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Glacial Refuge (glacial + refuge)
Selected AbstractsHarlequin duck Histrionicus histrionicus population structure in eastern NearcticJOURNAL OF AVIAN BIOLOGY, Issue 2 2002Serge Brodeur During May 1996 and April 1997, eight harlequin duck males were captured and fitted with satellite transmitters while migrating along the shores of Forillon National Park, Québec, Canada. Another 17 males were equipped with satellite transmitters in river systems of eastern Hudson Bay, Ungava Bay and northern Labrador in June 1997 and 1998. Our objectives were to determine relationships between breeding, moulting and wintering areas, and to determine whether distinct population segments existed among harlequin ducks in eastern North America. All birds tracked from Forillon migrated to Labrador. Moulting areas were identified for six birds. Forillon males were followed to the eastern North American major wintering site in Maine. Males captured in northern Québec and Labrador migrated to moult and winter in south-western Greenland. Our data suggest the presence of two demographically distinct population segments in eastern North America, perhaps originating from the Pleistocene glacial refuge in western Greenland and south of the Laurentide ice sheet in eastern Canada or United States. [source] Holocene vegetation and climate change on the Colorado Great Plains, USA, and the invasion of Colorado piñon (Pinus edulis)JOURNAL OF BIOGEOGRAPHY, Issue 12 2009R. Scott Anderson Abstract Aim, To reconstruct the last c. 7000 years of vegetation and climate change in an unusual region of modern Great Plains grassland and scarp woodland in south-east Colorado (USA), and to determine the late Holocene biogeography of Colorado piñon (Pinus edulis) at its easternmost extent, using a series of radiocarbon-dated packrat (Neotoma sp.) middens. Location, The West Carrizo Canyon drains the Chaquaqua Plateau, a plateau that projects into the western extent of the southern Great Plains grasslands in south-eastern Colorado, USA. Elevations of the study sites are 1448 to 1525 m a.s.l. Today the plateau is mostly Juniperus scopulorum,P. edulis woodland. Methods, Plant macrofossils and pollen assemblages were analysed from 11 14C-dated packrat middens. Ages ranged from 5990 yr bp (6839 cal. yr bp) to 280 yr bp (485 cal. yr bp). Results, The results presented here provide information on the establishment and expansion of Juniperus,P. edulis woodland at its eastern limits. The analysis of both plant macrofossils and pollen from the 11 middens documents changes in plant communities over the last 7000 years, and the establishment of P. edulis at its easternmost limit. Though very minor amounts of P. edulis pollen occur as early as the middle Holocene, plant macrofossils were only recovered in middens dating after c. 480 cal. yr bp. Main conclusions, Originally, midden research suggested a late glacial refuge to the north-east of the Carrizo Canyon site, and a middle Holocene expansion of P. edulis. Results reported here are consistent with a late Holocene expansion, here at its eastern limits, but noted elsewhere at its northern and north-eastern limits. In general, this late Holocene expansion is consistent with pollen data from sediments in Colorado and New Mexico, and suggests that P. edulis is still expanding its range at its present extremes. This has implications for further extension of its range due to changing climatic conditions in the future. [source] The recolonization of Europe by brown bears Ursus arctos Linnaeus, 1758 after the Last Glacial MaximumMAMMAL REVIEW, Issue 2 2005R. S. SOMMER ABSTRACT 1.,At the end of the Last Glacial Maximum brown bears Ursus arctos recolonized the glacial landscape of Central and Northern Europe faster than all other carnivorous mammal species of the Holocene fauna. Ursus arctos was recorded in Northern Europe from the beginning of the Late-Glacial. The recolonization of northern Central Europe may have taken place directly after the maximum glaciation. The distribution of the brown bear was restricted to glacial refugia only during the Last Glacial Maximum, for probably no more than 10 000 years. 2.,Genetic analyses have suggested three glacial refugia for the brown bear: the Iberian Peninsula, the Italian Peninsula and the Balkans. Subfossil records of Ursus arctos from north-western Moldova as well as reconstructed environmental conditions during the Last Glacial Maximum in this area suggest to us a fourth glacial refuge for the brown bear. Because of its connection to the Carpathians, we designate this as the ,Carpathian refuge'. 3.,Due to the low genetic distance between brown bears of northern Norway, Finland, Estonia, north-eastern Russia and the northern Carpathians (the so-called eastern lineage), the Carpathians were considered the geographical origin of the recolonization of these regions. During the recolonization of northern Europe the brown bear probably reached these areas rapidly from the putative Carpathian refuge. [source] Combined ecological niche modelling and molecular phylogeography revealed the evolutionary history of Hordeum marinum (Poaceae) , niche differentiation, loss of genetic diversity, and speciation in Mediterranean Quaternary refugiaMOLECULAR ECOLOGY, Issue 8 2007SABINE S. JAKOB Abstract The Hordeum marinum species group consists of two annual grasses of western Eurasian saline meadows or marshes. The two grasses split in the Quaternary about two million years ago. Hordeum marinum and the diploid of Hordeum gussoneanum (2×) co-occur throughout the Mediterranean basin, while the autotetraploid cytotype of H. gussoneanum (4×) overlaps with its diploid progenitor geographically only in the utmost Eastern Mediterranean, extending from there eastwards into Asia. Using chloroplast sequences of the trnL-F region, six newly developed chloroplast microsatellite loci, ecological predictive models based on climate data, and the present geographical distribution of the two species we analysed differentiation processes in the H. marinum group. The chloroplast data indicated clear differences in the history of both species. For H. marinum we found a subdivision between genetically variable populations from the Iberian Peninsula and the more uniform populations from the remaining Mediterranean. As an explanation, we assume Pleistocene fragmentation of an earlier widespread population and survival in an Iberian and a Central Mediterranean glacial refuge. Chloroplast variation was completely absent within the cytotypes of H. gussoneanum, indicating a severe and recent genetic bottleneck. Due to this lack of chloroplast variation only the combination of ecological habitat modelling with molecular data analyses allowed conclusions about the history of this taxon. The distribution areas of the two cytotypes of H. gussoneanum overlap today in parts of Turkey, indicating an area with similar climate conditions during polyploid formation. However, after its origin the polyploid cytotype underwent a pronounced ecological shift, compared to its diploid progenitor, allowing it to colonize mountainous inland habitats between the Mediterranean basin and Afghanistan. The extant sympatric occurrence of H. marinum and H. gussoneanum 2× in the Mediterranean region is interpreted as a result of secondary contact after fast Holocene range expansion out of different ice age refugia. [source] Could the tree diversity pattern in Europe be generated by postglacial dispersal limitation?ECOLOGY LETTERS, Issue 6 2007Jens-Christian Svenning Abstract The relative importance of contemporary climate and history as controls of geographical diversity patterns is intensely debated. A key example is the controversy over the extent to which temperate tree distributions and diversity patterns reflect postglacial dispersal limitation. Here, we focus on Central and Northern Europe, and show that recent estimates of tree migration rates < 100 m year,1 imply that many species have probably not reached equilibrium with climate in this region. We then demonstrate that geographical accessibility from glacial refuges explains 78% of the geographical variation in the region's tree diversity and is a much stronger diversity predictor than climate. Finally, we show that realistic estimates of migration rates can be derived from the observed tree diversity pattern by assuming it to be purely dispersal driven. In conclusion, the tree diversity pattern in Central and Northern Europe could, to a large extent, be a result of postglacial dispersal limitation. [source] The distribution of South American galaxiid fishes: the role of biological traits and post-glacial historyJOURNAL OF BIOGEOGRAPHY, Issue 1 2004Víctor Cussac Abstract Aim, The aim of this work is to update the distribution data of Galaxiidae in South America, relating extant distribution to physiological and reproductive characteristics of the species, latitude, temperature, and post-glacial opportunities for colonization. Location, Lakes and rivers of Patagonia. Methods, We compared, and eventually reconsidered, general data about distribution based on the original literature about capture sites, incorporating several published and unpublished data to the analysis of the biological traits and distribution of Galaxiidae. Results, The more consistent issue in the comprehension of galaxiid biogeography in South America is the ability to establish landlocked populations. Different founding events in landlocked populations of Galaxias maculatus suggest the possible existence of older and younger landlocked populations. This difference in the time since the establishment of lacustrine populations could have been expressed in their ability for colonization of post-glacial areas. Galaxias maculatus, Aplochiton and Brachygalaxias are more clearly excluded from the post-glacial area than G. platei. For all the species we could note a more abundant record of lake populations at the area of glacial refuges. It could be noted that the most successful species, Galaxias platei, is a specialized deep bottom dweller. Deep bottom dwelling helps to endure winter constraints and it appears to be an alternative to the colonization of the littoral and limnetic zones of post-glacial lakes, the prefered habitat of the other Patagonian fish species. Main conclusions, At the end of this process of post-glacial colonization, in the beginning of twentieth century, man introduced several salmonid species in Patagonia. In addition, antropogenic actions had its more recent consequences in global warming. Nowadays we were able to observe new localities for Brazilian fishes into the Austral Subregion and expect some changes in the distribution of Galaxiidae. Northern limits for all species and southern limits for landlocked G. maculatus, Brachigalaxias bullocki and Aplochiton zebra, could be displaced southward. Probably, the species less affected by the changes will be G. platei. These predictions could be accurately formulated using the model of B.J. Shuter & J.R. Post (1990) Transactions of the American Fisheries Society119, 314,336, when biological database on these species are completed. [source] Genetic variation and phylogeography of free-living mouse species (genus Mus) in the Balkans and the Middle EastMOLECULAR ECOLOGY, Issue 22 2007M. MACHOLÁN Abstract This work presents a study of the distribution and pattern of variation throughout the ranges of three free-living mouse species of the genus Mus,M. macedonicus, M. spicilegus, and a M. cypriacus , based on sequencing of two segments of the mitochondrial DNA (mtDNA) control region. The study shows a similar level of variability in the three species and suggests their recent population expansion. The highest proportion of variation is found within populations indicating low genetic structuring. Phylogenetic analysis confirms the significant divergence of a mitochondrial lineage of M. macedonicus from Israel, recently described as a new subspecies, M. macedonicus spretoides. Conversely, no genetic hiatus is revealed between European and Asian populations of M. macedonicus macedonicus. Although phylogenetic relationships among M. spicilegus populations could not be unravelled precisely, the results suggest a recent westward expansion of the species. The mtDNA divergence between M. macedonicus and M. spicilegus is 7.3%, suggesting their split between c. 700 000 and 1 million years ago. These dates correspond with a coalescent estimate about 720 000 years ago. On the other hand, M. cypriacus appeared almost twice as divergent from the former species (4.5%) as from the latter (8.8%) suggesting a divergence of c. 430 000,610 000 years ago (coalescent , 490 000 years ago) and 830 000,1.2 million years ago (coalescent , 780 000 years ago), respectively. Approximate times of population expansion have also been estimated for all taxa and groups of populations. Existence of several glacial refuges and various colonization scenarios are discussed; since all estimated divergence times fall within interglacial periods it seems that climatic oscillations did not play a crucial role in the evolution of the three species. [source] Intraspecific vicariant history and the evolution of adaptive morphological diversity in a fish species (Osmerus mordax)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009MARIE-FRANCE BARRETTE Vicariant geographic isolation and resource partitioning have long been independently identified as processes contributing to the morphological divergence of closely-related species. However, little is known about the extent to which vicariant history influences the adaptive ecological divergence associated with resource partitioning and trophic specialization within species. The present study thus quantified the contribution of vicariant historical genetic divergence to the adaptive contemporary morphological divergence of intraspecific feeding specialists in the Rainbow smelt (Pisces: Osmerus mordax). This species is characterized by the polyphyletic origin of two lacustrine feeding specialists originating in two intraspecific lineages associated with independent glacial refuges. The historical genetic segregation was initiated approximately 350 000 years ago, whereas the lacustrine trophic segregation arose within the past 10 000 years. Wild caught lacustrine smelt populations were grouped a priori based on known historical genetic identities (Acadian and Atlantic mitochondrial DNA clades) and contemporary feeding specializations (microphageous and macrophageous morphotypes). The present study demonstrated that independent suites of correlated morphological traits are associated with either vicariant history or contemporary feeding specializations. Second, functionally-similar feeding specialists exhibit distinct morphologies resulting largely from vicariant historical processes. Although, the evolutionary processes producing historical phenotypes remains unknown, the results obtained demonstrate how adaptive radiation associated with ecological resource partitioning and feeding specializations can be strongly influenced by intraspecific phenotypic diversification resulting from relatively recent vicariant histories. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 140,151. [source] | ||||||||||