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McLaughlin JF, Brock KM, Gates I, Pethkar A, Piattoni M, Rossi A, Lipshutz SE. Multivariate Models of Animal Sex: Breaking Binaries Leads to a Better Understanding of Ecology and Evolution. Integr Comp Biol 2023; 63:891-906. [PMID: 37156506 PMCID: PMC10563656 DOI: 10.1093/icb/icad027] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/28/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023] Open
Abstract
"Sex" is often used to describe a suite of phenotypic and genotypic traits of an organism related to reproduction. However, these traits-gamete type, chromosomal inheritance, physiology, morphology, behavior, etc.-are not necessarily coupled, and the rhetorical collapse of variation into a single term elides much of the complexity inherent in sexual phenotypes. We argue that consideration of "sex" as a constructed category operating at multiple biological levels opens up new avenues for inquiry in our study of biological variation. We apply this framework to three case studies that illustrate the diversity of sex variation, from decoupling sexual phenotypes to the evolutionary and ecological consequences of intrasexual polymorphisms. We argue that instead of assuming binary sex in these systems, some may be better categorized as multivariate and nonbinary. Finally, we conduct a meta-analysis of terms used to describe diversity in sexual phenotypes in the scientific literature to highlight how a multivariate model of sex can clarify, rather than cloud, studies of sexual diversity within and across species. We argue that such an expanded framework of "sex" better equips us to understand evolutionary processes, and that as biologists, it is incumbent upon us to push back against misunderstandings of the biology of sexual phenotypes that enact harm on marginalized communities.
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Affiliation(s)
- J F McLaughlin
- Department of Environmental Science, Policy, and Management, College of Natural Resources, University of California, Berkeley, CA 94720, USA
| | - Kinsey M Brock
- Department of Environmental Science, Policy, and Management, College of Natural Resources, University of California, Berkeley, CA 94720, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Isabella Gates
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, USA
| | - Anisha Pethkar
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, USA
| | - Marcus Piattoni
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, USA
| | - Alexis Rossi
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, USA
| | - Sara E Lipshutz
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, USA
- Department of Biology, Duke University, Durham, NC 27708, USA
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McLaughlin JF, Aguilar C, Bernstein JM, Navia-Gine WG, Cueto-Aparicio LE, Alarcon AC, Alarcon BD, Collier R, Takyar A, Vong SJ, López-Chong OG, Driver R, Loaiza JR, De León LF, Saltonstall K, Lipshutz SE, Arcila D, Brock KM, Miller MJ. Comparative phylogeography reveals widespread cryptic diversity driven by ecology in Panamanian birds. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023. [PMID: 36993716 DOI: 10.1101/2023.01.26.525769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
UNLABELLED Widespread species often harbor unrecognized genetic diversity, and investigating the factors associated with such cryptic variation can help us better understand the forces driving diversification. Here, we identify potential cryptic species based on a comprehensive dataset of COI mitochondrial DNA barcodes from 2,333 individual Panamanian birds across 429 species, representing 391 (59%) of the 659 resident landbird species of the country, as well as opportunistically sampled waterbirds. We complement this dataset with additional publicly available mitochondrial loci, such as ND2 and cytochrome b, obtained from whole mitochondrial genomes from 20 taxa. Using barcode identification numbers (BINs), we find putative cryptic species in 19% of landbird species, highlighting hidden diversity in the relatively well-described avifauna of Panama. Whereas some of these mitochondrial divergence events corresponded with recognized geographic features that likely isolated populations, such as the Cordillera Central highlands, the majority (74%) of lowland splits were between eastern and western populations. The timing of these splits are not temporally coincident across taxa, suggesting that historical events, such as the formation of the Isthmus of Panama and Pleistocene climatic cycles, were not the primary drivers of cryptic diversification. Rather, we observed that forest species, understory species, insectivores, and strongly territorial species-all traits associated with lower dispersal ability-were all more likely to have multiple BINs in Panama, suggesting strong ecological associations with cryptic divergence. Additionally, hand-wing index, a proxy for dispersal capability, was significantly lower in species with multiple BINs, indicating that dispersal ability plays an important role in generating diversity in Neotropical birds. Together, these results underscore the need for evolutionary studies of tropical bird communities to consider ecological factors along with geographic explanations, and that even in areas with well-known avifauna, avian diversity may be substantially underestimated. LAY SUMMARY - What factors are common among bird species with cryptic diversity in Panama? What role do geography, ecology, phylogeographic history, and other factors play in generating bird diversity?- 19% of widely-sampled bird species form two or more distinct DNA barcode clades, suggesting widespread unrecognized diversity.- Traits associated with reduced dispersal ability, such as use of forest understory, high territoriality, low hand-wing index, and insectivory, were more common in taxa with cryptic diversity. Filogeografía comparada revela amplia diversidad críptica causada por la ecología en las aves de Panamá. RESUMEN Especies extendidas frecuentemente tiene diversidad genética no reconocida, y investigando los factores asociados con esta variación críptica puede ayudarnos a entender las fuerzas que impulsan la diversificación. Aquí, identificamos especies crípticas potenciales basadas en un conjunto de datos de códigos de barras de ADN mitocondrial de 2,333 individuos de aves de Panama en 429 especies, representando 391 (59%) de las 659 especies de aves terrestres residentes del país, además de algunas aves acuáticas muestreada de manera oportunista. Adicionalmente, complementamos estos datos con secuencias mitocondriales disponibles públicamente de otros loci, tal como ND2 o citocroma b, obtenidos de los genomas mitocondriales completos de 20 taxones. Utilizando los números de identificación de código de barras (en ingles: BINs), un sistema taxonómico numérico que proporcina una estimación imparcial de la diversidad potencial a nivel de especie, encontramos especies crípticas putativas en 19% de las especies de aves terrestres, lo que destaca la diversidad oculta en la avifauna bien descrita de Panamá. Aunque algunos de estos eventos de divergencia conciden con características geográficas que probablemente aislaron las poblaciones, la mayoría (74%) de la divergencia en las tierras bajas se encuentra entre las poblaciones orientales y occidentales. El tiempo de esta divergencia no coincidió entre los taxones, sugiriendo que eventos históricos tales como la formación del Istmo de Panamá y los ciclos climáticos del pleistoceno, no fueron los principales impulsores de la especiación. En cambio, observamos asociaciones fuertes entre las características ecológicas y la divergencia mitocondriale: las especies del bosque, sotobosque, con una dieta insectívora, y con territorialidad fuerte mostraton múltiple BINs probables. Adicionalmente, el índice mano-ala, que está asociado a la capacidad de dispersión, fue significativamente menor en las especies con BINs multiples, sugiriendo que la capacidad de dispersión tiene un rol importamente en la generación de la diversidad de las aves neotropicales. Estos resultos demonstran la necesidad de que estudios evolutivos de las comunidades de aves tropicales consideren los factores ecológicos en conjunto con las explicaciones geográficos. Palabras clave: biodiversidad tropical, biogeografía, códigos de barras, dispersión, especies crípticas.
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Zhang S, Wu Z, Ma D, Zhai J, Han X, Jiang Z, Liu S, Xu J, Jiao P, Li Z. Chromosome-scale assemblies of the male and female Populus euphratica genomes reveal the molecular basis of sex determination and sexual dimorphism. Commun Biol 2022; 5:1186. [PMCID: PMC9636151 DOI: 10.1038/s42003-022-04145-7] [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: 05/08/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Reference-quality genomes of both sexes are essential for studying sex determination and sex-chromosome evolution, as their gene contents and expression profiles differ. Here, we present independent chromosome-level genome assemblies for the female (XX) and male (XY) genomes of desert poplar (Populus euphratica), resolving a 22.7-Mb X and 24.8-Mb Y chromosome. We also identified a relatively complete 761-kb sex-linked region (SLR) in the peritelomeric region on chromosome 14 (Y). Within the SLR, recombination around the partial repeats for the feminizing factor ARR17 (ARABIDOPSIS RESPONSE REGULATOR 17) was potentially suppressed by flanking palindromic arms and the dense accumulation of retrotransposons. The inverted small segments S1 and S2 of ARR17 exhibited relaxed selective pressure and triggered sex determination by generating 24-nt small interfering RNAs that induce male-specific hyper-methylation at the promoter of the autosomal targeted ARR17. We also detected two male-specific fusion genes encoding proteins with NB-ARC domains at the breakpoint region of an inversion in the SLR that may be responsible for the observed sexual dimorphism in immune responses. Our results show that the SLR appears to follow proposed evolutionary dynamics for sex chromosomes and advance our understanding of sex determination and the evolution of sex chromosomes in Populus. Reference-quality genomes of both sexes of the dioecious tree species, Populus euphratica, provide further insight into the evolution of Populus sex chromosomes and highlight male-specific fusion genes that may contribute to sexual dimorphism.
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Affiliation(s)
- Shanhe Zhang
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhihua Wu
- grid.453534.00000 0001 2219 2654College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 China
| | - De Ma
- grid.410753.4Novogene Bioinformatics Institute, Beijing, 100083 China
| | - Juntuan Zhai
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Xiaoli Han
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhenbo Jiang
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Shuo Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, College of Life Sciences, South-Central Minzu University, Wuhan, 430074 China
| | - Jingdong Xu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, College of Life Sciences, South-Central Minzu University, Wuhan, 430074 China
| | - Peipei Jiao
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
| | - Zhijun Li
- grid.443240.50000 0004 1760 4679College of Life Sciences and Technology, Tarim University/Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Xinjiang Production & Construction Corps/Research Center of Populus Euphratica, Aral, 843300 China
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Prichard MR, Grogan KE, Merritt JR, Root J, Maney DL. Allele-specific cis-regulatory methylation of the gene for vasoactive intestinal peptide in white-throated sparrows. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12831. [PMID: 36220804 PMCID: PMC9744568 DOI: 10.1111/gbb.12831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 08/05/2022] [Accepted: 08/31/2022] [Indexed: 11/06/2022]
Abstract
White-throated sparrows (Zonotrichia albicollis) offer a unique opportunity to connect genotype with behavioral phenotype. In this species, a rearrangement of the second chromosome is linked with territorial aggression; birds with a copy of this "supergene" rearrangement are more aggressive than those without it. The supergene has captured the gene VIP, which encodes vasoactive intestinal peptide, a neuromodulator that drives aggression in other songbirds. In white-throated sparrows, VIP expression is higher in the anterior hypothalamus of birds with the supergene than those without it, and expression of VIP in this region predicts the level of territorial aggression regardless of genotype. Here, we aimed to identify epigenetic mechanisms that could contribute to differential expression of VIP both in breeding adults, which exhibit morph differences in territorial aggression, and in nestlings, before territorial behavior develops. We extracted and bisulfite-converted DNA from samples of the hypothalamus in wild-caught adults and nestlings and used high-throughput sequencing to measure DNA methylation of a region upstream of the VIP start site. We found that the allele inside the supergene was less methylated than the alternative allele in both adults and nestlings. The differential methylation was attributed primarily to CpG sites that were shared between the alleles, not to polymorphic sites, which suggests that epigenetic regulation is occurring independently of the genetic differentiation within the supergene. This work represents an initial step toward understanding how epigenetic differentiation inside chromosomal inversions leads to the development of alternative behavioral phenotypes.
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Affiliation(s)
| | - Kathleen E. Grogan
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Departments of Anthropology and BiologyUniversity of CincinnatiCincinnatiOhioUSA
| | - Jennifer R. Merritt
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Zuckerman Mind Brain Behavior Institute and Department of Ecology, Evolution and Environmental BiologyColumbia UniversityNew YorkNew YorkUSA
| | - Jessica Root
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
- Present address:
Department of Pharmacology and Chemical BiologyEmory UniversityAtlantaGeorgiaUSA
| | - Donna L. Maney
- Department of PsychologyEmory UniversityAtlantaGeorgiaUSA
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Jeong H, Baran NM, Sun D, Chatterjee P, Layman TS, Balakrishnan CN, Maney DL, Yi SV. Dynamic molecular evolution of a supergene with suppressed recombination in white-throated sparrows. eLife 2022; 11:e79387. [PMID: 36040313 PMCID: PMC9427109 DOI: 10.7554/elife.79387] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/17/2022] [Indexed: 12/11/2022] Open
Abstract
In white-throated sparrows, two alternative morphs differing in plumage and behavior segregate with a large chromosomal rearrangement. As with sex chromosomes such as the mammalian Y, the rearranged version of chromosome two (ZAL2m) is in a near-constant state of heterozygosity, offering opportunities to investigate both degenerative and selective processes during the early evolutionary stages of 'supergenes.' Here, we generated, synthesized, and analyzed extensive genome-scale data to better understand the forces shaping the evolution of the ZAL2 and ZAL2m chromosomes in this species. We found that features of ZAL2m are consistent with substantially reduced recombination and low levels of degeneration. We also found evidence that selective sweeps took place both on ZAL2m and its standard counterpart, ZAL2, after the rearrangement event. Signatures of positive selection were associated with allelic bias in gene expression, suggesting that antagonistic selection has operated on gene regulation. Finally, we discovered a region exhibiting long-range haplotypes inside the rearrangement on ZAL2m. These haplotypes appear to have been maintained by balancing selection, retaining genetic diversity within the supergene. Together, our analyses illuminate mechanisms contributing to the evolution of a young chromosomal polymorphism, revealing complex selective processes acting concurrently with genetic degeneration to drive the evolution of supergenes.
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Affiliation(s)
- Hyeonsoo Jeong
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Nicole M Baran
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
- Department of Psychology, Emory UniversityAtlantaUnited States
- Department of Ecology, Evolution, Marine Biology, University of California, Santa BarbaraSanta BarbaraUnited States
| | - Dan Sun
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
- Department of Medicine Huddinge, Karolinska InstitutetStockholmSweden
| | - Paramita Chatterjee
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Thomas S Layman
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | | | - Donna L Maney
- Department of Psychology, Emory UniversityAtlantaUnited States
| | - Soojin V Yi
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
- Department of Ecology, Evolution, Marine Biology, University of California, Santa BarbaraSanta BarbaraUnited States
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Maney DL, Küpper C. Supergenes on steroids. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200507. [PMID: 35634926 PMCID: PMC9149793 DOI: 10.1098/rstb.2020.0507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/18/2021] [Indexed: 07/20/2023] Open
Abstract
At the birth of supergenes, the genomic landscape is dramatically re-organized leading to pronounced differences in phenotypes and increased intrasexual diversity. Two of the best-studied supergenes in vertebrates are arguably the inversion polymorphisms on chromosomes 2 and 11 in the white-throated sparrow (Zonotrichia albicollis) and the ruff (Calidris pugnax), respectively. In both species, regions of suppressed recombination determine plumage coloration and social behavioural phenotypes. Despite the apparent lack of gene overlap between these two supergenes, in both cases the alternative phenotypes seem to be driven largely by alterations in steroid hormone pathways. Here, we explore the interplay between genomic architecture and steroid-related genes. Due to the highly pleiotropic effects of steroid-related genes and their universal involvement in social behaviour and transcriptomic regulation, processes favouring their linkage are likely to have substantial effects on the evolution of behavioural phenotypes, individual fitness, and life-history strategies. We propose that inversion-related differentiation and regulatory changes in steroid-related genes lie at the core of phenotypic differentiation in both of these interesting species. This article is part of the theme issue 'Genetic basis of adaptation and speciation: from loci to causative mutations'.
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Affiliation(s)
- Donna L. Maney
- Department of Psychology, Emory University, Atlanta, GA 30322, USA
| | - Clemens Küpper
- Research Group of Behavioural Genetics and Evolutionary Ecology, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany
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Schlinger BA, Chiver I. Behavioral Sex Differences and Hormonal Control in a Bird with an Elaborate Courtship Display. Integr Comp Biol 2021; 61:1319-1328. [PMID: 33885763 DOI: 10.1093/icb/icab033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Gonadal hormones can activate performance of reproductive behavior in adult animals, but also organize sex-specific neural circuits developmentally. Few studies have examined the hormonal basis of sex differences in the performance of elaborate, physically complex and energetic male courtship displays. Here we describe our studies over more than 20 years examining sex difference and hormonal control of courtship in Golden-collared manakins (Manacus vitellinus) of Panamaian rainforests. Our recent studies of birds studied in an artificial "lek" in a rainforest aviary provide many new insights. Wild and captive males and females differ markedly in their performance of male-typical behaviors. Testosterone (T) treatment augments performance of virtually all of these behaviors in juvenile males with low levels of circulating T. By contrast, T-treatment of females (with low circulating T) either failed to activate some behaviors or activated male behaviors weakly or strongly. These results are discussed within a framework of our appreciation for hormonal vs genetic basis for sex differences in behavior with speculation about the neural mechanisms producing these patterns of hormonal activation.
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Affiliation(s)
- Barney A Schlinger
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095.,Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095.,Smithsonian Tropical Research Institute, Panama City, Panama
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Gutiérrez-Valencia J, Hughes PW, Berdan EL, Slotte T. The Genomic Architecture and Evolutionary Fates of Supergenes. Genome Biol Evol 2021; 13:6178796. [PMID: 33739390 PMCID: PMC8160319 DOI: 10.1093/gbe/evab057] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2021] [Indexed: 12/25/2022] Open
Abstract
Supergenes are genomic regions containing sets of tightly linked loci that control multi-trait phenotypic polymorphisms under balancing selection. Recent advances in genomics have uncovered significant variation in both the genomic architecture as well as the mode of origin of supergenes across diverse organismal systems. Although the role of genomic architecture for the origin of supergenes has been much discussed, differences in the genomic architecture also subsequently affect the evolutionary trajectory of supergenes and the rate of degeneration of supergene haplotypes. In this review, we synthesize recent genomic work and historical models of supergene evolution, highlighting how the genomic architecture of supergenes affects their evolutionary fate. We discuss how recent findings on classic supergenes involved in governing ant colony social form, mimicry in butterflies, and heterostyly in flowering plants relate to theoretical expectations. Furthermore, we use forward simulations to demonstrate that differences in genomic architecture affect the degeneration of supergenes. Finally, we discuss implications of the evolution of supergene haplotypes for the long-term fate of balanced polymorphisms governed by supergenes.
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Affiliation(s)
- Juanita Gutiérrez-Valencia
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - P William Hughes
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Emma L Berdan
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
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Sun D, Layman TS, Jeong H, Chatterjee P, Grogan K, Merritt JR, Maney DL, Yi SV. Genome-wide variation in DNA methylation linked to developmental stage and chromosomal suppression of recombination in white-throated sparrows. Mol Ecol 2021; 30:3453-3467. [PMID: 33421223 PMCID: PMC8359194 DOI: 10.1111/mec.15793] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 11/25/2020] [Accepted: 01/04/2021] [Indexed: 12/14/2022]
Abstract
Much of our knowledge on regulatory impacts of DNA methylation has come from laboratory‐bred model organisms, which may not exhibit the full extent of variation found in wild populations. Here, we investigated naturally‐occurring variation in DNA methylation in a wild avian species, the white‐throated sparrow (Zonotrichia albicollis). This species offers exceptional opportunities for studying the link between genetic differentiation and phenotypic traits because of a nonrecombining chromosome pair linked to both plumage and behavioural phenotypes. Using novel single‐nucleotide resolution methylation maps and gene expression data, we show that DNA methylation and the expression of DNA methyltransferases are significantly higher in adults than in nestlings. Genes for which DNA methylation varied between nestlings and adults were implicated in development and cell differentiation and were located throughout the genome. In contrast, differential methylation between plumage morphs was concentrated in the nonrecombining chromosome pair. Interestingly, a large number of CpGs on the nonrecombining chromosome, localized to transposable elements, have undergone dramatic loss of DNA methylation since the split of the ZAL2 and ZAL2m chromosomes. Changes in methylation predicted changes in gene expression for both chromosomes. In summary, we demonstrate changes in genome‐wide DNA methylation that are associated with development and with specific functional categories of genes in white‐throated sparrows. Moreover, we observe substantial DNA methylation reprogramming associated with the suppression of recombination, with implications for genome integrity and gene expression divergence. These results offer an unprecedented view of ongoing epigenetic reprogramming in a wild population. see also the Perspective by Jordan A. Anderson and Jenny Tung.
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Affiliation(s)
- Dan Sun
- School of Biological Sciences, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
| | - Thomas S Layman
- School of Biological Sciences, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Hyeonsoo Jeong
- School of Biological Sciences, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Paramita Chatterjee
- School of Biological Sciences, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Kathleen Grogan
- Department of Psychology, Emory University, Atlanta, GA, USA
| | | | - Donna L Maney
- Department of Psychology, Emory University, Atlanta, GA, USA
| | - Soojin V Yi
- School of Biological Sciences, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
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