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- Dehasque, Marianne, et al.
(författare)
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Combining Bayesian age models and genetics to investigate population dynamics and extinction of the last mammoths in northern Siberia
- 2021
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 259
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Tidskriftsartikel (refereegranskat)abstract
- To understand the causes and implications of an extinction event, detailed information is necessary. However, this can be challenging when working with poorly resolved paleontological data sets. One approach to increase the data resolution is by combining different methods. In this study, we used both radiocarbon and genetic data to reconstruct the population history and extinction dynamics of the woolly mammoth in northern Siberia. We generated 88 new radiocarbon dates and combined these with previously published dates from 626 specimens to construct Bayesian age models. These models show that mammoths disappeared on the eastern Siberian mainland before the onset of the Younger Dryas (12.9–11.7 ky cal BP). Mammoths did however persist in the northernmost parts of central and western Siberia until the early Holocene. Further genetic results of 131 high quality mitogenomes, including 22 new mitogenomes generated in this study, support the hypothesis that mammoths from, or closely related to, a central and/or west- Siberian population recolonized Wrangel Island over the now submerged northern Siberian plains. As mammoths became trapped on the island due to rising sea levels, they lived another ca. 6000 years on Wrangel Island before eventually going extinct ca. 4000 years ago.
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| 2. |
- Dehasque, Marianne, et al.
(författare)
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Temporal dynamics of woolly mammoth genome erosion prior to extinction
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A large number of species have recently recovered from near-extinction events. Understanding the genetic consequences of severe population declines followed by demographic recoveries is key to predict the long-term viability of species in order to mitigate future extinction risks. Although these species have avoided the immediate extinction threat, their long-term viability remains questionable due to the genetic consequences of population declines, which are not understood on a time scale beyond a few generations. The woolly mammoth (Mammuthus primigenius) population on Wrangel Island is an excellent model system to investigate long-term genetic consequences of a population bottleneck. Mammoths became isolated on the island in the early Holocene due to rising sea levels, and persisted for over 200 generations (~6,000 years) before becoming extinct ~4,000 years ago. To study the evolutionary processes leading up to the extinction of the woolly mammoth on the island, we analysed 21 Siberian woolly mammoth genomes, including that of one of the last known mammoths. Our results show that the Wrangel Island mammoths recovered quickly from an initially severe bottleneck, and subsequently remained demographically stable during the ensuing 6 millennia. Further, we find that highly deleterious mutations were gradually purged from the population, whereas there was an accumulation of mildly deleterious mutations. The gradual purging of highly deleterious mutations suggests an ongoing inbreeding depression that lasted for hundreds of generations. This time-lag between demographic and genetic recovery has wide-ranging implications for conservation management of recently bottlenecked present-day populations.
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| 3. |
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| 4. |
- Pečnerová, Patrícia, et al.
(författare)
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Genome-Based Sexing Provides Clues about Behavior and Social Structure in the Woolly Mammoth
- 2017
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 27:22, s. 3505-3510.e3
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Tidskriftsartikel (refereegranskat)abstract
- While present-day taxa are valuable proxies for understanding the biology of extinct species, it is also crucial to examine physical remains in order to obtain a more comprehensive view of their behavior, social structure, and life histories [1, 2]. For example, information on demographic parameters such as age distribution and sex ratios in fossil assemblages can be used to accurately infer socioecological patterns (e.g., [3]). Here we use genomic data to determine the sex of 98 woolly mammoth (Mammuthus primigenius) specimens in order to infer social and behavioral patterns in the last 60,000 years of the species' existence. We report a significant excess of males among the identified samples (69% versus 31%; p < 0.0002). We argue that this male bias among mammoth remains is best explained by males more often being caught in natural traps that favor preservation. Wehypothesize that this is a consequence of social structure in proboscideans, which is characterized by matriarchal hierarchy and sex segregation. Without the experience associated with living in a matriarchal family group, or a bachelor group with an experienced bull, young or solitary males may have been more prone to die in natural traps where good preservation is more likely.
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| 5. |
- Pečnerová, Patrícia, et al.
(författare)
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Mitogenome evolution in the last surviving woolly mammoth population reveals neutral and functional consequences of small population size
- 2017
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Ingår i: Evolution Letters. - : Oxford University Press (OUP). - 2056-3744. ; 1:6, s. 292-303
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Tidskriftsartikel (refereegranskat)abstract
- The onset of the Holocene was associated with a global temperature increase, which led to a rise in sea levels and isolation of the last surviving population of woolly mammoths on Wrangel Island. Understanding what happened with the population's genetic diversity at the time of the isolation and during the ensuing 6000 years can help clarify the effects of bottlenecks and subsequent limited population sizes in species approaching extinction. Previous genetic studies have highlighted questions about how the Holocene Wrangel population was established and how the isolation event affected genetic diversity. Here, we generated high-quality mitogenomes from 21 radiocarbon-dated woolly mammoths to compare the ancestral large and genetically diverse Late Pleistocene Siberian population and the small Holocene Wrangel population. Our results indicate that mitogenome diversity was reduced to one single haplotype at the time of the isolation, and thus that the Holocene Wrangel Island population was established by a single maternal lineage. Moreover, we show that the ensuing small effective population size coincided with fixation of a nonsynonymous mutation, and a comparative analysis of mutation rates suggests that the evolutionary rate was accelerated in the Holocene population. These results suggest that isolation on Wrangel Island led to an increase in the frequency of deleterious genetic variation, and thus are consistent with the hypothesis that strong genetic drift in small populations leads to purifying selection being less effective in removing deleterious mutations.
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