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Nali RC, Zamudio KR, Prado CPA. Hybridization despite elaborate courtship behavior and female choice in Neotropical tree frogs. Integr Zool 2023; 18:208-224. [PMID: 35041294 DOI: 10.1111/1749-4877.12628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanisms of hybridization can be elucidated by analyzing genotypes as well as phenotypes that could act as premating barriers, as the reproductive interactions among heterospecifics can alter the evolutionary history of species. In frogs, hybrids typically occur among species that reproduce explosively (in dense aggregations) with few opportunities for mate selection but are rare in species with elaborate courtship behaviors that may prevent erroneous mating. Using 21 microsatellite markers, we examined hybridization in the prolonged-breeding tree frogs Bokermannohyla ibitiguara and B. sazimai sampled within a contact zone in the Brazilian savanna (72 tadpoles; 74 adults). We also compared acoustic and morphological data. We confirmed both parental species genetically; STRUCTURE results confirmed 14 hybrids, 11 of which were second-generation according to NEWHYBRIDS, all with intermediate values of genetic dissimilarities compared to the parentals. Morphological and acoustic analyses revealed that hybrids showed variable but not necessarily intermediate phenotypes. Moreover, 2 hybrids exhibited call types different from parentals. The reproduction of B. ibitiguara involves territorial and aggressive males, elaborate courtships with acoustic and tactile stimuli, choosy females, and opportunistic strategies. Our study uncovers a rare case of viable hybridization among closely related frogs with such a combination of complex courtship behaviors and mate choice. We discuss the likely directionality and mechanisms behind this phenomenon, and highlight the importance of investigating hybridization even in species that show elaborate reproduction and female choice to advance our understanding of animal diversification.
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Affiliation(s)
- Renato C Nali
- Programa de Pós-Graduação em Ecologia, Evolução e Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil.,Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA.,Department of Integrative Biology, University of Texas, Austin, Texas, USA
| | - Cynthia P A Prado
- Programa de Pós-Graduação em Ecologia, Evolução e Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil.,Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, São Paulo, Brazil
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2
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Zeeman AN, Smallegange IM, Steel EB, Groot AT, Stewart KA. Toward an understanding of the chemical ecology of alternative reproductive tactics in the bulb mite (Rhizoglyphus robini). BMC Ecol Evol 2022; 22:5. [PMID: 34998364 PMCID: PMC8742560 DOI: 10.1186/s12862-021-01956-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 12/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Under strong sexual selection, certain species evolve distinct intrasexual, alternative reproductive tactics (ARTs). In many cases, ARTs can be viewed as environmentally-cued threshold traits, such that ARTs coexist if their relative fitness alternates over the environmental cue gradient. Surprisingly, the chemical ecology of ARTs has been underexplored in this context. To our knowledge, no prior study has directly quantified pheromone production for ARTs in a male-polymorphic species. Here, we used the bulb mite-in which males are either armed fighters that kill conspecifics, or unarmed scramblers (which have occasionally been observed to induce mating behavior in other males)-as a model system to gain insight into the role of pheromones in the evolutionary maintenance of ARTs. Given that scramblers forgo investment into weaponry, we tested whether scramblers produce higher quantities of the putative female sex-pheromone α-acaridial than fighters, which would improve the fitness of the scrambler phenotype through female mimicry by allowing avoidance of aggression from competitors. To this end, we sampled mites from a rich and a poor nutritional environment and quantified their production of α-acaridial through gas chromatography analysis. RESULTS We found a positive relationship between pheromone production and body size, but males exhibited a steeper slope in pheromone production with increasing size than females. Females exhibited a higher average pheromone production than males. We found no significant difference in slope of pheromone production over body size between fighters and scramblers. However, scramblers reached larger body sizes and higher pheromone production than fighters, providing some evidence for a potential female mimic strategy adopted by large scramblers. Pheromone production was significantly higher in mites from the rich nutritional environment than the poor environment. CONCLUSION Further elucidation of pheromone functionality in bulb mites, and additional inter- and intrasexual comparisons of pheromone profiles are needed to determine if the observed intersexual and intrasexual differences in pheromone production are adaptive, if they are a by-product of allometric scaling, or diet-mediated pheromone production under weak selection. We argue chemical ecology offers a novel perspective for research on ARTs and other complex life-history traits.
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Affiliation(s)
- Adam N Zeeman
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Isabel M Smallegange
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Emily Burdfield Steel
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Astrid T Groot
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Kathryn A Stewart
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
- Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands.
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3
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Cairns NA, Cicchino AS, Stewart KA, Austin JD, Lougheed SC. Cytonuclear discordance, reticulation and cryptic diversity in one of North America's most common frogs. Mol Phylogenet Evol 2020; 156:107042. [PMID: 33338660 DOI: 10.1016/j.ympev.2020.107042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 10/28/2020] [Accepted: 12/11/2020] [Indexed: 10/22/2022]
Abstract
Complicated phylogenetic histories benefit from diverse sources of inference. Pseudacris crucifer (spring peeper) spans most of eastern North America and comprises six mtDNA lineages that form multiple contact zones. The putative Miocene or early Pliocene origins of the oldest lineages within Pseudacris crucifer imply sufficient time for species-level divergence. To understand why this species appears unified while congeners have radiated, we analyze and compare male advertisement calls, mitochondrial, and nuclear markers and speak to the complex processes that have potentially influenced its contemporary patterns. We find extensive geographic and topological mitonuclear discordance, with three nuclear lineages containing 6 more-structured mtDNA lineages, and nuclear introgression at some contact zones. Male advertisement call differentiation is incongruent with the genetic structure as only one lineage appears differentiated. Occupying the Interior Highlands of the central United States, this Western lineage also has the most concordant mitochondrial and nuclear geographic patterns. Based on our findings we suggest that the antiquity of common ancestors was not as important as the maintenance of allopatry in the divergence in P. crucifer genetic lineages. We use multiple lines of evidence to generate hypotheses of isolation, reticulation, and discordance within this species and to expand our understanding of the early stages of speciation.
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Affiliation(s)
- N A Cairns
- Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada.
| | - A S Cicchino
- Department of Biology, Colorado State University, Fort Collins, CO 80523-1878, United States.
| | - K A Stewart
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 904 Science Park, 1098XH Amsterdam, North Holland, Netherlands
| | - J D Austin
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, United States.
| | - S C Lougheed
- Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada.
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Barreto SB, Knowles LL, Affonso PRADM, Batalha-Filho H. Riverscape properties contribute to the origin and structure of a hybrid zone in a Neotropical freshwater fish. J Evol Biol 2020; 33:1530-1542. [PMID: 32862491 DOI: 10.1111/jeb.13689] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 11/28/2022]
Abstract
Understanding the structure of hybrid zones provides valuable insights about species boundaries and speciation, such as the evolution of barriers to gene flow and the strength of selection. In river networks, studying evolutionary processes in hybrid zones can be especially challenging, given the influence of past and current river properties along with biological species-specific traits. Here, we suggest that a natural hybrid zone between two divergent lineages of the sexually dimorphic Neotropical fish Nematocharax venustus was probably established by secondary contact as a result of a river capture event between the Contas and Pardo river basins. This putative river capture is supported by hydrogeological evidence of elbows of capture, wind gaps and geological faults. The morphological (colour pattern) and genetic (mtDNA and RADseq) variation reveal a clinal transition between parental lineages along the main river, with predominance of F2 hybrids at the centre of the hybrid zone, absence of early generation backcrosses and different levels of hybridization in the tributaries. We highlight that different sources of information are crucial for understanding how the riverscape spatial history influences the connectivity between and within river systems and, consequently, the dynamics of gene flow between freshwater lineages/species.
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Affiliation(s)
| | - L Lacey Knowles
- Department of Ecology and Evolutionary Biology, Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
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Stewart KA, Taylor SA. Leveraging eDNA to expand the study of hybrid zones. Mol Ecol 2020; 29:2768-2776. [PMID: 32557920 PMCID: PMC7496085 DOI: 10.1111/mec.15514] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 04/18/2020] [Accepted: 06/05/2020] [Indexed: 02/06/2023]
Abstract
Hybrid zones are important windows into ecological and evolutionary processes. Our understanding of the significance and prevalence of hybridization in nature has expanded with the generation and analysis of genome‐spanning data sets. That said, most hybridization research still has restricted temporal and spatial resolution, which limits our ability to draw broad conclusions about evolutionary and conservation related outcomes. Here, we argue that rapidly advancing environmental DNA (eDNA) methodology could be adopted for studies of hybrid zones to increase temporal sampling (contemporary and historical), refine and geographically expand sampling density, and collect data for taxa that are difficult to directly sample. Genomic data in the environment offer the potential for near real‐time biological tracking of hybrid zones, and eDNA provides broad, but as yet untapped, potential to address eco‐evolutionary questions.
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Affiliation(s)
- Kathryn A Stewart
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Scott A Taylor
- Department Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, USA
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Abbott J, Rios‐Cardenas O, Morris MR. Insights from intralocus tactical conflict: adaptive states, interactions with ecology and population divergence. OIKOS 2019. [DOI: 10.1111/oik.06264] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Jessica Abbott
- Section for Evolutionary Ecology, Dept of Biology, Univ. Of Lund Sölvegatan 37 SE‐223 62 Lund Swede
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Pierson TW, Deitloff J, Sessions SK, Kozak KH, Fitzpatrick BM. Morphological Polymorphism Associated with Alternative Reproductive Tactics in a Plethodontid Salamander. Am Nat 2019; 193:608-618. [PMID: 30912974 DOI: 10.1086/702251] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Understanding polymorphism is a central problem in evolution and ecology, and alternative reproductive tactics (ARTs) provide compelling examples for studying the origin and maintenance of behavioral and morphological variation. Much attention has been given to examples where "parasitic" individuals exploit the reproductive investment of "bourgeois" individuals, but some ARTs are instead maintained by environmental heterogeneity, with alternative tactics exhibiting differential fitness in discontinuous reproductive niches. We use genomic, behavioral, karyological, and field observational data to demonstrate one such example in plethodontid salamanders. These ARTs ("searching" and "guarding" males) are associated with different reproductive niches and, unlike most other examples in amphibians, demonstrate substantial morphological differences and inflexibility within a reproductive season. Evidence suggests the existence of these ARTs within three putative species in the two-lined salamander (Eurycea bislineata) species complex, with other members of this clade fixed for one of the two tactics. We highlight directions for future research in this system, including the relationship between these ARTs and parental care.
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8
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Stewart KA, Draaijer R, Kolasa MR, Smallegange IM. The role of genetic diversity in the evolution and maintenance of environmentally-cued, male alternative reproductive tactics. BMC Evol Biol 2019; 19:58. [PMID: 30777004 PMCID: PMC6379956 DOI: 10.1186/s12862-019-1385-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/12/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alternative reproductive tactics (ARTs) are taxonomically pervasive strategies adopted by individuals to maximize reproductive success within populations. Even for conditionally-dependent traits, consensus postulates most ARTs involve both genetic and environmental interactions (GEIs), but to date, quantifying genetic variation underlying the threshold disposing an individual to switch phenotypes in response to an environmental cue has been a difficult undertaking. Our study aims to investigate the origins and maintenance of ARTs within environmentally disparate populations of the microscopic bulb mite, Rhizoglyphus robini, that express 'fighter' and 'scrambler' male morphs mediated by a complex combination of environmental and genetic factors. RESULTS Using never-before-published individual genetic profiling, we found all individuals across populations are highly inbred with the exception of scrambler males in stressed environments. In fact within the poor environment, scrambler males and females showed no significant difference in genetic differentiation (Fst) compared to all other comparisons, and although fighters were highly divergent from the rest of the population in both poor or rich environments (e.g., Fst, STRUCTURE), fighters demonstrated approximately three times less genetic divergence from the population in poor environments. AMOVA analyses further corroborated significant genetic differentiation across subpopulations, between morphs and sexes, and among subpopulations within each environment. CONCLUSION Our study provides new insights into the origin of ARTs in the bulb mite, highlighting the importance of GEIs: genetic correlations, epistatic interactions, and sex-specific inbreeding depression across environmental stressors. Asymmetric reproductive output, coupled with the purging of highly inbred individuals during environmental oscillations, also facilitates genetic variation within populations, despite evidence for strong directional selection. This cryptic genetic variation also conceivably facilitates stable population persistence even in the face of spatially or temporally unstable environmental challenges. Ultimately, understanding the genetic context that maintains thresholds, even for conditionally-dependent ARTs, will enhance our understanding of within population variation and our ability to predict responses to selection.
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Affiliation(s)
- K A Stewart
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands.
| | - R Draaijer
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands
| | - M R Kolasa
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17 St., 31-016, Krakow, Poland
| | - I M Smallegange
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94240, 1090 GE, Amsterdam, The Netherlands
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Becher C, Gumm JM. The roles of inter- and intra-sexual selection in behavioral isolation between native and invasive pupfishes. Curr Zool 2018; 64:135-144. [PMID: 29492046 PMCID: PMC5809032 DOI: 10.1093/cz/zox068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 11/18/2017] [Indexed: 11/14/2022] Open
Abstract
Male-male competition and female mate choice may both play important roles in driving and maintaining reproductive isolation between species. When previously allopatric species come into secondary contact with each other due to introductions, they provide an opportunity to evaluate the identity and strength of reproductive isolating mechanisms. If reproductive isolation is not maintained, hybridization may occur. We examined how reproductive isolating mechanisms mediate hybridization between endemic populations of the Red River pupfish Cyprinodon rubrofluviatilis and the recently introduced sheepshead minnow C. variegatus. In lab-based dominance trials, males of both species won the same number of competitions. However, male C. rubrofluviatilis that won competitions were more aggressive than C. variegatus winners, and more aggression was needed to win against competitor C. variagatus than allopatric C. rubrofluviatilis. Duration of fights also differed based on the relatedness of the competitor. In dichotomous mate choice trials, there were no conspecific or heterospecific preferences expressed by females of either species. Our findings that male-male aggression differs between closely and distantly related groups, but female choice does not suggest that male-male competition may be the more likely mechanism to impede gene flow in this system.
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Affiliation(s)
- Cory Becher
- Department of Biology, Stephen F. Austin State University, Nacogdoches, TX 75962, USA and.,Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Jennifer M Gumm
- Department of Biology, Stephen F. Austin State University, Nacogdoches, TX 75962, USA and
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