Within-population Genetic Diversity (within-population + genetic_diversity)

Distribution by Scientific Domains


Selected Abstracts


Distribution and population genetic structure of the Mediterranean pine shoot beetle Tomicus destruens in the Iberian Peninsula and Southern France

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2006
Teresa Vasconcelos
Abstract 1,The Mediterranean pine shoot beetle Tomicus destruens has long been indistinguishable from its congeneric Tomicus piniperda. Both species attack pines, and can be found in sympatry. The geographical distribution of T. destruens is still unclear in most of the Mediterranean Basin. 2,We aimed to describe the geographical distribution and zones of sympatry of both species in the Iberian Peninsula and France, and to study the molecular phylogeographical pattern of T. destruens. 3,Tomicus spp. adults were sampled in Portugal, Spain and France, and a portion of the mitochondrial genes COI and COII was sequenced for 84 individuals. Sequences were aligned to a data set previously obtained from French localities. 4,Tomicus destruens was found in all populations, except for one locality in Portugal and in the Landes (France). It was in sympatry with T. piniperda in two locations on Pinus pinaster and one location on Pinus radiata. 5,Within-population genetic diversity was high, but we found a significant pattern of spatial distribution of genetic variation, as well as a significant effect of the host tree. 6,The data suggest the existence of two glacial refugia, from which T. destruens recolonized its current range. One refugium was located in Portugal where the beetle probably evolved on P. pinaster. The corresponding haplotypes show a West,East frequency gradient. The other refugium was probably in the eastern range, where the beetles evolved on Pinus halepensis and P. pinea. The corresponding haplotypes show an East,West frequency gradient. [source]


Genetic diversity of Ranunculus acris L. (Ranunculaceae) populations in relation to species diversity and habitat type in grassland communities

MOLECULAR ECOLOGY, Issue 5 2004
Nidal Odat
Abstract Correlates between genetic diversity at intra- and interpopulation levels and the species diversity in plant communities are rarely investigated. Such correlates may give insights into the effect of local selective forces across different communities on the genetic diversity of local plant populations. This study has employed amplified fragment length polymorphism to assess the genetic diversity within and between 10 populations of Ranunculus acris in relation to the species diversity (richness and evenness) of grassland communities of two different habitat types, ,seminatural' and ,agriculturally improved', located in central Germany. Within-population genetic diversity estimated by Nei's unbiased gene diversity (HE) was high (0.258,0.334), and was not correlated with species richness (Pearson's r = ,0.17; P = 0.64) or species evenness (Pearson's r = 0.15; P = 0.68) of the plant communities. However, the genetic differentiation between R. acris populations was significantly correlated with the difference in species evenness (Mantel's r = 0.62, P = 0.02), but not with difference in species richness of plant communities (r = ,0.17, P = 0.22). Moreover, we also found that populations of R. acris from the ,seminatural' habitat were genetically different (amova, P < 0.05) from those in ,agriculturally improved' habitats, suggesting that gene flow between these habitat types is limited. The results reported in this study may indicate that habitat characteristics influence the genetic diversity of plant species. [source]


Genome scan in the mosquito Aedes rusticus: population structure and detection of positive selection after insecticide treatment

MOLECULAR ECOLOGY, Issue 2 2010
MARGOT PARIS
Abstract Identification of genes involved in local adaptation is particularly challenging for species functioning as a network of interconnected populations undergoing frequent extinctions,recolonizations, because populations are submitted to contrasted evolutionary pressures. Using amplified fragment length polymorphism markers, population genetic structure of the mosquito Aedes rusticus was analysed in five geographical areas of the French Rhône-Alpes region. We included a number of sites that were treated with the bio-insecticide Bacillus thuringiensis israelensis (Bti) for more than 15 years. Analysis of molecular variance revealed that most of the genetic variability was found within populations (96%), with no significant variation among geographical areas, although variation among populations within areas (4%) was significant. The global genetic differentiation index FST was low (0.0366 ± 0.167). However, pairwise FST values were significant and no isolation-by-distance at the regional level was observed, suggesting a metapopulation structure in this species. Bti -treatment had no effect on genetic structure and on within-population genetic diversity. Potential signatures of positive selection associated with Bti -treatment were detected for five loci, even though toxicological bioassays performed on field-collected larvae showed no significant difference in mortality between Bti -treated and nontreated sites. The difficulty of detecting moderate resistance in field-collected larvae together with possible differential persistence of toxins in the environment may explain our inability to detect a toxicological response to Bti in treated sites. The evidence for positive selection occurring at several genomic regions suggests a first step towards Bti resistance in natural mosquito populations treated with this bio-insecticide. Furthermore, this signal was detectable using genomic tools before any toxicological evidence for resistance could be identified. [source]


RAPD variation and population genetic structure in Prunus mahaleb (Rosaceae), an animal-dispersed tree

MOLECULAR ECOLOGY, Issue 9 2000
Pedro Jordano
Abstract We examined the patterns of random amplified polymorphic DNA (RAPD) variation among seven Prunus mahaleb (Rosaceae) populations extending over , 100 km2 to examine local differentiation in relation to spatial isolation due to both geographical distance and differences in elevation. No less than 51.4% of the RAPD loci were polymorphic, but very few were fixed and among-population variation accounted for 16.46% of variation in RAPD patterns. Mean gene diversity was 0.1441, with mean Nei's genetic diversity for individual populations ranging between 0.089 and 0.149. Mean GST value across loci was 0.1935 (range, 0.0162,0.4685), giving an average estimate for Nm of 1.191. These results suggest extensive gene flow among populations, but higher GST and lower Nm values relative to other outcrossing, woody species with endozoochorous dispersal, also suggest a process of isolation by distance. The combined effect of both geographical and elevation distances and nonoverlapping flowering and fruiting phenophases on the GST matrix was partially significant, revealing only marginal isolation of the P. mahaleb populations. The matrix correlation between estimated Nm values among populations and the geographical + elevation distance matrices (r = ,0.4623, P = 0.07), suggests a marginal trend for more isolated populations to exchange less immigrants. Long-distance seed dispersal by efficient medium-sized frugivorous birds and mammals is most likely associated to the high levels of within-population genetic diversity. However, vicariance factors and demographic bottlenecks (high postdispersal seed and seedling mortality) explain comparatively high levels of local differentiation. [source]


Genetic structure of Euclea schimperi (Ebenaceae) populations in monsoonal fog oases of the southern Arabian Peninsula

NORDIC JOURNAL OF BOTANY, Issue 3-4 2007
Jörg Meister
Euclea schimperi, a widespread Afromontane shrub or tree, occurs in the Arabian Peninsula in fragmented, semi-evergreen or evergreen woodland refugia in wet escarpment localities of the western and southern mountain chains. In the southern coastal mountains, the (semi-) evergreen woodland with E. schimperi is close to its ecological limit and consequently today very rare, with the exception of the monsoonal fog oases of east Yemen and south Oman in the central south coast of the Arabian Peninsula. Due to the steep precipitation gradient from the centre to the western edge in this monsoon affected area, E. schimperi is found in two different habitat types: in continuous woodland belts in the Hawf and Dhofar mountains, and in isolated, scattered woodland patches in the Fartak Mountains. Ten populations (138 individuals) from across the southern Arabian distribution area of the species were analysed using chloroplast microsatellites and AFLP fingerprinting to a) reconstruct the phylogeographical pattern of E. schimperi on the southern Arabian Peninsula and b) to evaluate the consequences of population fragmentation on the genetic diversity harboured in isolated patches vs cohering stands. Phylogeographical reconstructions show that the distribution area of E. schimperi in the southern Arabian Peninsula is characterised by a geographical split that separates the southwestern populations (representated by material from Jabal Eraf and Jabal Uthmar), from the southcentral populations, which themselves are split from each other into a western (Ras Fartak) and an eastern refugium (Hawf/Dhofar). The analysis of the within-population genetic diversity in E. schimperi populations resulted in a slightly, but not significantly higher genetic variation in small and isolated woodland patches (HS=0.302) compared to larger, cohering stands (HS=0.291). [source]


Genetic structure of Anogeissus dhofarica (Combretaceae) populations endemic to the monsoonal fog oases of the southern Arabian Peninsula

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
CHRISTOPH OBERPRIELER
Anogeissus dhofarica (Combretaceae) is an endemic tree of the monsoon affected coastal mountains of the southern Arabian Peninsula, being the character species of the Hybantho durae,Anogeissetum dhofaricae association, a drought deciduous, monsoon forest community found only in the Dhofar region of southern Oman and the eastern Al-Mahra region of south-east Yemen. Due to the steep precipitation gradient from the centre to the edges in this monsoon affected area, A. dhofarica is found in two different habitat types: in continuous woodland belts of the Hawf and Dhofar mountains, and in isolated, scattered woodland patches, as found especially in the Fartak Mts (south-east Yemen). Fifteen populations (212 individuals) from across the whole distribution area of the species were analysed using amplified fragment length polymorphism fingerprinting to: (1) evaluate the consequences of population fragmentation on the genetic diversity harboured in isolated patches versus cohering stands of the species and (2) to reconstruct the phylogeographical pattern of A. dhofarica as a consequence of oscillations in the monsoon activity during the Pleistocene and Holocene. The analysis of among-population genetic differentiation and within-population genetic diversity in A. dhofarica populations resulted in a lack of genetic pauperization and genetic differentiation of populations of the distinctly isolated patches of the Fartak Mts compared to the more luxurious forests of the Hawf and Dhofar regions. This is considered to be due to the high buffer capacity against the loss of genetic diversity caused by the long-lived life-form of the species combined with the capability to propagate clonally and the relatively recent fragmentation of Anogeissus forests into the described patches rather than due to high values of gene flow among remnant populations caused by bee pollination and anemochorical and hydrochorical diaspore dispersal. The phylogeographical pattern of the species argues for a quite recent fragmentation of a once continuous forest belt of A. dhofarica that is rather connected with climate changes in the Holocene than triggered by aridity,humidity oscillations reported for the Pleistocene. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 40,51. [source]