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Martin Stervander: "Speciation in finches on isolated islands"

  • Date: Jan 15, 2019
  • Time: 14:00 - 15:00
  • Speaker: Martin Stervander from the Institute of Ecology and Evolution (IE²) at University of Oregon, USA
  • For more information on the speaker, please check here: http://www.stervander.com/
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Miriam Liedvogel

Abstract

You are all familiar with the rock stars of speciation, the Darwin’s finches of Galápagos. But did you know of the world’s largest seedeater, or of Inaccessible Island? I will tell the tale of two insular finch systems that are not so well-known, but rather interesting to anyone with a flair for resource-driven selection, gene flow, and isolation. Via a short stop in the Gulf of Guinea off West Africa, home to the enigmatic São Tomé Grosbeak, I will take you on a journey to the middle of the South Atlantic. Here, Inaccessible Island and Nightingale Island are neighbours to the officially most remote human settlement on earth Tristan da Cunha. The former islands are home to a peculiar avifauna, including a pair each of small-billed and large-billed finch taxa, stemming from a South American colonization. On each island, the small-billed finches are feeding generalists, whereas the large-billed finches specialize on the fruits of the only tree species growing on the islands. Smaller and older Nightingale Island harbours the most divergent phenotypes, with small-billed finches being smaller than those on Inaccessible Island and large-billed finches being larger. The species do not hybridize. On Inaccessible Island, the small- and large-billed taxa mate entirely assortatively in the lowlands, whereas there is full hybridization in the woodland of the high plateau. And this on an island that is 14 square kilometers! With the help of genetic and genomic tools, we can establish that the constant gene flow erodes genome-wide differentiation between Inaccessible Island taxa, but one autosomal region differentiates body size and one region on a sex chromosome differentiates bill morphology. Using the genomic landscape of this miniature radiation, we aim at understanding the speciation mechanisms and the evolutionary history of the system.

 
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