Prehistoric human-induced range contraction of southern elephant seals in Australasia
Human migration across much of the globe has often coincided with both climate change events and the decline of large animal species. Due to the temporal overlap of these events, it has often proven difficult to confidently identify the causes of megafaunal extirpation. New Zealand (NZ) and Australi...
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ftunivotagoour:oai:ourarchive.otago.ac.nz:10523/7042 2023-05-15T13:52:08+02:00 Prehistoric human-induced range contraction of southern elephant seals in Australasia Askew, Megan Awhina Kara Waters, Jon Rawlence, Nic 2017-01-31T00:18:33Z http://hdl.handle.net/10523/7042 en eng University of Otago http://hdl.handle.net/10523/7042 All items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated. ancient DNA" "extinction" "Mirounga leonina" "New Zealand" "over-hunting" "range contraction" "southern elephant seal" "Tasmania Thesis or Dissertation 2017 ftunivotagoour 2022-05-11T19:19:19Z Human migration across much of the globe has often coincided with both climate change events and the decline of large animal species. Due to the temporal overlap of these events, it has often proven difficult to confidently identify the causes of megafaunal extirpation. New Zealand (NZ) and Australia represent two islands that have very different histories with respect to human colonisation times and megafaunal decline. Australia experienced ancient human colonisation, coinciding with major climatic transition periods, with early megafaunal declines. NZ, by contrast, experienced relatively recent human colonisation, coinciding with recent megafaunal declines. Pinnipeds represent a megafaunal assemblage particularly sensitive to human overexploitation. The largest among the pinnipeds is the southern elephant seal (Mirounga leonina), which has a circumpolar distribution, breeding on islands around Antarctica. M. leonina’s demography is of particular interest as both climatic and anthropogenic effects may have contributed to its recent history. Since M. leonina does not breed or haul out on ice, its distribution may be highly constrained by sea ice coverage, which reached a maximum during the Last Glacial Maximum, 18,000 years ago. Past and present diversity within species and populations can be inferred and compared using ancient DNA techniques. The mitochondrial hypervariable region 1 (HVR1) is a fast-evolving DNA region that has previously been sequenced from populations across the entire breeding range of M. leonina. This study focuses on the past and present HVR1 variation of M. leonina populations in the Australasian region and how they were affected by climatic and anthropogenic impacts. By sampling ancient DNA of M. leonina specimens from Tasmania and NZ, it was found that ancient M. leonina samples from New Zealand and modern samples from the Antipodes Islands shared the highest homology with the Macquarie Island breeding population. Tasmanian samples were found to be genetically distinct, further cementing their status as representing a prehistoric breeding population. These findings broadly confirm a substantial phylogeographic distinction between ‘Australasian’ and ‘South American’ populations of this species, consistent with separate glacial refugia. Collection records of M. leonina in an archaeological context show a decline of M. leonina remains after human colonisation in both NZ and Tasmania. Despite the NZ extinct population being genetically similar to extant populations, its rapid extinction seems attributable to human impacts. The presence of M. leonina remains for extended periods of Tasmania’s arhcaeological record might indicate a large reservoir population on King Island that was later driven to extinction by European sealers. The use of both genetic and archaeological data show that a multidisciplinary approach can be used to answer complex questions regarding ancient population expansions and contractions of a highly mobile species such as M. leonina. Thesis Antarc* Antarctica Antipodes Islands Elephant Seal Elephant Seals Macquarie Island Mirounga leonina Sea ice Southern Elephant Seal Southern Elephant Seals University of Otago: Research Archive (OUR Archive) King Island ENVELOPE(-58.100,-58.100,-62.000,-62.000) New Zealand |
institution |
Open Polar |
collection |
University of Otago: Research Archive (OUR Archive) |
op_collection_id |
ftunivotagoour |
language |
English |
topic |
ancient DNA" "extinction" "Mirounga leonina" "New Zealand" "over-hunting" "range contraction" "southern elephant seal" "Tasmania |
spellingShingle |
ancient DNA" "extinction" "Mirounga leonina" "New Zealand" "over-hunting" "range contraction" "southern elephant seal" "Tasmania Askew, Megan Awhina Kara Prehistoric human-induced range contraction of southern elephant seals in Australasia |
topic_facet |
ancient DNA" "extinction" "Mirounga leonina" "New Zealand" "over-hunting" "range contraction" "southern elephant seal" "Tasmania |
description |
Human migration across much of the globe has often coincided with both climate change events and the decline of large animal species. Due to the temporal overlap of these events, it has often proven difficult to confidently identify the causes of megafaunal extirpation. New Zealand (NZ) and Australia represent two islands that have very different histories with respect to human colonisation times and megafaunal decline. Australia experienced ancient human colonisation, coinciding with major climatic transition periods, with early megafaunal declines. NZ, by contrast, experienced relatively recent human colonisation, coinciding with recent megafaunal declines. Pinnipeds represent a megafaunal assemblage particularly sensitive to human overexploitation. The largest among the pinnipeds is the southern elephant seal (Mirounga leonina), which has a circumpolar distribution, breeding on islands around Antarctica. M. leonina’s demography is of particular interest as both climatic and anthropogenic effects may have contributed to its recent history. Since M. leonina does not breed or haul out on ice, its distribution may be highly constrained by sea ice coverage, which reached a maximum during the Last Glacial Maximum, 18,000 years ago. Past and present diversity within species and populations can be inferred and compared using ancient DNA techniques. The mitochondrial hypervariable region 1 (HVR1) is a fast-evolving DNA region that has previously been sequenced from populations across the entire breeding range of M. leonina. This study focuses on the past and present HVR1 variation of M. leonina populations in the Australasian region and how they were affected by climatic and anthropogenic impacts. By sampling ancient DNA of M. leonina specimens from Tasmania and NZ, it was found that ancient M. leonina samples from New Zealand and modern samples from the Antipodes Islands shared the highest homology with the Macquarie Island breeding population. Tasmanian samples were found to be genetically distinct, further cementing their status as representing a prehistoric breeding population. These findings broadly confirm a substantial phylogeographic distinction between ‘Australasian’ and ‘South American’ populations of this species, consistent with separate glacial refugia. Collection records of M. leonina in an archaeological context show a decline of M. leonina remains after human colonisation in both NZ and Tasmania. Despite the NZ extinct population being genetically similar to extant populations, its rapid extinction seems attributable to human impacts. The presence of M. leonina remains for extended periods of Tasmania’s arhcaeological record might indicate a large reservoir population on King Island that was later driven to extinction by European sealers. The use of both genetic and archaeological data show that a multidisciplinary approach can be used to answer complex questions regarding ancient population expansions and contractions of a highly mobile species such as M. leonina. |
author2 |
Waters, Jon Rawlence, Nic |
format |
Thesis |
author |
Askew, Megan Awhina Kara |
author_facet |
Askew, Megan Awhina Kara |
author_sort |
Askew, Megan Awhina Kara |
title |
Prehistoric human-induced range contraction of southern elephant seals in Australasia |
title_short |
Prehistoric human-induced range contraction of southern elephant seals in Australasia |
title_full |
Prehistoric human-induced range contraction of southern elephant seals in Australasia |
title_fullStr |
Prehistoric human-induced range contraction of southern elephant seals in Australasia |
title_full_unstemmed |
Prehistoric human-induced range contraction of southern elephant seals in Australasia |
title_sort |
prehistoric human-induced range contraction of southern elephant seals in australasia |
publisher |
University of Otago |
publishDate |
2017 |
url |
http://hdl.handle.net/10523/7042 |
long_lat |
ENVELOPE(-58.100,-58.100,-62.000,-62.000) |
geographic |
King Island New Zealand |
geographic_facet |
King Island New Zealand |
genre |
Antarc* Antarctica Antipodes Islands Elephant Seal Elephant Seals Macquarie Island Mirounga leonina Sea ice Southern Elephant Seal Southern Elephant Seals |
genre_facet |
Antarc* Antarctica Antipodes Islands Elephant Seal Elephant Seals Macquarie Island Mirounga leonina Sea ice Southern Elephant Seal Southern Elephant Seals |
op_relation |
http://hdl.handle.net/10523/7042 |
op_rights |
All items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated. |
_version_ |
1766256389521408000 |