			Home About us Contact

Colonization History (colonization + history)

Distribution by Scientific Domains

Life Sciences	81%

Selected Abstracts

Colonization history, ecological shifts and diversification in the evolution of endemic Galápagos weevils

MOLECULAR ECOLOGY, Issue 4 2008
A. S. SEQUEIRA
Abstract Mitochondrial DNA sequence data were obtained for eight species of flightless Galapaganus endemic weevils and one winged close relative in order to study their colonization history and modes of diversification in the Galápagos Archipelago. Contrary to most other insular radiations, the phylogeny estimates we recovered for Galapaganus do not follow the progression rule of island biogeography. The penalized likelihood age estimates of colonization of the archipelago exceed the age of the emerged islands and underscore the potential role of now sunken seamounts for the early evolution of Galapaganus. The phylogeny proposes one intra-island origin for Galapaganus endemics, but monophyly tests suggest a larger contribution of in-situ speciation on older islands. Generalist habitat preferences were reconstructed as ancestral while shifts to highland habitats were reconstructed as having evolved independently on different islands. Magnitudes and patterns of diversification rate were found to differ between older and younger islands. Our analyses reveal that the colonization sequence of islands and timing of colonization of Galapaganus could be linked with the geological and volcanic history of the islands in a rather complex scenario. Even though most islands appear to have been colonized soon after their emergence, there are notable deviations from the pattern of sequential colonization expected under the progression rule when considering only the extant emerged islands. Patterns of diversification rate variation on older and younger islands correspond to the volcanic activity or remnants of such activity, while the pattern of independent evolution of restricted habitat preferences in different islands suggests that habitat shifts could also have contributed to species diversity in Galapaganus. [source]

Can distribution models help refine inventory-based estimates of conservation priority?

DIVERSITY AND DISTRIBUTIONS, Issue 4 2010
A case study in the Eastern Arc forests of Tanzania, Kenya
Abstract Aim, Data shortages mean that conservation priorities can be highly sensitive to historical patterns of exploration. Here, we investigate the potential of regionally focussed species distribution models to elucidate fine-scale patterns of richness, rarity and endemism. Location, Eastern Arc Mountains, Tanzania and Kenya. Methods, Generalized additive models and land cover data are used to estimate the distributions of 452 forest plant taxa (trees, lianas, shrubs and herbs). Presence records from a newly compiled database are regressed against environmental variables in a stepwise multimodel. Estimates of occurrence in forest patches are collated across target groups and analysed alongside inventory-based estimates of conservation priority. Results, Predicted richness is higher than observed richness, with the biggest disparities in regions that have had the least research. North Pare and Nguu in particular are predicted to be more important than the inventory data suggest. Environmental conditions in parts of Nguru could support as many range-restricted and endemic taxa as Uluguru, although realized niches are subject to unknown colonization histories. Concentrations of rare plants are especially high in the Usambaras, a pattern mediated in models by moisture indices, whilst overall richness is better explained by temperature gradients. Tree data dominate the botanical inventory; we find that priorities based on other growth forms might favour the mountains in a different order. Main conclusions, Distribution models can provide conservation planning with high-resolution estimates of richness in well-researched areas, and predictive estimates of conservation importance elsewhere. Spatial and taxonomic biases in the data are essential considerations, as is the spatial scale used for models. We caution that predictive estimates are most uncertain for the species of highest conservation concern, and advocate using models and targeted field assessments iteratively to refine our understanding of which areas should be prioritised for conservation. [source]

Liriomyza huidobrensis in Yunnan, China: current distribution and genetic structure of a recently established population

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2002
Liping He
Abstract Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae) is a very serious and economically important pest around the world. Liriomyza huidobrensis in China was first reported from Kunming of Yunnan province in 1993. We report here that this pest has recently expanded its distribution, along with a host plant range extension and population explosion. The mitochondrial cytochrome oxidase II gene was sequenced for eight populations from Yunnan. All individuals were identical: no genetic variation was observed between populations either from different geographical localities or from different host plants. The phylogenetic analysis shows that the Yunnan population is grouped into the South American clade, which also includes other recently introduced Asian populations. Together with ecological data and colonization history of this pest, our results suggest that Yunnan population might have an ultimate, albeit not immediate, origin from South American populations. [source]

Phylogeography of the introduced species Rattus rattus in the western Indian Ocean, with special emphasis on the colonization history of Madagascar

JOURNAL OF BIOGEOGRAPHY, Issue 3 2010
Charlotte Tollenaere
Abstract Aim, To describe the phylogeographic patterns of the black rat, Rattus rattus, from islands in the western Indian Ocean where the species has been introduced (Madagascar and the neighbouring islands of Réunion, Mayotte and Grande Comore), in comparison with the postulated source area (India). Location, Western Indian Ocean: India, Arabian Peninsula, East Africa and the islands of Madagascar, Réunion, Grande Comore and Mayotte. Methods, Mitochondrial DNA (cytochrome b, tRNA and D-loop, 1762 bp) was sequenced for 71 individuals from 11 countries in the western Indian Ocean. A partial D-loop (419 bp) was also sequenced for eight populations from Madagascar (97 individuals), which were analysed in addition to six previously published populations from southern Madagascar. Results, Haplotypes from India and the Arabian Peninsula occupied a basal position in the phylogenetic tree, whereas those from islands were distributed in different monophyletic clusters: Madagascar grouped with Mayotte, while Réunion and Grand Comore were present in two other separate groups. The only exception was one individual from Madagascar (out of 190) carrying a haplotype that clustered with those from Réunion and South Africa. ,Isolation with migration' simulations favoured a model with no recurrent migration between Oman and Madagascar. Mismatch distribution analyses dated the expansion of Malagasy populations on a time-scale compatible with human colonization history. Higher haplotype diversity and older expansion times were found on the east coast of Madagascar compared with the central highlands. Main conclusions, Phylogeographic patterns supported the hypothesis of human-mediated colonization of R. rattus from source populations in either the native area (India) or anciently colonized regions (the Arabian Peninsula) to islands of the western Indian Ocean. Despite their proximity, each island has a distinct colonization history. Independent colonization events may have occurred simultaneously in Madagascar and Grande Comore, whereas Mayotte would have been colonized from Madagascar. Réunion was colonized independently, presumably from Europe. Malagasy populations may have originated from a single successful colonization event, followed by rapid expansion, first in coastal zones and then in the central highlands. The congruence of the observed phylogeographic pattern with human colonization events and pathways supports the potential relevance of the black rat in tracing human history. [source]

Local,regional boundary shifts in oribatid mite (Acari: Oribatida) communities: species,area relationships in arboreal habitat islands of a coastal temperate rain forest, Vancouver Island, Canada

JOURNAL OF BIOGEOGRAPHY, Issue 9 2007
Zoë Lindo
Abstract Aim, This study investigates the species,area relationship (SAR) for oribatid mite communities of isolated suspended soil habitats, and compares the shape and slope of the SAR with a nested data set collected over three spatial scales (core, patch and tree level). We investigate whether scale dependence is exhibited in the nested sampling design, use multivariate regression models to elucidate factors affecting richness and abundance patterns, and ask whether the community composition of oribatid mites changes in suspended soil patches of different sizes. Location, Walbran Valley, Vancouver Island, Canada. Methods, A total of 216 core samples were collected from 72 small, medium and large isolated suspended soil habitats in six western redcedar trees in June 2005. The relationship between oribatid species richness and habitat volume was modelled for suspended soil habitat isolates (type 3) and a nested sampling design (type 1) over multiple spatial scales. Nonlinear estimation parameterized linear, power and Weibull function regression models for both SAR designs, and these were assessed for best fit using R2 and Akaike's information criteria (,AIC) values. Factors affecting oribatid mite species richness and standardized abundance (number per g dry weight) were analysed by anova and linear regression models. Results, Sixty-seven species of oribatid mites were identified from 9064 adult specimens. Surface area and moisture content of suspended soils contributed to the variation in species richness, while overall oribatid mite abundance was explained by moisture and depth. A power-law function best described the isolate SAR (S = 3.97 × A0.12, R2 = 0.247, F1,70 = 22.450, P < 0.001), although linear and Weibull functions were also valid models. Oribatid mite species richness in nested samples closely fitted a power-law model (S = 1.96 × A0.39, R2 = 0.854, F1,18 = 2693.6, P < 0.001). The nested SAR constructed over spatial scales of core, patch and tree levels proved to be scale-independent. Main conclusions, Unique microhabitats provided by well developed suspended soil accumulations are a habitat template responsible for the diversity of canopy oribatid mites. Species,area relationships of isolate vs. nested species richness data differed in the rate of accumulation of species with increased area. We suggest that colonization history, stability of suspended soil environments, and structural habitat complexity at local and regional scales are major determinants of arboreal oribatid mite species richness. [source]

Genetic and morphometric differentiation among island populations of two Norops lizards (Reptilia: Sauria: Polychrotidae) on independently colonized islands of the Islas de Bahia (Honduras)

JOURNAL OF BIOGEOGRAPHY, Issue 7 2007
C. F. C. Klütsch
Abstract Aim, Anole lizards (Reptilia: Sauria: Polychrotidae) display remarkable morphological and genetic differentiation between island populations. Morphological differences between islands are probably due to both adaptive (e.g. differential resource exploitation and intra- or interspecific competition) and non-adaptive differentiation in allopatry. Anoles are well known for their extreme diversity and rapid adaptive speciation on islands. The main aim of this study was to use tests of morphological and genetic differentiation to investigate the population structure and colonization history of islands of the Islas de Bahia, off the coast of Honduras. Location, Five populations of Norops bicaorum and Norops lemurinus were sampled, four from islands of the Islas de Bahia and one from the mainland of Honduras. Methods, Body size and weight differentiation were measured in order to test for significant differences between sexes and populations. In addition, individuals were genotyped using the amplified fragment length polymorphism technique. Bayesian model-based and assignment/exclusion methods were used to study genetic differentiation between island and mainland populations and to test colonization hypotheses. Results, Assignment tests suggested migration from the mainland to the Cayos Cochinos, and from there independently to both Utila and Roatán, whereas migration between Utila and Roatán was lacking. Migration from the mainland to Utila was inferred, but was much less frequent. Morphologically, individuals from Utila appeared to be significantly different in comparison with all other localities. Significant differentiation between males of Roatán and the mainland was found in body size, whereas no significant difference was detected between the mainland and the Cayos Cochinos. Main conclusions, Significant genetic and morphological differentiation was found among populations. A stepping-stone model for colonization, in combination with an independent migration to Utila and Roatán, was suggested by assignment tests and was compatible with the observed morphological differentiation. [source]

Contrasting effects of long distance seed dispersal on genetic diversity during range expansion

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2006
R. BIALOZYT
Abstract Currently many attempts are made to reconstruct the colonization history of plant species after the last ice age. A surprising finding is that during the colonization phase genetic diversity did not decrease as much as expected. In this paper we examine whether long distance seed dispersal events could play a role in the unexpected maintenance of genetic diversity during range expansion. This study is based on simulations carried out with a maternally inherited haploid locus using a cellular automaton. The simulations reveal a close relationship between the frequency of long distance seed dispersal events and the amount of genetic diversity preserved during colonization. In particular, when the colonized region is narrow, a complete loss of genetic diversity results from the occurrence of very rare long distance dispersal (LDD) events. We call this phenomenon the ,embolism effect'. However, slightly higher rates of LDD events reverse this effect, up to the point that diversity is better preserved than in a pure diffusion model. This phenomenon is linked to the reorganization of the genetic structure during colonization and is called the ,reshuffling effect'. [source]

Inferring colonization history and dispersal patterns of a long-lived seabird by combining genetic and empirical data

JOURNAL OF ZOOLOGY, Issue 4 2010
L. C. Young
Abstract Identifying biological trends and threats to organisms that make long distance migrations are often the limiting factors in their conservation. Indeed, Laysan albatross Phoebastria immutabilis are highly vagile seabirds, foraging throughout the North Pacific Ocean. Despite mark,recapture data indicating natal philopatry, Laysan albatross recently re-colonized several anthropogenically extirpated breeding locations. At the same time, a breeding population in the north-western Hawaiian Islands was lost to erosion and it was hypothesized that the colonization events were due to displacement rather than dispersal. Nuclear and mitochondrial markers were used in a range wide survey to test whether natal philopatry corresponded to population structure in Laysan albatross, and to determine whether recent colonization events were a result of displacement from vanishing breeding habitat. Five microsatellite loci found little population structure (FST=0.01, P=0.001), and sequences from the mitochondrial control region revealed low population structure (,ST=0.05, P<0.001). The results were consistent with male-mediated dispersal and strong, but not absolute, philopatry by females. Mixed stock analyses and banding records from the newly colonized sites indicated contributions from multiple source populations, which contradicted the displacement hypothesis of a single source population and instead supported species-wide dispersal from all source colonies. High genetic diversity (,=0.045, h=0.989), rapid colonization, and great dispersal potential bode well for the conservation of Laysan albatross. However, it may be necessary to protect high-island nesting sites, preserve genetic diversity and maintain breeding populations in the face of projected sea level rises and persistent bycatch. [source]

Origins and colonization history of pandemic Vibrio parahaemolyticus in South America

MOLECULAR ECOLOGY, Issue 18 2010
JUAN ANSEDE-BERMEJO
Abstract The dynamics of dissemination of the environmental human pathogen Vibrio parahaemolyticus are uncertain. The O3:K6 clone was restricted to Asia until its detection along the Peruvian coasts and in northern Chile in 1997 in phase with the arrival of El Niño waters. A subsequent emergence of O3:K6 strains was detected in austral Chile in 2004. The origin of these 1997 and 2004 population radiations has not yet been conclusively determined. Multiple loci VNTR analysis using seven polymorphic loci was carried out with a number of representative strains from Asia, Peru and Chile to determine their genetic characteristics and population structure. Asian and Chilean subpopulations were the most genetically distant groups with an intermediate subpopulation in Peru. Population structure inferred from a minimum-spanning tree and Bayesian analysis divided the populations into two genetically distinct groups, consistent with the epidemic dynamics of the O3:K6 clone in South America. One group comprised strains from the original Asiatic population and strains arriving in Peru and Chile in 1997. The second group included the remaining Peruvian Strains and Chilean strains obtained from Puerto Montt in 2004. The analysis of the arrival of the O3:K6 clone at the Pacific coasts of South America has provided novel insights linking the origin of the invasion in 1997 to Asian populations and describing the successful establishment of the O3:K6 populations, first in Peru and subsequently in the South of Chile owing to a possible radiation of Peruvian populations. [source]

Colonization history, ecological shifts and diversification in the evolution of endemic Galápagos weevils

Inferring colonization history from analyses of spatial genetic structure within populations of Pinus strobus and Quercus rubra

MOLECULAR ECOLOGY, Issue 3 2006
F. A. JONES
Abstract Many factors interact to determine genetic structure within populations including adult density, the mating system, colonization history, natural selection, and the mechanism and spatial patterns of gene dispersal. We examined spatial genetic structure within colonizing populations of Quercus rubra seedlings and Pinus strobus juveniles and adults in an aspen,white pine forest in northern Michigan, USA. A 20-year spatially explicit demographic study of the forest enables us to interpret the results in light of recent colonization of the site for both species. We assayed 217 Q. rubra seedlings and 171 P. strobus individuals at 11 polymorphic loci using nine allozyme systems. Plant genotypes and locations were used in an analysis of spatial genetic structure. Q. rubra and P. strobus showed similar observed levels of heterozygosity, but Q. rubra seedlings have less heterozygosity than expected. Q. rubra seedlings show spatial genetic clumping of individuals on a scale to 25 m and levels of genetic relatedness expected from the clumped dispersion of half-siblings. In contrast, P. strobus has low levels of genetic relatedness at the smallest distance class and positive spatial genetic structure at scales < 10 m within the plot. The low density of adult Q. rubra outside the study plot and limited, spatially clumped rodent dispersal of acorns is likely responsible for the observed pattern of spatial genetic structure and the observed heterozygote deficit (i.e. a Wahlund effect). We attribute weaker patterns observed in P. strobus to the longer dispersal distance of seeds and the historical overlap of seed shadows from adults outside of the plot coupled with the overlap of seed shadows from younger, more recently established reproductive adults. The study demonstrates the utility of long-term demographic data in interpreting mechanisms responsible for generating contemporary patterns of genetic structure within populations. [source]

Mitochondrial DNA and microsatellite variation in the eider duck (Somateria mollissima) indicate stepwise postglacial colonization of Europe and limited current long-distance dispersal

MOLECULAR ECOLOGY, Issue 6 2004
R. Tiedemann
Abstract To unravel the postglacial colonization history and the current intercolony dispersal in the common eider, Somateria mollissima, we analysed genetic variation at a part of the mitochondrial control region and five unlinked autosomal microsatellite loci in 175 eiders from 11 breeding colonies, covering the entire European distribution range of this species. As a result of extreme female philopatry, mitochondrial DNA differentiation is substantial both among local colonies and among distant geographical regions. Our study further corroborates the previous hypothesis of a single Pleistocene refugium for European eiders. A nested clade analysis on mitochondrial haplotypes suggests that (i) the Baltic Sea eider population is genetically closest to a presumably ancestral population and that (ii) the postglacial recolonization progressed in a stepwise fashion via the North Sea region and the Faroe Islands to Iceland. Current long-distance dispersal is limited. Differentiation among colonies is much less pronounced at microsatellite loci. The geographical pattern of this nuclear genetic variation is to a large extent explained by isolation by distance. As female dispersal is very limited, the geographical pattern of nuclear variation is probably explained by male-mediated gene flow among breeding colonies. Our study provides genetic evidence for the assumed prominent postglacial colonization route shaping the present terrestrial fauna of the North Atlantic islands Iceland and the Faroes. It suggests that this colonization had been a stepwise process originating in continental Europe. It is the first molecular study on eider duck populations covering their entire European distribution range. [source]

Chloroplast DNA phylogeography reveals colonization history of a Neotropical tree, Cedrela odorata L., in Mesoamerica

MOLECULAR ECOLOGY, Issue 6 2003
S. Cavers
Abstract Spanish Cedar (Cedrela odorata L.) is a globally important timber species which has been severely exploited in Mesoamerica for over 200 years. Using polymerase chain reaction,restriction fragment length polymorphisms, its chloroplast (cp) DNA phylogeography was studied in Mesoamerica with samples from 29 populations in six countries. Five haplotypes were characterized, phylogenetically grouped into three lineages (Northern, Central and Southern). Spatial analysis of ordered genetic distance confirmed deviation from a pattern of isolation by distance. The geographically proximate Northern and Central cpDNA lineages were genetically the most differentiated, with the Southern lineage appearing between them on a minimum spanning tree. However, populations possessing Southern lineage haplotypes occupy distinct moist habitats, in contrast to populations possessing Northern and Central lineage haplotypes which occupy drier and more seasonal habitats. Given the known colonization of the proto-Mesoamerican peninsula by South American flora and fauna prior to the formation of the Isthmus of Panama, it seems most likely that the observed population structure in C. odorata results from repeated colonization of Mesoamerica from South American source populations. Such a model would imply an ancient, pre-Isthmian colonization of a dry-adapted type (possessing the Northern lineage or a prototype thereof), with a secondary colonization via the land bridge. Following this, a more recent (possibly post-Pleistocene) expansion of moist-adapted types possessing the Southern lineage from the south fits the known vegetation history of the region. [source]

Genetic variation and population structure in the endangered greater horseshoe bat Rhinolophus ferrumequinum

MOLECULAR ECOLOGY, Issue 8 2000
Stephen J. Rossiter
Abstract Following a dramatic decline last century, the British population of the endangered greater horseshoe bat Rhinolophus ferrumequinum is highly fragmented. To examine the consequences of fragmentation and limited dispersal on patterns of genetic structure and variation, we used microsatellite markers to screen bats from around 50% of the known maternity colonies in Britain, and two areas from continental Europe. Analyses revealed that Welsh and English colonies were genetically isolated. This, and lower variability in Britain than north France, may result from either genetic drift, or the species' colonization history. Gene flow among most neighbouring colonies was not generally restricted, with one exception. These findings have important implications for the ongoing conservation management of this species. [source]

Mitochondrial and Y Chromosome Diversity in the English-Speaking Caribbean

ANNALS OF HUMAN GENETICS, Issue 6 2007
J. Benn Torres
Summary The transatlantic slave trade lasted over three centuries and represents one of the largest forced migrations in human history. The biological repercussions are not well understood especially in African-Caribbean populations. This paper explores the effects of the forced migration, isolation, and admixture on genetic diversity using mitochondrial and Y chromosome markers for 501 individuals from Dominica, Grenada, Jamaica, St. Kitts, St. Lucia, St. Thomas, St. Vincent, and Trinidad. Genetic diversity and population genetic structure analyses of mitochondrial data and Y chromosome data indicate that there was no post-migration loss in genetic diversity in the African derived lineages. Genetic structure was observed between the islands for both genetic systems. This may be due to isolation, differences in the number and source of Africans imported, depopulation of indigenous populations, and/or differences in colonization history. Nearly 10% of the individuals belonged to a non-African mitochondrial haplogroup. In contrast, Y chromosome admixture estimates showed that there was nearly 30% European contribution to these Caribbean populations. This study sheds light on the history of Africans in the Americas as well as contributing to our understanding of the nature and extent of diversity within the African Diaspora. [source]

A new cytochrome b phylogroup of the common vole (Microtus arvalis) endemic to the Balkans and its implications for the evolutionary history of the species

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010
ELENA V. BU
The phylogeographic architecture of the common vole, Microtus arvalis, has been well-studied using mitochondrial DNA and used to test hypotheses relating to glacial refugia. The distribution of the five described cytochrome b (cyt b) lineages in Europe west of Russia has been interpreted as a consequence of postglacial expansion from both southern and central European refugia. A recently proposed competing model suggests that the ,cradle' of the M. arvalis lineages is in western central Europe from where they dispersed in different directions after the Last Glacial Maximum. In the present study, we report a new cyt b lineage of the common vole from the Balkans that is not closely related to any other lineage and whose presence might help resolve these issues of glacial refugia. The Balkan phylogroup occurs along the southern distributional border of M. arvalis in central and eastern Bosnia and Herzegovina, Montenegro, and eastern Serbia. Further north and west in Slovenia, Bosnia and Herzegovina, and Serbia, common voles belong to the previously-described Eastern lineage, whereas both lineages are sympatric in one site in Bosnia and Herzegovina. The Balkan phylogroup most reasonably occupied a glacial refugium already known for various Balkan endemic species, in contrast to the recently proposed model. South-east Europe is an absolutely crucial area for understanding the postglacial colonization history of small mammals in Europe and the present study adds to the very few previous detailed phylogeographic studies of this region. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 788,796. [source]

Genetic variation in Irish pygmy shrews Sorex minutus (Soricomorpha: Soricidae): implications for colonization history

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
ALLAN D. MCDEVITT
The status of the pygmy shrew (Sorex minutus L.) as a native or an introduced species in Ireland has been subject to much debate. To examine this and other aspects of the colonization history of the Irish pygmy shrew, genetic variation was determined in 247 pygmy shrews collected throughout Ireland, using mitochondrial control region sequences and five polymorphic microsatellite loci. Genetic diversity was low for both types of marker. The median-joining network for control region sequences was star-like, suggesting that the colonization of Ireland involved a small number of founders and rapid population expansion thereafter; this was supported by other statistics. Molecular dating with both mitochondrial DNA and microsatellite data is consistent with a human introduction. This would have been several thousand years ago; a recent colonization within historical times can be ruled out. This is the first detailed population genetic study of the pygmy shrew anywhere in its range. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 918,927. [source]

mtDNA analysis reveals the ongoing speciation on Greek populations of Microtus (Terricola) thomasi (Arvicolidae, Rodentia)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2008
GIORGOS TRYFONOPOULOS
The present article extends our previous work on the phylogenetic history of Microtus (Terricola) thomasi, analysing cytochrome b, 12S rRNA, 16S rRNA and the control region in 65 Greek populations. The analysis revealed three clades: one grouping the populations from Peloponnisos (Southern Greece); the second, the populations from Agios (Ag.) Stefanos and Evvoia island (Central East Greece); and the third, all the remaining populations with no geographical substructure. Genetic distances were low for most populations, with only the populations of Evvoia and Ag. Stefanos being substantially distant. Thus, although this species has a recent colonization history and probably descends from a highly polymorphic ancestor, a monophyletic and highly differentiated lineage is formed in Greece and is distributed in Ag. Stefanos and Evvoia. Molecular differentiation, distinct geographical distribution and restriction of gene flow between this lineage and the rest of the Greek populations provide evidence for its probable subspecific status, Microtus (Tericola) thomasi atticus. A possible mechanism leading the differentiation process of the proposed subspecies is suggested, based on the displacement of this species in central Greece by its congeneric, probably better-fitted Microtus (Microtus) guentheri and the subsequent separation of Ag. Stefanos and Evvoia from the remaining Greek populations. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 117,130. [source]

Tracking island colonization history and phenotypic shifts in Indian Ocean bulbuls (Hypsipetes: Pycnonotidae)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2005
BEN H. WARREN
Molecular phylogenies of island organisms provide useful systems for testing hypotheses of convergent or parallel evolution, since selectively neutral molecular characters are likely to be independent of phenotype, and the existence of similar environments on multiple isolated islands provides numerous opportunities for populations to evolve independently under the same constraints. Here we construct a phylogenetic hypothesis for Hypsipetes bulbuls of the western Indian Ocean, and use this to test hypotheses of colonization pattern and phenotypic change among islands of the region. Mitochondrial sequence data were collected from all extant taxa of the region, combined with sequence data from relevant lineages in Asia. Data are consistent with a single Hypsipetes colonization of the western Indian Ocean from Asia within the last 2.6 Myr. The expansion of Hypsipetes appears to have occurred rapidly, with descendants found across the breadth of its western Indian Ocean range. The data suggest that a more recent expansion of Hypsipetes madagascariensis from Madagascar led to the colonization of Aldabra and a secondary colonization of the Comoros. Groupings of western Indian Ocean Hypsipetes according to phenotypic similarities do not correspond to mtDNA lineages, suggesting that these similarities have evolved by convergence or parallelism. The direction of phenotypic change cannot be inferred with confidence, since the primary expansion occurred rapidly relative to the rate of mtDNA substitution, and the colonization sequence remains uncertain. However, evidence from biogeography and comparison of independent colonization events are consistent with the persistence of a small grey continental bulbul in India and Madagascar, and multiple independent origins of large size and green plumage in insular island populations of the Comoros, Mascarenes and Seychelles. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 271,287. [source]