Haplotype variation in a mitochondrial tandem repeat of Norway spruce (Picea abies) populations suggests a serious founder effect during postglacial re-colonization of the western Alps

Populations from 13 elevational transects of Norway spruce [Picea abies (L.) Karst] across the Alpine range were sampled to elucidate the geographical pattern of genetic variation in relation to postglacial re-colonization and to study elevational effects on haplotypic diversity. We assessed fragment length variation in a tandem repeat region of the mitochondrial (mt) nad1 intron 2. This maternally inherited genetic marker is suited to infer migration as it is dispersed by seed only. A total of 10 haplotypes was found, most of which were due to repeat copy number variation. An analysis of molecular variance (amova) showed that overall population differentiation was high (F(ST)=0.41), and it revealed a significant differentiation between monomorphic western and moderately to highly variable eastern Alpine populations. This phylogeographic pattern may be explained by a founder effect during postglacial re-colonization. An early arriving haplotype, assumed to originate from a western Carpathian refugium, could expand into suitable habitats, reducing the chances for establishment of subsequently arriving haplotypes. On the other hand, the high variation in populations within an Italian transect of the south-eastern Alps may be the consequence of merging migration pathways from and close distance to putative glacial refugia, most likely those assumed in the Carpathian mountains and on the Balkan peninsula or possibly in the central plains of Italy. An effect of elevation on haplotypic diversity was not evident, though a low, but significant, partition of total genetic variation was attributed to among-population variation in one Italian transect. Various factors, such as vertical seed dispersal and forest management, may account for blurring an otherwise established pattern of genetic variation on a small geographical scale.     

POPULATION STRUCTURE AND PHYSIOLOGICAL DIFFERENTIATION OF HAPLOTYPES OF CALOGLOSSA LEPRIEURII (RHODOPHYTA) IN A MANGROVE INTERTIDAL ZONE

Zonation of macroalgae in the intertidal zone has been well documented. However, studies of zonation of macroalgae have predominantly examined the distribution of different species rather than the distribution of variants within a species. This study investigated the spatial variation of plastid haplotypes of the mangrove red alga Caloglossa leprieurii (Montagne) J. Agardh at a site in eastern Australia and tests for physiological differences (growth, photosynthesis) between those haplotypes. RUBISCO spacer plastid haplotypes were scored using single-stranded comformational polymorphism, and the population structure at two sites was examined using a nested sampling design comparing between sites, among transects within sites, and among quadrats within transects. Growth rates at various salinities and light intensities and the photosynthesis–irradiance curves of the three main haplotypes were compared. The two sites showed a high degree of genetic differentiation across a short distance, suggesting limited gene flow. The distribution of haplotypes was patchy and did not reflect a zonation pattern along the intertidal gradient. The three haplotypes were physiologically differentiated with haplotype A, with a lower growth rate and a lower photosynthetic efficiency at higher light intensities. There is some evidence of physiological differentiation between life history phases in C. leprieurii with sporophytes having a higher growth rate than females under most conditions. Our results suggest a correlation between our culture results and our population data. Haplotypes (haplotype A) and life history phases (gametophytes) with lower performance (growth and photosynthetic efficiency) under our culture conditions were correlated with a minor representation in the field. This is the first study to integrate population-level data with physiological parameters toward an understanding of the distribution and relative abundance of red algal genetic variants.     

Fine-scale spatial genetic structure of an endangered marsh herb, Caldesia grandis (Alismataceae)

The endangered marsh herb, Caldesia grandis, is native to China. We investigated the spatial structure of the genetic variation of three populations of C. grandis using RAPD markers and spatial autocorrelation analysis, based on the method of equal distance interval. A total of 157 individuals were sampled from four patches collected from the region of Hunan and Yunnan Provinces, China. Among the polymorphic bands generated by seven selective primers, polymorphic bands with frequencies ranging from 20 to 80% were used to calculate Moran's I spatial autocorrelation coefficient for each patch. We found significant spatial structure of genetic variation in the three patches in Bei Hai (BH) (patches BH-1 and BH-2) and Guai Hu (GH) (patch GH-1) populations of C. grandis (with significant positive autocorrelation within the short distance class). In contrast, the genetic variation in the Lang Pan Hu (LPH) population (patch LPH-1) was found to be randomly distributed. The different spatial distribution patterns may be attributed to environment differences. These results have implications for the conservation and management of this species, especially for sampling strategies for ex situ conservation.     

Genetic variation and population structure of swimming crab (Portunus trituberculatus) inferred from mitochondrial control region

Genetic variation and population structure in Portunus trituberculatus along the coast of China were revealed according to 617 bp of mitochondrial DNA control region. 90 polymorphic sites defined 53 distinct haplotypes, showing a moderately high diversity among 72 individuals sampled from eight localities. Neighbor-joining tree, statistics analyses of gene flow and genetic differentiation index indicated two populations from Beihai and Laizhou had differentiated. The population from Yingkou, Dandong, Laizhou and Beihai had smaller genetic diversity compared to that from Ningbo, Lianyungang, Qingdao and Japan according to the genetic distance. And mantel test showed significant positive correlation between genetic distance and geographic distance for P. trituberculatus. TCS parsimony network suggested that all the animals sampled were probably the result of recent divergence from a common ancestral haplotype but for Laizhou population. Moreover, the haplotype distribution appeared to correlate with a recent colonization followed by localized genetic differentiation. Mismatch distribution results suggested that Ningbo, Yingkou, Qingdao, Lianyungang and Japan populations, particularly Dandong population had experienced a sudden demographic or spatial expansion. The Pleistocene glaciations might contribute to this process.     

GENETIC STRUCTURE OF GEOGRAPHICALLY MARGINAL POPULATIONS OF PONDEROSA PINE

Eleven populations of ponderosa pine (Pinus ponderosa) located on an east-west transect of the Palmer Divide of Central Colorado were studied. Within each population transects of approximately 20 × 250 m were established. In seven populations the transects represented contrasting ecological conditions such as north and south facing slopes. Within each transect 200–250 trees greater than 10 cm in height were tagged, their locations mapped, their ages determined and their diameters and heights measured. Electrophoretic analyses of mature needle tissue indicated that while most of the allozyme variation resided within transects, significant genetic heterogeneity could be found between populations and transects. Among populations consistent patterns of genetic variation were observed at only two loci. Five of the 13 loci had consistent but very small differences between transects within populations. Considerable genetic heterogeneity occurred among 20 m sections of the transects and among age classes within transects. The genetic structure of these populations can be explained by mosaic patterns of seedling recruitment characteristic of these ponderosa pine stands. Only a few maternal trees contribute to each patch of seedlings, and this localized founder effect produces the genetic structure observed in these populations.     

毛茛叶报春高分化的谱系地理结构

毛茛叶报春（Primula ranunculoides Chen）是我国特有的珍稀濒危花卉,其野生种质资源已十分稀少。为了揭示其谱系地理结构,本文对11个居群114个个体的叶绿体trnL-F和trnS-G基因片段进行了测序分析。结果共检测到10个单倍型,除YJPA和YJPB两居群共享一个单倍型（H9）外,其余各居群均仅有一个特有单倍型,居群内不存在单倍型多样性。毛茛叶报春具高分化的谱系地理结构,居群间的总平均遗传距离达0.015,单倍型间的平均突变次数高达31.2步,两者均显著高于同属的近缘种。其种子散布能力弱、生境片断化和地理隔离明显及两年生的生活史可能是导致其高分化谱系地理结构产生的主要原因。Samova、Structure以及TCS分析均支持将毛茛叶报春11个居群的遗传结构分为6组,它们与地形（山脉）关系密切对应,彼此间分化明显,因此建议不同山体的居群应视为不同的保护单元进行遗传管理。     

Genetic Variation of Sclerotinia sclerotiorum from Multiple Crops in the North Central United States

Sclerotinia sclerotiorum is an important pathogen of numerous crops in the North Central region of the United States. The objective of this study was to examine the genetic diversity of 145 isolates of the pathogen from multiple hosts in the region. Mycelial compatibility groups (MCG) and microsatellite haplotypes were determined and analyzed for standard estimates of population genetic diversity and the importance of host and distance for genetic variation was examined. MCG tests indicated there were 49 different MCGs in the population and 52 unique microsatellite haplotypes were identified. There was an association between MCG and haplotype such that isolates belonging to the same MCG either shared identical haplotypes or differed at no more than 2 of the 12 polymorphic loci. For the majority of isolates, there was a one-to-one correspondence between MCG and haplotype. Eleven MCGs shared haplotypes. A single haplotype was found to be prevalent throughout the region. The majority of genetic variation in the isolate collection was found within rather than among host crops, suggesting little genetic divergence of S. sclerotiorum among hosts. There was only weak evidence of isolation by distance. Pairwise population comparisons among isolates from canola, dry bean, soybean and sunflower suggested that gene flow between host-populations is more common for some crops than others. Analysis of linkage disequilibrium in the isolates from the four major crops indicated primarily clonal reproduction, but also evidence of genetic recombination for isolates from canola and sunflower. Accordingly, genetic diversity was highest for populations from canola and sunflower. Distribution of microsatellite haplotypes across the study region strongly suggest that specific haplotypes of S. sclerotiorum are often found on multiple crops, movement of individual haplotypes among crops is common and host identity is not a barrier to gene flow for S. sclerotiorum in the north central United States.     

Effect of altitude on the genetic structure of an Alpine grass, Poa hiemata

Background and Aims

The persistence of plants inhabiting restricted alpine areas under climate change will depend upon many factors including levels of genetic variation in adaptive traits, population structure, and breeding system.

Methods

Using microsatellite markers, the genetic structure of populations of a relatively common alpine grass, Poa hiemata, is examined across three altitudinal gradients within the restricted Australian alpine zone where this species has previously been shown to exhibit local adaptation across a narrow altitudinal gradient.

Key Results

Genetic variation across six microsatellite markers revealed genetic structuring along altitudinal transects, and a reduction in genetic variation at high and low altitude extremes relative to sites central within transects. There was less genetic variation among transect sites compared with altitudinal gradients within transects, even though distances among transects were relatively larger. Central sites within transects were less differentiated than those at extremes.

Conclusions

These patterns suggest higher rates of gene flow among sites at similar altitudes than along transects, a process that could assist altitudinal adaptation. Patterns of spatial autocorrelation and isolation by distance changed with altitude and may reflect altered patterns of dispersal via pollen and/or seed. There was evidence for selfing and clonality in neighbouring plants. Levels of gene flow along transects were insufficient to prevent adaptive changes in morphological traits, given previously measured levels of selection.Key words: Poa hiemata, genetic structure, altitudinal gradient, microsatellite, gene flow, climate change     

Endangered species in small habitat patches can possess high genetic diversity: the case of the Tana River red colobus and mangabey

We used mtDNA sequence data from the Tana River red colobus and mangabey to determine how their population genetic structure was influenced by dispersal and habitat fragmentation. The colobus and mangabey are critically endangered primates endemic to gallery forests in eastern Kenya. The forests are a Pliocene–Pleistocene refugium that has recently undergone significant habitat loss and fragmentation due to human activities. We expected both primates to exhibit low levels of genetic diversity due to elevated genetic drift in their small populations, and to show a strong correspondence between genetic and geographic distance due to disruption of gene flow between forests by habitat fragmentation. Additionally, because mangabey females are philopatric, we expected their mtDNA variation to be homogeneous within forest patches but to be heterogeneous between patches. In contrast, colobus have a female-biased dispersal and so we expected their mtDNA variation to be homogeneous within and between forest patches. We found high levels of haplotype and nucleotide diversity as well as high levels of sequence divergence between haplotype groups in both species. The red colobus had significantly higher genetic variation than the mangabey did. Most of the genetic variation in both primates was found within forest fragments. Although both species showed strong inter-forest patch genetic structure we found no correspondence between genetic and geographic distances for the two primates. We attributed the high genetic diversity to recent high effective population size, and high sequence divergence and strong genetic structures to long-term habitat changes in the landscape.     

Genetic structure of desert ground squirrels over a 20-degree-latitude transect from Oregon through the Baja California peninsula

The genetic structure of populations over a wide geographical area should reflect the demographic and evolutionary processes that have shaped a species across its range. We examined the population genetic structure of antelope ground squirrels (Ammospermophilus leucurus) across the complex of North American deserts from the Great Basin of Oregon to the cape region of the Baja California peninsula. We sampled 73 individuals from 13 major localities over this 2500-km transect, from 43 to 22 degrees north. Our molecular phylogeographical analysis of 555 bp of the mitochondrial cytochrome b gene and 510 bp of the control region revealed great genetic uniformity in a single clade that extends from Oregon to central Baja California. A second distinct clade occupies the southern half of the peninsula. The minimal geographical structure of the northern clade, its low haplotype diversity and the distribution of pairwise differences between haplotypes suggest a rapid northward expansion of the population that must have followed a northward desert habitat shift associated with the most recent Quaternary climate warming and glacial retreat. The higher haplotype diversity within the southern clade and distribution of pairwise differences between haplotypes suggest that the southern clade has a longer, more stable history associated with a southern peninsular refugium. This system, as observed, reflects both historical and contemporary ecological and evolutionary responses to physical environmental gradients within genetically homogeneous populations.     

Tropical metacommunities along elevational gradients: effects of forest type and other environmental factors

Elevational gradients provide a natural experiment for assessing the extent to which the structure of animal metacommunities is molded by biotic and abiotic characteristics that change gradually, or is molded by aspects of plant community composition and physiognomy that change in a more discrete fashion. We used a metacommunity framework to integrate species‐specific responses to environmental gradients as an approach to detect emergent patterns at the mesoscale in the Luquillo Mountains of Puerto Rico. Elements of metacommunity structure (coherence, species turnover and range boundary clumping) formed the basis for distinguishing among random, checkerboard, Gleasonian, Clementsian, evenly spaced and nested patterns. Paired elevational transects (300–1000 m a.s.l.) were sampled at 50 m intervals to decouple underlying environmental mechanisms: a mixed forest transect reflected changes in abiotic and biotic conditions, including forest type (i.e. tabonuco, palo colorado and elfin forests), whereas another transect reflected changes in environmental conditions but not forest type, as its constituent plots were located within palm forest. Based on distributional data (presence versus absence of species), the mixed forest transect exhibited Clementsian structure, whereas the palm forest transect exhibited quasi‐Gleasonian structure. In contrast, the distribution of modes in species abundance was random with respect to the latent environmental gradient in the mixed forest transect and clumped with respect to the latent environmental gradient in the palm forest transect. Such contrasts suggest that the environmental factors affecting abundance differed in form or type from those affecting distributional boundaries. Variation among elevational strata with respect to the first axis of correspondence from reciprocal averaging was highly correlated with elevation along each transect, even though axis scores were not correlated between mixed forest and palm forest transects. This suggests that the identity of the environmental characteristics, or the form of response by the fauna to those characteristics, differed between the two elevational transects. Despite the proximity of the transects, the patchy configuration of palm forest, and the pervasive distribution of the dominant palm species, the relative importance of abiotic variables and habitat in structuring gastropod metacommunities differed between transects, which is remarkable and attests to the sensitivity of metacommunity structure to environmental variation.     

Hierarchical genetic structure and gene flow in three sympatric species of Amazonian rodents

The population genetic structure of three species of Amazonian rodents ( Oligoryzomys microtis, Oryzomys capito , and Mesomys hispidus ) is examined for mtDNA sequence haplotypes of the cytochrome b gene by hierarchical analysis of variance and gene flow estimates based on fixation indices ( N _ST) and coalescence methods. Species samples are from the same localities along 1000 km of the Rio Juruá in western Amazonian Brazil, but each species differs in important life history traits such as population size and reproductive rate. Average haplotype differentiation, hierarchical haplotype apportionment, and gene flow estimates are contrasted in discussing the current and past population structure. Two species exhibit isolation by distance patterns wherein gene flow is largely limited to geographically adjacent localities. Mesomys exhibits this pattern throughout its range along the river. More than 75% of haplotype variation is apportioned among localities and regions, and estimates of Nm for pair-wise comparisons are nearly always less than 1. Oligoryzomys shows weak isolation by distance, but only over the largest geographical distances. Nm values for this species are nearly always above 1 and most (about 80%) of haplotype variation is contained within local populations. In contrast, Oryzomys exhibits no genetic structure throughout its entire distribution; Nm values average 17 and nearly 90% of the total haplotype variance is contained within local populations. Although gene flow estimates are high, the pattern of Nm as a function of geographical distance suggests that this species experienced a more recent invasion of the region and is still in genetic disequilibrium under its current demographic conditions.     

Genetic population structure of Tectura paleacea: implications for the mechanisms regulating population structure in patchy coastal habitats

The seagrass limpet Tectura paleacea (Gastropoda; Patellogastropoda) belongs to a seagrass obligate lineage that has shifted from the Caribbean in the late Miocene, across the Isthmus of Panama prior to the closing of the Panamanian seaway, and then northward to its modern Baja California - Oregon distribution. To address whether larval entrainment by seagrass beds contributes to population structuring, populations were sampled at six California/Oregon localities approximately 2 degrees latitude apart during two post-settlement periods in July 2002 and June 2003. Partial cytochrome oxidase b (Cytb) sequences were obtained from 20 individuals (10 per year) from each population in order to determine the levels of population subdivision/connectivity. From the 120 individuals sequenced, there were eighty-one unique haplotypes, with the greatest haplotype diversity occurring in southern populations. The only significant genetic break detected was consistent with a peri-Point Conception (PPC) biogeographic boundary while populations north and south of Point Conception were each panmictic. The data further indicate that populations found south of the PPC biogeographic boundary originated from northern populations. This pattern of population structure suggests that seagrass patches are not entraining the larvae of T. paleacea by altering flow regimes within their environment; a process hypothesized to produce extensive genetic subdivision on fine geographic scales. In contrast to the haplotype data, morphological patterns vary significantly over very fine geographic scales that are inconsistent with the observed patterns of genetic population structure, indicating that morphological variation in T. paleacea might be attributed to differential ecophenotypic expression in response to local habitat variability throughout its distribution. These results suggest that highly localized conservation efforts may not be as effective as large-scale conservation efforts in near shore marine environments.     

Mitochondrial DNA signatures of restricted gene flow within divergent lineages of an atyid shrimp (Paratya australiensis)

We measured spatial genetic structure within three previously described mitochondrial lineages of the atyid shrimp, Paratya australiensis, occurring in upland streams of two major catchments within the Sydney Water Supply Catchment, New South Wales, Australia. In all three lineages, there was significant spatial structuring of genetic variation between catchments. In two lineages, recurrent but restricted maternal gene flow has apparently predominated in shaping within-catchment genetic structure, although this framework may be overlaid with episodic contiguous/long-distance expansion events. In the third lineage, there was no evidence of spatial genetic structuring within one of the catchments, because one haplotype was both common and widespread throughout the sampled area. High-frequency haplotypes were also shared among subcatchments in the other two lineages, and we discuss both historical and contemporary processes that may have left these genetic signatures. Our results are generally concordant with previous reports of significant population structuring in P. australiensis, occurring in upland river reaches elsewhere in eastern Australia. We propose that restricted dispersal and gene flow among upland populations of P. australiensis is linked to dramatic architectural structuring within and among mountain streams.     

Population genetic structure of two water strider species in the Ecuadorian Amazon

1. We used mtDNA sequence variation to estimate population genetic structure between and among water strider populations of Potamobates williamsi and P . sumaco in the Ecuadorian Amazon.
2. Sequencing of the COI mitochondrial gene revealed 16 haplotypes, which were summarised into four haplotype groups. P . williamsi and P . sumaco shared two common and widespread haplotypes.
3. Population structure was moderate and gene flow was low. Both air and river distances were significantly correlated with gene flow and, thus, indicative of isolation by distance.
4. The genetic structure within and among populations of P. williamsi and P. sumaco was probably not influenced by the dynamic tropical lotic system.     

Species traits and the response of open‐habitat species to forest edge in landscape mosaics

Human driven changes in land‐use have increased the need to understand how landscape structure affects species distribution. We studied how forest edges affected the distribution of birds in grasslands recently encroached by forest patches. We investigated how species’ biological traits influenced their response to vegetation change near forest edges. We censured birds along 300‐m line transects run into the open habitat perpendicularly to forest edges. We recorded habitat variables and landscape context along each transect and characterized edges and forest patches. We recorded 33 bird species in 153 transects for a total of 654 individuals. We analyzed species response to edges with generalized linear mixed models. Habitat preference was prevalent to explain species response to forest edges. The abundance of open‐habitat birds such as skylark Alauda arvensis decreased significantly in the vicinity of edges. This negative response extended within 150 m from the edge. The effect was disproportionately higher in open‐habitat species with high conservation concern. The abundance of species feeding or/and breeding in both forest and open habitat, such as woodlarks Lullula arborea, sharply increased near edges (positive edge response). Abundance of shrub and non‐shrub dependent species increased with distance to edge. The two species groups did no differ in abundance/distance to edge relationship. Intensity of species response to forest edges varied among transects in relation to transect vegetation characteristics. Edge length or aspect, diet and nest height had no direct effect. We discuss the possible role of variation in resources and nest predation risk to explain observed patterns.     

Hierarchical analysis of colony and population genetic structure of the eastern subterranean termite, Reticulitermes flavipes, using two classes of molecular markers

Termites (Isoptera) comprise a large and important group of eusocial insects, yet, in contrast to the eusocial Hymenoptera (ants, bees, wasps), the breeding systems of termites remain poorly understood. In this study, I inferred the breeding system of the subterranean termite Reticulitermes flavipes based on colony and population genetic structure as determined from microsatellite and mitochondrial DNA markers. Termites were sampled from natural wood debris from three undisturbed, forested sites in central North Carolina. In each site, two transects separated by 1 km were sampled at approximately 15-m intervals. A total of 1272 workers collected from 57 collection points were genotyped at six microsatellite loci, and mitochondrial DNA haplotype was determined for a subset of these individuals using either restriction fragment length polymorphism or sequence variation in the AT-rich region. Colonies appeared to be localized: workers from the 57 collection points represented 56 genetically distinct colonies with only a single colony occupying two collection points located 15 m apart. Genetic analysis of family structure and comparisons of estimates of F-statistics (F(IT), F(IC), F(CT)) and coefficients of relatedness (r) among nestmate workers with results of computer simulations of potential breeding systems suggested that 77% of all colonies were simple families headed by outbred monogamous pairs, whereas the remaining colonies were extended (inbred) families headed by low numbers of neotenics (about two females and one male) who were the direct offspring of the colony founders. There was no detectable isolation by distance among colonies along transects, suggesting that colony reproduction by budding is not common and that dispersal of reproductives during mating flights is not limited over this distance. Higher-level analysis of the microsatellite loci indicated weak but significant differentiation among sites (F(ST) = 0.06), a distance of 16-38 km, and between transects within sites (F(ST) = 0.06), a distance of 1 km. No significant differentiation at either the transect or site level was detected in the mitochondrial DNA sequence data. These results indicate that the study populations of R. flavipes have a breeding system characterized by monogamous pairs of outbred reproductives and relatively low levels of inbreeding because most colonies do not live long enough to produce neotenics, and those colonies that do generate neotenics contain an effectively small number of them.     

Mitochondrial DNA variation in the European otter (Lutra lutra) and the use of spatial autocorrelation analysis in conservation

To add genetic information to the international conservation efforts on European otters Lutra lutra, we investigated the genetic population structure in and around a known "source" population of the otter, the Oberlausitz (OL) in eastern Germany. This was complemented by a first survey of genetic variation levels in the Central European otter population. Sequence analysis of 300bp of the mitochondrial control region in 76 specimens from the eastern German study region and 53 individuals from several other European populations revealed a low level of genetic variation, with only 5 haplotypes present and nucleotide diversities within populations ranging from 0.00% to 0.17%. Apart from eastern Germany, one haplotype was by far the most abundant one, from which other, only locally occurring types, could be derived by a single point mutation. This suggests a single Pleistocene refugium from which the analyzed European regions have been reinvaded after the glaciations. Within eastern Germany, two abundant haplotypes were found. Their occurrence differed significantly among subregions of eastern Germany. The uneven distribution of a locally restricted but abundant haplotype could be explained by isolation-by-distance and might reflect emigration from the OL source population to surrounding regions. This suggests that vital local populations can indeed serve as "sources" for the invasion of surrounding areas. Given a suitable genetic marker, we suggest a spatial autocorrelation analysis to monitor the genetic effect of such an emigration from a source population.     

Breeding structure of Glossina pallidipes populations evaluated by mitochondrial variation

Mitochondrial DNA diversity was studied at four loci in six natural populations of the tsetse fly Glossina pallidipes from Zimbabwe, Mozambique, Kenya, and Ethiopia. Single-locus diversity varied from 0.39 at 12S to 0.65 at COII. A total of 32 haplotypes was found with a mean of 6.4 +/- 2.9 per locus. To study breeding structure, diversity at two loci, COII and 16S2, was evaluated in 18 populations sampled from an area of approximately 1,611,000 km2 and in three laboratory cultures. Twenty-six haplotypes were detected at the two loci and mean haplotype diversity over all natural populations was 0.63. A high degree of population subdivision was detected within and among the Ethiopian and Kenya populations. The Zimbabwe and Zambia populations showed much less variation and differentiation than the northern populations. A population in Mozambique showed high levels of haplotype variation and affinities closest to populations in eastern Kenya, some 1700 km to the north. Analysis of variance of haplotype frequencies showed that 51.5% of the total lay within populations, 13% among populations within five nested groups, and 35.5% among the five groups. Wright's FST was 0.485, Nei's GST was 0.33, and Weir and Cunningham's theta = 0.45. Ecological data show that G. pallidipes is highly vagile. The large amount of genetic differentiation may be explained by genetic drift that occurred in scattered, relict populations during the rinderpest panzootic of the late 19th and early 20th centuries.     

Individual differences in migratory behavior shape population genetic structure and microhabitat choice in sympatric blackcaps (Sylvia atricapilla)

In migratory birds, traits such as orientation and distance are known to have a strong genetic background, and they often exhibit considerable within‐population variation. How this variation relates to evolutionary responses to ongoing selection is unknown because the underlying mechanisms that translate environmental changes into population genetic changes are unclear. We show that within‐population genetic structure in southern German blackcaps (Sylvia atricapilla) is related to individual differences in migratory behavior. Our 3‐year study revealed a positive correlation between individual migratory origins, denoted via isotope (δ²H) values, and genetic distances. Genetic diversity and admixture differed not only across a recently established migratory polymorphism with NW‐ and SW‐migrating birds but also across δ²H clusters within the same migratory route. Our results suggest assortment based on individual migratory origins which would facilitate evolutionary responses. We scrutinized arrival times and microhabitat choice as potential mechanisms mediating between individual variation in migratory behavior and assortment. We found significant support that microhabitat choice, rather than timing of arrival, is associated with individual variation in migratory origins. Moreover, examining genetic diversity across the migratory divide, we found migrants following the NW route to be genetically more distinct from each other compared with migrants following the traditional SW route. Our study suggests that migratory behavior shapes population genetic structure in blackcaps not only across the migratory divide but also on an individual level independent of the divide. Thus, within‐population variation in migratory behavior might play an important role in translating environmental change into genetic change.