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Nadachowska‐Brzyska K, Konczal M, Babik W. Navigating the temporal continuum of effective population size. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13740] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | | | - Wieslaw Babik
- Jagiellonian University in Kraków Faculty of Biology Institute of Environmental Sciences Kraków Poland
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Lehnen L, Jan PL, Besnard AL, Fourcy D, Kerth G, Biedermann M, Nyssen P, Schorcht W, Petit EJ, Puechmaille SJ. Genetic diversity in a long-lived mammal is explained by the past's demographic shadow and current connectivity. Mol Ecol 2021; 30:5048-5063. [PMID: 34402111 DOI: 10.1111/mec.16123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 08/06/2021] [Accepted: 08/11/2021] [Indexed: 01/25/2023]
Abstract
Within-species genetic diversity is crucial for the persistence and integrity of populations and ecosystems. Conservation actions require an understanding of factors influencing genetic diversity, especially in the context of global change. Both population size and connectivity are factors greatly influencing genetic diversity; the relative importance of these factors can, however, change through time. Hence, quantifying the degree to which population size or genetic connectivity are shaping genetic diversity, and at which ecological time scale (past or present), is challenging, yet essential for the development of efficient conservation strategies. In this study, we estimated the genetic diversity of 42 colonies of Rhinolophus hipposideros, a long-lived mammal vulnerable to global change, sampling locations spanning its continental northern range. Here, we present an integrative approach that disentangles and quantifies the contribution of different connectivity measures in addition to contemporary colony size and historic bottlenecks in shaping genetic diversity. In our study, the best model explained 64% of the variation in genetic diversity. It included historic bottlenecks, contemporary colony size, connectivity and a negative interaction between the latter two. Contemporary connectivity explained most genetic diversity when considering a 65 km radius around the focal colonies, emphasizing the large geographic scale at which the positive impact of connectivity on genetic diversity is most profound and hence, the minimum scale at which conservation should be planned. Our results highlight that the relative importance of the two main factors shaping genetic diversity varies through time, emphasizing the relevance of disentangling them to ensure appropriate conservation strategies.
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Affiliation(s)
- Lisa Lehnen
- Applied Zoology and Nature Conservation, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany
| | - Pierre-Loup Jan
- ESE, Ecology and Ecosystem Health, Institut Agro, INRAE, Rennes, France
| | | | - Damien Fourcy
- ESE, Ecology and Ecosystem Health, Institut Agro, INRAE, Rennes, France
| | - Gerald Kerth
- Applied Zoology and Nature Conservation, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany
| | - Martin Biedermann
- Interessengemeinschaft für Fledermausschutz und -forschung in Thüringen (IFT) e.V, Bad Liebenstein, Germany
| | | | | | - Eric J Petit
- ESE, Ecology and Ecosystem Health, Institut Agro, INRAE, Rennes, France.,NACHTaktiv - Biologists for Bat research GbR, Erfurt, Germany
| | - Sebastien J Puechmaille
- Applied Zoology and Nature Conservation, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany
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Arredondo A, Mourato B, Nguyen K, Boitard S, Rodríguez W, Noûs C, Mazet O, Chikhi L. Inferring number of populations and changes in connectivity under the n-island model. Heredity (Edinb) 2021; 126:896-912. [PMID: 33846579 PMCID: PMC8178352 DOI: 10.1038/s41437-021-00426-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 12/11/2022] Open
Abstract
Inferring the demographic history of species is one of the greatest challenges in populations genetics. This history is often represented as a history of size changes, ignoring population structure. Alternatively, when structure is assumed, it is defined a priori as a population tree and not inferred. Here we propose a framework based on the IICR (Inverse Instantaneous Coalescence Rate). The IICR can be estimated for a single diploid individual using the PSMC method of Li and Durbin (2011). For an isolated panmictic population, the IICR matches the population size history, and this is how the PSMC outputs are generally interpreted. However, it is increasingly acknowledged that the IICR is a function of the demographic model and sampling scheme with limited connection to population size changes. Our method fits observed IICR curves of diploid individuals with IICR curves obtained under piecewise stationary symmetrical island models. In our models we assume a fixed number of time periods during which gene flow is constant, but gene flow is allowed to change between time periods. We infer the number of islands, their sizes, the periods at which connectivity changes and the corresponding rates of connectivity. Validation with simulated data showed that the method can accurately recover most of the scenario parameters. Our application to a set of five human PSMCs yielded demographic histories that are in agreement with previous studies using similar methods and with recent research suggesting ancient human structure. They are in contrast with the view of human evolution consisting of one ancestral population branching into three large continental and panmictic populations with varying degrees of connectivity and no population structure within each continent.
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Affiliation(s)
- Armando Arredondo
- Université de Toulouse, Institut National des Sciences Appliquées, Institut de Mathématiques de Toulouse, Toulouse, France. .,Institut de Mathématiques de Toulouse; UMR5219. Université de Toulouse, Toulouse, France.
| | - Beatriz Mourato
- Institut de Mathématiques de Toulouse; UMR5219. Université de Toulouse, Toulouse, France.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Khoa Nguyen
- Université de Toulouse, Institut National des Sciences Appliquées, Institut de Mathématiques de Toulouse, Toulouse, France
| | - Simon Boitard
- CBGP, Université de Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Willy Rodríguez
- Institut de Mathématiques de Toulouse; UMR5219. Université de Toulouse, Toulouse, France.,ENAC - Ecole Nationale de l'Aviation Civile, Université de Toulouse, Toulouse, France
| | | | - Olivier Mazet
- Université de Toulouse, Institut National des Sciences Appliquées, Institut de Mathématiques de Toulouse, Toulouse, France.,Institut de Mathématiques de Toulouse; UMR5219. Université de Toulouse, Toulouse, France
| | - Lounès Chikhi
- Instituto Gulbenkian de Ciência, Oeiras, Portugal. .,Laboratoire Évolution & Diversité Biologique (EDB UMR 5174), CNRS, IRD, UPS, Université de Toulouse Midi-Pyrénées, Toulouse, France.
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Yao Z, Liu K, Deng S, He X. An instantaneous coalescent method insensitive to population structure. J Genet Genomics 2021; 48:219-224. [PMID: 34001433 DOI: 10.1016/j.jgg.2021.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/23/2021] [Accepted: 03/05/2021] [Indexed: 01/28/2023]
Abstract
Conventional coalescent inferences of population history make the critical assumption that the population under examination is panmictic. However, most populations are structured. This complicates the prevailing coalescent analyses and sometimes leads to inaccurate estimates. To develop a coalescent method unhampered by population structure, we perform two analyses. First, we demonstrate that the coalescent probability of two randomly sampled alleles from the immediate preceding generation (one generation back) is independent of population structure. Second, motivated by this finding, we propose a new coalescent method: i-coalescent analysis. The i-coalescent analysis computes the instantaneous coalescent rate by using a phylogenetic tree of sampled alleles. Using simulated data, we broadly demonstrate the capability of i-coalescent analysis to accurately reconstruct population size dynamics of highly structured populations, although we find this method often requires larger sample sizes for structured populations than for panmictic populations. Overall, our results indicate i-coalescent analysis to be a useful tool, especially for the inference of population histories with intractable structure such as the developmental history of cell populations in the organs of complex organisms.
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Affiliation(s)
- Zeqi Yao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Kehui Liu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shanjun Deng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xionglei He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
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Kerdoncuff E, Lambert A, Achaz G. Testing for population decline using maximal linkage disequilibrium blocks. Theor Popul Biol 2020; 134:171-181. [DOI: 10.1016/j.tpb.2020.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 03/26/2020] [Accepted: 03/29/2020] [Indexed: 02/02/2023]
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