Moleculary Systematics and Biogeography of the Galaxidae
To test competing hypotheses about the relative roles of vicariance and dispersal in the freshwater fishes in Galaxiidae, a phylogenetic framework and a time scale for species divergence were estimated using mitochondrial and nuclear DNA sequences. Relaxed clock dating revealed that the Galaxiidae o...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Thesis |
Language: | English |
Published: |
|
Subjects: | |
Online Access: | http://hdl.handle.net/1807/65494 |
id |
ftunivtoronto:oai:localhost:1807/65494 |
---|---|
record_format |
openpolar |
spelling |
ftunivtoronto:oai:localhost:1807/65494 2023-05-15T13:59:31+02:00 Moleculary Systematics and Biogeography of the Galaxidae Ybazeta, Gustavo Baker, Allan Ecology and Evolutionary Biology WITHHELD_TWO_YEAR http://hdl.handle.net/1807/65494 en_ca eng http://hdl.handle.net/1807/65494 Galaxiidae Systematics Biogeography Molecular clock Vicariance Dispersal 0472 0307 0369 Thesis ftunivtoronto 2020-06-17T11:21:59Z To test competing hypotheses about the relative roles of vicariance and dispersal in the freshwater fishes in Galaxiidae, a phylogenetic framework and a time scale for species divergence were estimated using mitochondrial and nuclear DNA sequences. Relaxed clock dating revealed that the Galaxiidae originated in Gondwana in the late Cretaceous and thus vicariance cannot be ruled out for the two basal lineages, Galaxiella and Brachygalaxias. These two lineages are ancient relicts that rafted to their present distributions or were fragmented by the separation of Australia from South America via Antarctica. The opening of the Drake passage between South America and Antarctica initiated the proto-Antarctic Circumpolar Current (pACC) and counter-clockwise circulation in the South Atlantic, on which marine stage ancestors could have dispersed to South Africa and New Zealand via Australia during the late Eocene. Thus dispersal explains the disjunct distribution of the clade comprised of G. platei, G. zebratus and Neochanna spp. in South America, South Africa, and Australasia. The narrowing of the Drake passage and collapse of the pACC from about 24-14 Mya likely prevented further contact between South America and South Africa. Tectonic events around the globe produced an anomalous warming event, which along with the uplift of New Zealand provided empty niches and promoted the radiation of Galaxias. Most of the speciation in the other clades occurred during this time. When the Antarctic Circumpolar Current was reactivated at the end of the Mid-Miocene Climatic Optimum (MMCO) about 15–14 Mya, it provided a marine conveyor belt for the dispersal of the ancestor of Galaxias maculatus from Australia to South America, and later to Australia and New Zealand. The integration of divergence times estimated on the phylogeny with ancestral area reconstruction supports an origin in Gondwana and subsequent oceanic dispersal as the explanation for the distribution of the Galaxiidae across the southern continents. PhD Thesis Antarc* Antarctic Antarctica Drake Passage University of Toronto: Research Repository T-Space Antarctic Drake Passage New Zealand The Antarctic |
institution |
Open Polar |
collection |
University of Toronto: Research Repository T-Space |
op_collection_id |
ftunivtoronto |
language |
English |
topic |
Galaxiidae Systematics Biogeography Molecular clock Vicariance Dispersal 0472 0307 0369 |
spellingShingle |
Galaxiidae Systematics Biogeography Molecular clock Vicariance Dispersal 0472 0307 0369 Ybazeta, Gustavo Moleculary Systematics and Biogeography of the Galaxidae |
topic_facet |
Galaxiidae Systematics Biogeography Molecular clock Vicariance Dispersal 0472 0307 0369 |
description |
To test competing hypotheses about the relative roles of vicariance and dispersal in the freshwater fishes in Galaxiidae, a phylogenetic framework and a time scale for species divergence were estimated using mitochondrial and nuclear DNA sequences. Relaxed clock dating revealed that the Galaxiidae originated in Gondwana in the late Cretaceous and thus vicariance cannot be ruled out for the two basal lineages, Galaxiella and Brachygalaxias. These two lineages are ancient relicts that rafted to their present distributions or were fragmented by the separation of Australia from South America via Antarctica. The opening of the Drake passage between South America and Antarctica initiated the proto-Antarctic Circumpolar Current (pACC) and counter-clockwise circulation in the South Atlantic, on which marine stage ancestors could have dispersed to South Africa and New Zealand via Australia during the late Eocene. Thus dispersal explains the disjunct distribution of the clade comprised of G. platei, G. zebratus and Neochanna spp. in South America, South Africa, and Australasia. The narrowing of the Drake passage and collapse of the pACC from about 24-14 Mya likely prevented further contact between South America and South Africa. Tectonic events around the globe produced an anomalous warming event, which along with the uplift of New Zealand provided empty niches and promoted the radiation of Galaxias. Most of the speciation in the other clades occurred during this time. When the Antarctic Circumpolar Current was reactivated at the end of the Mid-Miocene Climatic Optimum (MMCO) about 15–14 Mya, it provided a marine conveyor belt for the dispersal of the ancestor of Galaxias maculatus from Australia to South America, and later to Australia and New Zealand. The integration of divergence times estimated on the phylogeny with ancestral area reconstruction supports an origin in Gondwana and subsequent oceanic dispersal as the explanation for the distribution of the Galaxiidae across the southern continents. PhD |
author2 |
Baker, Allan Ecology and Evolutionary Biology |
format |
Thesis |
author |
Ybazeta, Gustavo |
author_facet |
Ybazeta, Gustavo |
author_sort |
Ybazeta, Gustavo |
title |
Moleculary Systematics and Biogeography of the Galaxidae |
title_short |
Moleculary Systematics and Biogeography of the Galaxidae |
title_full |
Moleculary Systematics and Biogeography of the Galaxidae |
title_fullStr |
Moleculary Systematics and Biogeography of the Galaxidae |
title_full_unstemmed |
Moleculary Systematics and Biogeography of the Galaxidae |
title_sort |
moleculary systematics and biogeography of the galaxidae |
publishDate |
|
url |
http://hdl.handle.net/1807/65494 |
geographic |
Antarctic Drake Passage New Zealand The Antarctic |
geographic_facet |
Antarctic Drake Passage New Zealand The Antarctic |
genre |
Antarc* Antarctic Antarctica Drake Passage |
genre_facet |
Antarc* Antarctic Antarctica Drake Passage |
op_relation |
http://hdl.handle.net/1807/65494 |
_version_ |
1766268097532002304 |