Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa

<p>Abstract</p> <p>Background</p> <p>The Eastern Arc Mountains of Africa have become one of the focal systems with which to explore the patterns and mechanisms of diversification among montane species and populations. One unresolved question is the extent to which populations inhabiting montane forest interact with those of adjacent lowland forest abutting the coast of eastern Africa. The Tiny Greenbul (<it>Phyllastephus debilis</it>) represents the only described bird species within the Eastern Arc/coastal forest mosaic, which is polytypic across an altitudinal gradient: the subspecies <it>albigula </it>(green head) is distributed in the montane Usambara and Nguru Mountains whereas the subspecies <it>rabai </it>(grey head) is found in Tanzanian lowland and foothill forest. Using a combination of morphological and genetic data, we aim to establish if the pattern of morphological differentiation in the Tiny Greenbul (<it>Phyllastrephus debilis</it>) is the result of disruptive selection along an altitudinal gradient or a consequence of secondary contact following population expansion of two differentiated lineages.</p> <p>Results</p> <p>We found significant biometric differences between the lowland (<it>rabai</it>) and montane (<it>albigula</it>) populations in Tanzania. The differences in shape are coupled with discrete differences in the coloration of the underparts. Using multi-locus data gathered from 124 individuals, we show that lowland and montane birds form two distinct genetic lineages. The divergence between the two forms occurred between 2.4 and 3.1 Myrs ago.</p> <p>Our coalescent analyses suggest that limited gene flow, mostly from the subspecies <it>rabai </it>to <it>albigula</it>, is taking place at three mid-altitude localities, where lowland and montane rainforest directly abut. The extent of this introgression appears to be limited and is likely a consequence of the recent expansion of <it>rabai </it>further inland.</p> <p>Conclusion</p> <p>The clear altitudinal segregation in morphology found within the Tiny Greenbul is the result of secondary contact of two highly differentiated lineages rather than disruptive selection in plumage pattern across an altitudinal gradient. Based on our results, we recommend <it>albigula </it>be elevated to species rank.</p

Rediscovery of the rare sea snake hydrophis parviceps Smith 1935: identification and conservation status

Smith's small-headed sea snake, Hydrophis parviceps, was originally described in 1935 from a single type specimen collected in southern Vietnam. Since this time there has been only one further record for the species—a specimen collected near the type locality in 1960 that has since been lost. Through field surveys in southern Vietnam in 2001, we obtained three additional specimens of this poorly known sea snake from fisheries bycatch. In the current paper, we present morphological and molecular data for the three new specimens and the holotype, and redescribe H. parviceps based on data synthesized for all five specimens known to date. We also discuss the conservation status of the species based on its vulnerability to fisheries bycatch mortality and seemingly low abundance within a very restricted geographic distribution.Arne R. Rasmussen, Johan Elmberg, Kate L. Sanders, and Peter Gravlun

Genetic structure of the Danish red deer ('Cervus elaphus')

The red deer ('Cervus elaphus') population in Denmark became almost extinct in recent historical times due to over-hunting. The species has subsequently recovered within remote areas, but non-Danish individuals have been introduced at several localities. To assess genetic structure, past demographic history, and the possibility of a still existing original stock, we analysed 349 specimens from 11 geographically separate areas and from three enclosed areas, genotyping 11 microsatellite loci. Moreover, an 826-bp fragment of the control region of the mitochondrial DNA was sequenced for 116 recent specimens and seven museum specimens. There was a significant difference in mean expected heterozygosity (HE) between the three enclosed areas and the 11 unenclosed areas. Significant departures from Hardy–Weinberg equilibrium were observed in the three enclosed areas and in nine of the unenclosed areas. The overall degree of genetic differentiation among all 14 areas was significant (FST = 0.09,