molecular variance from mitochondrial DNA (mtDNA) control region sequences (n = 193) showed considerable differentiation among populations (F(ST) = 0.17, Phi(ST) = 0.21, P < 0.001) suggesting little or no female gene flow or interchange. All 3 populations showed higher mtDNA diversity than expected given their small population sizes and isolation. To explain the source of this variation, 22 control region haplotypes from New Zealand were compared with 108 haplotypes worldwide representing 586 individuals from 19 populations and including both inshore and offshore ecotypes as described in the Western North Atlantic. All haplotypes found in the Pacific, regardless of population habitat use (i.e., coastal or pelagic), are more divergent from populations described as inshore ecotype in the Western North Atlantic than from populations described as offshore ecotype. Analysis of gene flow indicated long-distance dispersal among coastal and pelagic populations worldwide (except for those haplotypes described as inshore ecotype in the Western North Atlantic), suggesting that these populations are interconnected on an evolutionary timescale. This finding suggests that habitat specialization has occurred independently in different ocean basins, perhaps with Tursiops aduncus filling the ecological niche of the inshore ecotype in some coastal regions of the Indian and Western Pacific Oceans.     

线粒体基因和核基因揭示自然屏障和第四纪更新世气候振荡影响双斑乙蠊谱系地理格局

[目的]明确双斑乙蠊Sigmella biguttata种群间遗传分化程度,并揭示该种地理分布格局成因.[方法]PCR扩增双斑乙蠊19个地理种群284头个体的线粒体基因COⅠ,COⅡ和ND1以及核基因ITS的序列;使用MEGA v.7.0,DnaSP v.5.0和Arlequin v.3.5软件分析双斑乙蠊地理种群的遗...     

Genetic variation and clonal diversity in four clonal sedges (Carex) along the Arctic coast of Eurasia

We studied the structure of genetic variation (at both ramet- and genet-level) and clonal diversity within and among populations in the four closely related arctic clonal sedges Carex bigelowii, C. ensifolia, C. lugens and C. stans by use of allozyme markers. Compared to other sedges and arctic plants, the studied taxa all had high levels of genetic variation, both within populations and taxa. These taxa contained most of the total gene diversity (H(T)) within populations and a small part of the diversity among populations (G(ST) ranged 0.05--0.43). Carex bigelowii had genetic variation (H(S) = 0.173, mean for populations) at a comparable level to other outbreeding arctic plants and to other widespread, rhizomatous and mainly outbreeding Carex species. In contrast, C. ensifolia (H(S) = 0.335), C. lugens (H(S) = 0.339) and C. stans (H(S) = 0.294) had within-population variations that were higher than in most other studied Carex species and for arctic plants in general. Genetic variation was not related to any tested environmental variable, but it was lower in areas deglaciated only 10,000 years BP compared to areas deglaciated 60,000 years BP or not glaciated at all during the Weichselian. All the populations were multiclonal, except for two populations of C. stans that were monoclonal. In contrast to genetic variation, clonal diversity decreased with latitude and did not differ between areas with different times of deglaciation. In accordance with previous studies, C. bigelowii and C. lugens were found to be outbreeding, while C. ensifolia and C. stans had mixed mating systems.     

Assessing the diversity of New Zealand freshwater harpacticoid copepods (Crustacea: Copepoda) using mitochondrial DNA (COI) barcodes

Taxonomic and ecological studies of freshwater harpacticoid copepods are limited globally by the ability to easily and accurately identify specimens. Here, we test the use of the mitochondrial cytochrome c oxidase subunit I (COI) gene locus as a tool for assessing the diversity of freshwater Harpacticoida. We obtained sequences from New Zealand harpacticoid copepods, representing two families, five genera and nine species, including the non-indigenous Elaphoidella sewelli. All species were delineated by the COI gene. However, high intraspecific diversity was evident among populations of Elaphoidella bidens (>12%), and between North and South Island populations of Bryocamptus pygmaeus (>18%), potentially indicating the presence of morphologically cryptic taxa. We suggest that mitochondrial DNA (COI) sequences can provide a useful tool for the routine identification of freshwater harpacticoid copepods. Applications of these data will include assessing species diversity and biogeography as well as assisting with the detection of non-indigenous species.     

Contrasting microsatellite variation between subalpine and western larch, two closely related species with different distribution patterns

Subalpine larch (Larix lyallii Parl.) and western larch (Larix occidentalis Nutt.) represent two closely related species with contrasting abundance and distribution patterns in Western North America. Genetic diversity at seven informative microsatellite loci was determined for 19 populations of subalpine larch and nine populations of western larch. Contrasting genetic diversity and patterns of population differentiation were observed between the two species. The overall within-population genetic diversity parameters were lower in subalpine larch (A = 3.2; A(P) = 3.6; H(E) = 0.418) than in western larch (A(P) = 5.51; H(E) = 0.580), a pattern that is likely related to historical or demographic factors. No evidence of interspecific hybridization was observed. Significantly more population differentiation (theta = 0.15; R(ST) = 0.07), consistent with more restricted gene flow, was observed for subalpine larch as compared to western larch (theta = 0.05; R(ST) = 0.04). Under the assumption of an infinite allele mutation model, 12 of the 19 subalpine larch populations showed signs of deviation from the mutation-drift equilibrium, which suggests Holocene population bottlenecks and fluctuations in effective population size for this species. None of the western larch populations deviated significantly from the mutation-drift equilibrium. For both species, Mantel's test revealed a significant positive relationship between geographical and genetic distances indicative of isolation by distance. A similar geographical structure was detected in both species, suggesting at least two genetically distinct glacial populations in each species. The various implications for gene conservation are discussed.     

Karyotype and genetic evolution in speciation of subterranean mole rats of the genus Spalax in Turkey

Karyotype (2fl) and allozymc diversity at 37 gene loci were determined in 69 subterranean mole rats in Turkey belonging to the two superspecies: the ancestor Spalax leucodon ( n = 55; 20 populations) and the descendant S. ehrenbergi ( n = 14; lour populations). We identified remarkable variation of diploid chromosome numbers in the S. leucodon superspecies: 2 n = 38. 40. 50, 54, 60 and 62; and in the S. ehrenbergi superspecies: 2 n = 52, 56 and 58. Genetic diversity indices were low on average in both S. leucodon and S. ehrenbergi superspecies: Allele diversity, A = 1.081 and 1.074; polymorphism, P-5%= 0.077 and 0.068; heterozygosity, H = 0.038 and 0.027; and gene diversity, H, = 0.038 and 0.034, respectively. H ranged from 0 in mesic or semimesic regions to 0.088 in arid Anatolia. We consider the populations with different diploid chromosome numbers, 2 n , as good biological species. Karyotypic diversity may mark extensive ecological speciation. Nei's genetic distances, D (average 0.174, range 0.002 0.422) and ecogeographical criteria suggest that almost each population may represent a different biological species, but critical future testing is necessary to support this claim. Karyotypes and allozymes are nonrandomly distributed across Turkey, displaying remarkable correlations with climatic and biolir factors. Both In and H are significantly correlated with aridity stress (2 n /rainfall, r , =–0.74; P < 0.001), and in our region also with climatic unpredictability. These results support the niche-width genetic variation hypothesis in space and time. Climatic selection in Turkey appears to be a major architect of karyotype and genetic (allozymc) diversity and divergence in mole rat evolution, in both speciation and adaptation.