Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals
Thesis (MSc)--Stellenbosch University, 2022. ENGLISH ABSTRACT: The challenges presented by the vast ocean confounds our understanding of speciation mechanisms in marine environments. As a result, most of our contemporary understanding of what drives speciation in marine environments is limited to a...
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2022
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ftunstellenbosch:oai:scholar.sun.ac.za:10019.1/125100 2024-05-12T08:11:34+00:00 Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals Malan, Amore Matthee, Conrad Adolf Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. 2022-08-14T03:00:10Z xv, 87 pages : illustrations(some color), maps application/pdf http://hdl.handle.net/10019.1/125100 af_ZA afr Stellenbosch : Stellenbosch University http://hdl.handle.net/10019.1/125100 Stellenbosch University Phylogeography Marine mammals -- Geographical distribution -- Climatic factors South African fur seal -- Ecology Climatic changes -- Southern Ocean Population genetics Seals (Animals) -- Genetics Seals (Animals) -- Environmental aspects UCTD Thesis 2022 ftunstellenbosch 2024-04-17T14:18:32Z Thesis (MSc)--Stellenbosch University, 2022. ENGLISH ABSTRACT: The challenges presented by the vast ocean confounds our understanding of speciation mechanisms in marine environments. As a result, most of our contemporary understanding of what drives speciation in marine environments is limited to a few taxonomic groups. In the case of coastal marine mammals, investigating the mechanisms responsible for speciation is especially confounded by disjunct distributions and perceived weak dispersal barriers. Only a few studies exist that investigates speciation mechanisms involved in marine mammals. This thesis thus aims to expand on our evolutionary understanding of marine mammals by presenting a case study from the Southern Oceans brown fur seal, Arctocephalus pusillus, which comprises two subspecies: Arctocephalus p. pusillus in Southern African and A. p. doriferus in Australia. The following two main hypotheses are posed i) the subspecies are genetically differentiated because cross-oceanic dispersals are rare, and ii) oceanic distance coupled with paleoclimate played an influential role in the incipient speciation of this taxon. To address these hypotheses, I estimated the population genetic structure, migration rates, and demographic histories using diversity- and variance metrics, Bayesian cluster analyses, Discriminant Analysis of Principal Components (DAPC), and approximate Bayesian computation (ABC). For this, thirteen microsatellites from 268 seals were genotyped and added to a previously sequenced mitochondrial control region (mtCR) dataset. Results confirmed that the subspecies have significantly diverged into two genetic groups, suggesting that the Indian Ocean currently acts as a geographical barrier to gene flow, as evident in the significant differentiation between subspecies (nuDNA: FST = 0.101, p ≤ 0.0001; mtCR: ΦST = 0.269, p ≤ 0.0001), the strong support for two continental clusters in Structure (ΔK = 1813.1), and a lack of immigrants after divergence (less than one immigrant per generation). At ... Thesis Southern Ocean Stellenbosch University: SUNScholar Research Repository Southern Ocean Indian |
institution |
Open Polar |
collection |
Stellenbosch University: SUNScholar Research Repository |
op_collection_id |
ftunstellenbosch |
language |
Afrikaans |
topic |
Phylogeography Marine mammals -- Geographical distribution -- Climatic factors South African fur seal -- Ecology Climatic changes -- Southern Ocean Population genetics Seals (Animals) -- Genetics Seals (Animals) -- Environmental aspects UCTD |
spellingShingle |
Phylogeography Marine mammals -- Geographical distribution -- Climatic factors South African fur seal -- Ecology Climatic changes -- Southern Ocean Population genetics Seals (Animals) -- Genetics Seals (Animals) -- Environmental aspects UCTD Malan, Amore Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
topic_facet |
Phylogeography Marine mammals -- Geographical distribution -- Climatic factors South African fur seal -- Ecology Climatic changes -- Southern Ocean Population genetics Seals (Animals) -- Genetics Seals (Animals) -- Environmental aspects UCTD |
description |
Thesis (MSc)--Stellenbosch University, 2022. ENGLISH ABSTRACT: The challenges presented by the vast ocean confounds our understanding of speciation mechanisms in marine environments. As a result, most of our contemporary understanding of what drives speciation in marine environments is limited to a few taxonomic groups. In the case of coastal marine mammals, investigating the mechanisms responsible for speciation is especially confounded by disjunct distributions and perceived weak dispersal barriers. Only a few studies exist that investigates speciation mechanisms involved in marine mammals. This thesis thus aims to expand on our evolutionary understanding of marine mammals by presenting a case study from the Southern Oceans brown fur seal, Arctocephalus pusillus, which comprises two subspecies: Arctocephalus p. pusillus in Southern African and A. p. doriferus in Australia. The following two main hypotheses are posed i) the subspecies are genetically differentiated because cross-oceanic dispersals are rare, and ii) oceanic distance coupled with paleoclimate played an influential role in the incipient speciation of this taxon. To address these hypotheses, I estimated the population genetic structure, migration rates, and demographic histories using diversity- and variance metrics, Bayesian cluster analyses, Discriminant Analysis of Principal Components (DAPC), and approximate Bayesian computation (ABC). For this, thirteen microsatellites from 268 seals were genotyped and added to a previously sequenced mitochondrial control region (mtCR) dataset. Results confirmed that the subspecies have significantly diverged into two genetic groups, suggesting that the Indian Ocean currently acts as a geographical barrier to gene flow, as evident in the significant differentiation between subspecies (nuDNA: FST = 0.101, p ≤ 0.0001; mtCR: ΦST = 0.269, p ≤ 0.0001), the strong support for two continental clusters in Structure (ΔK = 1813.1), and a lack of immigrants after divergence (less than one immigrant per generation). At ... |
author2 |
Matthee, Conrad Adolf Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
format |
Thesis |
author |
Malan, Amore |
author_facet |
Malan, Amore |
author_sort |
Malan, Amore |
title |
Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
title_short |
Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
title_full |
Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
title_fullStr |
Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
title_full_unstemmed |
Marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
title_sort |
marine mammal speciation: the role of oceanic distance and historical climatic change on the evolutionary divergence of brown fur seals |
publisher |
Stellenbosch : Stellenbosch University |
publishDate |
2022 |
url |
http://hdl.handle.net/10019.1/125100 |
geographic |
Southern Ocean Indian |
geographic_facet |
Southern Ocean Indian |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
http://hdl.handle.net/10019.1/125100 |
op_rights |
Stellenbosch University |
_version_ |
1798855315389677568 |