| 1. |
- Anderson, Tovi M., et al.
(författare)
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Molecular and Evolutionary History of Melanism in North American Gray Wolves
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 323:5919, s. 1339-1343
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Tidskriftsartikel (refereegranskat)abstract
- Morphological diversity within closely related species is an essential aspect of evolution and adaptation. Mutations in the Melanocortin 1 receptor (Mc1r) gene contribute to pigmentary diversity in natural populations of fish, birds, and many mammals. However, melanism in the gray wolf, Canis lupus, is caused by a different melanocortin pathway component, the K locus, that encodes a beta-defensin protein that acts as an alternative ligand for Mc1r. We show that the melanistic K locus mutation in North American wolves derives from past hybridization with domestic dogs, has risen to high frequency in forested habitats, and exhibits a molecular signature of positive selection. The same mutation also causes melanism in the coyote, Canis latrans, and in Italian gray wolves, and hence our results demonstrate how traits selected in domesticated species can influence the morphological diversity of their wild relatives.
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| 2. |
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| 3. |
- Barsh, Gregory S., et al.
(författare)
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How the Gray Wolf Got Its Color - Response
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5936, s. 34-34
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Berger, E., et al.
(författare)
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An Intermediate Luminosity Transient in NGC 300 : The Eruption of a Dust-Enshrouded Massive Star
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 699, s. 1850-1865
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Tidskriftsartikel (refereegranskat)abstract
- We present multi-epoch high-resolution optical spectroscopy, UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an intermediate luminosity optical transient recently discovered in the nearby galaxy NGC 300. We find that the transient (NGC 300 OT2008-1) has a peak absolute magnitude of M bol ≈ -11.8 mag, intermediate between novae and supernovae, and similar to the recent events M85 OT2006-1 and SN 2008S. Our high-resolution spectra, the first for this event, are dominated by intermediate velocity (~200-1000 km s-1) hydrogen Balmer lines and Ca II emission and absorption lines that point to a complex circumstellar environment, reminiscent of the yellow hypergiant IRC+10420. In particular, we detect asymmetric Ca II H&K absorption with a broad red wing extending to ~103 km s-1, indicative of gas inflow at high velocity (possibly the wind of a massive binary companion). The low luminosity, intermediate velocities, and overall similarity to a known eruptive star indicate that the event did not result in a complete disruption of the progenitor. We identify the progenitor in archival Spitzer observations, with deep upper limits from Hubble data. The spectral energy distribution points to a dust-enshrouded star with a luminosity of about 6 × 104 L sun, indicative of a ~10-20 M sun progenitor (or binary system). This conclusion is in good agreement with our interpretation of the outburst and circumstellar properties. The lack of significant extinction in the transient spectrum indicates that the dust surrounding the progenitor was cleared by the outburst. We thus predict that the progenitor should be eventually visible with Hubble if the transient event marks an evolutionary transition to a dust-free state, or with Spitzer if the event marks a cyclical process of dust formation.
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| 5. |
- Castroviejo-Fisher, Santiago, 1979-
(författare)
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Species Limits, and Evolutionary History of Glassfrogs
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recognizing the mechanisms of speciation and the limits of species is essential to understand the origin of biodiversity and how to conserve it. The general aims of my investigations during my doctoral studies were two-fold: to study evolutionary patterns and processes, and to provide specific and superspecific taxonomic classifications that try to reflect evolutionary history. I have focused my research on anurans in their biodiversity hotspot, the American Tropics. I have used morphological, behavioral (mating calls), and genetic (DNA sequences) characters to study species boundaries between frogs of the genus Pristimantis and the family Centrolenidae (glassfrogs). The results show that the exclusive use of single lines of evidence or the application of arbitrary thresholds impair and bias our ability to recognize new species and limit the possibility to understand evolutionary processes. Only an integrative approach combining every source of evidence provides the necessary feedback to discover all species and test their identity by comparing independent sets of data. This approach further allows identifying those species that probably represent stable comparative units (well supported species hypotheses) and to flag taxa that require further assessment. Phylogenetic reconstructions based on seven nuclear and mitochondrial genes for about 100 species of glassfrogs revealed that previous hypotheses of relationships were mislead by rampant convergent evolution at the phenotypic level. None of the previously suggested classifications fit with the reconstructed evolutionary history. Consequently, we proposed a new classification consistent with this phylogeny. I also studied the tempo and mode of diversification among glassfrogs. Based on sequences from ten genes in 87 species, I estimated species divergence times, age-range correlation between sister species, and reconstructed ancestral areas and dispersal/vicariance events. The results revealed a complex model of diversification where geographical isolation seems to be the dominant scenario for speciation and only clades of altitudinal generalists have been able to spread across the Neotropical rainforests.
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| 6. |
- Fox-Dobbs, Kena, et al.
(författare)
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Pleistocene megafauna from eastern Beringia: paleoecological and paleoenvironmental interpretations of stable carbon and nitrogen isotope and radiocarbon records
- 2008
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 261:1-2, s. 30-46
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Tidskriftsartikel (refereegranskat)abstract
- Late Pleistocene eastern Beringia is a model paleo-ecosystem for the study of potential and realized species interactions within a diverse mammalian fauna. Beringian paleontological records store a wealth of information that can be used to investigate how predator-prey and competitive interactions among consumers shifted in response to past episodes of environmental change. Two such recent periods of rapid climate change are the Last Glacial Maximum (LGM) and the end of glacial conditions at the beginning of the Holocene. Here we assemble carbon and nitrogen stable isotope, and AMS C-14 data collected from bone collagen of late Pleistocene carnivores and megafaunal prey species from the interior of eastern Beringia (Alaska), and reconstruct the diets of ancient Alaskan carnivores and herbivores. We are able to account for the relative influences of diet versus changing environmental conditions on variances in consumer isotope values, to identify species hiatuses in the fossil record, and to draw conclusions about paleoenvironmental conditions from faunal chronologies. Our isotopic results suggest that there was dietary niche overlap among some Beringian herbivore species, and partitioning among other species. We rely upon delta C-13 and delta N-15 values of modem Alaskan C-3 plant types to infer Beringian herbivore dietary niches. Horse, bison, yak, and mammoth primarily consumed grasses, sedges, and herbaceous plant species. Caribou and woodland muskox focused upon tundra plants, including lichen, fungi, and mosses. The network of Beringian carnivore interaction was complex and dynamic, some species (wolves) persisted for long periods of time, while others were only present during specific timeframes (large felids and ursids). Beringian carnivore diets included all measured herbivore species, although mammoth and muskox only appeared in carnivore diets during specific times in the late Pleistocene. We identified the potential presence of unmeasured diet sources that may have included forest-dwelling cervids and/or plant materials. None of the large-bodied carnivore species we analyzed (except short-faced bear) were specialized predators of a single prey species during the late Pleistocene. Differences in carnivore diet and dietary breadth between time periods either reflect changes in the relative abundances of prey on the Beringian landscape, or changes in competitive interactions among Beringian carnivore species
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| 7. |
- Hailer, Frank, et al.
(författare)
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Hybridization among Three Native North American Canis Species in a Region of Natural Sympatry
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:10, s. e3333-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Population densities of many species throughout the world are changing due to direct persecution as well as anthropogenic habitat modification. These changes may induce or increase the frequency of hybridization among taxa. If extensive, hybridization can threaten the genetic integrity or survival of endangered species. Three native species of the genus Canis, coyote (C. latrans), Mexican wolf (C. lupus baileyi) and red wolf (C. rufus), were historically sympatric in Texas, United States. Human impacts caused the latter two to go extinct in the wild, although they survived in captive breeding programs. Morphological data demonstrate historic reproductive isolation between all three taxa. While the red wolf population was impacted by introgressive hybridization with coyotes as it went extinct in the wild, the impact of hybridization on the Texas populations of the other species is not clear. Methodology/Principal Findings: We surveyed variation at maternally and paternally inherited genetic markers (mitochondrial control region sequence and Y chromosome microsatellites) in coyotes from Texas, Mexican wolves and red wolves from the captive breeding programs, and a reference population of coyotes from outside the historic red wolf range. Levels of variation and phylogenetic analyses suggest that hybridization has occasionally taken place between all three species, but that the impact on the coyote population is very small. Conclusion/Significance: Our results demonstrate that the factors driving introgressive hybridization in sympatric Texan Canis are multiple and complex. Hybridization is not solely determined by body size or sex, and density-dependent effects do not fully explain the observed pattern either. No evidence of hybridization was identified in the Mexican wolf captive breeding program, but introgression appears to have had a greater impact on the captive red wolves.
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| 8. |
- Koblmüller, Stephan, et al.
(författare)
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More is Better
- 2009
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 18:24, s. 4994-4996
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Koblmuller, Stephan, et al.
(författare)
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Origin and status of the Great Lakes wolf
- 2009
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 18:11, s. 2313-2326
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Tidskriftsartikel (refereegranskat)abstract
- An extensive debate concerning the origin and taxonomic status of wolf-like canids in the North American Great Lakes region and the consequences for conservation politics regarding these enigmatic predators is ongoing. Using maternally, paternally and biparentally inherited molecular markers, we demonstrate that the Great Lakes wolves are a unique population or ecotype of gray wolves. Furthermore, we show that the Great Lakes wolves experienced high degrees of ancient and recent introgression of coyote and western gray wolf mtDNA and Y-chromosome haplotypes, and that the recent demographic bottleneck caused by persecution and habitat depletion in the early 1900s is not reflected in the genetic data.
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| 10. |
- Leonard, Jennifer A, et al.
(författare)
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A rapid loss of stripes : the evolutionary history of the extinct quagga.
- 2005
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Ingår i: Biol Lett. - 1744-9561. ; 1:3, s. 291-5
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Tidskriftsartikel (refereegranskat)abstract
- Twenty years ago, the field of ancient DNA was launched with the publication of two short mitochondrial (mt) DNA sequences from a single quagga (Equus quagga) museum skin, an extinct South African equid (Higuchi et al. 1984 Nature312, 282-284). This was the first extinct species from which genetic information was retrieved. The DNA sequences of the quagga showed that it was more closely related to zebras than to horses. However, quagga evolutionary history is far from clear. We have isolated DNA from eight quaggas and a plains zebra (subspecies or phenotype Equus burchelli burchelli). We show that the quagga displayed little genetic diversity and very recently diverged from the plains zebra, probably during the penultimate glacial maximum. This emphasizes the importance of Pleistocene climate changes for phylogeographic patterns in African as well as Holarctic fauna.
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