Seminarios EBD, Borja Milá, 5/03/2020

Описание: "El no va más: Avian diversification within oceanic islands"
Borja Milá
Investigador Distinguido
Departamento Biodiversidad y Biología Evolutiva
Museo Nacional de Ciencias Naturales - CSIC
https://borjamila.com
Recently diverged taxa showing marked phenotypic and ecological
diversity are optimal systems to understand the genetic processes
underlying speciation. We used genome-wide markers to investigate the
diversification of the Reunion gray white eye (Zosterops borbonicus)
on the small volcanic island of Reunion (Mascarene archipelago), where
this species complex exhibits four geographic forms that are
parapatrically distributed across the island and differ strikingly in
plumage color. Using population genomic and phylogenetic analyses, we
reconstructed the population history of the different forms and
confirmed the monophyly of the complex. One form restricted to the
highlands is separated by a steep ecological gradient from three
distinct lowland forms which meet at narrow hybrid zones that are not
associated with environmental variables. Landscapes of genomic
variation reveal that signatures of selection associated with
elevation can be found at multiple regions across the genome, whereas
most loci associated with the lowland forms are located on the Z sex
chromosome. We identified TYRP1, a Z-linked color gene, as a likely
candidate locus underlying color variation among lowland forms.
Overall, low dispersal capabilities in this island bird combined with
both geographical and ecological opportunities seem to explain how
divergence occurred at such a small spatial scale. I will also present
some new results from a similar case of recent within-island
divergence driven by ecological opportunity in the common chaffinch
(Fringilla coelebs) within the island of La Palma.