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Bell DA, Kovach RP, Robinson ZL, Whiteley AR, Reed TE. The ecological causes and consequences of hard and soft selection. Ecol Lett 2021; 24:1505-1521. [PMID: 33931936 DOI: 10.1111/ele.13754] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 02/17/2021] [Accepted: 03/15/2021] [Indexed: 01/01/2023]
Abstract
Interactions between natural selection and population dynamics are central to both evolutionary-ecology and biological responses to anthropogenic change. Natural selection is often thought to incur a demographic cost that, at least temporarily, reduces population growth. However, hard and soft selection clarify that the influence of natural selection on population dynamics depends on ecological context. Under hard selection, an individual's fitness is independent of the population's phenotypic composition, and substantial population declines can occur when phenotypes are mismatched with the environment. In contrast, under soft selection, an individual's fitness is influenced by its phenotype relative to other interacting conspecifics. Soft selection generally influences which, but not how many, individuals survive and reproduce, resulting in little effect on population growth. Despite these important differences, the distinction between hard and soft selection is rarely considered in ecology. Here, we review and synthesize literature on hard and soft selection, explore their ecological causes and implications and highlight their conservation relevance to climate change, inbreeding depression, outbreeding depression and harvest. Overall, these concepts emphasise that natural selection and evolution may often have negligible or counterintuitive effects on population growth-underappreciated outcomes that have major implications in a rapidly changing world.
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Affiliation(s)
- Donovan A Bell
- Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | | | - Zachary L Robinson
- Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Andrew R Whiteley
- Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Thomas E Reed
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.,Environmental Research Institute, University College Cork, Lee Road, Cork, Ireland
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O'Toole B, Simmons NB, Hekkala E. Reconstructing the Genomic Diversity of a Widespread Sub-Saharan Bat (Pteropodidae: Eidolon helvum) Using Archival Museum Collections. ACTA CHIROPTEROLOGICA 2020. [DOI: 10.3161/15081109acc2020.22.2.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Brian O'Toole
- Department of Biological Sciences, Fordham University, 441 East Fordham Road, Bronx, NY 10458, USA
| | - Nancy B. Simmons
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, 200 Central Park West, New York, NY 10024, USA
| | - Evon Hekkala
- Department of Biological Sciences, Fordham University, 441 East Fordham Road, Bronx, NY 10458, USA
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Delgado ML, Manosalva A, Urbina MA, Habit E, Link O, Ruzzante DE. Genomic basis of the loss of diadromy in Galaxias maculatus: Insights from reciprocal transplant experiments. Mol Ecol 2020; 29:4857-4870. [PMID: 33048403 DOI: 10.1111/mec.15686] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 12/18/2022]
Abstract
Diadromy is known for having major effects on the distribution and richness of aquatic species, and so does its loss. The loss of diadromy has led to the diversification of many species, yet research focusing on understanding its molecular basis and consequences are limited. This is particularly true for amphidromous species despite being the most abundant group of diadromous species. Galaxias maculatus, an amphidromous species and one of the most widely distributed fishes in the Southern Hemisphere, exhibits many instances of nonmigratory or resident populations. The existence of naturally replicated resident populations in Patagonia can serve as an ideal system for the study of the mechanisms that lead to the loss of the diadromy and its ecological and evolutionary consequences. Here, we studied two adjacent river systems in which resident populations are genetically differentiated yet derived from the same diadromous population. By combining a reciprocal transplant experiment with genomic data, we showed that the two resident populations followed different evolutionary pathways by exhibiting a differential response in their capacity to survive in salt water. While one resident population was able to survive salt water, the other was not. Genomic analyses provided insights into the genes that distinguished (a) migratory from nonmigratory populations; (b) populations that can vs those that cannot survive a saltwater environment; and (c) between these resident populations. This study demonstrates that the loss of diadromy can be achieved by different pathways and that environmental (selection) and random (genetic drift) forces shape this dynamic evolutionary process.
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Affiliation(s)
| | - Aliro Manosalva
- Departamento de Sistemas Acuáticos, Facultad de Ciencias Ambientales y Centro EULA, Universidad de Concepción, Concepción, Chile
| | - Mauricio A Urbina
- Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile.,Instituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, Chile
| | - Evelyn Habit
- Departamento de Sistemas Acuáticos, Facultad de Ciencias Ambientales y Centro EULA, Universidad de Concepción, Concepción, Chile
| | - Oscar Link
- Departamento de Ingeniería Civil, Facultad de Ingeniería, Universidad de Concepción, Concepción, Chile
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Isolation-by-time population structure in potamodromous Dourado Salminus brasiliensis in southern Brazil. CONSERV GENET 2016. [DOI: 10.1007/s10592-016-0882-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Genetic structure of a montane perennial plant: the influence of landscape and flowering phenology. CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0751-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Lewis B, Grant WS, Brenner RE, Hamazaki T. Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. PLoS One 2015; 10:e0130184. [PMID: 26090990 PMCID: PMC4474552 DOI: 10.1371/journal.pone.0130184] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 05/18/2015] [Indexed: 12/13/2022] Open
Abstract
The average sizes of Pacific salmon have declined in some areas in the Northeast Pacific over the past few decades, but the extent and geographic distribution of these declines in Alaska is uncertain. Here, we used regression analyses to quantify decadal trends in length and age at maturity in ten datasets from commercial harvests, weirs, and spawner abundance surveys of Chinook salmon Oncorhynchus tshawytscha throughout Alaska. We found that on average these fish have become smaller over the past 30 years (~6 generations), because of a decline in the predominant age at maturity and because of a decrease in age-specific length. The proportion of older and larger 4-ocean age fish in the population declined significantly (P < 0.05) in all stocks examined by return year or brood year. Our analyses also indicated that the age-specific lengths of 4-ocean fish (9 of 10 stocks) and of 3-ocean fish (5 of 10 stocks) have declined significantly (P < 0.05). Size-selective harvest may be driving earlier maturation and declines in size, but the evidence is not conclusive, and additional factors, such as ocean conditions or competitive interactions with other species of salmon, may also be responsible. Regardless of the cause, these wide-spread phenotypic shifts influence fecundity and population abundance, and ultimately may put populations and associated fisheries at risk of decline.
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Affiliation(s)
- Bert Lewis
- Alaska Department of Fish and Game, Commercial Fisheries Division, Anchorage, Alaska, United States of America
- * E-mail:
| | - W. Stewart Grant
- Alaska Department of Fish and Game, Commercial Fisheries Division, Anchorage, Alaska, United States of America
| | - Richard E. Brenner
- Alaska Department of Fish and Game, Commercial Fisheries Division, Juneau, Alaska, United States of America
| | - Toshihide Hamazaki
- Alaska Department of Fish and Game, Commercial Fisheries Division, Anchorage, Alaska, United States of America
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Eliminating Variation in Age at Spawning Leads to Genetic Divergence Within a Single Salmon Population. JOURNAL OF FISH AND WILDLIFE MANAGEMENT 2014. [DOI: 10.3996/122013-jfwm-086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Abstract
Most coho salmon Oncorhynchus kisutch in Washington state spawn at 3 y of age, creating the potential for three temporal populations or “broodlines” at each spawning site. This is generally prevented by a portion of males in each site that mature and reproduce at 2 y of age, resulting in population structure in which the geographic component is stronger than the temporal component. The Quilcene National Fish Hatchery, located on Big Quilcene River in the Hood Canal region of Washington state, selected against late returning coho salmon by excluding all but the earliest returning fish from its broodstock for an unknown number of generations, and restricted gene flow among broodlines by excluding 2-y-old males for 27 generations. The resulting hatchery population exhibited three distinct broodlines that returned in alternating years: an “early” broodline that arrived 1 mo before the wild fish, a “late” broodline that arrived at the same time as the wild fish, and a “middle” broodline that arrived in between these two broodlines. We evaluated temporal and geographic components of population genetic structure in coho salmon from the Quilcene National Fish Hatchery and nine other sites from Puget Sound and the Strait of Juan de Fuca using 10 microsatellite loci. Genetic diversity at the Quilcene National Fish Hatchery was lowest in the early broodline and highest in the late broodline. Divergence among broodlines at the Quilcene National Fish Hatchery was greater than that observed at any other site, and was also greater than that observed between any of the sites. This apparent reversal of the relative magnitudes of temporal and geographic components for this species emphasizes the importance of variable age-at-maturity in shaping population genetic structure.
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Gharrett AJ, Joyce J, Smoker WW. Fine-scale temporal adaptation within a salmonid population: mechanism and consequences. Mol Ecol 2013; 22:4457-69. [DOI: 10.1111/mec.12400] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/08/2013] [Accepted: 05/23/2013] [Indexed: 01/18/2023]
Affiliation(s)
- Anthony J. Gharrett
- Fisheries Division; School of Fisheries and Ocean Sciences; University of Alaska Fairbanks; 17101 Point Lena Loop Road Juneau AK 99801 USA
| | - John Joyce
- Fisheries Division; School of Fisheries and Ocean Sciences; University of Alaska Fairbanks; 17101 Point Lena Loop Road Juneau AK 99801 USA
- Auke Bay Laboratories; Alaska Fisheries Science Center; National Marine Fisheries Service; NOAA; 17109 Point Lena Loop Road Juneau AK 99801 USA
| | - William W. Smoker
- Fisheries Division; School of Fisheries and Ocean Sciences; University of Alaska Fairbanks; 17101 Point Lena Loop Road Juneau AK 99801 USA
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Kovach RP, Gharrett AJ, Tallmon DA. Genetic change for earlier migration timing in a pink salmon population. Proc Biol Sci 2012; 279:3870-8. [PMID: 22787027 DOI: 10.1098/rspb.2012.1158] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To predict how climate change will influence populations, it is necessary to understand the mechanisms, particularly microevolution and phenotypic plasticity, that allow populations to persist in novel environmental conditions. Although evidence for climate-induced phenotypic change in populations is widespread, evidence documenting that these phenotypic changes are due to microevolution is exceedingly rare. In this study, we use 32 years of genetic data (17 complete generations) to determine whether there has been a genetic change towards earlier migration timing in a population of pink salmon that shows phenotypic change; average migration time occurs nearly two weeks earlier than it did 40 years ago. Experimental genetic data support the hypothesis that there has been directional selection for earlier migration timing, resulting in a substantial decrease in the late-migrating phenotype (from more than 30% to less than 10% of the total abundance). From 1983 to 2011, there was a significant decrease--over threefold--in the frequency of a genetic marker for late-migration timing, but there were minimal changes in allele frequencies at other neutral loci. These results demonstrate that there has been rapid microevolution for earlier migration timing in this population. Circadian rhythm genes, however, did not show any evidence for selective changes from 1993 to 2009.
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Affiliation(s)
- Ryan P Kovach
- Biology and Wildlife Department, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
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