1
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Thompson KA, Brandvain Y, Coughlan JM, Delmore KE, Justen H, Linnen CR, Ortiz-Barrientos D, Rushworth CA, Schneemann H, Schumer M, Stelkens R. The Ecology of Hybrid Incompatibilities. Cold Spring Harb Perspect Biol 2024; 16:a041440. [PMID: 38151331 PMCID: PMC11368197 DOI: 10.1101/cshperspect.a041440] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Ecologically mediated selection against hybrids, caused by hybrid phenotypes fitting poorly into available niches, is typically viewed as distinct from selection caused by epistatic Dobzhansky-Muller hybrid incompatibilities. Here, we show how selection against transgressive phenotypes in hybrids manifests as incompatibility. After outlining our logic, we summarize current approaches for studying ecology-based selection on hybrids. We then quantitatively review QTL-mapping studies and find traits differing between parent taxa are typically polygenic. Next, we describe how verbal models of selection on hybrids translate to phenotypic and genetic fitness landscapes, highlighting emerging approaches for detecting polygenic incompatibilities. Finally, in a synthesis of published data, we report that trait transgression-and thus possibly extrinsic hybrid incompatibility in hybrids-escalates with the phenotypic divergence between parents. We discuss conceptual implications and conclude that studying the ecological basis of hybrid incompatibility will facilitate new discoveries about mechanisms of speciation.
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Affiliation(s)
- Ken A Thompson
- Department of Biology, Stanford University, Stanford, California 94305, USA
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA
| | - Yaniv Brandvain
- Department of Plant and Microbial Biology, University of Minnesota - Twin Cities, St Paul, Minnesota 55108, USA
| | - Jenn M Coughlan
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, Connecticut 06511, USA
| | - Kira E Delmore
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Hannah Justen
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Catherine R Linnen
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Daniel Ortiz-Barrientos
- School of Biological Sciences, The University of Queensland, Centre of Excellence for Plant Success in Nature and Agriculture, St Lucia, Queensland 4072, Australia
| | - Catherine A Rushworth
- Department of Biology and Ecology Center, Utah State University, Logan, Utah 84322, USA
| | - Hilde Schneemann
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Molly Schumer
- Department of Biology, Stanford University, Stanford, California 94305, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., Calnali 43240, Mexico
- Hanna H. Gray Fellow, Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA
| | - Rike Stelkens
- Division of Population Genetics, Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
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2
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Shibata Y, Toji N, Wang H, Go Y, Wada K. Expansion of learning capacity elicited by interspecific hybridization. SCIENCE ADVANCES 2024; 10:eadn3409. [PMID: 38896617 PMCID: PMC11186503 DOI: 10.1126/sciadv.adn3409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 05/14/2024] [Indexed: 06/21/2024]
Abstract
Learned behavior, a fundamental adaptive trait in fluctuating environments, is shaped by species-specific constraints. This phenomenon is evident in songbirds, which acquire their species-specific songs through vocal learning. To explore the neurogenetic mechanisms underlying species-specific song learning, we generated F1 hybrid songbirds by crossing Taeniopygia guttata with Aidemosyne modesta. These F1 hybrids demonstrate expanded learning capacities, adeptly mimicking songs from both parental species and other heterospecific songs more extensively than their parental counterparts. Despite the conserved size of brain regions and neuron numbers in the neural circuits for song learning and production, single-cell transcriptomics reveals distinctive transcriptional characteristics in the F1 hybrids, especially in vocal-motor projection neurons. These neurons exhibit enrichment for nonadditively expressed genes, particularly those related to ion channel activity and cell adhesion, which are associated with the degree of song learning among F1 individuals. Our findings provide insights into the emergence of altered learning capabilities through hybridization, linked to cell type-specific transcriptional changes.
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Affiliation(s)
- Yukino Shibata
- Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan
- Research Fellowship for Young Scientists of the Japan Society for the Promotion of Science, Sapporo 060-0810, Japan
| | - Noriyuki Toji
- Research Fellowship for Young Scientists of the Japan Society for the Promotion of Science, Sapporo 060-0810, Japan
- Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hongdi Wang
- Evolutionary Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0497, Japan
| | - Yasuhiro Go
- Graduate School of Information Science, University of Hyogo, Kobe 650-0047, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8585, Japan
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8585, Japan
| | - Kazuhiro Wada
- Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan
- Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
- Research and Education Center for Brain Science, Hokkaido University, Sapporo 060-8638, Japan
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3
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Toji N, Sawai A, Wang H, Ji Y, Sugioka R, Go Y, Wada K. A predisposed motor bias shapes individuality in vocal learning. Proc Natl Acad Sci U S A 2024; 121:e2308837121. [PMID: 38198530 PMCID: PMC10801888 DOI: 10.1073/pnas.2308837121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/04/2023] [Indexed: 01/12/2024] Open
Abstract
The development of individuality during learned behavior is a common trait observed across animal species; however, the underlying biological mechanisms remain understood. Similar to human speech, songbirds develop individually unique songs with species-specific traits through vocal learning. In this study, we investigate the developmental and molecular mechanisms underlying individuality in vocal learning by utilizing F1 hybrid songbirds (Taeniopygia guttata cross with Taeniopygia bichenovii), taking an integrating approach combining experimentally controlled systematic song tutoring, unbiased discriminant analysis of song features, and single-cell transcriptomics. When tutoring with songs from both parental species, F1 hybrid individuals exhibit evident diversity in their acquired songs. Approximately 30% of F1 hybrids selectively learn either song of the two parental species, while others develop merged songs that combine traits from both species. Vocal acoustic biases during vocal babbling initially appear as individual differences in songs among F1 juveniles and are maintained through the sensitive period of song vocal learning. These vocal acoustic biases emerge independently of the initial auditory experience of hearing the biological father's and passive tutored songs. We identify individual differences in transcriptional signatures in a subset of cell types, including the glutamatergic neurons projecting from the cortical vocal output nucleus to the hypoglossal nuclei, which are associated with variations of vocal acoustic features. These findings suggest that a genetically predisposed vocal motor bias serves as the initial origin of individual variation in vocal learning, influencing learning constraints and preferences.
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Affiliation(s)
- Noriyuki Toji
- Biological Sciences, Faculty of Science, Hokkaido University, Sapporo060-0810, Japan
- Research Fellow of the Japan Society for the Promotion of Science, Sapporo060-0810, Japan
| | - Azusa Sawai
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Sapporo060-0810, Japan
| | - Hongdi Wang
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Sapporo060-0810, Japan
| | - Yu Ji
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Sapporo060-0810, Japan
| | - Rintaro Sugioka
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Sapporo060-0810, Japan
| | - Yasuhiro Go
- Cognitive Genomics Research Group, Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki444-8585, Japan
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Okazaki444-8585, Japan
- Division of Behavioral Development, Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki444-8585, Japan
| | - Kazuhiro Wada
- Biological Sciences, Faculty of Science, Hokkaido University, Sapporo060-0810, Japan
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Sapporo060-0810, Japan
- Research and Education Center for Brain Science, Hokkaido University, Sapporo060-8638, Japan
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4
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Reifová R, Ament-Velásquez SL, Bourgeois Y, Coughlan J, Kulmuni J, Lipinska AP, Okude G, Stevison L, Yoshida K, Kitano J. Mechanisms of Intrinsic Postzygotic Isolation: From Traditional Genic and Chromosomal Views to Genomic and Epigenetic Perspectives. Cold Spring Harb Perspect Biol 2023; 15:a041607. [PMID: 37696577 PMCID: PMC10547394 DOI: 10.1101/cshperspect.a041607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Intrinsic postzygotic isolation typically appears as reduced viability or fertility of interspecific hybrids caused by genetic incompatibilities between diverged parental genomes. Dobzhansky-Muller interactions among individual genes, and chromosomal rearrangements causing problems with chromosome synapsis and recombination in meiosis, have both long been considered as major mechanisms behind intrinsic postzygotic isolation. Recent research has, however, suggested that the genetic basis of intrinsic postzygotic isolation can be more complex and involves, for example, overall divergence of the DNA sequence or epigenetic changes. Here, we review the mechanisms of intrinsic postzygotic isolation from genic, chromosomal, genomic, and epigenetic perspectives across diverse taxa. We provide empirical evidence for these mechanisms, discuss their importance in the speciation process, and highlight questions that remain unanswered.
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Affiliation(s)
- Radka Reifová
- Department of Zoology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | | | - Yann Bourgeois
- DIADE, University of Montpellier, CIRAD, IRD, 34090 Montpellier, France
| | - Jenn Coughlan
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, Connecticut 06520, USA
| | - Jonna Kulmuni
- Institute for Biodiversity and Ecosystem Dynamics, Department of Evolutionary and Population Biology, University of Amsterdam, 1012 Amsterdam, The Netherlands
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, 00100 Helsinki, Finland
| | - Agnieszka P Lipinska
- Department of Algal Development and Evolution, Max Planck Institute for Biology, 72076 Tuebingen, Germany
- CNRS, UMR 8227, Integrative Biology of Marine Models, Sorbonne Université, Station Biologique de Roscoff, 29680 Roscoff, France
| | - Genta Okude
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Laurie Stevison
- Department of Biological Sciences, Auburn University, Auburn, Alabama 36849, USA
| | - Kohta Yoshida
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Jun Kitano
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
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5
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Alario A, Trevino M, Justen H, Woodman CJ, Roth TC, Delmore KE. Learning and memory in hybrid migratory songbirds: cognition as a reproductive isolating barrier across seasons. Sci Rep 2023; 13:10866. [PMID: 37407574 DOI: 10.1038/s41598-023-37379-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/21/2023] [Indexed: 07/07/2023] Open
Abstract
Hybrid zones can be used to identify traits that maintain reproductive isolation and contribute to speciation. Cognitive traits may serve as post-mating reproductive isolating barriers, reducing the fitness of hybrids if, for example, misexpression occurs in hybrids and disrupts important neurological mechanisms. We tested this hypothesis in a hybrid zone between two subspecies of Swainson's thrushes (Catharus ustulatus) using two cognitive tests-an associative learning spatial test and neophobia test. We included comparisons across the sexes and seasons (spring migration and winter), testing if hybrid females performed worse than males (as per Haldane's rule) and if birds (regardless of ancestry or sex) performed better during migration, when they are building navigational maps and encountering new environments. We documented reduced cognitive abilities in hybrids, but this result was limited to males and winter. Hybrid females did not perform worse than males in either season. Although season was a significant predictor of performance, contrary to our prediction, all birds learned faster during the winter. The hypothesis that cognitive traits could serve as post-mating isolating barriers is relatively new; this is one of the first tests in a natural hybrid zone and non-food-caching species. We also provide one of the first comparisons of cognitive abilities between seasons. Future neurostructural and neurophysiological work should be used to examine mechanisms underlying our behavioral observations.
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Affiliation(s)
- Ashley Alario
- Texas A&M University, 3528 TAMU, College Station, TX, 77843, USA
| | - Marlene Trevino
- Texas A&M University, 3528 TAMU, College Station, TX, 77843, USA
| | - Hannah Justen
- Texas A&M University, 3528 TAMU, College Station, TX, 77843, USA
| | | | - Timothy C Roth
- Department of Psychology, Franklin and Marshall College, Lancaster, PA, 17603, USA
| | - Kira E Delmore
- Texas A&M University, 3528 TAMU, College Station, TX, 77843, USA.
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6
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Alexander A, Robbins MB, Holmes J, Moyle RG, Peterson AT. Limited movement of an avian hybrid zone in relation to regional variation in magnitude of climate change. Mol Ecol 2022; 31:6634-6648. [PMID: 36210655 PMCID: PMC9729445 DOI: 10.1111/mec.16727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 01/13/2023]
Abstract
Studies of natural hybrid zones can provide documentation of range shifts in response to climate change and identify loci important to reproductive isolation. Using a temporal (36-38 years) comparison of the black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee hybrid zone, we investigated movement of the western portion of the zone (western Missouri) and assessed whether loci and pathways underpinning reproductive isolation were similar to those in the eastern portion of the hybrid zone. Using 92 birds sampled along the hybrid zone transect in 2016 and 68 birds sampled between 1978 and 1980, we generated 11,669 SNPs via ddRADseq. These SNPs were used to assess movement of the hybrid zone through time and to evaluate variation in introgression among loci. We demonstrate that the interface has moved ~5 km to the northwest over the last 36-38 years, that is, at only one-fifth the rate at which the eastern portion (e.g., Pennsylvania, Ohio) of the hybrid zone has moved. Temperature trends over the last 38 years reveal that eastern areas have warmed 50% more than western areas in terms of annual mean temperature, possibly providing an explanation for the slower movement of the hybrid zone in Missouri. Our results suggest hybrid zone movement in broadly distributed species, such as chickadees, will vary between areas in response to local differences in the impacts of climate change.
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Affiliation(s)
- Alana Alexander
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.,Corresponding author.
| | - Mark B. Robbins
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA
| | - Jesse Holmes
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - Robert G. Moyle
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - A. Townsend Peterson
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
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7
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Vila-Pouca C, De Waele H, Kotrschal A. The effect of experimental hybridization on cognition and brain anatomy: Limited phenotypic variation and transgression in Poeciliidae. Evolution 2022; 76:2864-2878. [PMID: 36181444 PMCID: PMC10091962 DOI: 10.1111/evo.14644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/05/2022] [Accepted: 09/22/2022] [Indexed: 01/22/2023]
Abstract
Hybridization can promote phenotypic variation and often produces trait combinations distinct from the parental species. This increase in available variation can lead to the manifestation of functional novelty when new phenotypes bear adaptive value under the environmental conditions in which they occur. Although the role of hybridization as a driver of variation and novelty in traits linked to fitness is well recognized, it remains largely unknown whether hybridization can fuel behavioral novelty by promoting phenotypic variation in brain morphology and/or cognitive traits. To address this question, we investigated the effect of hybridization on brain anatomy, learning ability, and cognitive flexibility in first- and second-generation hybrids of two closely related fish species (Poecilia reticulata and Poecilia wingei). Overall, we found that F1 and F2 hybrids showed intermediate brain morphology and cognitive traits compared to parental groups. Moreover, as phenotypic dispersion and transgression were low for both brain and cognitive traits, we suggest that hybridization is not a strong driver of brain anatomical and cognitive diversification in these Poeciliidae. To determine the generality of this conclusion, hybridization experiments with cognitive tests need to be repeated in other families.
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Affiliation(s)
- Catarina Vila-Pouca
- Behavioural Ecology Group, Wageningen University & Research, Wageningen, 6700 HB, The Netherlands
| | - Hannah De Waele
- Behavioural Ecology Group, Wageningen University & Research, Wageningen, 6700 HB, The Netherlands
| | - Alexander Kotrschal
- Behavioural Ecology Group, Wageningen University & Research, Wageningen, 6700 HB, The Netherlands
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8
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Pouca CV, Vedder S, Kotrschal A. Hybridization may promote variation in cognitive phenotypes in experimental guppy hybrids. Am Nat 2022; 200:607-619. [DOI: 10.1086/720731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Driver R, Ferretti V, Burton ES, McCoy MW, Duerr KC, Curry RL. Spatiotemporal variation in hatching success and nestling sex ratios track rapid movement of a songbird hybrid zone. Am Nat 2022; 200:264-274. [DOI: 10.1086/720207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Anderson JL, Heard SB, Sweeney J, Pureswaran DS. Mate choice errors may contribute to slow spread of an invasive Eurasian longhorn beetle in North America. NEOBIOTA 2022. [DOI: 10.3897/neobiota.71.72843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Tetropium fuscum (Coleoptera: Cerambycidae) is a Eurasian longhorn beetle and forest pest that first became invasive to Nova Scotia, Canada around 1990. In the time since its introduction, T. fuscum has spread only about 150 km from its point of introduction. In its invasive range, T. fuscum co-exists with its congener Tetropium cinnamopterum. Although they are ecologically similar species, T. fuscum tends to infest healthier trees and has a smaller host range than T. cinnamopterum. If they successfully interbreed, this could lead to hybrid individuals that are more problematic than either parent species. On the other hand, if T. fuscum can make mating errors in the field, but is not producing hybrid offspring, then this waste of mating resources could help explain the slow spread of T. fuscum in North America. We conducted no-choice and choice mating experiments between T. fuscum and T. cinnamopterum males and females and determined that both T. fuscum and T. cinnamopterum males make mate-choice errors with heterospecific females in a laboratory setting. Our results suggest that mating errors may play a role in the slow spread of T. fuscum in North America.
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11
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Shogren EH. Cognition: 'Caching' in to find the genetic basis of spatial cognitive ability. Curr Biol 2022; 32:R37-R39. [PMID: 35015993 DOI: 10.1016/j.cub.2021.11.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Natural selection on spatial cognition requires genetic heritability of traits contributing to cognitive ability. A new study of food-caching birds demonstrates that genomic markers linked to neural development are associated with variation in cognitive phenotypes.
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Affiliation(s)
- Elsie H Shogren
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
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12
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Branch CL, Semenov GA, Wagner DN, Sonnenberg BR, Pitera AM, Bridge ES, Taylor SA, Pravosudov VV. The genetic basis of spatial cognitive variation in a food-caching bird. Curr Biol 2021; 32:210-219.e4. [PMID: 34735793 DOI: 10.1016/j.cub.2021.10.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/15/2021] [Accepted: 10/14/2021] [Indexed: 01/02/2023]
Abstract
Spatial cognition is used by most organisms to navigate their environment. Some species rely particularly heavily on specialized spatial cognition to survive, suggesting that a heritable component of cognition may be under natural selection. This idea remains largely untested outside of humans, perhaps because cognition in general is known to be strongly affected by learning and experience.1-4 We investigated the genetic basis of individual variation in spatial cognition used by non-migratory food-caching birds to recover food stores and survive harsh montane winters. Comparing the genomes of wild, free-living birds ranging from best to worst in their performance on a spatial cognitive task revealed significant associations with genes involved in neuron growth and development and hippocampal function. These results identify candidate genes associated with differences in spatial cognition and provide a critical link connecting individual variation in spatial cognition with natural selection.
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Affiliation(s)
- Carrie L Branch
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA.
| | - Georgy A Semenov
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Dominique N Wagner
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Benjamin R Sonnenberg
- Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada, Reno, NV 89557, USA
| | - Angela M Pitera
- Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada, Reno, NV 89557, USA
| | - Eli S Bridge
- Ecology and Evolutionary Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Vladimir V Pravosudov
- Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada, Reno, NV 89557, USA.
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13
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Serrato-Capuchina A, D’Agostino ERR, Peede D, Roy B, Isbell K, Wang J, Matute DR. P-elements strengthen reproductive isolation within the Drosophila simulans species complex. Evolution 2021; 75:2425-2440. [PMID: 34463356 PMCID: PMC8772388 DOI: 10.1111/evo.14319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 04/29/2021] [Accepted: 05/06/2021] [Indexed: 11/28/2022]
Abstract
Determining mechanisms that underlie reproductive isolation (RI) is key to understanding how species boundaries are maintained in nature. Transposable elements (TEs) are ubiquitous across eukaryotic genomes. However, the role of TEs in modulating the strength of RI between species is poorly understood. Several species of Drosophila have been found to harbor P-elements (PEs), yet only D. simulans is known to be currently polymorphic for their presence in wild populations. PEs can cause RI between PE-containing (P) and PE-lacking (M) lineages of the same species. However, it is unclear whether they also contribute to the magnitude of RI between species. Here, we use the simulans species complex to assess whether differences in PE status between D. simulans and its sister species, which do not harbor PEs, contribute to multiple barriers to gene flow between species. We show that crosses involving a P D. simulans father and an M mother from a sister species exhibit lower F1 female fecundity than crosses involving an M D. simulans father and an M sister-species mother. We also find that another TE, I-element, might play a minor role in determining the frequency of dysgenesis between species. Our results suggest that the presence of PEs in a species can strengthen isolation from its sister species, providing evidence that TEs can play a role in RI.
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Affiliation(s)
- Antonio Serrato-Capuchina
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Emmanuel R. R. D’Agostino
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - David Peede
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Baylee Roy
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Kristin Isbell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Jeremy Wang
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Daniel R. Matute
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
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14
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Odor preferences in hybrid chickadees: implications for reproductive isolation and asymmetric introgression. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03069-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Martin-Roy R, Nygård E, Nouhaud P, Kulmuni J. Differences in Thermal Tolerance between Parental Species Could Fuel Thermal Adaptation in Hybrid Wood Ants. Am Nat 2021; 198:278-294. [PMID: 34260873 DOI: 10.1086/715012] [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] [Indexed: 11/03/2022]
Abstract
AbstractGenetic variability is essential for adaptation and could be acquired via hybridization with a closely related lineage. We use ants to investigate thermal adaptation and the link between temperature and genetic variation arising from hybridization. We test for differences in cold and heat tolerance between Finnish Formica polyctena and Formica aquilonia wood ants and their naturally occurring hybrids. Using workers, we find that the parental individuals differ in both cold and heat tolerances and express thermal limits that reflect their global distributions. Hybrids, however, cannot combine thermal tolerance of parental species as they have the same heat tolerance as F. polyctena but not the same cold tolerance as F. aquilonia. We then focus on a single hybrid population to investigate the relationship between temperature variation and genetic variation across 16 years using reproductive individuals. On the basis of the thermal tolerance results, we expected the frequency of putative F. polyctena alleles to increase in warm years and F. aquilonia alleles to increase in cold years. We find support for this in hybrid males but not in hybrid females. These results contribute to understanding the outcomes of hybridization, which may be sex specific or depend on the environment. Furthermore, genetic variability resulting from hybridization could help hybrid wood ants cope with changing thermal conditions.
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16
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Serrato-Capuchina A, Schwochert TD, Zhang S, Roy B, Peede D, Koppelman C, Matute DR. Pure species discriminate against hybrids in the Drosophila melanogaster species subgroup. Evolution 2021; 75:1753-1774. [PMID: 34043234 DOI: 10.1111/evo.14259] [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: 03/01/2020] [Revised: 01/20/2021] [Accepted: 02/09/2021] [Indexed: 12/11/2022]
Abstract
Introgression, the exchange of alleles between species, is a common event in nature. This transfer of alleles between species must happen through fertile hybrids. Characterizing the traits that cause defects in hybrids illuminates how and when gene flow is expected to occur. Inviability and sterility are extreme examples of fitness reductions but are not the only type of defects in hybrids. Some traits specific to hybrids are more subtle but are important to determine their fitness. In this report, we study whether F1 hybrids between two species pairs of Drosophila are as attractive as the parental species. We find that in both species pairs, the sexual attractiveness of the F1 hybrids is reduced and that pure species discriminate strongly against them. We also find that the cuticular hydrocarbon (CHC) profile of the female hybrids is intermediate between the parental species. Perfuming experiments show that modifying the CHC profile of the female hybrids to resemble pure species improves their chances of mating. Our results show that behavioral discrimination against hybrids might be an important component of the persistence of species that can hybridize.
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Affiliation(s)
- Antonio Serrato-Capuchina
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Timothy D Schwochert
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Stephania Zhang
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Baylee Roy
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - David Peede
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Caleigh Koppelman
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
| | - Daniel R Matute
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599
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17
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Bennett KFP, Lim HC, Braun MJ. Sexual selection and introgression in avian hybrid zones: Spotlight on Manacus. Integr Comp Biol 2021; 61:1291-1309. [PMID: 34128981 DOI: 10.1093/icb/icab135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hybrid zones offer a window into the processes and outcomes of evolution, from species formation or fusion to genomic underpinnings of specific traits and isolating mechanisms. Sexual selection is believed to be an important factor in speciation processes, and hybrid zones present special opportunities to probe its impact. The manakins (Aves, Pipridae) are a promising group in which to study the interplay of sexual selection and natural hybridization: they show substantial variation across the family in the strength of sexual selection they experience, they readily hybridize within and between genera, and they appear to have formed hybrid species, a rare event in birds. A hybrid zone between two manakins in the genus Manacus is unusual in that plumage and behavioral traits of one species have introgressed asymmetrically into populations of the second species through positive sexual selection, then apparently stalled at a river barrier. This is one of a handful of documented examples of asymmetric sexual trait introgression with a known selective mechanism. It offers opportunities to examine reproductive isolation, introgression, plumage color evolution, and natural factors enhancing or constraining the effects of sexual selection in real time. Here, we review previous work in this system, propose new hypotheses for observed patterns, and recommend approaches to test them.
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Affiliation(s)
- Kevin F P Bennett
- Behavior, Ecology, Evolution, and Systematics Program, University of Maryland, College Park, MD, USA.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Haw Chuan Lim
- Department of Biology, George Mason University, Manassas, VA, USA.,Center for Conservation Genomics, Smithsonian Conservation Biology Institute, Washington, DC, USA
| | - Michael J Braun
- Behavior, Ecology, Evolution, and Systematics Program, University of Maryland, College Park, MD, USA.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
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18
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Animal personality adds complexity to the processes of divergence between sympatric morphs of Arctic charr. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.02.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Matute DR, Cooper BS. Comparative studies on speciation: 30 years since Coyne and Orr. Evolution 2021; 75:764-778. [PMID: 33491225 PMCID: PMC8247902 DOI: 10.1111/evo.14181] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/16/2020] [Accepted: 12/22/2020] [Indexed: 12/28/2022]
Abstract
Understanding the processes of population divergence and speciation remains a core question in evolutionary biology. For nearly a hundred years evolutionary geneticists have characterized reproductive isolation (RI) mechanisms and specific barriers to gene flow required for species formation. The seminal work of Coyne and Orr provided the first comprehensive comparative analysis of speciation. By combining phylogenetic hypotheses and species range data with estimates of genetic divergence and multiple mechanisms of RI across Drosophila, Coyne and Orr's influential meta-analyses answered fundamental questions and motivated new analyses that continue to push the field forward today. Now 30 years later, we revisit the five questions addressed by Coyne and Orr, identifying results that remain well supported and others that seem less robust with new data. We then consider the future of speciation research, with emphasis on areas where novel methods and data motivate potential progress. While the literature remains biased towards Drosophila and other model systems, we are enthusiastic about the future of the field.
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Affiliation(s)
- Daniel R. Matute
- Biology DepartmentUniversity of North CarolinaChapel HillNorth Carolina27510
| | - Brandon S. Cooper
- Division of Biological SciencesUniversity of MontanaMissoulaMontana59812
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20
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Zhang L, Hood GR, Roush AM, Shzu SA, Comerford MS, Ott JR, Egan SP. Asymmetric, but opposing reductions in immigrant viability and fecundity promote reproductive isolation among host-associated populations of an insect herbivore. Evolution 2020; 75:476-489. [PMID: 33330984 DOI: 10.1111/evo.14148] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/27/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023]
Abstract
Immigrant inviability can contribute to reproductive isolation (RI) during ecological speciation by reducing the survival of immigrants in non-native environments. However, studies that assess the fitness consequence of immigrants moving from native to non-native environments typically fail to explore the potential role of concomitant reductions in immigrant fecundity despite recent evidence suggesting its prominent role during local adaptation. Here, we evaluate the directionality and magnitude of both immigrant viability and fecundity to RI in a host-specific gall-forming wasp, Belonocnema treatae. Using reciprocal transplant experiments replicated across sites, we measure immigrant viability and fecundity by comparing differences in the incidence of gall formation (viability) and predicted the number of eggs per female (fecundity) between residents and immigrants in each of two host-plant environments. Reduced immigrant viability was found in one host environment while reduced immigrant fecundity was found in the other. Such habitat-dependent barriers resulted in asymmetric RI between populations. By surveying recent literature on local adaptation, we find that asymmetry in immigrant viability and fecundity are widespread across disparate taxa, which highlights the need to combine estimates of both common and overlooked barriers in cases of potential bi-directional gene flow to create a more comprehensive view of the evolution of RI.
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Affiliation(s)
- Linyi Zhang
- Department of BioSciences, Rice University, Houston, Texas, 77005
| | - Glen R Hood
- Department of BioSciences, Rice University, Houston, Texas, 77005.,Department of Biological Sciences, Wayne State University, Detroit, Michigan, 48202
| | - Amy M Roush
- Department of BioSciences, Rice University, Houston, Texas, 77005
| | - Shih An Shzu
- Department of BioSciences, Rice University, Houston, Texas, 77005
| | | | - James R Ott
- Population and Conservation Biology Program, Department of Biology, Texas State University, San Marcos, Texas, 78666
| | - Scott P Egan
- Department of BioSciences, Rice University, Houston, Texas, 77005
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21
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Coughlan JM, Matute DR. The importance of intrinsic postzygotic barriers throughout the speciation process. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190533. [PMID: 32654642 DOI: 10.1098/rstb.2019.0533] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Intrinsic postzygotic barriers can play an important and multifaceted role in speciation, but their contribution is often thought to be reserved to the final stages of the speciation process. Here, we review how intrinsic postzygotic barriers can contribute to speciation, and how this role may change through time. We outline three major contributions of intrinsic postzygotic barriers to speciation. (i) reduction of gene flow: intrinsic postzygotic barriers can effectively reduce gene exchange between sympatric species pairs. We discuss the factors that influence how effective incompatibilities are in limiting gene flow. (ii) early onset of species boundaries via rapid evolution: intrinsic postzygotic barriers can evolve between recently diverged populations or incipient species, thereby influencing speciation relatively early in the process. We discuss why the early origination of incompatibilities is expected under some biological models, and detail how other (and often less obvious) incompatibilities may also serve as important barriers early on in speciation. (iii) reinforcement: intrinsic postzygotic barriers can promote the evolution of subsequent reproductive isolation through processes such as reinforcement, even between relatively recently diverged species pairs. We incorporate classic and recent empirical and theoretical work to explore these three facets of intrinsic postzygotic barriers, and provide our thoughts on recent challenges and areas in the field in which progress can be made. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- Jenn M Coughlan
- Department of Biology, University of North Carolina, 120 South Road, Coker Hall, Chapel Hill, NC 27599, USA
| | - Daniel R Matute
- Department of Biology, University of North Carolina, 120 South Road, Coker Hall, Chapel Hill, NC 27599, USA
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22
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Irwin DE. Assortative Mating in Hybrid Zones Is Remarkably Ineffective in Promoting Speciation. Am Nat 2020; 195:E150-E167. [DOI: 10.1086/708529] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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23
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Wagner DN, Curry RL, Chen N, Lovette IJ, Taylor SA. Genomic regions underlying metabolic and neuronal signaling pathways are temporally consistent in a moving avian hybrid zone. Evolution 2020; 74:1498-1513. [PMID: 32243568 DOI: 10.1111/evo.13970] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 12/15/2022]
Abstract
The study of hybrid zones can provide insight into the genetic basis of species differences that are relevant for the maintenance of reproductive isolation. Hybrid zones can also provide insight into climate change, species distributions, and evolution. The hybrid zone between black-capped chickadees (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis) is shifting northward in response to increasing winter temperatures but is not increasing in width. This pattern indicates strong selection against chickadees with admixed genomes. Using high-resolution genomic data, we identified regions of the genomes that are outliers in both time points and do not introgress between the species; these regions may be involved in the maintenance of reproductive isolation. Genes involved in metabolic regulation processes were overrepresented in this dataset. Several gene ontology categories were also temporally consistent-including glutamate signaling, synaptic transmission, and catabolic processes-but the nucleotide variants leading to this pattern were not. Our results support recent findings that hybrids between black-capped and Carolina chickadees have higher basal metabolic rates than either parental species and suffer spatial memory and problem-solving deficits. Metabolic breakdown, as well as spatial memory and problem-solving, in hybrid chickadees may act as strong postzygotic isolation mechanisms in this moving hybrid zone.
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Affiliation(s)
- Dominique N Wagner
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
| | - Robert L Curry
- Department of Biology, Villanova University, Villanova, Pennsylvania, 19085
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, New York, 14627
| | - Irby J Lovette
- Cornell Lab of Ornithology, Cornell University, Ithaca, New York, 14850
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
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24
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25
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Van Huynh A, Rice AM. Conspecific olfactory preferences and interspecific divergence in odor cues in a chickadee hybrid zone. Ecol Evol 2019; 9:9671-9683. [PMID: 31534684 PMCID: PMC6745874 DOI: 10.1002/ece3.5497] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/11/2019] [Accepted: 07/06/2019] [Indexed: 12/25/2022] Open
Abstract
Understanding how mating cues promote reproductive isolation upon secondary contact is important in describing the speciation process in animals. Divergent chemical cues have been shown to act in reproductive isolation across many animal taxa. However, such cues have been overlooked in avian speciation, particularly in passerines, in favor of more traditional signals such as song and plumage. Here, we aim to test the potential for odor to act as a mate choice cue, and therefore contribute to premating reproductive isolation between the black-capped (Poecile atricapillus) and Carolina chickadee (P. carolinensis) in eastern Pennsylvania hybrid zone populations. Using gas chromatography-mass spectrometry, we document significant species differences in uropygial gland oil chemistry, especially in the ratio of ester to nonester compounds. We also show significant preferences for conspecific over heterospecific odor cues in wild chickadees using a Y-maze design. Our results suggest that odor may be an overlooked but important mating cue in these chickadees, potentially promoting premating reproductive isolation. We further discuss several promising avenues for future research in songbird olfactory communication and speciation.
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Affiliation(s)
- Alex Van Huynh
- Department of Biological SciencesLehigh UniversityBethlehemPAUSA
| | - Amber M. Rice
- Department of Biological SciencesLehigh UniversityBethlehemPAUSA
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26
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Baiz MD, Tucker PK, Cortés-Ortiz L. Multiple forms of selection shape reproductive isolation in a primate hybrid zone. Mol Ecol 2019; 28:1056-1069. [PMID: 30582763 PMCID: PMC6888905 DOI: 10.1111/mec.14966] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 10/22/2018] [Indexed: 01/02/2023]
Abstract
Speciation occurs when populations diverge and become reproductively isolated from each other. Natural selection is commonly accepted to play a large role in this process, and it has been widely assumed that reproductive isolation often results as a by-product of divergence driven by adaptation in allopatry. When such populations come into secondary contact, reinforcement can act to strengthen reproductive isolation, but the frequency and importance of this process are still unknown. Here, we explored genomic signatures of selection in allopatry and sympatry for loci associated with reproductive isolation using a natural primate hybrid zone. By analysing reduced-representation sequencing data, we quantified admixture and population structure across a howler monkey hybrid zone and examined the relationship between locus-specific differentiation and introgression. We detected extensive admixture that was mostly limited to the narrow contact zone. Loci with reduced introgression into the heterospecific genomic background (the pattern expected for loci associated with reproductive isolation due to selection against hybrids) were significantly more differentiated between allopatric parental populations than loci with neutral and increased introgression, supporting the hypothesis that reproductive isolation is a by-product of divergence in allopatry. Further, loci with reduced introgression showed greater differentiation in sympatry than in allopatry, suggesting a role for reinforcement. Thus, our results reflect multiple forms of selection that have shaped reproductive isolation in this system. We conclude that reproductive isolation may have initially been driven by divergence in allopatry, but later reinforced by divergent selection in sympatry.
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Affiliation(s)
- Marcella D Baiz
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, Michigan
| | - Priscilla K Tucker
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, Michigan
| | - Liliana Cortés-Ortiz
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, Michigan
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27
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28
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Rice AM, McQuillan MA. Maladaptive learning and memory in hybrids as a reproductive isolating barrier. Proc Biol Sci 2018; 285:20180542. [PMID: 29848649 PMCID: PMC5998094 DOI: 10.1098/rspb.2018.0542] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/10/2018] [Indexed: 01/02/2023] Open
Abstract
Selection against hybrid offspring, or postzygotic reproductive isolation, maintains species boundaries in the face of gene flow from hybridization. In this review, we propose that maladaptive learning and memory in hybrids is an important, but overlooked form of postzygotic reproductive isolation. Although a role for learning in premating isolation has been supported, whether learning deficiencies can contribute to postzygotic isolation has rarely been tested. We argue that the novel genetic combinations created by hybridization have the potential to impact learning and memory abilities through multiple possible mechanisms, and that any displacement from optima in these traits is likely to have fitness consequences. We review evidence supporting the potential for hybridization to affect learning and memory, and evidence of links between learning abilities and fitness. Finally, we suggest several avenues for future research. Given the importance of learning for fitness, especially in novel and unpredictable environments, maladaptive learning and memory in hybrids may be an increasingly important source of postzygotic reproductive isolation.
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Affiliation(s)
- Amber M Rice
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Michael A McQuillan
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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