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Porretta D, Canestrelli D. The ecological importance of hybridization. Trends Ecol Evol 2023; 38:1097-1108. [PMID: 37620217 DOI: 10.1016/j.tree.2023.07.003] [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: 03/12/2023] [Revised: 07/16/2023] [Accepted: 07/20/2023] [Indexed: 08/26/2023]
Abstract
Hybridization as an evolutionary process has been studied in depth over the past few decades. Research has focused on its role in shaping reproductive barriers, its adaptive value, and its genomic consequences. In contrast, our knowledge of ecological dimensions of hybridization is still in its infancy, despite hybridization being an inherently ecological interaction. Using examples from various organisms, we show that hybridization can affect and be affected by non-reproductive interactions, including predation, competition, parasitism, mutualism, commensalism, and organism-environment interactions, with significant implications for community structure and ecosystem functioning. However, since these dimensions of hybridization have mostly been revealed from studies designed to decipher other evolutionary processes, we argue that much of the eco-evolutionary importance of hybridization is yet to be discovered.
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Affiliation(s)
- Daniele Porretta
- Department of Environmental Biology, Sapienza University of Rome, Italy.
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2
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OUP accepted manuscript. Zool J Linn Soc 2022. [DOI: 10.1093/zoolinnean/zlac032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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3
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Ospina OE, Lemmon AR, Dye M, Zdyrski C, Holland S, Stribling D, Kortyna ML, Lemmon EM. Neurogenomic divergence during speciation by reinforcement of mating behaviors in chorus frogs (Pseudacris). BMC Genomics 2021; 22:711. [PMID: 34600496 PMCID: PMC8487493 DOI: 10.1186/s12864-021-07995-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 09/10/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Species interactions can promote mating behavior divergence, particularly when these interactions are costly due to maladaptive hybridization. Selection against hybridization can indirectly cause evolution of reproductive isolation within species, a process termed cascade reinforcement. This process can drive incipient speciation by generating divergent selection pressures among populations that interact with different species assemblages. Theoretical and empirical studies indicate that divergent selection on gene expression networks has the potential to increase reproductive isolation among populations. After identifying candidate synaptic transmission genes derived from neurophysiological studies in anurans, we test for divergence of gene expression in a system undergoing cascade reinforcement, the Upland Chorus Frog (Pseudacris feriarum). RESULTS Our analyses identified seven candidate synaptic transmission genes that have diverged between ancestral and reinforced populations of P. feriarum, including five that encode synaptic vesicle proteins. Our gene correlation network analyses revealed four genetic modules that have diverged between these populations, two possessing a significant concentration of neurotransmission enrichment terms: one for synaptic membrane components and the other for metabolism of the neurotransmitter nitric oxide. We also ascertained that a greater number of genes have diverged in expression by geography than by sex. Moreover, we found that more genes have diverged within females as compared to males between populations. Conversely, we observed no difference in the number of differentially-expressed genes within the ancestral compared to the reinforced population between the sexes. CONCLUSIONS This work is consistent with the idea that divergent selection on mating behaviors via cascade reinforcement contributed to evolution of gene expression in P. feriarum. Although our study design does not allow us to fully rule out the influence of environment and demography, the fact that more genes diverged in females than males points to a role for cascade reinforcement. Our discoveries of divergent candidate genes and gene networks related to neurotransmission support the idea that neural mechanisms of acoustic mating behaviors have diverged between populations, and agree with previous neurophysiological studies in frogs. Increasing support for this hypothesis, however, will require additional experiments under common garden conditions. Our work points to the importance of future replicated and tissue-specific studies to elucidate the relative contribution of gene expression divergence to the evolution of reproductive isolation during incipient speciation.
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Affiliation(s)
- Oscar E Ospina
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
- Present address: Department of Biostatistics and Bioinformatics, Moffitt Cancer Center, 13131 USF Magnolia Drive, Tampa, FL, 33612, USA
| | - Alan R Lemmon
- Department of Scientific Computing, Florida State University, 400 Dirac Science Library, Tallahassee, FL, 32306, USA
| | - Mysia Dye
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
| | - Christopher Zdyrski
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
- Present address: Genetics and Genomics Program, Iowa State University, 2437 Pammel Drive, Ames, IA, 50011, USA
| | - Sean Holland
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
| | - Daniel Stribling
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
- Present address: Department of Molecular Genetics and Microbiology, Genetics Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Michelle L Kortyna
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA
| | - Emily Moriarty Lemmon
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, 50011, Ames, IA, USA.
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4
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Calabrese GM, Pfennig KS. Reinforcement and the Proliferation of Species. J Hered 2021; 111:138-146. [PMID: 31850499 DOI: 10.1093/jhered/esz073] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 11/23/2019] [Indexed: 12/20/2022] Open
Abstract
Adaptive radiations are characterized by the rapid proliferation of species. Explaining how adaptive radiations occur therefore depends, in part, on identifying how populations become reproductively isolated-and ultimately become different species. Such reproductive isolation could arise when populations adapting to novel niches experience selection to avoid interbreeding and, consequently, evolve mating traits that minimize such hybridization via the process of reinforcement. Here, we highlight that a downstream consequence of reinforcement is divergence of conspecific populations, and this further divergence can instigate species proliferation. Moreover, we evaluate when reinforcement will-and will not-promote species proliferation. Finally, we discuss empirical approaches to test what role, if any, reinforcement plays in species proliferation and, consequently, in adaptive radiation. To date, reinforcement's downstream effects on species proliferation remain largely unknown and speculative. Because the ecological and evolutionary contexts in which adaptive radiations occur are conducive to reinforcement and its downstream consequences, adaptive radiations provide an ideal framework in which to evaluate reinforcement's role in diversification.
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Affiliation(s)
- Gina M Calabrese
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Karin S Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, NC
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5
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The neglected diversity of the Ochthebius fauna from Eastern Atlantic and Central and Western Mediterranean coastal rockpools (Coleoptera, Hydraenidae). ORG DIVERS EVOL 2020. [DOI: 10.1007/s13127-020-00463-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Guo K, Chen C, Liang XF, Qu YF, Ji X. Female northern grass lizards judge mates by body shape to reinforce local adaptation. Front Zool 2020; 17:22. [PMID: 32774436 PMCID: PMC7409496 DOI: 10.1186/s12983-020-00367-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/24/2020] [Indexed: 12/03/2022] Open
Abstract
Background Identifying the factors that contribute to divergence among populations in mate preferences is important for understanding of the manner in which premating reproductive isolation might arise and how this isolation may in turn contribute to the evolutionary process of population divergence. Here, we offered female northern grass lizards (Takydromus septentrionalis) a choice of males between their own population and another four populations to test whether the preferences that females display in the mating trials correlate with phenotypic adaptation to local environments, or to the neutral genetic distance measured by divergence of mitochondrial DNA sequence loci. Results Females showed a strong preference for native over foreign males. Females that mated with native versus foreign males did not differ from each other in mating latency, or copulation duration. From results of the structural equation modelling we knew that: 1) geographical distance directly contributed to genetic differentiation and environmental dissimilarity; 2) genetic differentiation and environmental dissimilarity indirectly contributed to female mate preference, largely through their effects on morphological divergence; and 3) females judged mates by body shape (appearance) and discriminated more strongly against morphologically less familiar allopatric males. Conclusions Local adaptation rather than neutral genetic distance influences female mate preference in T. septentrionalis. The tendency to avoid mating with foreign males may indicate that, in T. septentrionalis, local adaptations are more valuable than genetic novelties. Our results highlight the importance of comprehensive studies integrating ecological, molecular and behavioral approaches to understand population divergence in female mate preferences as the consequence of local adaptations.
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Affiliation(s)
- Kun Guo
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 Jiangsu China
| | - Chen Chen
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 Jiangsu China
| | - Xiao-Fang Liang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 Jiangsu China
| | - Yan-Fu Qu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 Jiangsu China
| | - Xiang Ji
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023 Jiangsu China
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7
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Shizuka D, Hudson EJ. To accept or reject heterospecific mates: behavioural decisions underlying premating isolation. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190484. [PMID: 32420857 DOI: 10.1098/rstb.2019.0484] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Premating isolation in animals involves decision-making processes that affect whether individuals accept or reject heterospecific mates. An integrative understanding of the behavioural processes underlying heterospecific acceptance can clarify the conditions under which premating isolation evolves. As an illustration, we review how Reeve's (Reeve 1989 Am. Nat. 133, 407-435. (doi:10.1086/284926)) acceptance threshold model can help make sense of patterns of premating isolation in nature. This model derives a threshold trait value for acceptance for rejection of recipients of an action (e.g. mating) based on the fitness consequences of these decisions. We show that the maintenance of partial reproductive isolation can be an outcome of optimal acceptance thresholds, even in the face of reinforcement. We also use this model to clarify how the composition of multispecies communities can shape premating isolation. The acceptance threshold model can also be viewed as the behavioural underpinning of reproductive character displacement and cascading reinforcement. Finally, we highlight potential limitations of the acceptance threshold model with respect to investigating the role of sexual selection in speciation, and we propose that integration of behavioural models in speciation research will help us gain a full picture of the mechanisms underlying premating isolation. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- Daizaburo Shizuka
- School of Biological Sciences, University of Nebraska-Lincoln, 402 Manter Hall, Lincoln, NE 68588-0118, USA
| | - Emily J Hudson
- School of Biological Sciences, University of Nebraska-Lincoln, 402 Manter Hall, Lincoln, NE 68588-0118, USA.,Department of Biological Sciences, Vanderbilt University, Box 351634 Station B, Nashville, TN 37235-1634, USA
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8
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Ancient hybridization and mtDNA introgression behind current paternal leakage and heteroplasmy in hybrid zones. Sci Rep 2019; 9:19177. [PMID: 31844110 PMCID: PMC6914795 DOI: 10.1038/s41598-019-55764-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 11/29/2019] [Indexed: 01/18/2023] Open
Abstract
Hybridization between heterospecific individuals has been documented as playing a direct role in promoting paternal leakage and mitochondrial heteroplasmy in both natural populations and laboratory conditions, by relaxing the egg-sperm recognition mechanisms. Here, we tested the hypothesis that hybridization can lead to mtDNA heteroplasmy also indirectly via mtDNA introgression. By using a phylogenetic approach, we showed in two reproductively isolated beetle species, Ochthebius quadricollis and O. urbanelliae, that past mtDNA introgression occurred between them in sympatric populations. Then, by developing a multiplex allele-specific PCR assay, we showed the presence of heteroplasmic individuals and argue that their origin was through paternal leakage following mating between mtDNA-introgressed and pure conspecific individuals. Our results highlight that mtDNA introgression can contribute to promote paternal leakage, generating genetic novelty in a way that has been overlooked to date. Furthermore, they highlight that the frequency and distribution of mtDNA heteroplasmy can be deeply underestimated in natural populations, as i) the commonly used PCR-Sanger sequencing approach can fail to detect mitochondrial heteroplasmy, and ii) specific studies aimed at searching for it in populations where mtDNA-introgressed and pure individuals co-occur remain scarce, despite the fact that mtDNA introgression has been widely documented in several taxa and populations.
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Castillo DM, Moyle LC. Conspecific sperm precedence is reinforced, but postcopulatory sexual selection weakened, in sympatric populations of Drosophila. Proc Biol Sci 2019; 286:20182535. [PMID: 30900533 PMCID: PMC6452082 DOI: 10.1098/rspb.2018.2535] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/06/2019] [Indexed: 12/21/2022] Open
Abstract
Sexual selection can accelerate speciation by driving the evolution of reproductive isolation, but forces driving speciation could also reciprocally feedback on sexual selection. This might be particularly important in the context of 'reinforcement', where selection acts directly to increase prezygotic barriers to reduce the cost of heterospecific matings. Using assays of sperm competition within and between two sister species, we show a signature of reinforcement where these species interact: populations of Drosophila pseudoobscura that co-occur with sister species D. persimilis have an elevated ability to outcompete heterospecific sperm, consistent with selection for increased postcopulatory isolation. We also find these D. pseudoobscura populations have decreased sperm competitive ability against conspecifics, reducing the opportunity for sexual selection within these populations. Our findings demonstrate that direct selection to increase reproductive isolation against other species can compromise the efficacy of sexual selection within species, a collateral effect of reproductive traits responding to heterospecific interactions.
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Affiliation(s)
- Dean M. Castillo
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, USA
| | - Leonie C. Moyle
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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10
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Mastrantonio V, Latrofa MS, Porretta D, Lia RP, Parisi A, Iatta R, Dantas-Torres F, Otranto D, Urbanelli S. Paternal leakage and mtDNA heteroplasmy in Rhipicephalus spp. ticks. Sci Rep 2019; 9:1460. [PMID: 30728407 PMCID: PMC6365633 DOI: 10.1038/s41598-018-38001-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 12/13/2018] [Indexed: 12/27/2022] Open
Abstract
Paternal leakage of mitochondrial DNA (mtDNA) and heteroplasmy have been recently described in several animal species. In arthropods, by searching in the Scopus database, we found only 23 documented cases of paternal leakage. Therefore, although arthropods represent a large fraction of animal biodiversity, this phenomenon has been investigated only in a paucity of species in this phylum, thus preventing a reliable estimate of its frequency. Here, we investigated the occurrence of paternal leakage and mtDNA heteroplasmy in ticks belonging to one of the most significant tick species complexes, the so-called Rhipicephalus sanguineussensu lato. By developing a multiplex allele-specific PCR assay targeting a fragment of the 12S rRNA ribosomal region of the mtDNA, we showed the occurrence of paternal leakage and mtDNA heteroplasmy in R. sanguineuss.l. ticks originated from experimental crosses, as well as in individuals collected from the field. Our results add a new evidence of paternal leakage in arthropods and document for the first time this phenomenon in ticks. Furthermore, they suggest the importance of using allele-specific assays when searching for paternal leakage and/or heteroplasmy, as standard sequencing methods may fail to detect the rare mtDNA molecules.
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Affiliation(s)
| | | | - Daniele Porretta
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
| | - Riccardo Paolo Lia
- Department of Veterinary Medicine, University of Bari, 70010, Valenzano, Bari, Italy
| | - Antonio Parisi
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Contrada S. Pietro Piturno, 70017 Putignano, Bari, Italy
| | - Roberta Iatta
- Department of Veterinary Medicine, University of Bari, 70010, Valenzano, Bari, Italy
| | - Filipe Dantas-Torres
- Department of Veterinary Medicine, University of Bari, 70010, Valenzano, Bari, Italy.,Department of Immunology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, 50740465, Recife, Pernambuco, Brazil
| | - Domenico Otranto
- Department of Veterinary Medicine, University of Bari, 70010, Valenzano, Bari, Italy
| | - Sandra Urbanelli
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy
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11
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Moran RL, Fuller RC. Male-driven reproductive and agonistic character displacement in darters and its implications for speciation in allopatry. Curr Zool 2018; 64:101-113. [PMID: 29492043 PMCID: PMC5809036 DOI: 10.1093/cz/zox069] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [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: 12/23/2022] Open
Abstract
Selection against hybridization can cause mating traits to diverge between species in sympatry via reproductive character displacement (RCD). Additionally, selection against interspecific fighting can cause aggressive traits to diverge between sympatric species via agonistic character displacement (ACD). By directly affecting conspecific recognition traits, RCD and ACD between species can also incidentally cause divergence in mating and fighting traits among populations within a species [termed cascade RCD (CRCD) and cascade ACD]. Here, we demonstrate patterns consistent with male-driven RCD and ACD in 2 groups of darters (orangethroat darter clade Ceasia and rainbow darter Etheostoma caeruleum). In both groups, males that occur in sympatry (between Ceasia and E. caeruleum) have higher levels of preference for mating and fighting with conspecifics over heterospecifics than do males from allopatry. This is consistent with RCD and ACD. We also found patterns consistent with CRCD and cascade ACD among species of Ceasia. Ceasia males that are sympatric to E. caeruleum (but allopatric to one another) also have heightened preferences for mating and fighting with conspecific versus heterospecific Ceasia. In contrast, Ceasia males that are allopatric to E. caeruleum readily mate and fight with heterospecific Ceasia. We suggest that RCD and ACD between Ceasia and E. caeruleum has incidentally led to divergence in mating and fighting traits among Ceasia species. This study is unique in that male preferences evolve via both RCD (male preference for conspecific females) and ACD (male preference to fight conspecific males) which leads to subsequent divergence among allopatric lineages.
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Affiliation(s)
- Rachel L Moran
- School of Integrative Biology, University of Illinois, Champaign, IL 61820, USA
| | - Rebecca C Fuller
- School of Integrative Biology, University of Illinois, Champaign, IL 61820, USA
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12
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Lemmon EM, Juenger TE. Geographic variation in hybridization across a reinforcement contact zone of chorus frogs ( Pseudacris). Ecol Evol 2017; 7:9485-9502. [PMID: 29187984 PMCID: PMC5696400 DOI: 10.1002/ece3.3443] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 08/02/2017] [Accepted: 08/31/2017] [Indexed: 12/11/2022] Open
Abstract
Reinforcement contact zones, which are secondary contact zones where species are diverging in reproductive behaviors due to selection against hybridization, represent natural laboratories for studying speciation‐in‐action. Here, we examined replicate localities across the entire reinforcement contact zone between North American chorus frogs Pseudacris feriarum and P. nigrita to investigate geographic variation in hybridization frequencies and to assess whether reinforcement may have contributed to increased genetic divergence within species. Previous work indicated these species have undergone reproductive character displacement (RCD) in male acoustic signals and female preferences due to reinforcement. We also examined acoustic signal variation across the contact zone to assess whether signal characteristics reliably predict hybrid index and to elucidate whether the degree of RCD predicts hybridization rate. Using microsatellites, mitochondrial sequences, and acoustic signal information from >1,000 individuals across >50 localities and ten sympatric focal regions, we demonstrate: (1) hybridization occurs and (2) varies substantially across the geographic range of the contact zone, (3) hybridization is asymmetric and in the direction predicted from observed patterns of asymmetric RCD, (4) in one species, genetic distance is higher between conspecific localities where one or both have been reinforced than between nonreinforced localities, after controlling for geographic distance, (5) acoustic signal characters strongly predict hybrid index, and (6) the degree of RCD does not strongly predict admixture levels. By showing that hybridization occurs in all sympatric localities, this study provides the fifth and final line of evidence that reproductive character displacement is due to reinforcement in the chorus frog contact zone. Furthermore, this work suggests that the dual action of cascade reinforcement and partial geographic isolation is promoting genetic diversification within one of the reinforced species.
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Affiliation(s)
| | - Thomas E Juenger
- Department of Integrative Biology University of Texas, Austin Austin TX USA
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13
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Rice AM, McQuillan MA, Seears HA, Warren JA. Population differentiation at a regional scale in spadefoot toads: contributions of distance and divergent selective environments. Curr Zool 2016; 62:193-206. [PMID: 29491906 PMCID: PMC5804232 DOI: 10.1093/cz/zow010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/16/2016] [Indexed: 11/12/2022] Open
Abstract
The causes of population differentiation can provide insight into the origins of early barriers to gene flow. Two key drivers of population differentiation are geographic distance and local adaptation to divergent selective environments. When reproductive isolation arises because some populations of a species are under selection to avoid hybridization while others are not, population differentiation and even speciation can result. Spadefoot toad populations Spea multiplicata that are sympatric with a congener have undergone reinforcement. This reinforcement has resulted not only in increased reproductive isolation from the congener, but also in the evolution of reproductive isolation from nearby and distant conspecific allopatric populations. We used multiple approaches to evaluate the contributions of geographic distance and divergent selective environments to population structure across this regional scale in S. multiplicata, based on genotypes from six nuclear microsatellite markers. We compared groups of populations varying in both geographic location and in the presence of a congener. Hierarchical F-statistics and results from cluster analyses and discriminant analyses of principal components all indicate that geographic distance is the stronger contributor to genetic differentiation among S. multiplicata populations at a regional scale. However, we found evidence that adaptation to divergent selective environments also contributes to population structure. Our findings highlight how variation in the balance of evolutionary forces acting across a species' range can lead to variation in the relative contributions of geographic distance and local adaptation to population differentiation across different spatial scales.
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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
| | - Heidi A Seears
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Joanna A Warren
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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14
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Castillo DM, Gibson AK, Moyle LC. Assortative mating and self-fertilization differ in their contributions to reinforcement, cascade speciation, and diversification. Curr Zool 2016; 62:169-181. [PMID: 29491904 PMCID: PMC5804227 DOI: 10.1093/cz/zow004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 01/07/2016] [Indexed: 11/14/2022] Open
Abstract
Cascade speciation and reinforcement can evolve rapidly when traits are pleiotropic and act as both signal/cue in nonrandom mating. Here, we examine the contribution of two key traits-assortative mating and self-fertilization-to reinforcement and (by extension) cascade speciation. First, using a population genetic model of reinforcement we find that both assortative mating and self-fertilization can make independent contributions to increased reproductive isolation, consistent with reinforcement. Self-fertilization primarily evolves due to its 2-fold transmission advantage when inbreeding depression (d) is lower (d < 0.45) but evolves as a function of the cost of hybridization under higher inbreeding depression (0.45 < d < 0.48). When both traits can evolve simultaneously, increased self-fertilization often prohibits the evolution of assortative mating. We infer that, under specific conditions, mating system transitions are more likely to lead to increased reproductive isolation and initiate cascade speciation, than assortative mating. Based on the results of our simulations, we hypothesized that transitions to self-fertilization could contribute to clade-wide diversification if reinforcement or cascade speciation is common. We tested this hypothesis with comparative data from two different groups. Consistent with our hypothesis, there was a trend towards uniparental reproduction being associated with increased diversification rate in the Nematode phylum. For the plant genus Mimulus, however, self-fertilization was associated with reduced diversification. Reinforcement driving speciation via transitions to self-fertilization might be short lived or unsustainable across macroevolutionary scales in some systems (some plants), but not others (such as nematodes), potentially due to differences in susceptibility to inbreeding depression and/or the ability to transition between reproductive modes.
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Affiliation(s)
- Dean M. Castillo
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
| | - Amanda K. Gibson
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
| | - Leonie C. Moyle
- Department of Biology, 1001 East Third Street, Indiana University, Bloomington, IN 47405, USA
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15
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Pfennig KS. Reinforcement as an initiator of population divergence and speciation. Curr Zool 2016; 62:145-154. [PMID: 29491902 PMCID: PMC5804236 DOI: 10.1093/cz/zow033] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 12/29/2015] [Indexed: 02/02/2023] Open
Abstract
When hybridization results in reduced fitness, natural selection is expected to favor the evolution of traits that minimize the likelihood of hybridizing in the first place. This process, termed reinforcement (or, more generally, reproductive character displacement), thereby contributes to the evolution of enhanced reproductive isolation between hybridizing groups. By enhancing reproductive isolation in this way, reinforcement plays an important role in the final stages of speciation. However, reinforcement can also contribute to the early stages of speciation. Specifically, because selection to avoid hybridization occurs only in sympatric populations, the unfolding of reinforcement can lead to the evolution of traits in sympatric populations that reduce reproduction between conspecifics in sympatry versus those in allopatry. Thus, reinforcement between species can lead to reproductive isolation—and possibly speciation—between populations in sympatry versus those in allopatry or among different sympatric populations. Here, I describe how this process can occur, the conditions under which it is most likely to occur, and the empirical data needed to evaluate the hypothesis that reinforcement can initiate speciation.
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Affiliation(s)
- Karin S Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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Yukilevich R, Aoki F. Is cascade reinforcement likely when sympatric and allopatric populations exchange migrants? Curr Zool 2016; 62:155-167. [PMID: 29491903 PMCID: PMC5804230 DOI: 10.1093/cz/zow007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 12/18/2015] [Indexed: 11/13/2022] Open
Abstract
When partially reproductively isolated species come back into secondary contact, these taxa may diverge in mating preferences and sexual cues to avoid maladaptive hybridization, a process known as reinforcement. This phenomenon often leads to reproductive character displacement (RCD) between sympatric and allopatric populations of reinforcing species that differ in their exposure to hybridization. Recent discussions have reinvigorated the idea that RCD may give rise to additional speciation between conspecific sympatric and allopatric populations, dubbing the concept "cascade reinforcement." Despite some empirical studies supporting cascade reinforcement, we still know very little about the conditions for its evolution. In the present article, we address this question by developing an individual-based population genetic model that explicitly simulates cascade reinforcement when one of the hybridizing species is split into sympatric and allopatric populations. Our results show that when sympatric and allopatric populations reside in the same environment and only differ in their exposure to maladaptive hybridization, migration between them generally inhibits the evolution of cascade by spreading the reinforcement alleles from sympatry into allopatry and erasing RCD. Under these conditions, cascade reinforcement only evolved when migration rate between sympatric and allopatric populations was very low. This indicates that stabilizing sexual selection in allopatry is generally ineffective in preventing the spread of reinforcement alleles. Only when sympatric and allopatric populations experienced divergent ecological selection did cascade reinforcement evolve in the presence of substantial migration. These predictions clarify the conditions for cascade reinforcement and facilitate our understanding of existing cases in nature.
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Affiliation(s)
| | - Fumio Aoki
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794
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Humphreys DP, Rundle HD, Dyer KA. Patterns of reproductive isolation in the Drosophila subquinaria complex: can reinforced premating isolation cascade to other species? Curr Zool 2016; 62:183-191. [PMID: 29491905 PMCID: PMC5804228 DOI: 10.1093/cz/zow005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/17/2015] [Indexed: 12/29/2022] Open
Abstract
The reinforcement of premating barriers due to reduced hybrid fitness in sympatry may cause secondary sexual isolation within a species as a by-product. Consistent with this, in the fly Drosophila subquinaria, females that are sympatric with D. recens mate at very low rates not only with D. recens, but also with conspecific D. subquinaria males from allopatry. Here, we ask if these effects of reinforcement cascade more broadly to affect sexual isolation with other closely related species. We assay reproductive isolation of these species with D. transversa and find that choosy D. subquinaria females from the region sympatric with D. recens discriminate strongly against male D. transversa, whereas D. subquinaria from the allopatric region do not. This increased sexual isolation cannot be explained by natural selection to avoid mating with this species, as they are allopatric in geographic range and we do not identify any intrinsic postzygotic isolation between D. subquinaria and D. transversa. Variation in epicuticular hydrocarbons, which are used as mating signals in D. subquinaria, follow patterns of premating isolation: D. transversa and allopatric D. subquinaria are most similar to each other and differ from sympatric D. subquinaria, and those of D. recens are distinct from the other two species. We suggest that the secondary effects of reinforcement may cascade to strengthen reproductive isolation with other species that were not a target of selection. These effects may enhance the divergence that occurs in allopatry to help explain why some species are already sexually isolated upon secondary contact.
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Affiliation(s)
- Devon P Humphreys
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Howard D Rundle
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5; Canada
| | - Kelly A Dyer
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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Pfennig KS, Rice AM. Reinforcement generates reproductive isolation between neighbouring conspecific populations of spadefoot toads. Proc Biol Sci 2015; 281:20140949. [PMID: 24990680 DOI: 10.1098/rspb.2014.0949] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reproductive character displacement is the adaptive evolution of traits that minimize deleterious reproductive interactions between species. When arising from selection to avoid hybridization, this process is referred to as reinforcement. Reproductive character displacement generates divergence not only between interacting species, but also between conspecific populations that are sympatric with heterospecifics versus those that are allopatric. Consequently, such conspecific populations can become reproductively isolated. We compared female mate preferences in, and evaluated gene flow between, neighbouring populations of spadefoot toads that did and did not occur with heterospecifics (mixed- and pure-species populations, respectively). We found that in mixed-species populations females significantly preferred conspecifics. Such females also tended to prefer a conspecific call character that was dissimilar from heterospecifics. By contrast, females from pure-species populations did not discriminate conspecific from heterospecific calls. They also preferred a more exaggerated conspecific call character that resembles heterospecific males. Moreover, gene flow was significantly reduced between mixed- and pure-species population types. Thus, character displacement (and, more specifically, reinforcement) may initiate reproductive isolation between conspecific populations that differ in interactions with heterospecifics.
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Affiliation(s)
- Karin S Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
| | - Amber M Rice
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA
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19
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Kozak GM, Roland G, Rankhorn C, Falater A, Berdan EL, Fuller RC. Behavioral Isolation due to Cascade Reinforcement in Lucania Killifish. Am Nat 2015; 185:491-506. [PMID: 25811084 DOI: 10.1086/680023] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Reinforcement occurs when behavioral isolation is strengthened between species due to selection against hybridization in sympatry. Mate preferences and their target traits may change in sympatry as a consequence of reinforcement. This can potentially generate further behavioral isolation within species if sympatric populations evolve extreme preferences or traits that cause them to reject individuals from foreign populations as mates or be rejected as mates. This process is known as cascade reinforcement. We measured behavioral isolation between sympatric and allopatric populations of Lucania killifish to determine whether isolation evolves due to reinforcement between species and whether reinforcement affects preferences within species, consistent with the cascade reinforcement hypothesis. We measured mate preferences in both sexes between species (Lucania parva vs. Lucania goodei) and within species (among populations of L. parva). Between species, both male and female preferences for conspecifics were highest in sympatric populations. Within species, L. parva females from sympatric populations preferred their own native males over foreign males. Allopatric L. parva females and all L. parva males showed no preferences within species. Within species, behavioral isolation showed no association with ecological variables, such as salinity. Thus, reinforcement is a primary factor generating behavioral isolation in Lucania killifish, creating strong preferences in both sexes among species and leading to cascade reinforcement of female mate preference within species.
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Affiliation(s)
- Genevieve M Kozak
- Department of Animal Biology, University of Illinois, Champaign, Illinois 61820
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20
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Urbanelli S, Porretta D, Mastrantonio V, Bellini R, Pieraccini G, Romoli R, Crasta G, Nascetti G. Hybridization, natural selection, and evolution of reproductive isolation: a 25-years survey of an artificial sympatric area between two mosquito sibling species of the Aedes mariae complex. Evolution 2014; 68:3030-8. [PMID: 25041755 DOI: 10.1111/evo.12490] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 06/15/2014] [Indexed: 11/28/2022]
Abstract
Natural selection can act against maladaptive hybridization between co-occurring divergent populations leading to evolution of reproductive isolation among them. A critical unanswered question about this process that provides a basis for the theory of speciation by reinforcement, is whether natural selection can cause hybridization rates to evolve to zero. Here, we investigated this issue in two sibling mosquitoes species, Aedes mariae and Aedes zammitii, that show postmating reproductive isolation (F1 males sterile) and partial premating isolation (different height of mating swarms) that could be reinforced by natural selection against hybridization. In 1986, we created an artificial sympatric area between the two species and sampled about 20,000 individuals over the following 25 years. Between 1986 and 2011, the composition of mating swarms and the hybridization rate between the two species were investigated across time in the sympatric area. Our results showed that A. mariae and A. zammitii have not completed reproductive isolation since their first contact in the artificial sympatric area. We have discussed the relative role of factors such as time of contact, gene flow, strength of natural selection, and biological mechanisms causing prezygotic isolation to explain the observed results.
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Affiliation(s)
- Sandra Urbanelli
- Department of Environmental Biology, University of Rome "La Sapienza", Rome, Italy.
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