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Liguori A. Multigenerational Life-History Responses to pH in Distinct Populations of the Copepod Tigriopus californicus. THE BIOLOGICAL BULLETIN 2022; 242:97-117. [PMID: 35580028 DOI: 10.1086/719573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Intertidal zones are highly dynamic and harsh habitats: organisms that persist there must face many stressors, including drastic changes in seawater pH, which can be strongly influenced by biological processes. Coastal ecosystems are heterogeneous in space and time, and populations can be exposed to distinct selective pressures and evolve different capacities for acclimation to changes in pH. Tigriopus californicus is a harpacticoid copepod found in high-shore rock pools on the west coast of North America. It is a model system for studying population dynamics in diverse environments, but little is known about its responses to changes in seawater pH. I quantified the effects of pH on the survivorship, fecundity, and development of four T. californicus populations from San Juan Island, Washington, across three generations. For all populations and generations, copepod cultures had lower survivorship and delayed development under extended exposure to higher pH treatments (pH 7.5 and pH 8.0), whereas cultures maintained in lower pH (7.0) displayed stable population growth over time. Reciprocal transplants between treatments demonstrated that these pH effects were reversible. Life histories were distinct between populations, and there were differences in the magnitudes of pH effects on development and culture growth that persisted through multiple generations. These results suggest that T. californicus might not have the generalist physiology that might be expected of an intertidal species, and it could be adapted to lower average pH conditions than those that occur in adjacent open waters.
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Geographic Cline and Genetic Introgression Effects on Seed Morphology Variation and Germination Fitness in Two Closely Related Pine Species in Southeast Asia. FORESTS 2022. [DOI: 10.3390/f13030374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
There is still limited information on how genetic introgression impacts morphological variation and population fitness in long-lived conifer species. Two closely related pine species, Pinus kesiya Royle ex Gordon and Pinus yunnanensis Franch. are widely distributed over Southeast Asia and Yunnan province of China, with a large spatial scale of asymmetric genetic introgression and hybridization, and form a hybrid lineage, P. kesiya var. langbianensis, where their ranges overlap in southeast Yunnan. We compared seed trait variation and germination performance between hybrids and parental species and characterized environmental gradients to investigate the genetic and ecological evolutionary consequences of genetic introgression. We found that seed width (SW) differed significantly among the three pines, and all the seed traits were significantly negatively correlated with latitude and associated with the mean temperatures of the driest and wettest quarters. A higher germination fitness of hybrids was detected at a low temperature, indicating that they had better adaptability to temperature stress than their parental species during the germination process. Our results suggest that environmental factors shape seed phenotypic variation in the pine species and that genetic introgression significantly affects seed germination fitness. Therefore, assisting gene flow in natural forest populations might facilitate their adaptation to climate change.
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Pereira RJ, Lima TG, Pierce-Ward NT, Chao L, Burton RS. Recovery from hybrid breakdown reveals a complex genetic architecture of mitonuclear incompatibilities. Mol Ecol 2021; 30:6403-6416. [PMID: 34003535 DOI: 10.1111/mec.15985] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/29/2021] [Accepted: 05/11/2021] [Indexed: 01/03/2023]
Abstract
Reproductive isolation is often achieved when genes that are neutral or beneficial in their genomic background become functionally incompatible in a foreign genomic background, causing inviability, sterility or other forms of low fitness in hybrids. Recent studies suggest that mitonuclear interactions are among the initial incompatibilities to evolve at early stages of population divergence across taxa. Yet, the genomic architecture of mitonuclear incompatibilities has rarely been elucidated. We employ an experimental evolution approach starting with low-fitness F2 interpopulation hybrids of the copepod Tigriopus californicus, in which frequencies of compatible and incompatible nuclear alleles change in response to an alternative mitochondrial background. After about nine generations, we observe a generalized increase in population size and in survivorship, suggesting efficiency of selection against maladaptive phenotypes. Whole genome sequencing of evolved populations showed some consistent allele frequency changes across three replicates of each reciprocal cross, but markedly different patterns between mitochondrial backgrounds. In only a few regions (~6.5% of the genome), the same parental allele was overrepresented irrespective of the mitochondrial background. About 33% of the genome showed allele frequency changes consistent with divergent selection, with the location of these genomic regions strongly differing between mitochondrial backgrounds. In 87% and 89% of these genomic regions, the dominant nuclear allele matched the associated mitochondrial background, consistent with mitonuclear co-adaptation. These results suggest that mitonuclear incompatibilities have a complex polygenic architecture that differs between populations, potentially generating genome-wide barriers to gene flow between closely related taxa.
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Affiliation(s)
- Ricardo J Pereira
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thiago G Lima
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - N Tessa Pierce-Ward
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Lin Chao
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Ronald S Burton
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
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4
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Thompson KA, Urquhart-Cronish M, Whitney KD, Rieseberg LH, Schluter D. Patterns, Predictors, and Consequences of Dominance in Hybrids. Am Nat 2021; 197:E72-E88. [PMID: 33625966 DOI: 10.1086/712603] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractCompared to those of their parents, are the traits of first-generation (F1) hybrids typically intermediate, biased toward one parent, or mismatched for alternative parental phenotypes? To address this empirical gap, we compiled data from 233 crosses in which traits were measured in a common environment for two parent taxa and their F1 hybrids. We find that individual traits in F1s are halfway between the parental midpoint and one parental value. Considering pairs of traits together, a hybrid's bivariate phenotype tends to resemble one parent (parent bias) about 50% more than the other, while also exhibiting a similar magnitude of mismatch due to different traits having dominance in conflicting directions. Using data from an experimental field planting of recombinant hybrid sunflowers, we illustrate that parent bias improves fitness, whereas mismatch reduces fitness. Our study has three major conclusions. First, hybrids are not phenotypically intermediate but rather exhibit substantial mismatch. Second, dominance is likely determined by the idiosyncratic evolutionary trajectories of individual traits and populations. Finally, selection against hybrids likely results from selection against both intermediate and mismatched phenotypes.
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5
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Thompson KA. Experimental Hybridization Studies Suggest That Pleiotropic Alleles Commonly Underlie Adaptive Divergence between Natural Populations. Am Nat 2020; 196:E16-E22. [PMID: 32552104 DOI: 10.1086/708722] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The alleles used for adaptation can pleiotropically affect traits under stabilizing selection. The fixation of alleles with deleterious pleiotropic side effects causes compensatory alleles to be favored by selection. Such compensatory alleles might segregate in interpopulation hybrids, resulting in segregation variance for traits where parents have indistinguishable phenotypes. If adaptation typically involves pleiotropy and compensation, then the segregation variance for traits under stabilizing selection is expected to increase with the magnitude of adaptive phenotypic divergence between parents. This prediction has not been tested empirically, and I gathered data from experimental hybridization studies to evaluate it. I found that pairs of parents that are more phenotypically divergent beget hybrids with more segregation variance in traits for which the parents are statistically indistinguishable. This result suggests that adaptive divergence between pairs of natural populations proceeds via pleiotropy and compensation and that deleterious transgressive segregation variance accumulates systematically as populations diverge.
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6
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Hudson J, McQuaid CD, Rius M. Contemporary climate change hinders hybrid performance of ecologically dominant marine invertebrates. J Evol Biol 2020; 34:60-72. [PMID: 32096898 DOI: 10.1111/jeb.13609] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 02/03/2020] [Accepted: 02/15/2020] [Indexed: 12/28/2022]
Abstract
Human activities alter patterns of biodiversity, particularly through species extinctions and range shifts. Two of these activities are human mediated transfer of species and contemporary climate change, and both allow previously isolated genotypes to come into contact and hybridize, potentially altering speciation rates. Hybrids have been shown to survive environmental conditions not tolerated by either parent, suggesting that, under some circumstances, hybrids may be able to expand their ranges and perform well under rapidly changing conditions. However, studies assessing how hybridization influences contemporary range shifts are scarce. We performed crosses on Pyura herdmani and Pyura stolonifera (Chordata, Tunicata), two closely related marine invertebrate species that are ecologically dominant and can hybridize. These sister species live in sympatry along the coasts of southern Africa, but one has a disjunct distribution that includes northern hemisphere sites. We experimentally assessed the performance of hybrid and parental crosses using different temperature regimes, including temperatures predicted under future climate change scenarios. We found that hybrids showed lower performance than parental crosses at the experimental temperatures, suggesting that hybrids are unlikely to expand their ranges to new environments. In turn, we found that the more widespread species performed better at a wide array of temperatures, indicating that this parental species may cope better with future conditions. This study illustrates how offspring fitness may provide key insights to predict range expansions and how contemporary climate change may mediate both the ability of hybrids to expand their ranges and the occurrence of speciation as a result of hybridization.
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Affiliation(s)
- Jamie Hudson
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | | | - Marc Rius
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK.,Department of Zoology, Centre for Ecological Genomics and Wildlife Conservation, University of Johannesburg, Auckland Park, South Africa
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7
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Zhang Z, Bendixsen DP, Janzen T, Nolte AW, Greig D, Stelkens R. Recombining Your Way Out of Trouble: The Genetic Architecture of Hybrid Fitness under Environmental Stress. Mol Biol Evol 2020; 37:167-182. [PMID: 31518427 PMCID: PMC6984367 DOI: 10.1093/molbev/msz211] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hybridization between species can either promote or impede adaptation. But we know very little about the genetic basis of hybrid fitness, especially in nondomesticated organisms, and when populations are facing environmental stress. We made genetically variable F2 hybrid populations from two divergent Saccharomyces yeast species. We exposed populations to ten toxins and sequenced the most resilient hybrids on low coverage using ddRADseq to investigate four aspects of their genomes: 1) hybridity, 2) interspecific heterozygosity, 3) epistasis (positive or negative associations between nonhomologous chromosomes), and 4) ploidy. We used linear mixed-effect models and simulations to measure to which extent hybrid genome composition was contingent on the environment. Genomes grown in different environments varied in every aspect of hybridness measured, revealing strong genotype–environment interactions. We also found selection against heterozygosity or directional selection for one of the parental alleles, with larger fitness of genomes carrying more homozygous allelic combinations in an otherwise hybrid genomic background. In addition, individual chromosomes and chromosomal interactions showed significant species biases and pervasive aneuploidies. Against our expectations, we observed multiple beneficial, opposite-species chromosome associations, confirmed by epistasis- and selection-free computer simulations, which is surprising given the large divergence of parental genomes (∼15%). Together, these results suggest that successful, stress-resilient hybrid genomes can be assembled from the best features of both parents without paying high costs of negative epistasis. This illustrates the importance of measuring genetic trait architecture in an environmental context when determining the evolutionary potential of genetically diverse hybrid populations.
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Affiliation(s)
- Zebin Zhang
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Devin P Bendixsen
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Thijs Janzen
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Institute of Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Arne W Nolte
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Institute of Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Duncan Greig
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Centre for Life's Origins and Evolution (CLOE), Department of Genetics, Evolution, and Environment, University College London, London, United Kingdom
| | - Rike Stelkens
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden.,Max Planck Institute for Evolutionary Biology, Plön, Germany
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8
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Baums IB, Baker AC, Davies SW, Grottoli AG, Kenkel CD, Kitchen SA, Kuffner IB, LaJeunesse TC, Matz MV, Miller MW, Parkinson JE, Shantz AA. Considerations for maximizing the adaptive potential of restored coral populations in the western Atlantic. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01978. [PMID: 31332879 PMCID: PMC6916196 DOI: 10.1002/eap.1978] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/13/2019] [Accepted: 06/21/2019] [Indexed: 05/06/2023]
Abstract
Active coral restoration typically involves two interventions: crossing gametes to facilitate sexual larval propagation; and fragmenting, growing, and outplanting adult colonies to enhance asexual propagation. From an evolutionary perspective, the goal of these efforts is to establish self-sustaining, sexually reproducing coral populations that have sufficient genetic and phenotypic variation to adapt to changing environments. Here, we provide concrete guidelines to help restoration practitioners meet this goal for most Caribbean species of interest. To enable the persistence of coral populations exposed to severe selection pressure from many stressors, a mixed provenance strategy is suggested: genetically unique colonies (genets) should be sourced both locally as well as from more distant, environmentally distinct sites. Sourcing three to four genets per reef along environmental gradients should be sufficient to capture a majority of intraspecies genetic diversity. It is best for practitioners to propagate genets with one or more phenotypic traits that are predicted to be valuable in the future, such as low partial mortality, high wound healing rate, high skeletal growth rate, bleaching resilience, infectious disease resilience, and high sexual reproductive output. Some effort should also be reserved for underperforming genets because colonies that grow poorly in nurseries sometimes thrive once returned to the reef and may harbor genetic variants with as yet unrecognized value. Outplants should be clustered in groups of four to six genets to enable successful fertilization upon maturation. Current evidence indicates that translocating genets among distant reefs is unlikely to be problematic from a population genetic perspective but will likely provide substantial adaptive benefits. Similarly, inbreeding depression is not a concern given that current practices only raise first-generation offspring. Thus, proceeding with the proposed management strategies even in the absence of a detailed population genetic analysis of the focal species at sites targeted for restoration is the best course of action. These basic guidelines should help maximize the adaptive potential of reef-building corals facing a rapidly changing environment.
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Affiliation(s)
- Iliana B. Baums
- Department of BiologyPennsylvania State UniversityUniversity ParkPennsylvania16803USA
| | - Andrew C. Baker
- Department of Marine Biology and EcologyRosenstiel School of Marine and Atmospheric ScienceUniversity of MiamiMiamiFlorida33149USA
| | - Sarah W. Davies
- Department of BiologyBoston UniversityBostonMassachusetts02215USA
| | | | - Carly D. Kenkel
- Department of Biological SciencesUniversity of Southern CaliforniaLos AngelesCalifornia90007USA
| | - Sheila A. Kitchen
- Department of BiologyPennsylvania State UniversityUniversity ParkPennsylvania16803USA
| | - Ilsa B. Kuffner
- U.S. Geological Survey600 4th Street S.St. PetersburgFlorida33701USA
| | - Todd C. LaJeunesse
- Department of BiologyPennsylvania State UniversityUniversity ParkPennsylvania16803USA
| | - Mikhail V. Matz
- Department of Integrative BiologyThe University of Texas at AustinAustinTexas78712USA
| | | | - John E. Parkinson
- SECORE InternationalMiamiFlorida33145USA
- Department of Integrative BiologyUniversity of South FloridaTampaFlorida33620USA
| | - Andrew A. Shantz
- Department of BiologyPennsylvania State UniversityUniversity ParkPennsylvania16803USA
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9
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Abstract
Interspecific hybridization is the process where closely related species mate and produce offspring with admixed genomes. The genomic revolution has shown that hybridization is common, and that it may represent an important source of novel variation. Although most interspecific hybrids are sterile or less fit than their parents, some may survive and reproduce, enabling the transfer of adaptive variants across the species boundary, and even result in the formation of novel evolutionary lineages. There are two main variants of hybrid species genomes: allopolyploid, which have one full chromosome set from each parent species, and homoploid, which are a mosaic of the parent species genomes with no increase in chromosome number. The establishment of hybrid species requires the development of reproductive isolation against parental species. Allopolyploid species often have strong intrinsic reproductive barriers due to differences in chromosome number, and homoploid hybrids can become reproductively isolated from the parent species through assortment of genetic incompatibilities. However, both types of hybrids can become further reproductively isolated, gaining extrinsic isolation barriers, by exploiting novel ecological niches, relative to their parents. Hybrids represent the merging of divergent genomes and thus face problems arising from incompatible combinations of genes. Thus hybrid genomes are highly dynamic and undergo rapid evolutionary change, including genome stabilization in which selection against incompatible combinations results in fixation of compatible ancestry block combinations within the hybrid species. The potential for rapid adaptation or speciation makes hybrid genomes a particularly exciting subject of in evolutionary biology. Here we summarize how introgressed alleles or hybrid species can establish and how the resulting hybrid genomes evolve.
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Affiliation(s)
- Anna Runemark
- Department of Biology, Lund University, Lund, Sweden
- * E-mail:
| | - Mario Vallejo-Marin
- Biological and Environmental Sciences, University of Stirling, Stirling, Scotland, United Kingdom
| | - Joana I. Meier
- St John's College, Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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10
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Ma X, Hu W, Smilauer P, Yin M, Wolinska J. Daphnia galeata
and D. dentifera
are geographically and ecologically separated whereas their hybrids occur in intermediate habitats: A survey of 44 Chinese lakes. Mol Ecol 2019; 28:785-802. [DOI: 10.1111/mec.14991] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 11/21/2018] [Accepted: 12/14/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Xiaolin Ma
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science; Fudan University; Shanghai China
| | - Wei Hu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science; Fudan University; Shanghai China
| | - Petr Smilauer
- Department of Ecosystem Biology, Faculty of Science; University of South Bohemia; Ceske Budejovice Czech Republic
| | - Mingbo Yin
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science; Fudan University; Shanghai China
| | - Justyna Wolinska
- Department of Ecosystem Research; Leibniz-Institute of Freshwater Ecology and Inland Fisheries; Berlin Germany
- Department of Biology, Chemistry, Institute of Biology; Freie Universität Berlin; Berlin Germany
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11
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Sun PY, Foley HB, Wu L, Nguyen C, Chaudhry S, Bao VWW, Leung KMY, Edmands S. Long-term laboratory culture causes contrasting shifts in tolerance to two marine pollutants in copepods of the genus Tigriopus. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:3183-3192. [PMID: 29019110 DOI: 10.1007/s11356-017-0398-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/02/2017] [Indexed: 06/07/2023]
Abstract
Organismal chemical tolerance is often used to assess ecological risk and monitor water quality, yet tolerance can differ between field- and lab-raised organisms. In this study, we examined how tolerance to copper (Cu) and tributyltin oxide (TBTO) in two species of marine copepods, Tigriopus japonicus and T. californicus, changed across generations under benign laboratory culture (in the absence of pre-exposure to chemicals). Both copepod species exhibited similar chemical-specific changes in tolerance, with laboratory maintenance resulting in increased Cu tolerance and decreased TBTO tolerance. To assess potential factors underlying these patterns, chemical tolerance was measured in conjunction with candidate environmental variables (temperature, UV radiation, diet type, and starvation). The largest chemical-specific effect was found for starvation, which decreased TBTO tolerance but had no effect on Cu tolerance. Understanding how chemical-specific tolerance can change in the laboratory will be critical in strengthening bioassays and their applications for environmental protection and chemical management.
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Affiliation(s)
- Patrick Y Sun
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA.
| | - Helen B Foley
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA
| | - Leslie Wu
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA
| | - Charlene Nguyen
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA
| | - Shiven Chaudhry
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA
| | - Vivien W W Bao
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Kenneth M Y Leung
- The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Suzanne Edmands
- Department of Biological Science and Wrigley Institute for Environmental Studies, University of Southern California, 3616 Trousdale PKWY STE 107, Los Angeles, CA, 90089, USA
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12
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Leong W, Sun PY, Edmands S. Latitudinal Clines in Temperature and Salinity Tolerance in Tidepool Copepods. J Hered 2017; 109:71-77. [DOI: 10.1093/jhered/esx061] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 07/13/2017] [Indexed: 12/21/2022] Open
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13
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Hwang AS, Pritchard VL, Edmands S. Recovery from hybrid breakdown in a marine invertebrate is faster, stronger and more repeatable under environmental stress. J Evol Biol 2016; 29:1793-803. [DOI: 10.1111/jeb.12913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 05/30/2016] [Indexed: 11/26/2022]
Affiliation(s)
- A. S. Hwang
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - V. L. Pritchard
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - S. Edmands
- Department of Biological Sciences University of Southern California Los Angeles CA USA
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14
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Stelkens RB, Schmid C, Seehausen O. Hybrid breakdown in cichlid fish. PLoS One 2015; 10:e0127207. [PMID: 25996870 PMCID: PMC4440740 DOI: 10.1371/journal.pone.0127207] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/13/2015] [Indexed: 12/22/2022] Open
Abstract
Studies from a wide diversity of taxa have shown a negative relationship between genetic compatibility and the divergence time of hybridizing genomes. Theory predicts the main breakdown of fitness to happen after the F1 hybrid generation, when heterosis subsides and recessive allelic (Dobzhansky-Muller) incompatibilities are increasingly unmasked. We measured the fitness of F2 hybrids of African haplochromine cichlid fish bred from species pairs spanning several thousand to several million years divergence time. F2 hybrids consistently showed the lowest viability compared to F1 hybrids and non-hybrid crosses (crosses within the grandparental species), in agreement with hybrid breakdown. Especially the short- and long-term survival (2 weeks to 6 months) of F2 hybrids was significantly reduced. Overall, F2 hybrids showed a fitness reduction of 21% compared to F1 hybrids, and a reduction of 43% compared to the grandparental, non-hybrid crosses. We further observed a decrease of F2 hybrid viability with the genetic distance between grandparental lineages, suggesting an important role for negative epistatic interactions in cichlid fish postzygotic isolation. The estimated time window for successful production of F2 hybrids resulting from our data is consistent with the estimated divergence time between the multiple ancestral lineages that presumably hybridized in three major adaptive radiations of African cichlids.
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Affiliation(s)
| | - Corinne Schmid
- Department of Aquatic Ecology and Macroevolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
| | - Ole Seehausen
- Department of Aquatic Ecology and Macroevolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
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15
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Ermakov EL, Rusanovskaya OO. Seasonal dynamics of the phenotypic structure of a natural Epischura baicalensis Sars population from quantitative morphological traits. CONTEMP PROBL ECOL+ 2015. [DOI: 10.1134/s1995425515020055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Stelkens RB, Brockhurst MA, Hurst GDD, Miller EL, Greig D. The effect of hybrid transgression on environmental tolerance in experimental yeast crosses. J Evol Biol 2014; 27:2507-19. [PMID: 25262771 DOI: 10.1111/jeb.12494] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/22/2014] [Accepted: 09/01/2014] [Indexed: 01/29/2023]
Abstract
Evidence is rapidly accumulating that hybridization generates adaptive variation. Transgressive segregation in hybrids could promote the colonization of new environments. Here, we use an assay to select hybrid genotypes that can proliferate in environmental conditions beyond the conditions tolerated by their parents, and we directly compete them against parental genotypes in habitats across environmental clines. We made 45 different hybrid swarms by crossing yeast strains (both Saccharomyces cerevisiae and S. paradoxus) with different genetic and phenotypic divergence. We compared the ability of hybrids and parents to colonize seven types of increasingly extreme environmental clines, representing both natural and novel challenges (mimicking pollution events). We found that a significant majority of hybrids had greater environmental ranges compared to the average of both their parents' ranges (mid-parent transgression), but only a minority of hybrids had ranges exceeding their best parent (best-parent transgression). Transgression was affected by the specific strains involved in the cross and by the test environment. Genetic and phenotypic crossing distance predicted the extent of transgression in only two of the seven environments. We isolated a set of potentially transgressive hybrids selected at the extreme ends of the clines and found that many could directly outcompete their parents across whole clines and were between 1.5- and 3-fold fitter on average. Saccharomyces yeast is a good model for quantitative and replicable experimental speciation studies, which may be useful in a world where hybridization is becoming increasingly common due to the relocation of plants and animals by humans.
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Affiliation(s)
- R B Stelkens
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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17
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Morphological Variation in Wild Marmosets (Callithrix penicillata and C. geoffroyi) and Their Hybrids. Evol Biol 2014. [DOI: 10.1007/s11692-014-9284-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Rollinson N, Keith DM, Houde ALS, Debes PV, McBride MC, Hutchings JA. Risk assessment of inbreeding and outbreeding depression in a captive-breeding program. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:529-540. [PMID: 24476089 DOI: 10.1111/cobi.12188] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 07/07/2013] [Indexed: 06/03/2023]
Abstract
Captive-breeding programs can be implemented to preserve the genetic diversity of endangered populations such that the controlled release of captive-bred individuals into the wild may promote recovery. A common difficulty, however, is that programs are founded with limited wild broodstock, and inbreeding can become increasingly difficult to avoid with successive generations in captivity. Program managers must choose between maintaining the genetic purity of populations, at the risk of inbreeding depression, or interbreeding populations, at the risk of outbreeding depression. We evaluate these relative risks in a captive-breeding program for 3 endangered populations of Atlantic salmon (Salmo salar). In each of 2 years, we released juvenile F(1) and F(2) interpopulation hybrids, backcrosses, as well as inbred and noninbred within-population crosstypes into 9 wild streams. Juvenile size and survival was quantified in each year. Few crosstype effects were observed, but interestingly, the relative fitness consequences of inbreeding and outbreeding varied from year to year. Temporal variation in environmental quality might have driven some of these annual differences, by exacerbating the importance of maternal effects on juvenile fitness in a year of low environmental quality and by affecting the severity of inbreeding depression differently in different years. Nonetheless, inbreeding was more consistently associated with a negative effect on fitness, whereas the consequences of outbreeding were less predictable. Considering the challenges associated with a sound risk assessment in the wild and given that the effect of inbreeding on fitness is relatively predictable, we suggest that risk can be weighted more strongly in terms of the probable outcome of outbreeding. Factors such as genetic similarities between populations and the number of generations in isolation can sometimes be used to assess outbreeding risk, in lieu of experimentation.
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Affiliation(s)
- Njal Rollinson
- Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
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Vijendravarma RK, Kawecki TJ. Epistasis and maternal effects in experimental adaptation to chronic nutritional stress in Drosophila. J Evol Biol 2013; 26:2566-80. [PMID: 24118120 DOI: 10.1111/jeb.12248] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 11/30/2022]
Abstract
Based on ecological and metabolic arguments, some authors predict that adaptation to novel, harsh environments should involve alleles showing negative (diminishing return) epistasis and/or that it should be mediated in part by evolution of maternal effects. Although the first prediction has been supported in microbes, there has been little experimental support for either prediction in multicellular eukaryotes. Here we use a line-cross design to study the genetic architecture of adaptation to chronic larval malnutrition in a population of Drosophila melanogaster that evolved on an extremely nutrient-poor larval food for 84 generations. We assayed three fitness-related traits (developmental rate, adult female weight and egg-to-adult viability) under the malnutrition conditions in 14 crosses between this selected population and a nonadapted control population originally derived from the same base population. All traits showed a pattern of negative epistasis between alleles improving performance under malnutrition. Furthermore, evolutionary changes in maternal traits accounted for half of the 68% increase in viability and for the whole of 8% reduction in adult female body weight in the selected population (relative to unselected controls). These results thus support both of the above predictions and point to the importance of nonadditive effects in adaptive microevolution.
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Affiliation(s)
- R K Vijendravarma
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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