Genomic analysis of the process leading up to the extinction of the woolly mammoth
Species worldwide are subject to contractions in both abundance and geographical range, and their persistence in a changing environment may thus depend on the ability to survive in small and fragmented populations. Despite the urgent need to understand how extinction works, our knowledge of pre-exti...
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Stockholms universitet, Zoologiska institutionen
2018
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ftstockholmuniv:oai:DiVA.org:su-149655 2023-05-15T18:44:23+02:00 Genomic analysis of the process leading up to the extinction of the woolly mammoth Pečnerová, Patrícia 2018 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149655 eng eng Stockholms universitet, Zoologiska institutionen Swedish Museum of Natural History Stockholm : Department of Zoology, Stockholm University orcid:0000-0001-9350-1987 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149655 urn:isbn:978-91-7797-089-7 urn:isbn:978-91-7797-090-3 info:eu-repo/semantics/openAccess woolly mammoth Mammuthus primigenius extinction Wrangel Island ancient DNA palaeogenetics population genetics genomics genomic erosion genetic drift inbreeding population size Evolutionary Biology Evolutionsbiologi Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2018 ftstockholmuniv 2023-02-23T21:43:22Z Species worldwide are subject to contractions in both abundance and geographical range, and their persistence in a changing environment may thus depend on the ability to survive in small and fragmented populations. Despite the urgent need to understand how extinction works, our knowledge of pre-extinction genetic processes is limited because techniques allowing population and conservation genomics to be studied in wild threatened populations have become available only recently. In this thesis, I used the last surviving population of the woolly mammoth (Mammuthus primigenius) as a model for studying pre-extinction population dynamics. I used ancient DNA as a tool to study microevolutionary processes in real time, analysing genetic changes in response to environmental shifts at the end of the last Ice Age and exploring impacts of genetic drift and inbreeding as woolly mammoths became isolated on Wrangel Island and survived for 6000 years at small population size. Using mitochondrial genomes, I found evidence of a founder effect that decreased the maternal diversity to a single lineage at the time when mammoths became trapped on Wrangel Island (~10,500 years ago). Moreover, a two- to three-fold higher mitochondrial mutation rate in Holocene and a fixed, potentially detrimental mutation in the ATP6 gene encoding for one of the key enzymes of the oxidative phosphorylation pathway, is consistent with the hypothesis that selection is less effective in removing deleterious mutations in small populations. A loss of diversity was also observed in an immunity gene that belongs to the major histocompatibility complex (MHC), even though the MHC is considered to be under balancing selection. Low-coverage genomic data was analysed in order to estimate endogenous DNA content and molecular sex of the mammoth samples. The observation of a male bias (69%) in the sex ratio led to the conclusion that male mammoths were more likely to die in a way that ensured good preservation. Another potential way of getting information about life ... Doctoral or Postdoctoral Thesis Wrangel Island Stockholm University: Publications (DiVA) Wrangel Island ENVELOPE(-179.385,-179.385,71.244,71.244) |
institution |
Open Polar |
collection |
Stockholm University: Publications (DiVA) |
op_collection_id |
ftstockholmuniv |
language |
English |
topic |
woolly mammoth Mammuthus primigenius extinction Wrangel Island ancient DNA palaeogenetics population genetics genomics genomic erosion genetic drift inbreeding population size Evolutionary Biology Evolutionsbiologi |
spellingShingle |
woolly mammoth Mammuthus primigenius extinction Wrangel Island ancient DNA palaeogenetics population genetics genomics genomic erosion genetic drift inbreeding population size Evolutionary Biology Evolutionsbiologi Pečnerová, Patrícia Genomic analysis of the process leading up to the extinction of the woolly mammoth |
topic_facet |
woolly mammoth Mammuthus primigenius extinction Wrangel Island ancient DNA palaeogenetics population genetics genomics genomic erosion genetic drift inbreeding population size Evolutionary Biology Evolutionsbiologi |
description |
Species worldwide are subject to contractions in both abundance and geographical range, and their persistence in a changing environment may thus depend on the ability to survive in small and fragmented populations. Despite the urgent need to understand how extinction works, our knowledge of pre-extinction genetic processes is limited because techniques allowing population and conservation genomics to be studied in wild threatened populations have become available only recently. In this thesis, I used the last surviving population of the woolly mammoth (Mammuthus primigenius) as a model for studying pre-extinction population dynamics. I used ancient DNA as a tool to study microevolutionary processes in real time, analysing genetic changes in response to environmental shifts at the end of the last Ice Age and exploring impacts of genetic drift and inbreeding as woolly mammoths became isolated on Wrangel Island and survived for 6000 years at small population size. Using mitochondrial genomes, I found evidence of a founder effect that decreased the maternal diversity to a single lineage at the time when mammoths became trapped on Wrangel Island (~10,500 years ago). Moreover, a two- to three-fold higher mitochondrial mutation rate in Holocene and a fixed, potentially detrimental mutation in the ATP6 gene encoding for one of the key enzymes of the oxidative phosphorylation pathway, is consistent with the hypothesis that selection is less effective in removing deleterious mutations in small populations. A loss of diversity was also observed in an immunity gene that belongs to the major histocompatibility complex (MHC), even though the MHC is considered to be under balancing selection. Low-coverage genomic data was analysed in order to estimate endogenous DNA content and molecular sex of the mammoth samples. The observation of a male bias (69%) in the sex ratio led to the conclusion that male mammoths were more likely to die in a way that ensured good preservation. Another potential way of getting information about life ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Pečnerová, Patrícia |
author_facet |
Pečnerová, Patrícia |
author_sort |
Pečnerová, Patrícia |
title |
Genomic analysis of the process leading up to the extinction of the woolly mammoth |
title_short |
Genomic analysis of the process leading up to the extinction of the woolly mammoth |
title_full |
Genomic analysis of the process leading up to the extinction of the woolly mammoth |
title_fullStr |
Genomic analysis of the process leading up to the extinction of the woolly mammoth |
title_full_unstemmed |
Genomic analysis of the process leading up to the extinction of the woolly mammoth |
title_sort |
genomic analysis of the process leading up to the extinction of the woolly mammoth |
publisher |
Stockholms universitet, Zoologiska institutionen |
publishDate |
2018 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149655 |
long_lat |
ENVELOPE(-179.385,-179.385,71.244,71.244) |
geographic |
Wrangel Island |
geographic_facet |
Wrangel Island |
genre |
Wrangel Island |
genre_facet |
Wrangel Island |
op_relation |
orcid:0000-0001-9350-1987 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149655 urn:isbn:978-91-7797-089-7 urn:isbn:978-91-7797-090-3 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766235058529632256 |