Genetic variability and structure of natural and domesticated populations of Caribbean pine (Pinus caribaea Morelet)

 Isozyme analysis of seed samples derived from natural and managed populations of the tropical pine Pinus caribaea vars ‘bahamensis’ and ‘caribaea’ was used to assess population genetic structure in its native range and to detect changes occurring during early domestication of the species. Baseline data from natural populations of the two varieties showed that populations sampled as seed are characterized by high gene diversity (mean H_e=0.26) and a low level of inbreeding ( mean F_is=0.15). A UPGMA tree of genetic relatedness among populations indicates that the two varieties represent distinct evolutionary units. Within each variety there is significant differentiation among populations, and this is greater for the more fragmented populations of var ‘bahamensis’ (F_st=0.08) than for var ‘caribaea’ (F_st=0.02). Seed from a seed orchard population of var ‘caribaea’ established within its natural range showed no change in genetic diversity but did show a reduced inbreeding coefficient (F_is=0.09) compared with its progenitor populations, suggesting a decrease in selfing and/or biparental inbreeding. A bulked seed sample from an exotic plantation of var ‘bahamensis’ in Australia displayed a large increase in the inbreeding coefficient (F_is=0.324) compared with that found in natural populations, possibly due to elevated self-fertilization. Finally, a bulked seed sample from an exotic plantation population of var ‘caribaea’ from China showed enhanced genetic diversity, an increase in the inbreeding coefficient and more linkage disequilibrium than its presumed progenitor populations. It was also genetically divergent from them. RFLP analysis of chloroplast DNA variation in the Chinese sample suggested that seeds of the related taxa P. elliottii and P. taeda, or seeds derived from hybridization with these taxa growing in the seed production area, had been included in the seed crop during harvesting. We conclude that monitoring of appropriate genetic markers may be an effective means of identifying potentially deleterious genetic changes occurring during forest tree domestication. Received: 10 August 1998 / Accepted: 8 September 1998     

Population genetic structure of <Emphasis Type="Italic">Tamarix chinensis</Emphasis> in the Yellow River Delta,China

Tamarix chinensis, with its important ecological significance, is a vital dominant plant in the Yellow River Delta of China. To understand its genetic structure and population dynamics, five populations of T. chinensis, consisting of 140 individuals, were analyzed in this study using inter simple sequence repeat markers. Seventy-eight polymerase chain reaction fragments were scored, of which 62 were polymorphic. The mean percentage of polymorphic loci (P), the mean Nei’s gene diversity (h), and the mean Shannon’s information index (I) were 79.5%, 0.239, and 0.363, respectively. These indexes indicated that a moderate level of genetic diversity existed in T. chinensis populations of the Yellow River Delta. Both analysis of molecular variance (AMOVA) (Φ _st = 0.169) and Popgene (G _st = 0.159) analyses revealed the low level of genetic differences among the five populations of T. chinensis. The results implied that relatively frequent gene flow existed among populations. However, slightly uneven genetic diversity was also found among populations. Unweighted pair group method with arithmetic mean and principal component analysis showed that populations with similar soil salinity had a close relationship, rather than populations with closer geographical distance. A significant negative correlation between genetic diversity and soil salinity of the five populations (r = −0.958, p < 0.01) showed that soil salinity played an important role in shaping the population genetic structure of T. chinensis in the Yellow River Delta, China.     

Genetic diversity and conservation units in wild and captive populations of endangered freshwater fishes: a case of <Emphasis Type="Italic">Hemigrammocypris rasborella</Emphasis> in Shizuoka,Japan

Population structure and genetic diversity were examined using partial mitochondrial cytochrome b gene sequences of four wild, one reintroduced, and five captive populations of the endangered cyprinid Hemigrammocypris rasborella from three river systems in the easternmost region of the species’ range in Shizuoka Prefecture, central Honshu, Japan. We detected loss of genetic diversity from portions of the wild and captive populations, as well as suspected nonindigenous haplotypes in some captive, reintroduced, and even wild populations. Given the population structure revealed, we suggest that the populations should be managed with consideration for both the endemism and viability (avoidance of inbreeding depression) of the local populations.     

Characterization of 22 microsatellites loci from the endangered Houbara bustard (Chlamydotis undulata undulata)

Here we present a new set of 22 microsatellite loci isolated from Chlamydotis undulata undulata, an endangered Houbara bustard found across North Africa. The number of alleles per locus ranged from one to nine, and heterozygosities ranged from 0.167 to 0.944. Total exclusionary probabilities using these loci for the first and the second parent were 0.992932 and 0.999915, respectively. Successful cross‐amplification was observed in eight other Otididae species (12–22 of the 22 loci). These microsatellite markers are powerful tools for genetic identification, paternity assignment and population genetic studies.     

Conservation of population structure and genetic diversity under captive breeding of remnant coaster brook trout (<Emphasis Type="Italic">Salvelinus fontinalis</Emphasis>) populations

Rebuilding wild populations often involves captive broodstocks derived from small, remnant populations. We measured a hatchery program’s ability to conserve genetic diversity when founding captive broodstocks from such populations. Migratory coaster brook trout were extirpated from most of their historic range in US waters of Lake Superior and were proposed for listing under the Endangered Species Act. Two captive broodstocks, one with 19 founders and another with 99 founders, were established to rebuild US populations. We used microsatellite markers to examine genetic variation in source populations and early hatchery generations. Broodstocks retained the strong differentiation found between source populations; however, one founder, with a low probability of belonging to either source population, sired 5.7% of F₁ progeny. We found small changes in within-population genetic variation across successive wild and hatchery generations of broodstocks. Evaluation of stage-specific survivorship indicated that equalizing family sizes of embryos produced modest gains in the effective number of breeders, and that survival in the hatchery was nearly random across families. Our study demonstrates the value of genetic monitoring during initial stages of hatchery programs for small and declining populations.     

Genetic diversity assessment of sub-samples of cacao, Theobroma cacao L. collections in West Africa using simple sequence repeats marker

Knowledge of genebank and on-farm genetic diversity, particularly in an introduced crop species, is crucial to the management and utilization of the genetic resources available. Microsatellite markers were used to determine genetic diversity in 574 accessions of cacao, Theobroma cacao L., representing eight groups covering parental populations in West Africa, genebank, and farmers’ populations in Nigeria. From the 12 microsatellite markers used, a total of 144 alleles were detected with a mean allelic richness of 4.39 alleles/locus. The largest genetic diversity was found in the Upper Amazon parent population (H _nb  = 0.730), followed by the 1944 Posnette’s Introduction (H _nb  = 0.704), and was lowest in the Local parent population (H _nb  = 0.471). Gene diversity was appreciably high in the farmers’ populations (H _nb  = 0.563–0.624); however, the effective number of alleles was lower than that found in the genebank’s Posnette’s population. Fixation index estimates indicated deficiency of heterozygotes in the Upper Amazon and the Local parent populations (F _is  = 0.209 and 0.160, respectively), and excess of heterozygotes in the Trinitario parent population (F _is  = −0.341). The presence of inbreeding in the Local parent populations and substructure (Wahlund effect) in the Upper Amazon were suggested for the deficiency of heterozygotes observed. Non-significant genetic differentiation observed between the genebank’s and farmers’ populations indicated significant impact of national breeding programs on varieties grown in farmers’ plantations. From this study, we showed that appreciable genetic diversity was present in on-farm and field genebank collections of cacao that can be exploited for crop improvement in West Africa. Suggestions for future conservation of on-farm genetic diversity and local landraces are further discussed.     

Conservation genetics of Butte County meadowfoam (Limnanthes floccosa ssp. californica Arroyo), an endangered vernal pool endemic

The endangered annual plant Limnanthes floccosa ssp. californica Arroyo is restricted to vernal pools in Butte County, California. To identify populations with unique genetic resources, guide reintroduction efforts, and design seed collection scenarios for long-term ex situ seed storage we determined extant genetic diversity and structure by surveying 457 individuals from 21 distinct populations using nine polymorphic microsatellite markers. We found low within population genetic diversity: low allelic diversity (1.9 [0.06 SE] alleles/locus); low heterozygosity (H _obs = 0.10 ± 0.018, H _exp = 0.19 ± 0.015), and a high fixation index (0.556 ± 0.044). The number of polymorphic loci ranged between 11 and 89%. Bayesian ordination determined 20 distinct populations and we found high genetic structure among these (F _st = 0.65, P < 0.0001). We identified notable gene flow barriers across populations, confirming regional structuring between three previously defined population density centers and two outlying populations (F _st = 0.21, P < 0.0001). Population size estimates ranged between ~50 and >5,000 extant plants per site. Our study confirms previous isozyme-based results and suggests that the loss of any population would represent a significant loss in the species’ genetic diversity. Recovery requires active restoration of existing populations and permanent habitat protection. We recommend close comparison of microhabitats of declining populations with genetically similar populations, to determine the potential for human assisted gene flow via seed movement to recover declining populations.     

A Study of Conservation Genetics in Cupressus chengiana,an Endangered Endemic of China,Using ISSR Markers

ISSR markers were used to analyze the genetic diversity and genetic structure of eight natural populations of Cupressus chengiana in China. ISSR analysis using 10 primers was carried out on 92 different samples. At the species level, 136 polymorphic loci were detected. The percentage of polymorphic bands (PPB) was 99%. Genetic diversity (H _e) was 0.3120, effective number of alleles (A _e) was 1.5236, and Shannon’s information index (I) was 0.4740. At the population level, PPB = 48%, A _e=1.2774, H _e=0.1631, and I=0.2452. Genetic differentiation (G _st) detected by Nei’s genetic diversity analysis suggested 48% occurred among populations. The partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (54%) and among populations (46%; P < 0.0003). The average number of individuals exchanged between populations per generation (N _m ) was 0.5436. Samples from the same population clustered in the same population-specific cluster, and two groups of Sichuan and Gansu populations were distinguishable. A significantly positive correlation between genetic and geographic distance was detected (r=0.6701). Human impacts were considered one of the main factors to cause the rarity of C. chengiana, and conservation strategies are suggested based on the genetic characters and field investigation, e.g., protection of wild populations, reestablishment of germplasm bank, and reintroduction of more genetic diversity.     

Genetic diversity and structure in the rare Colorado endemic plant <Emphasis Type="Italic">Physaria bellii</Emphasis> Mulligan (Brassicaceae)

Physaria bellii (Brassicaceae) is a rare, outcrossing perennial endemic to shale and sandstone outcrops along the Front Range of northern Colorado, USA. This species is locally abundant, but ranked G2/S2—imperiled because of threats to its habitat and a small number of populations—according to NatureServe’s standardized ranking system. Leaf tissue from ten populations was analyzed with ISSR (Inter-Simple Sequence Repeat) markers to discern the amount of genetic diversity and degree of population subdivision in P. bellii. Genetic diversity was moderate (0.22) and a moderately high degree of population structure was found (F _ST calculated using two algorithms ranged from 0.17 to 0.24). An AMOVA partitioned most of the variation among individuals within populations (76%), and the remainder among populations (24%). Results from a Principal Coordinates analysis were consistent with the geographic distribution of populations. A Mantel test of the correlation between genetic and geographic distances was highly significant (P < 0.001). The pattern of variation thus appears to be distributed along a gradient, and efforts to conserve this species should involve preserving enough populations so that gene flow between populations is not interrupted.     

Genetic Variability and Genetic Structure of Wild and Semi-domestic Populations of Tasar Silkworm (Antheraea mylitta ) Ecorace Daba as Revealed through ISSR Markers

The genetic diversity in the wild and semi-domestic populations of Daba ecorace of Antheraea mylitta was studied to ascertain the distribution of variability within and among populations of semi-domestic bivoltine (DB), trivoltine (DT) and nature grown wild populations (DN) with inter-simple sequence repeat (ISSR) markers. A total of 138 markers were produced among 56 individuals of the three populations, of which 98% were polymorphic. For the individual populations, the percentage polymorphism was 58.69, 52.9 and 77.54 for DB, DT and DN, respectively. Average number of observed (1.791 ± 0.408) and effective alleles (1.389 ± 0.348) was also high in the wild populations in comparison to the bivoltine and trivoltine semi-domestic populations. Genetic diversity (H_t) in DB, DT and DN was 0.180 ± 0.033, 0.153 ± 0.032 and 0.235 ± 0.033, respectively and within-population genetic diversity (H_s) ranged from 0.166 to 0.259 with a mean of 0.189. Mean gene differentiation (G_ST) was found to be 0.25. Shanon’s diversity index was 0.278, 0.237 and 0.361 for DB, DT and DN and overall it was 0.391. Gene flow (N_m) among the populations was 1.509. The dendrogram produced by UPGMA with Dice’s genetic distance matrices resulted in the formation of three major clusters separating the three populations. Considerable intra- and inter-population variability is found in all three populations. The population structure analysis further suggests that the semi-domestic populations of Daba ecorace are at the threshold of differentiating themselves. The high genetic variability present within wild Daba population of A. mylitta is of much importance for conservation as well as utilization in systematic breeding program.     

Patterns of genetic variation within a captive population of Amur tigerPanthera tigris altaica

Eight founders and thirty-one descendants were sampled as the Founder group and the Offspring group respectively from a captive population of Amur tigerPanthera tigris altaica Temminck, 1844 for population genetic analysis with RAPD and ISSR markers. Integrated with demographic data during the initial recovery stage, results showed: (1) increasing the population size (N) and the effective population size (N _e) greatly retard lose of genetic variation induced mainly by genetic drift and selection; (2) recombination and admixture could cause the Offspring group (5.711%) and the Founder group (10.383%) to hold different linkage disequilibrium (LD); (3) further Ohta’s variance analysis indicated genetic drift (87.3%) and epistatic selection (12.7%) maintained LD in population, whereas GENEDROP analysis supported epistatic selection largely derived from artificial selection of managers; (4) both Tajima’s test and Fu’s test confirmed the statistic neutrality of genetic markers used, moreover the positive value of Tajima’sD (0.090) together with the result that π (25.286) was bigger than ϑ (24.898) revealed the Founder group was admixture population, while the negative Tajima’sD value (−0.053) together with the result that π (23.679) was less than ϑ (23.912) disclosed the Offspring group experienced selective sweep.     

Genetic structure of the critically endangered Red‐headed Wood Pigeon Columba janthina nitens and its implications for the management of threatened island populations

The Red‐headed Wood Pigeon Columba janthina nitens is endemic to the Ogasawara Islands, an oceanic island chain located 1000 km south of the main islands of Japan. The subspecies is at high risk of extinction because of its small population size and restricted habitat range. We undertook genetic analyses of this pigeon using sequences of a portion of the mitochondrial control region and five microsatellite markers to estimate the genetic characteristics of two wild populations from the Bonin and Volcano Islands, as well as one captive breeding population. The genetic diversity of the wild individuals was exceptionally low in both the mitochondria (nucleotide diversity = 0.00105) and at the microsatellite (3.2 alleles per locus and H_E = 0.12) loci. Higher numbers of microsatellite genotypes were observed in the Volcano Islands population than in the Bonin Islands population, which may be because of the relatively low impact of human disturbance. The most common mitochondrial haplotypes and microsatellite alleles observed in the two wild populations were completely fixed in the captive population. Our results suggest that the genetic diversity of the captive population needs to be increased. However, introduction of a wild individual into a captive population can lead to a decreased genetic diversity in the wild population and therefore should be done with caution. The genetic differentiation between the Bonin and the Volcano island groups was low, and the populations of the two island groups should be regarded as a single evolutionarily significant unit. However, special consideration is required for habitat conservation in the Volcano Islands, which may be functioning as a sanctuary for the Red‐headed Wood Pigeon. For the long‐term conservation of threatened bird species that live on remote oceanic islands, determination of management units considering gene flow caused by their flying capacity and maintenance of genetically suitable wild and captive populations are essential.     

Patterns of differentiation among endangered pondberry populations

Pondberry, Lindera melissifolia, is an endangered and partially clonally reproducing shrub species found in isolated populations that inhabit seasonally wet depressions in forested areas of the lower Mississippi River alluvial valley and southeastern regions of the United States. With eleven microsatellite loci, we quantified population genetic differentiation and diversity among 450 genets in 10 locations distributed across pondberry’s range. We used estimates of F _st and Jost’s D _est to measure genetic differences between populations and between geographic regions. The largest pairwise regional difference was found between eastern and western regional population groups (F _st = 0.23, D _est = 0.67), with the northern-most population groups in each region exhibiting larger divergence from each other than the southern-most population groups. Genetic diversity was lowest in the Sand Pond Conservation Area (A _e = 1.9, H _e = 0.36), which was the northern-most pondberry population, and highest in the Francis Marion National Forest (A _e = 4.1, H _e = 0.69), although we identified only 17 genets in that admixed population. Following adjustments for estimated null allele frequencies, we identified heterozygote excess in four eastern populations and found no evidence for inbreeding in any population. The observed patterns of differentiation indicate a phylogeography that exhibits an Appalachian Mountain discontinuity coupled with northward migrations along the Southern Atlantic Coastal Plain and into the Mississippi Alluvial Plain. The genetic consequences of this proposed phylogeographical structure may affect selection of germplasm sources for population reestablishment programs across pondberry’s range.     

How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands

Ex situ management is an important conservation tool that allows the preservation of biological diversity outside natural habitats while supporting survival in the wild. Captive breeding followed by re‐introduction is a possible approach for endangered species conservation and preservation of genetic variability. The Cayman Turtle Centre Ltd was established in 1968 to market green turtle (Chelonia mydas) meat and other products and replenish wild populations, thought to be locally extirpated, through captive breeding. We evaluated the effects of this re‐introduction programmme using molecular markers (13 microsatellites, 800‐bp D‐loop and simple tandem repeat mitochondrial DNA sequences) from captive breeders (N = 257) and wild nesting females (N = 57) (sampling period: 2013–2015). We divided the captive breeders into three groups: founders (from the original stock), and then two subdivisions of F₁ individuals corresponding to two different management strategies, cohort 1995 (“C1995”) and multicohort F₁ (“MCF1”). Loss of genetic variability and increased relatedness was observed in the captive stock over time. We found no significant differences in diversity among captive and wild groups, and similar or higher levels of haplotype variability when compared to other natural populations. Using parentage and sibship assignment, we determined that 90% of the wild individuals were related to the captive stock. Our results suggest a strong impact of the re‐introduction programmme on the present recovery of the wild green turtle population nesting in the Cayman Islands. Moreover, genetic relatedness analyses of captive populations are necessary to improve future management actions to maintain genetic diversity in the long term and avoid inbreeding depression.     

Diversification across the Palaearctic desert belt throughout the Pleistocene: phylogeographic history of the Houbara–Macqueen's bustard complex (Otididae: Chlamydotis) as revealed by mitochondrial DNA

Studies on the influence of Pleistocene climatic fluctuations and associated habitat changes on arid‐adapted bird species living in the Holarctic region are comparatively rare. In contrast to temperate species, the populations of arid‐adapted avian species might be characterized by low genetic differentiation because periods of population isolation were associated with the short interglacial periods, while population expansion events might have occurred during the longer glacial periods when steppe‐like vegetation might have been prevalent. In this study, we tested this hypothesis in a widespread arid‐adapted taxon of the Palaearctic desert belt, the Houbara–Macqueen's bustard complex. The later includes the Houbara bustard Chlamydotis undulata, comprising the North African subspecies Chlamydotis u. undulata and Chlamydotis u. fuertaventurae from the Canary Islands, and the Asian Macqueen's bustard Chlamydotis macqueenii. A long fragment (1042 bp) of the Cyt‐b gene was investigated in 39 representatives of the two species to assess phylogenetic and phylogeographic patterns, and demographic history and to compute divergence time estimates using a Bayesian relaxed molecular clock approach based on different coalescent priors. While the two species are genetically distinct, we found little intraspecific genetic differentiation. The divergence time of the two species falls within a period of extreme aridity at around 0.9 million years ago, which most likely resulted in an east–west vicariance along the Arabo‐Saharan deserts. Differentiation within Houbara and Macqueen's bustard occurred later during the Middle to Upper Pleistocene, and as we have predicted, periods of range expansion were associated to the last glacial period at least in the Macqueen's bustard.     

Study of the variability of erythrocyte enzymes in captive and wild populations of the black lemur (Eulemur macaco macaco). An indispensable preliminary in captive breeding programmes

A study of ten erythrocyte enzymes (PGM I, II, III, G6PD, 6PGD, GLO I, ADA, Est D, DIA, AcP, CA II, and AK) performed on 89 wild and 32 captiveEulemur macaco macaco shows that most systems are monomorphic except four (GLO I, CA II, 6PGD, and NADH DIA). The polymorphism of these markers allows us to make a satisfactory analysis of the variability on this species, especially on the view of comparing wild and captive populations, and shows that: (1) the population does not contain all phenotypes existing in the wild CA_a, CA_{a + b}, DIA_IV, GLO I_{B − C}, and PGD_c are completely absent in all captive populations and DIA_{III + IV} is only present in three out of 32 animals; (2) in the Nosy-komba Island, the PGD_c and DIA_IV are absent and DIA_{III + IV} and GLO I_{B − C} are only present in 1 out of 46 analyzed samples, showing that this population constitutes an isolate. The possibility to use these data for a strategy of Lemur conservation is discussed.     

Significant genetic admixture after reintroduction of peregrine falcon (<Emphasis Type="Italic">Falco peregrinus</Emphasis>) in Southern Scandinavia

The peregrine falcon (Falco peregrinus) population in southern Scandinavia was almost extinct in the 1970’s. A successful reintroduction project was launched in 1974, using captive breeding birds of northern and southern Scandinavian, Finnish and Scottish origin. We examined the genetic structure in the pre-bottleneck population using eleven microsatellite markers and compared the data with the previously genotyped captive breeding population and contemporary wild population. Museum specimens between 53 and 130 years old were analyzed. Despite an apparent loss of historical genetic diversity, the contemporary population shows a relatively high level of genetic variation. Considerable gene introgression from captive breeding stock used to repopulate the former range of southern Scandinavian peregrines may have altered the genetic composition of this population. Both the historical and contemporary northern and southern Scandinavian populations are genetically differentiated. The reintroduction project implemented in the region and the use of non-native genetic stock likely prevented the southern Scandinavian population from extinction and thus helped maintain the level of genetic diversity and prevent inbreeding depression. The population is rapidly increasing in numbers and range and shows no indication of reduced fitness or adaptive capabilities in the wake of the severe bottleneck and the reintroduction.     

Molecular genetic relationships among east Palaerctic ground squirrels of the genus <Emphasis Type="Italic">Spermophilus</Emphasis> (Sciuridae,Rodentia)

Abstact  Genetic diversity in the four east Palearctic ground squirrel species of the genus Spermophilus—S. undulatus, S. parryi (subgenus Urocitellus), S. dauricus, and S. relictus (subgenus Citellus)—was investigated using RAPD PCR with ten random primers. Siberian chipmunk, Tamias sibiricus, was used as an out-group. Molecular markers for different taxonomic ranks were identified, including those for the genera Spermophilus and Tamias, subgenera Urocitellus and Citellus, as well as for each of the four species, S.undulatus, S. parryi, S. dauricus, and S. relictus. For the ground squirrel species and subgenera, genetic differentiation indices (H _t, H _s, D _st, G _st,Nm, and D) were calculated. In addition, for these groups the NJ phylogenetic reconstructions and UPGMA dendrograms of genetic similarity of the individuals and combined populations were constructed. Comparative molecular genetic analysis revealed a high genetic differentiation between S. undulatus, S. dauricus, S. relictus, and S. parryi (G _st= 0.58 to 0.82; D= 0.53 to 1.06), along with a low level of genetic differentiation of the subgenera Citellus and Urocitellus (G _st = 0.33; D= 0.27), distinguished in accordance with the existing taxonomic systems of the genus Spermophilus Original Russian Text ? M.V. Tsvirka, L.N. Spiridonova, V.P. Korablev, 2008, published in Genetika, 2008, Vol. 44, No. 8, pp. 1108–1116.     

Protecting evolutionary significant units for the remnant populations of <Emphasis Type="Italic">Berchemiella wilsonii</Emphasis> var. <Emphasis Type="Italic">pubipetiolata</Emphasis> (Rhamnaceae)

Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered tree in eastern China. Habitat destruction has resulted in fragmentation of remnant populations and extinction of local populations. AFLP and cpDNA markers were used to determine the population structure of remnant populations of B. wilsonii var. pubipetiolata. Moderate nuclear genomic diversity was found within each of the four remnant populations (H _S = 0.141–0.172), while the cpDNA haplotype diversity in each population ranged from 0.356 to 0.681. Six haplotypes were identified by a combined cpRFLP and cpSSR analysis in a total of 89 individuals. AMOVA revealed significantly AFLP genetic differentiation within and between regions (Φ_SC = 0.196, Φ_CT = 0.396, respectively), and a high cpDNA haplotype differentiation between regions (Φ_CT = 0.849). The results suggest low gene flow between populations of B. wilsonii var. pubipetiolata. Strong genetic divergence between two regional populations as revealed by both AFLP and cpDNA markers provided convincing evidence that two distinct evolutionary lineages existed, and should be recognized as ‘evolutionary significant units’ (ESUs) for conservation concerns.     

Genetic structure of Brandt’s vole (<Emphasis Type="Italic">Lasiopodomys brandtii</Emphasis>) populations in Inner Mongolia,China, based on microsatellite analysis

Brandt’s vole (Lasiopodomys brandtii) distribution is discontinuous in Inner Mongolia with some populations isolated from others. Recently, some isolated populations have suffered extinction, and the factors responsible remain elusive. Genetic drift is one of the processes affecting population genetic differentiation, and can play a substantial role in the divergence of small, isolated populations. Using seven microsatellite markers, we genotyped four geographically isolated populations of Brandt’s vole, all of which exhibit episodic fluctuations in population density. The results showed a strong genetic differentiation among the geographically distinct populations (total F _ST = 0.124) and in particular, one population (Zhengxiangbaiqi) was isolated from all others (F _ST values were greatest between Zhengxiangbaiqi and other populations). Furthermore, high levels of inbreeding (F _IS values ranged from 0.205 to 0.290) within each distinct population suggest that inbreeding has and is likely occurring in Brandt’s vole populations. These processes can decrease average individual fitness and consequently increase the risk of extinction of the species.