1
|
Wang X, Heckel G. Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles. Genome Res 2024; 34:851-862. [PMID: 38955466 PMCID: PMC11293545 DOI: 10.1101/gr.278487.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 05/14/2024] [Indexed: 07/04/2024]
Abstract
Island populations often experience different ecological and demographic conditions than their counterparts on the continent, resulting in divergent evolutionary forces affecting their genomes. Random genetic drift and selection both may leave their imprints on island populations, although the relative impact depends strongly on the specific conditions. Here we address their contributions to the island syndrome in a rodent with an unusually clear history of isolation. Common voles (Microtus arvalis) were introduced by humans on the Orkney archipelago north of Scotland >5000 years ago and rapidly evolved to exceptionally large size. Our analyses show that the genomes of Orkney voles were dominated by genetic drift, with extremely low diversity, variable Tajima's D, and very high divergence from continental conspecifics. Increased d N/d S ratios over a wide range of genes in Orkney voles indicated genome-wide relaxation of purifying selection. We found evidence of hard sweeps on key genes of the lipid metabolism pathway only in continental voles. The marked increase of body size in Orkney-a typical phenomenon of the island syndrome-may thus be associated to the relaxation of positive selection on genes related to this pathway. On the other hand, a hard sweep on immune genes of Orkney voles likely reflects the divergent ecological conditions and possibly the history of human introduction. The long-term isolated Orkney voles show that adaptive changes may still impact the evolutionary trajectories of such populations despite the pervasive consequences of genetic drift at the genome level.
Collapse
Affiliation(s)
- Xuejing Wang
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Gerald Heckel
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland;
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| |
Collapse
|
2
|
Renaud S, Amar L, Chevret P, Romestaing C, Quéré JP, Régis C, Lebrun R. Inner ear morphology in wild versus laboratory house mice. J Anat 2024; 244:722-738. [PMID: 38214368 PMCID: PMC11021637 DOI: 10.1111/joa.13998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/08/2023] [Accepted: 12/08/2023] [Indexed: 01/13/2024] Open
Abstract
The semicircular canals of the inner ear are involved in balance and velocity control. Being crucial to ensure efficient mobility, their morphology exhibits an evolutionary conservatism attributed to stabilizing selection. Release of selection in slow-moving animals has been argued to lead to morphological divergence and increased inter-individual variation. In its natural habitat, the house mouse Mus musculus moves in a tridimensional space where efficient balance is required. In contrast, laboratory mice in standard cages are severely restricted in their ability to move, which possibly reduces selection on the inner ear morphology. This effect was tested by comparing four groups of mice: several populations of wild mice trapped in commensal habitats in France; their second-generation laboratory offspring, to assess plastic effects related to breeding conditions; a standard laboratory strain (Swiss) that evolved for many generations in a regime of mobility reduction; and hybrids between wild offspring and Swiss mice. The morphology of the semicircular canals was quantified using a set of 3D landmarks and semi-landmarks analyzed using geometric morphometric protocols. Levels of inter-population, inter-individual (disparity) and intra-individual (asymmetry) variation were compared. All wild mice shared a similar inner ear morphology, in contrast to the important divergence of the Swiss strain. The release of selection in the laboratory strain obviously allowed for an important and rapid drift in the otherwise conserved structure. Shared traits between the inner ear of the lab strain and domestic pigs suggested a common response to mobility reduction in captivity. The lab-bred offspring of wild mice also differed from their wild relatives, suggesting plastic response related to maternal locomotory behavior, since inner ear morphology matures before birth in mammals. The signature observed in lab-bred wild mice and the lab strain was however not congruent, suggesting that plasticity did not participate to the divergence of the laboratory strain. However, contrary to the expectation, wild mice displayed slightly higher levels of inter-individual variation than laboratory mice, possibly due to the higher levels of genetic variance within and among wild populations compared to the lab strain. Differences in fluctuating asymmetry levels were detected, with the laboratory strain occasionally displaying higher asymmetry scores than its wild relatives. This suggests that there may indeed be a release of selection and/or a decrease in developmental stability in the laboratory strain.
Collapse
Affiliation(s)
- Sabrina Renaud
- Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France
| | - Léa Amar
- Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France
| | - Pascale Chevret
- Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France
| | - Caroline Romestaing
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), UMR 5023, CNRS, ENTPE, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France
| | - Jean-Pierre Quéré
- Centre de Biologie et Gestion des Populations (INRA/IRD/Cirad/Montpellier SupAgro), Campus International de Baillarguet, Montferrier-sur-Lez Cedex, France
| | - Corinne Régis
- Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, Université Claude Bernard Lyon 1, Université de Lyon, Villeurbanne, France
| | - Renaud Lebrun
- Institut des Sciences de l'Évolution (ISE-M), UMR 5554, CNRS/UM/IRD/EPHE, Université de Montpellier, Montpellier, France
| |
Collapse
|
3
|
Wang X, Peischl S, Heckel G. Demographic history and genomic consequences of 10,000 generations of isolation in a wild mammal. Curr Biol 2023; 33:2051-2062.e4. [PMID: 37178689 DOI: 10.1016/j.cub.2023.04.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/20/2022] [Accepted: 04/17/2023] [Indexed: 05/15/2023]
Abstract
Increased human activities caused the isolation of populations in many species-often associated with genetic depletion and negative fitness effects. The effects of isolation are predicted by theory, but long-term data from natural populations are scarce. We show, with full genome sequences, that common voles (Microtus arvalis) in the Orkney archipelago have remained genetically isolated from conspecifics in continental Europe since their introduction by humans over 5,000 years ago. Modern Orkney vole populations are genetically highly differentiated from continental conspecifics as a result of genetic drift processes. Colonization likely started on the biggest Orkney island and vole populations on smaller islands were gradually split off, without signs of secondary admixture. Despite having large modern population sizes, Orkney voles are genetically depauperate and successive introductions to smaller islands resulted in further reduction of genetic diversity. We detected high levels of fixation of predicted deleterious variation compared with continental populations, particularly on smaller islands, yet the fitness effects realized in nature are unknown. Simulations showed that predominantly mildly deleterious mutations were fixed in populations, while highly deleterious mutations were purged early in the history of the Orkney population. Relaxation of selection overall due to benign environmental conditions on the islands and the effects of soft selection may have contributed to the repeated, successful establishment of Orkney voles despite potential fitness loss. Furthermore, the specific life history of these small mammals, resulting in relatively large population sizes, has probably been important for their long-term persistence in full isolation.
Collapse
Affiliation(s)
- Xuejing Wang
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Stephan Peischl
- Interfaculty Bioinformatics Unit, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland; Swiss Institute of Bioinformatics, Amphipôle, Quartier UNIL-Sorge, 1015 Lausanne, Switzerland
| | - Gerald Heckel
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland; Swiss Institute of Bioinformatics, Amphipôle, Quartier UNIL-Sorge, 1015 Lausanne, Switzerland.
| |
Collapse
|
4
|
Romaniuk AA, Troalen LG, Bendrey R, Herman JS, Owen O, Smith C. Pests or prey? Micromammal species within an ancient anthropic environment at the Norse settlement site of Tuquoy (Westray, Orkney). ROYAL SOCIETY OPEN SCIENCE 2023; 10:221462. [PMID: 37035288 PMCID: PMC10073909 DOI: 10.1098/rsos.221462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Micromammals, like rodents and shrews, adapt rapidly to take advantage of new food sources, habitats and ecological niches, frequently thriving in anthropogenic environments. Their remains, often retrieved during archaeological investigations, can be a valuable source of information about the past environmental conditions as well as interspecies interactions and human activity. However, the research on such finds rarely covers multiple approaches, often relying on single species or data type (e.g. identification/information for proxy studies). Here we investigate micromammal remains from the Norse and medieval (AD tenth-fourteenth centuries) archaeological site at Tuquoy, Orkney, to elucidate the relationships between micromammals, humans and other species present using a variety of data. Four micromammal species were identified, and their species dynamics as well as relationships with humans could be inferred by tracking changes in spatial and temporal location of remains, from their taphonomic history and by age estimation for individual animals. A larger, predatory assemblage was also identified, with species composition differing from that in the rest of the archaeological assemblage, and possibly therefore representing small mammal species composition in the wild. The assemblage was probably deposited by a diurnal raptor, though identification to species is not certain due to post-depositional processes.
Collapse
Affiliation(s)
- Andrzej A. Romaniuk
- School of History, Classics and Archaeology, The University of Edinburgh, Teviot Place, Edinburgh EH8 9AG, UK
- Institute for Advanced Studies in the Humanities, The University of Edinburgh, Hope Park Square, Edinburgh EH8 9NW, UK
| | - Lore G. Troalen
- Department of Collections Services, National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, UK
| | - Robin Bendrey
- School of History, Classics and Archaeology, The University of Edinburgh, Teviot Place, Edinburgh EH8 9AG, UK
| | - Jeremy S. Herman
- Department of Natural Sciences, National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, UK
| | - Olwyn Owen
- Institute of Archaeology, University of the Highlands and Islands, Orkney College, East Road, Kirkwall, Orkney KW15 1LX
| | - Catherine Smith
- Alder Archaeology Ltd, 55 South Methven Street, Perth PH1 5NX, UK
| |
Collapse
|
5
|
Bite Force Performance from wild Derived mice has Undetectable Heritability Despite Having Heritable Morphological Components. Evol Biol 2022. [DOI: 10.1007/s11692-022-09582-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
AbstractFitness-related traits tend to have low heritabilities. Conversely, morphology tends to be highly heritable. Yet, many fitness-related performance traits such as running speed or bite force depend critically on morphology. Craniofacial morphology correlates with bite performance in several groups including rodents. However, within species, this relationship is less clear, and the genetics of performance, morphology and function are rarely analyzed in combination. Here, we use a half-sib design in outbred wild-derived Mus musculus to study the morphology-bite force relationship and determine whether there is additive genetic (co-)variance for these traits. Results suggest that bite force has undetectable additive genetic variance and heritability in this sample, while morphological traits related mechanically to bite force exhibit varying levels of heritability. The most heritable traits include the length of the mandible which relates to bite force. Despite its correlation with morphology, realized bite force was not heritable, which suggests it is less responsive to selection in comparison to its morphological determinants. We explain this paradox with a non-additive, many-to-one mapping hypothesis of heritable change in complex traits. We furthermore propose that performance traits could evolve if pleiotropic relationships among the determining traits are modified.
Collapse
|