Dghhsrhsh

Solo disponible en BuenasTareas
  • Páginas : 6 (1338 palabras )
  • Descarga(s) : 0
  • Publicado : 30 de agosto de 2012
Leer documento completo
Vista previa del texto
Coalescence methods reveal the impact of vicariance on the spatial genetic structure of Elephantulus edwardii (Afrotheria, Macroscelidea).
H. A. Smith, T. J. Robinson and B. J. Van Vuuren

South African endemic rock elephant-shrew is the only strictly endemic of South Africa and little is know about its basic biology that is fundamental to evaluating its recognition as vulnerable in the IUCNRed List. Clearly, given the difficulties associated with morphological identification, a genetic delimitation of E. edwardii would contribute significantly to the development of accurate identification schemes for this species and, importantly from a conservation perspective to a more accurate definition of the geographical limits for this local endemic. Consequently the aims of this work areinvestigate the phylogeographical population structure of the Cape rock elephant-shrew across its geographical range and this would provide a fundamental link between populations processes and regional patterns of diversity and biogeography.
In total 106 specimens were sequenced (cyt b and 5’ side of the hypervariable control region) and to validate species status and to ensure the correctidentification of E. edwardii specimens, barcoding was done by sequencing DNA from E. rupestris, Macroscelides proboscideus, E. capensis and E. karoensis. A maximum likelihood and Bayesian coalescent approach were applied to these data specifically, coalescent methods challenge the traditional practice of phylogeography in that they separate the effects of historical vicariance, isolation and ancestralpolymorphism from migration through the simultaneous estimation of population parameters such a migration rate time of populations divergence and time of the most common recent ancestor.
The three elephant-shrew that have overlapping distribution in the southern and western region of South Africa (E. edwardii, E. rupestris, M. proboscideus) are monophyletic. The analysis provided evidence ofthree distinct E. edwardii clades:
- The Karoo clade, evidence is support of a undescribed species, consistently grouped separately from the remainder of the E. edwardii specimens.
- The northern Namaqua clade is the most distinct linages within the Cape rock elephant-shrew were derived from specimens collected at the Namaqua National Park, Kamieskroon, Prieska, Calvinia, Nieuwoudtville and VanRhynsdorp, they argue that past fragmentation occurring approximately 1.7 Ma. Is largely responsible for separating the Namaqua (northern) linage from the remainder of the central Fynbos Cape Rock elephant-shrew populations and the absence of gene flow and/or shared haplotypes between these suggests reproductive isolation.
The central Fynbos clade, in this clade four evolutionary linages wereidentified: the northwestern, western, southern and eastern linages. They argue that the geographical occurrence of these four linages broadly resembles the climatic differences and vegetation types related to the position of mountain range shaping the Cape Fold Belt.
Finally the mitochondrial analysis proved useful in identified genetic variation, past fragmentation and the impact of ancestralpolymorphism in shaping the genetic profiles of northern Namaqua and central Fynbos clades.
Rodrigues fruit bats (Pteropus rodricensis, Megachiroptera: Pteropodidae) retain genetic diversity despite population decline and founder events.
John O’Brien, Gary F. McCracken and Ludovic Say.

Endemic to the remote tropical Indian Ocean Island of Rodrigues, the Rodrigues fruit bat has been the focus ofconservations efforts since the mild 1970s when the total population was reduced to less than 80 individuals. The greatest contributing factor to this decline has been habitat destruction, exacerbated by overhunting. This populations decline is expected to result in significant erosion of genetic variability in the wild populations, inbreeding depression and increased lineage extinction through...
tracking img