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Multilocus Phylogeography of Reed Buntings

Carvalho Martins, Frederico (2016) BION01 20161
Degree Projects in Biology
Abstract
In order to understand how the Pleistocene glacial cycles have influenced the diversification in the Reed Bunting (Emberiza schoeniclus) subspecies complex, we conducted a multilocus phylogeographic study. We analysed DNA sequences from 32 breeding populations, covering the species’ Palearctic distribution, and used population genetics, phylogenetic and coalescent methods to uncover genetic structure and to estimate time of diverging events within the species. Neutral mitochondrial and nuclear markers revealed two major clades that diverged in the mid Pleistocene and are presently segregated into East and West Eurasia. Both clades show signs of postglacial population expansion, but interestingly, they had different genetic structure.... (More)
In order to understand how the Pleistocene glacial cycles have influenced the diversification in the Reed Bunting (Emberiza schoeniclus) subspecies complex, we conducted a multilocus phylogeographic study. We analysed DNA sequences from 32 breeding populations, covering the species’ Palearctic distribution, and used population genetics, phylogenetic and coalescent methods to uncover genetic structure and to estimate time of diverging events within the species. Neutral mitochondrial and nuclear markers revealed two major clades that diverged in the mid Pleistocene and are presently segregated into East and West Eurasia. Both clades show signs of postglacial population expansion, but interestingly, they had different genetic structure. Eastern populations had higher values of molecular diversity and were not only different from western population, but sub-populations within the clades are also genetically different, which is not found in the west. These results strongly suggest the past existence of one glacial refugium in the west and two to three glacial refugia in the east. Our findings show that the genetic variability alone cannot explain the large number of described subspecies, which implies that morphological divergence has occurred very rapidly. The neutral genetic variation between Reed Bunting populations may have resulted from separation in glacial refugia and posterior expansion, whereas phenotypic variation may have been a consequence of postglacial expansion and adaptation to newly occupied habitats in combination with sexual selection. (Less)
Popular Abstract
Reed Bunting: What are the origins of its subspecies?

It is widely accepted that there is morphological and genetic variation between individuals/populations of the same species. For species that live in temperate areas some of this variation may have been a consequence of the Quaternary ice ages because it influenced the distribution and population size of plants and animals.

One of these was a bird called the Reed Bunting (Emberiza schoeniclus). Through its Eurasian range, the species have 20 described subspecies that vary on colour, size and bill shape. The genetic variability of some of these subspecies has been documented but all the studies conducted so far analysed only part of the geographical distribution of this species,... (More)
Reed Bunting: What are the origins of its subspecies?

It is widely accepted that there is morphological and genetic variation between individuals/populations of the same species. For species that live in temperate areas some of this variation may have been a consequence of the Quaternary ice ages because it influenced the distribution and population size of plants and animals.

One of these was a bird called the Reed Bunting (Emberiza schoeniclus). Through its Eurasian range, the species have 20 described subspecies that vary on colour, size and bill shape. The genetic variability of some of these subspecies has been documented but all the studies conducted so far analysed only part of the geographical distribution of this species, and used different and a low number of genetic markers.

Having all these in mind, I investigated the present phylogeographic structure of the Reed Bunting using a multilocus approach and sampled individuals covering the species distribution. My aim was to understand the relationship between the different subspecies, trace their possible origin and estimate the divergence time between them.

The three neutral markers showed that the Reed Bunting subspecies complex can be resumed into two most important clades. These clades diverged in the mid Pleistocene and are now geographically structured, roughly corresponding to East and West Eurasia. Within the eastern clade there is high genetic differentiation between populations, which does not occur in the western clade. These results strongly suggest that western populations came from one glacial refugium, whereas eastern populations originated from two to three glacial refugia.

Our findings also show that the genetic variability alone cannot explain the large number of described subspecies, which implies that morphological divergence has occurred very rapidly. The neutral genetic variation between Reed Bunting populations may have resulted from separation in glacial refugia and posterior expansion, whereas phenotypic variation may have been a consequence of postglacial expansion and adaptation to newly occupied habitats in combination with sexual selection.

Supervisors: Bengt Hansson and Júlio M. Neto
Master´s Degree Project in Biology, 45credits 2016
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Carvalho Martins, Frederico
supervisor
organization
course
BION01 20161
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8891419
date added to LUP
2016-09-12 11:08:00
date last changed
2016-09-12 11:08:00
@misc{8891419,
  abstract     = {In order to understand how the Pleistocene glacial cycles have influenced the diversification in the Reed Bunting (Emberiza schoeniclus) subspecies complex, we conducted a multilocus phylogeographic study. We analysed DNA sequences from 32 breeding populations, covering the species’ Palearctic distribution, and used population genetics, phylogenetic and coalescent methods to uncover genetic structure and to estimate time of diverging events within the species. Neutral mitochondrial and nuclear markers revealed two major clades that diverged in the mid Pleistocene and are presently segregated into East and West Eurasia. Both clades show signs of postglacial population expansion, but interestingly, they had different genetic structure. Eastern populations had higher values of molecular diversity and were not only different from western population, but sub-populations within the clades are also genetically different, which is not found in the west. These results strongly suggest the past existence of one glacial refugium in the west and two to three glacial refugia in the east. Our findings show that the genetic variability alone cannot explain the large number of described subspecies, which implies that morphological divergence has occurred very rapidly. The neutral genetic variation between Reed Bunting populations may have resulted from separation in glacial refugia and posterior expansion, whereas phenotypic variation may have been a consequence of postglacial expansion and adaptation to newly occupied habitats in combination with sexual selection.},
  author       = {Carvalho Martins, Frederico},
  language     = {eng},
  note         = {Student Paper},
  title        = {Multilocus Phylogeography of Reed Buntings},
  year         = {2016},
}