1
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Wang D, Abbott J, Brenninger FA, Klein K, Nava-Bolaños A, Yong L, Richter XYL. Female alternative reproductive tactics: diversity and drivers. Trends Ecol Evol 2024:S0169-5347(24)00140-X. [PMID: 38955568 DOI: 10.1016/j.tree.2024.06.002] [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: 01/19/2024] [Revised: 06/04/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024]
Abstract
It is often argued that anisogamy causes alternative reproductive tactics (ARTs) to be more common in males than females. We challenge this view by pointing out logical flaws in the argument. We then review recent work on the diversity of female ARTs, listing several understudied types such as solitary versus communal breeding and facultative parthenogenesis. We highlight an important difference between male and female ARTs that caused female ARTs to be overlooked: male ARTs tend to focus on successful fertilization, whereas female ARTs occur at many stages of reproduction and often form complex networks of decision points. We propose to study correlated female ARTs as a whole to better understand their drivers and eco-evolutionary dynamics.
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Affiliation(s)
- Daiping Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang, 100101 Beijing, China; University of the Chinese Academy of Sciences, 100049 Beijing, China
| | - Jessica Abbott
- Department of Biology, Lund University, 22362 Lund, Sweden
| | - Franziska A Brenninger
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Kora Klein
- Faculty of Biology, Johannes Gutenberg-Universität Mainz, 55122 Mainz, Germany
| | - Angela Nava-Bolaños
- Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Campus Juriquilla, Universidad Nacional Autónoma de México, Boulevard Juriquilla, Jurica La Mesa, Juriquilla, 76230 Querétaro, México
| | - Lengxob Yong
- Marine Resources Research Institute, South Carolina Department of Natural Resources, Charleston, SC 29412, USA
| | - Xiang-Yi Li Richter
- Institute of Ecology and Evolution, Baltzerstrasse 6, University of Bern, 3012 Bern, Switzerland.
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2
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Cornetti L, Fields PD, Du Pasquier L, Ebert D. Long-term balancing selection for pathogen resistance maintains trans-species polymorphisms in a planktonic crustacean. Nat Commun 2024; 15:5333. [PMID: 38909039 PMCID: PMC11193740 DOI: 10.1038/s41467-024-49726-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 06/18/2024] [Indexed: 06/24/2024] Open
Abstract
Balancing selection is an evolutionary process that maintains genetic polymorphisms at selected loci and strongly reduces the likelihood of allele fixation. When allelic polymorphisms that predate speciation events are maintained independently in the resulting lineages, a pattern of trans-species polymorphisms may occur. Trans-species polymorphisms have been identified for loci related to mating systems and the MHC, but they are generally rare. Trans-species polymorphisms in disease loci are believed to be a consequence of long-term host-parasite coevolution by balancing selection, the so-called Red Queen dynamics. Here we scan the genomes of three crustaceans with a divergence of over 15 million years and identify 11 genes containing identical-by-descent trans-species polymorphisms with the same polymorphisms in all three species. Four of these genes display molecular footprints of balancing selection and have a function related to immunity. Three of them are located in or close to loci involved in resistance to a virulent bacterial pathogen, Pasteuria, with which the Daphnia host is known to coevolve. This provides rare evidence of trans-species polymorphisms for loci known to be functionally relevant in interactions with a widespread and highly specific parasite. These findings support the theory that specific antagonistic coevolution is able to maintain genetic diversity over millions of years.
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Affiliation(s)
- Luca Cornetti
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
- Syngenta Crop Protection AG, Stein, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Louis Du Pasquier
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.
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3
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MacPherson B, Scott R, Gras R. Using individual-based modelling to investigate a pluralistic explanation for the prevalence of sexual reproduction in animal species. Ecol Modell 2023. [DOI: 10.1016/j.ecolmodel.2022.110191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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4
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Dinges ZM, Lively CM. Asymmetric density-dependent competition does not contribute to the maintenance of sex in a mixed population of sexual and asexual Potamopyrgus antipodarum. J Evol Biol 2022; 35:1012-1019. [PMID: 35647767 DOI: 10.1111/jeb.14030] [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: 01/20/2022] [Revised: 04/28/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022]
Abstract
Asexual reproduction is expected to have a twofold reproductive advantage over sexual reproduction, owing to the cost of producing males in sexual subpopulations. The persistence of sexual females, thus, requires an advantage to sexual reproduction, at least periodically. Here, we tested the hypothesis that asexual females are more sensitive to limited resources. Under this idea, fluctuations in the availability of resources (per capita) could periodically favour sexual females when resources become limited. We combined sexual and asexual freshwater snails (Potamopyrgus antipodarum) together in nylon mesh enclosures at three different densities in an outdoor mesocosm. After 1 month, we counted the brood size of fertile female snails. We found that fecundity declined significantly with increasing density. However, sexual females did not produce more offspring than asexual females at any of the experimental densities. Our results, thus, suggest that the cost of sexual reproduction in P. antipodarum is not ameliorated by periods of intense resource competition.
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Affiliation(s)
- Zoe M Dinges
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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5
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Parasitic manipulation or by-product of infection: an experimental approach using trematode-infected snails. J Helminthol 2022; 96:e2. [PMID: 34991736 DOI: 10.1017/s0022149x21000699] [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: 11/08/2022]
Abstract
Natural selection should favour parasite genotypes that manipulate hosts in ways that enhance parasite fitness. However, it is also possible that the effects of infection are not adaptive. Here we experimentally examined the phenotypic effects of infection in a snail-trematode system. These trematodes (Atriophallophorus winterbourni) produce larval cysts within the snail's shell (Potamopyrgus antipodarum); hence the internal shell volume determines the total number of parasite cysts produced. Infected snails in the field tend to be larger than uninfected snails, suggesting the hypothesis that parasites manipulate host growth so as to increase the space available for trematode reproduction. To test the hypothesis, we exposed juvenile snails to trematode eggs. Snails were then left to grow for about one year in 800-l outdoor mesocosms. We found that uninfected males were smaller than uninfected females (sexual dimorphism). We also found that infection did not affect the shell dimensions of males. However, infected females were smaller than uninfected females. Hence, infection stunts the growth of females, and (contrary to the hypothesis) it results in a smaller internal volume for larval cysts. Finally, infected females resembled males in size and shape, suggesting the possibility that parasitic castration prevents the normal development of females. These results thus indicate that the parasite is not manipulating the growth of infected hosts so as to increase the number of larval cysts, although alternative adaptive explanations are possible.
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6
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MacPherson B, Scott R, Gras R. Using individual-based modelling to investigate the possible role that the Red Tooth effect plays in maintaining sexual reproduction. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2021.109730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Fredericksen M, Ameline C, Krebs M, Hüssy B, Fields PD, Andras JP, Ebert D. Infection phenotypes of a coevolving parasite are highly diverse, structured, and specific. Evolution 2021; 75:2540-2554. [PMID: 34431523 PMCID: PMC9290032 DOI: 10.1111/evo.14323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 06/30/2021] [Accepted: 07/26/2021] [Indexed: 12/27/2022]
Abstract
Understanding how diversity is maintained in natural populations is a major goal of evolutionary biology. In coevolving hosts and parasites, negative frequency-dependent selection is one mechanism predicted to maintain genetic variation. While much is known about host diversity, parasite diversity remains understudied in coevolutionary research. Here, we survey natural diversity in a bacterial parasite by characterizing infection phenotypes for over 50 isolates in relation to 12 genotypes of their host, Daphnia magna. We find striking phenotypic variation among parasite isolates, and we discover the parasite can infect its host through at least five different attachment sites. Variation in attachment success at each site is explained to varying degrees by host and parasite genotypes. A spatial correlation analysis showed that infectivity of different isolates does not correlate with geographic distance, meaning isolates from widespread populations are equally able to infect the host. Overall, our results reveal that infection phenotypes of this parasite are highly diverse. Our results are consistent with the prediction that under Red Queen coevolutionary dynamics both the host and the parasite should show high genetic diversity for traits of functional importance in their interactions.
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Affiliation(s)
- Maridel Fredericksen
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
| | - Camille Ameline
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
| | - Michelle Krebs
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
| | - Benjamin Hüssy
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
| | - Jason P Andras
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland.,Department of Biological Sciences, Clapp Laboratory, Mount Holyoke College, South Hadley, Massachusetts
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, CH-4051, Switzerland
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8
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Gowler CD, Rogalski MA, Shaw CL, Hunsberger KK, Duffy MA. Density, parasitism, and sexual reproduction are strongly correlated in lake Daphnia populations. Ecol Evol 2021; 11:10446-10456. [PMID: 34367587 PMCID: PMC8328469 DOI: 10.1002/ece3.7847] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 01/06/2023] Open
Abstract
Many organisms can reproduce both asexually and sexually. For cyclical parthenogens, periods of asexual reproduction are punctuated by bouts of sexual reproduction, and the shift from asexual to sexual reproduction has large impacts on fitness and population dynamics. We studied populations of Daphnia dentifera to determine the amount of investment in sexual reproduction as well as the factors associated with variation in investment in sex. To do so, we tracked host density, infections by nine different parasites, and sexual reproduction in 15 lake populations of D. dentifera for 3 years. Sexual reproduction was seasonal, with male and ephippial female production beginning as early as late September and generally increasing through November. However, there was substantial variation in the prevalence of sexual individuals across populations, with some populations remaining entirely asexual throughout the study period and others shifting almost entirely to sexual females and males. We found strong relationships between density, prevalence of infection, parasite species richness, and sexual reproduction in these populations. However, strong collinearity between density, parasitism, and sexual reproduction means that further work will be required to disentangle the causal mechanisms underlying these relationships.
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Affiliation(s)
- Camden D. Gowler
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
| | - Mary A. Rogalski
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
- Biology and Environmental StudiesBowdoin CollegeBrunswickMEUSA
| | - Clara L. Shaw
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPAUSA
| | | | - Meghan A. Duffy
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
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9
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Selection for Plastic, Pathogen-Inducible Recombination in a Red Queen Model with Diploid Antagonists. Pathogens 2021; 10:pathogens10070898. [PMID: 34358051 PMCID: PMC8308896 DOI: 10.3390/pathogens10070898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/30/2021] [Accepted: 07/11/2021] [Indexed: 12/26/2022] Open
Abstract
Antagonistic interactions and co-evolution between a host and its parasite are known to cause oscillations in the population genetic structure of both species (Red Queen dynamics). Potentially, such oscillations may select for increased sex and recombination in the host, although theoretical models suggest that this happens under rather restricted values of selection intensity, epistasis, and other parameters. Here, we explore a model in which the diploid parasite succeeds to infect the diploid host only if their phenotypes at the interaction-mediating loci match. Whenever regular oscillations emerge in this system, we test whether plastic, pathogen-inducible recombination in the host can be favored over the optimal constant recombination. Two forms of the host recombination dependence on the parasite pressure were considered: either proportionally to the risk of infection (prevention strategy) or upon the fact of infection (remediation strategy). We show that both forms of plastic recombination can be favored, although relatively infrequently (up to 11% of all regimes with regular oscillations, and up to 20% of regimes with obligate parasitism). This happens under either strong overall selection and high recombination rate in the host, or weak overall selection and low recombination rate in the host. In the latter case, the system’s dynamics are considerably more complex. The prevention strategy is favored more often than the remediation one. It is noteworthy that plastic recombination can be favored even when any constant recombination is rejected, making plasticity an evolutionary mechanism for the rescue of host recombination.
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10
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Fields C, Levin M. Why isn't sex optional? Stem-cell competition, loss of regenerative capacity, and cancer in metazoan evolution. Commun Integr Biol 2020; 13:170-183. [PMID: 33403054 PMCID: PMC7746248 DOI: 10.1080/19420889.2020.1838809] [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: 10/01/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/15/2022] Open
Abstract
Animals that can reproduce vegetatively by fission or budding and also sexually via specialized gametes are found in all five primary animal lineages (Bilateria, Cnidaria, Ctenophora, Placozoa, Porifera). Many bilaterian lineages, including roundworms, insects, and most chordates, have lost the capability of vegetative reproduction and are obligately gametic. We suggest a developmental explanation for this evolutionary phenomenon: obligate gametic reproduction is the result of germline stem cells winning a winner-take-all competition with non-germline stem cells for control of reproduction and hence lineage survival. We develop this suggestion by extending Hamilton's rule, which factors the relatedness between parties into the cost/benefit analysis that underpins cooperative behaviors, to include similarity of cellular state. We show how coercive or deceptive cell-cell signaling can be used to make costly cooperative behaviors appear less costly to the cooperating party. We then show how competition between stem-cell lineages can render an ancestral combination of vegetative reproduction with facultative sex unstable, with one or the other process driven to extinction. The increased susceptibility to cancer observed in obligately-sexual lineages is, we suggest, a side-effect of deceptive signaling that is exacerbated by the loss of whole-body regenerative abilities. We suggest a variety of experimental approaches for testing our predictions.
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Affiliation(s)
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA, USA
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11
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Rushworth CA, Brandvain Y, Mitchell‐Olds T. Identifying the fitness consequences of sex in complex natural environments. Evol Lett 2020; 4:516-529. [PMID: 33312687 PMCID: PMC7719549 DOI: 10.1002/evl3.194] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/14/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
In the natural world, sex prevails, despite its costs. Although much effort has been dedicated to identifying the intrinsic costs of sex (e.g., the cost of males), few studies have identified the ecological fitness consequences of sex. Furthermore, correlated biological traits that differ between sexuals and asexuals may alter these costs, or even render the typical costs of sex irrelevant. We conducted a large-scale, multisite, reciprocal transplant using multiple sexual and asexual genotypes of a native North American wildflower to show that sexual genotypes have reduced lifetime fitness, despite lower herbivory. We separated the effects of sex from those of hybridity, finding that overwinter survival is elevated in asexuals regardless of hybridity, but herbivores target hybrid asexuals more than nonhybrid asexual or sexual genotypes. Survival is lowest in homozygous sexual lineages, implicating inbreeding depression as a cost of sex. Our results show that the consequences of sex are shaped not just by sex itself, but by complex natural environments, correlated traits, and the identity and availability of mates.
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Affiliation(s)
- Catherine A. Rushworth
- Department of Evolution and EcologyUniversity of California, DavisDavisCalifornia95616
- University and Jepson HerbariaUniversity of California, BerkeleyBerkeleyCalifornia94720
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesota55108
- Department of BiologyDuke UniversityDurhamNorth Carolina27708
| | - Yaniv Brandvain
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesota55108
| | - Tom Mitchell‐Olds
- Department of BiologyDuke UniversityDurhamNorth Carolina27708
- Center for Genomic and Computational BiologyDuke UniversityDurhamNorth Carolina27708
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12
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Million KM, Bhattacharya A, Dinges ZM, Montgomery S, Smith E, Lively CM. DNA Content Variation and SNP Diversity Within a Single Population of Asexual Snails. J Hered 2020; 112:58-66. [PMID: 33245337 DOI: 10.1093/jhered/esaa048] [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: 02/20/2020] [Accepted: 11/19/2020] [Indexed: 01/09/2023] Open
Abstract
A growing body of research suggests that many clonal populations maintain genetic diversity even without occasional sexual reproduction. The purpose of our study was to document variation in single-nucleotide polymorphism (SNP) diversity, DNA content, and pathogen susceptibility in clonal lineages of the New Zealand freshwater snail, Potamopyrgus antipodarum. We studied snails that were collected from multiple field sites around a single lake (Lake Alexandrina), as well as isofemale clonal lineages that had been isolated and maintained in the laboratory. We used the kompetitive allele specific PCR (KASP) method to genotype our samples at 46 nuclear SNP sites, and we used flow cytometry to estimate DNA content. We found high levels of SNP diversity, both in our field samples and in our clonal laboratory lines. We also found evidence of high variation in DNA content among clones, even among clones with identical genotypes across all SNP sites. Controlled pathogen exposures of the laboratory populations revealed variation in susceptibility among distinct clonal genotypes, which was independent of DNA content. Taken together, these results show high levels of diversity among asexual snails, especially for DNA content, and they suggest rapid genome evolution in asexuals.
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Affiliation(s)
- Kara M Million
- Department of Biology, Indiana University, Bloomington, IN
| | - Amrita Bhattacharya
- Department of Biology, Indiana University, Bloomington, IN.,Department of Biology, Penn State University, Mueller Laboratory, State College, PA
| | - Zoe M Dinges
- Department of Biology, Indiana University, Bloomington, IN
| | | | - Eries Smith
- Department of Biology, Indiana University, Bloomington, IN
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13
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Koch HR, Wagner S, Becks L. Antagonistic species interaction drives selection for sex in a predator-prey system. J Evol Biol 2020; 33:1180-1191. [PMID: 32500538 DOI: 10.1111/jeb.13658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 05/22/2020] [Indexed: 01/26/2023]
Abstract
The evolutionary maintenance of sexual reproduction has long challenged biologists as the majority of species reproduce sexually despite inherent costs. Providing a general explanation for the evolutionary success of sex has thus proven difficult and resulted in numerous hypotheses. A leading hypothesis suggests that antagonistic species interaction can generate conditions selecting for increased sex due to the production of rare or novel genotypes that are beneficial for rapid adaptation to recurrent environmental change brought on by antagonism. To test this ecology-based hypothesis, we conducted experimental evolution in a predator (rotifer)-prey (algal) system by using continuous cultures to track predator-prey dynamics and in situ rates of sex in the prey over time and within replicated experimental populations. Overall, we found that predator-mediated fluctuating selection for competitive versus defended prey resulted in higher rates of genetic mixing in the prey. More specifically, our results showed that fluctuating population sizes of predator and prey, coupled with a trade-off in the prey, drove the sort of recurrent environmental change that could provide a benefit to sex in the prey, despite inherent costs. We end with a discussion of potential population genetic mechanisms underlying increased selection for sex in this system, based on our application of a general theoretical framework for measuring the effects of sex over time, and interpreting how these effects can lead to inferences about the conditions selecting for or against sexual reproduction in a system with antagonistic species interaction.
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Affiliation(s)
- Hanna R Koch
- Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, D-Plön, Germany
| | - Sophia Wagner
- Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, D-Plön, Germany
| | - Lutz Becks
- Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, D-Plön, Germany
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14
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Lohr JN, Haag CR. Parasite-driven replacement of a sexual by a closely related asexual taxon in nature. Ecology 2020; 101:e03105. [PMID: 32452541 DOI: 10.1002/ecy.3105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/22/2020] [Accepted: 04/15/2020] [Indexed: 11/09/2022]
Abstract
Asexual species are thought to suffer more from coevolving parasites than related sexuals. Yet a variety of studies do not find the patterns predicted by theory. Here, to shine light on this conundrum, we investigate one such case of an asexual advantage in the presence of parasites. We follow the frequency dynamics of sexual and asexual Daphnia pulex in a natural pond that was initially dominated by sexuals. Coinciding with an epidemic of a microsporidian parasite infecting both sexuals and asexuals, the pond was rapidly taken over by the initially rare asexuals. With experiments comparing multiple sexual and asexual clones from across the local metapopulation, we confirm that asexuals are less susceptible and also suffer less from the parasite once infected. These results are consistent with the parasite-driven, ecological replacement of dominant sexuals by closely related, but more resistant asexuals, ultimately leading to the extinction of the formerly superior sexual competitor. Our study is one of the clearest examples from nature, backed up by experimental verification, showing a parasite-mediated reversal of competition dynamics. The experiments show that, across the metapopulation, asexuals have an advantage in the presence of parasites. In this metapopulation, asexuals are relatively rare, likely due to their recent invasion. While we cannot rule out other reasons for the observed patterns, the results are consistent with a temporary parasite-mediated advantage of asexuals due to the fact that they are rare, which is an underappreciated aspect of the Red Queen Hypothesis.
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Affiliation(s)
- Jennifer N Lohr
- Department of Biology, Ecology and Evolution, University of Fribourg, Chemin du Musée 10, 1700, Fribourg, Switzerland.,Tvärminne Zoological Station, J.A. Palménin tie 260, 10900, Hanko, Finland.,Department of Genetics, Evolution and Environment, University College London, Institute of Healthy Ageing, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom
| | - Christoph R Haag
- Department of Biology, Ecology and Evolution, University of Fribourg, Chemin du Musée 10, 1700, Fribourg, Switzerland.,Tvärminne Zoological Station, J.A. Palménin tie 260, 10900, Hanko, Finland.,CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, 1919, route de Mende, 34293, Montpellier Cedex 5, France
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15
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A new species of Atriophallophorus Deblock & Rosé, 1964 (Trematoda: Microphallidae) described from in vitro-grown adults and metacercariae from Potamopyrgus antipodarum (Gray, 1843) (Mollusca: Tateidae). J Helminthol 2019; 94:e108. [PMID: 31779720 DOI: 10.1017/s0022149x19000993] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The adult and metacercaria life stages of a new species of the microphallid genus Atriophallophorus Deblock & Rosé, 1964 are described from specimens collected at Lake Alexandrina (South Island, New Zealand). In addition to molecular analyses of ribosomal and mitochondrial genes, metacercariae of Atriophallophorus winterbourni n. sp. from the snail host Potamopyrgus antipodarum (Gray) were grown in vitro to characterize internal and external morphology of adults using light and scanning electron microscopy and histological techniques. Atriophallophorus winterbourni n. sp. is readily distinguishable from Atriophallophorus coxiellae Smith, 1973 by having a different structure of the prostatic chamber, sub-circular and dorsal to genital atrium, rather than cylindrical, fibrous, elongate and placed between the seminal vesicle and the genital atrium. The new species is most similar to Atriophallophorus minutus (Price, 1934) with regards to the prostatic chamber and the morphometric data, but possesses elongate-oval testes and subtriangular ovary rather than oval and transversely oval in A. minutus. Phylogenetic analyses including sequence data for A. winterbourni n. sp. suggested a congeneric relationship of the new species to a hitherto undescribed metacercariae reported from Australia, both forming a strongly supported clade closely related to Microphallus and Levinseniella. In addition, we provide an amended diagnosis of Atriophallophorus to accommodate the new species and confirm the sinistral interruption of the outer rim of the ventral sucker caused by the protrusion of the dextral parietal atrial scale at the base of the phallus.
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16
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Abstract
The origin and subsequent maintenance of sex and recombination are among the most elusive and controversial problems in evolutionary biology. Here, we propose a novel hypothesis, suggesting that sexual reproduction not only evolved to reduce the negative effects of the accumulation of deleterious mutations and processes associated with pathogen and/or parasite resistance but also to prevent invasion by transmissible selfish neoplastic cheater cells, henceforth referred to as transmissible cancer cells. Sexual reproduction permits systematic change of the multicellular organism's genotype and hence an enhanced detection of transmissible cancer cells by immune system. Given the omnipresence of oncogenic processes in multicellular organisms, together with the fact that transmissible cancer cells can have dramatic effects on their host fitness, our scenario suggests that the benefits of sex and concomitant recombination will be large and permanent, explaining why sexual reproduction is, despite its costs, the dominant mode of reproduction among eukaryotes.
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17
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Zilio G, Moesch L, Bovet N, Sarr A, Koella JC. The effect of parasite infection on the recombination rate of the mosquito Aedes aegypti. PLoS One 2018; 13:e0203481. [PMID: 30300349 PMCID: PMC6177114 DOI: 10.1371/journal.pone.0203481] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022] Open
Abstract
Sexual reproduction and meiotic recombination generate new genetic combinations and may thereby help an individual infected by a parasite to protect its offspring from being infected. While this idea is often used to understand the evolutionary forces underlying the maintenance of sex and recombination, it also suggests that infected individuals should increase plastically their rate of recombination. We tested the latter idea with the mosquito Aedes aegypti and asked whether females infected by the microsporidian Vavraia culicis were more likely to have recombinant offspring than uninfected females. To measure the rate of recombination over a chromosome we analysed combinations of microsatellites on chromosome 3 in infected and uninfected females, in the (uninfected) males they copulated with and in their offspring. As predicted, the infected females were more likely to have recombinant offspring than the uninfected ones. These results show the ability of a female to diversify her offspring in response to parasitic infection by plastically increasing her recombination rate.
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Affiliation(s)
- Giacomo Zilio
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Lea Moesch
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Environmental Systems Science, ETHZ, Zurich, Switzerland
| | - Nathalie Bovet
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Anouk Sarr
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Jacob C. Koella
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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Gibson AK, Delph LF, Vergara D, Lively CM. Periodic, Parasite-Mediated Selection For and Against Sex. Am Nat 2018; 192:537-551. [PMID: 30332578 DOI: 10.1086/699829] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Asexual lineages should rapidly replace sexual populations. Why sex then? The Red Queen hypothesis proposes that parasite-mediated selection against common host genotypes could counteract the per capita birth rate advantage of asexuals. Under the Red Queen hypothesis, fluctuations in parasite-mediated selection can drive fluctuations in the asexual population, leading to the coexistence of sexual and asexual reproduction. Does shifting selection by parasites drive fluctuations in the fitness and frequency of asexuals in nature? Combining long-term field data with mesocosm experiments, we detected a shift in the direction of parasite selection in the snail Potamopyrgus antipodarum and its coevolving parasite, Microphallus sp. In the early 2000s, asexuals were more infected than sexuals. A decade later, the asexuals had declined in frequency and were less infected than sexuals. Over time, the mean infection prevalence of asexuals equaled that of sexuals but varied far more. This variation in asexual infection prevalence suggests the potential for parasite-mediated fluctuations in asexual fitness. Accordingly, we detected fitness consequences of the shift in parasite selection: when they were less infected than sexuals, asexuals increased in frequency in the field and in paired mesocosms that isolated the effect of parasites. The match between field and experiment argues that coevolving parasites drive temporal change in the relative fitness and frequency of asexuals, potentially promoting the coexistence of reproductive modes in P. antipodarum.
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Lynch ZR, Penley MJ, Morran LT. Turnover in local parasite populations temporarily favors host outcrossing over self-fertilization during experimental evolution. Ecol Evol 2018; 8:6652-6662. [PMID: 30038764 PMCID: PMC6053587 DOI: 10.1002/ece3.4150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/28/2018] [Accepted: 03/29/2018] [Indexed: 11/12/2022] Open
Abstract
The ubiquity of outcrossing in plants and animals is difficult to explain given its costs relative to self-fertilization. Despite these costs, exposure to changing environmental conditions can temporarily favor outcrossing over selfing. Therefore, recurring episodes of environmental change are predicted to favor the maintenance of outcrossing. Studies of host-parasite coevolution have provided strong support for this hypothesis. However, it is unclear whether multiple exposures to novel parasite genotypes in the absence of coevolution are sufficient to favor outcrossing. Using the nematode Caenorhabditis elegans and the bacterial parasite Serratia marcescens, we studied host responses to parasite turnover. We passaged several replicates of a host population that was well-adapted to the S. marcescens strain Sm2170 with either Sm2170 or one of three novel S. marcescens strains, each derived from Sm2170, for 18 generations. We found that hosts exposed to novel parasites maintained higher outcrossing rates than hosts exposed to Sm2170. Nonetheless, host outcrossing rates declined over time against all but the most virulent novel parasite strain. Hosts exposed to the most virulent novel strain exhibited increased outcrossing rates for approximately 12 generations, but did not maintain elevated levels of outcrossing throughout the experiment. Thus, parasite turnover can transiently increase host outcrossing. These results suggest that recurring episodes of parasite turnover have the potential to favor the maintenance of host outcrossing. However, such maintenance may require frequent exposure to novel virulent parasites, rapid rates of parasite turnover, and substantial host gene flow.
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20
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Neiman M, Meirmans PG, Schwander T, Meirmans S. Sex in the wild: How and why field-based studies contribute to solving the problem of sex. Evolution 2018; 72:1194-1203. [PMID: 29645091 DOI: 10.1111/evo.13485] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/27/2018] [Indexed: 02/06/2023]
Abstract
Why and how sexual reproduction is maintained in natural populations, the so-called "queen of problems," is a key unanswered question in evolutionary biology. Recent efforts to solve the problem of sex have often emphasized results generated from laboratory settings. Here, we use a survey of representative "sex in the wild" literature to review and synthesize the outcomes of empirical studies focused on natural populations. Especially notable results included relatively strong support for mechanisms involving niche differentiation and a near absence of attention to adaptive evolution. Support for a major role of parasites is largely confined to a single study system, and only three systems contribute most of the support for mutation accumulation hypotheses. This evidence for taxon specificity suggests that outcomes of particular studies should not be more broadly extrapolated without extreme caution. We conclude by suggesting steps forward, highlighting tests of niche differentiation mechanisms in both laboratory and nature, and empirical evaluation of adaptive evolution-focused hypotheses in the wild. We also emphasize the value of leveraging the growing body of genomic resources for nonmodel taxa to address whether the clearance of harmful mutations and spread of beneficial variants in natural populations proceeds as expected under various hypotheses for sex.
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Affiliation(s)
- Maurine Neiman
- Department of Biology, University of Iowa, Iowa City, Iowa 52242
| | - Patrick G Meirmans
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, 1090GE Amsterdam, The Netherlands
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Stephanie Meirmans
- Academic Medical Center (AMC), University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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21
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Maron JL, Johnson MTJ, Hastings AP, Agrawal AA. Fitness consequences of occasional outcrossing in a functionally asexual plant (Oenothera biennis). Ecology 2018; 99:464-473. [PMID: 29205317 DOI: 10.1002/ecy.2099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 10/20/2017] [Accepted: 10/30/2017] [Indexed: 11/08/2022]
Abstract
Many clonal organisms occasionally outcross, but the long-term consequences of such infrequent events are often unknown. During five years, representing three to five plant generations, we followed 16 experimental field populations of the forb, Oenothera biennis, originally planted with the same 18 original genotypes. Oenothera biennis usually self fertilizes, which, due to its genetic system (permanent translocation heterozygosity), results in seeds that are clones of the maternal plant. However, rare outcrossing produces genetically novel offspring (but without recombination or increased heterozygosity). We sought to understand whether novel genotypes produced through natural outcrossing had greater fecundity or different multigenerational dynamics compared to our original genotypes. We further assessed whether any differences in fitness or abundances through time between original and novel genotypes were exaggerated in the presence vs. absence of insect herbivores. Over the course of the experiment, we genotyped >12,500 plants using microsatellite DNA markers to identify and track the frequency of specific genotypes and estimated fecundity on a subset (>3,000) of plants. The effective outcrossing rate was 7.3% in the first year and ultimately 50% of the plants were of outcrossed origin by the final year of the experiment. Lifetime fruit production per plant was on average 32% higher across all novel genotypes produced via outcrossing compared to the original genotypes, and this fecundity advantage was significantly enhanced in populations lacking herbivores. Among 43 novel genotypes that were abundant enough to phenotype with replication, plants produced nearly 30% more fruits than the average of their specific two parental genotypes, and marginally more fruits (8%) than their most fecund parent. Mean per capita fecundity of novel genotypes predicted their relative frequencies at the end of the experiment. Novel genotypes increased more dramatically in herbivore-present compared to suppressed populations (45% vs. 27% of all plants), countering the increased competition from dandelions (Taraxacum officinale) that resulted from herbivore suppression. Increased interspecific competition likely also lead to the lower realized fitness of novel vs. original genotypes in herbivore-suppressed populations. These results demonstrate that rare outcrossing and the generation of novel genotypes can create high-fecundity progeny, with the biotic environment influencing the dynamical outcome of such advantages.
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Affiliation(s)
- John L Maron
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Marc T J Johnson
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada
| | - Amy P Hastings
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
| | - Anurag A Agrawal
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
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22
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Auld SKJR, Tinkler SK, Tinsley MC. Sex as a strategy against rapidly evolving parasites. Proc Biol Sci 2017; 283:rspb.2016.2226. [PMID: 28003455 PMCID: PMC5204169 DOI: 10.1098/rspb.2016.2226] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/18/2016] [Indexed: 11/20/2022] Open
Abstract
Why is sex ubiquitous when asexual reproduction is much less costly? Sex disrupts coadapted gene complexes; it also causes costs associated with mate finding and the production of males who do not themselves bear offspring. Theory predicts parasites select for host sex, because genetically variable offspring can escape infection from parasites adapted to infect the previous generations. We examine this using a facultative sexual crustacean, Daphnia magna, and its sterilizing bacterial parasite, Pasteuria ramosa. We obtained sexually and asexually produced offspring from wild-caught hosts and exposed them to contemporary parasites or parasites isolated from the same population one year later. We found rapid parasite adaptation to replicate within asexual but not sexual offspring. Moreover, sexually produced offspring were twice as resistant to infection as asexuals when exposed to parasites that had coevolved alongside their parents (i.e. the year two parasite). This fulfils the requirement that the benefits of sex must be both large and rapid for sex to be favoured by selection.
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Affiliation(s)
- Stuart K J R Auld
- Division of Biological and Environmental Sciences, University of Stirling, Room 3B164, Cottrell Building, Stirling, Stirlingshire FK9 4LA, UK
| | - Shona K Tinkler
- Division of Biological and Environmental Sciences, University of Stirling, Room 3B164, Cottrell Building, Stirling, Stirlingshire FK9 4LA, UK
| | - Matthew C Tinsley
- Division of Biological and Environmental Sciences, University of Stirling, Room 3B164, Cottrell Building, Stirling, Stirlingshire FK9 4LA, UK
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23
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Mutuku MW, Lu L, Otiato FO, Mwangi IN, Kinuthia JM, Maina GM, Laidemitt MR, Lelo EA, Ochanda H, Loker ES, Mkoji GM. A Comparison of Kenyan Biomphalaria pfeifferi and B. Sudanica as Vectors for Schistosoma mansoni, Including a Discussion of the Need to Better Understand the Effects of Snail Breeding Systems on Transmission. J Parasitol 2017; 103:669-676. [PMID: 28708450 DOI: 10.1645/17-72] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024] Open
Abstract
In Kenya, schistosomes infect an estimated 6 million people with >30 million people at risk of infection. We compared compatibility with, and ability to support and perpetuate, Schistosoma mansoni of Biomphalaria pfeifferi and Biomphalaria sudanica, 2 prominent freshwater snail species involved in schistosomiasis transmission in Kenya. Field-derived B. pfeifferi (from a stream in Mwea, central Kenya) and B. sudanica (from Nawa, Lake Victoria, in western Kenya) were exposed to S. mansoni miracidia isolated from fecal samples of naturally infected humans from Mwea or Nawa. Juvenile (<6 mm shell diameter), young adult (6-9 mm), and adult snails (>9 mm) were each exposed to a single miracidium. Schistosoma mansoni developed faster and consistently had higher infection rates (39.6-80.7%) in B. pfeifferi than in B. sudanica (2.4-21.5%), regardless of the source of S. mansoni or the size of the snails used. Schistosoma mansoni from Nawa produced higher infection rates in both B. pfeifferi and B. sudanica than did S. mansoni from Mwea. Mean daily cercariae production was greater for B. pfeifferi exposed to sympatric than allopatric S. mansoni (583-1,686 vs. 392-1,232), and mean daily cercariae production among B. sudanica were consistently low (50-590) with no significant differences between sympatric or allopatric combinations. Both non-miracidia-exposed and miracidia-exposed B. pfeifferi had higher mortality rates than for B. sudanica, but mean survival time of shedding snails (9.3-13.7 wk) did not differ significantly between the 2 species. A small proportion (1.5%) of the cercariae shedding B. pfeifferi survived up to 40 wk post-exposure. Biomphalaria pfeifferi was more likely to become infected and to shed more cercariae than B. sudanica, suggesting that the risk per individual snail of perpetuating transmission in Kenyan streams or lacustrine habitats may differ considerably. High infection rates exhibited by the preferential self-fertilizing B. pfeifferi relative to the out-crossing B. sudanica point to the need to investigate further the role of host breeding systems in influencing transmission of schistosomiasis by snail hosts.
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Affiliation(s)
- Martin W Mutuku
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Lijun Lu
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Fredrick O Otiato
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Ibrahim N Mwangi
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Joseph M Kinuthia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Geoffrey M Maina
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Martina R Laidemitt
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Eric A Lelo
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Horace Ochanda
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Eric S Loker
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Gerald M Mkoji
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
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24
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Kamiya M, Saba E, West JA. Marginal distribution and high heterozygosity of asexual Caloglossa vieillardii (Delesseriaceae, Rhodophyta) along the Australian coasts. JOURNAL OF PHYCOLOGY 2017; 53:1283-1293. [PMID: 28833125 DOI: 10.1111/jpy.12580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 08/03/2017] [Indexed: 06/07/2023]
Abstract
In animals and land plants, many asexual species originate through inter- or intraspecific crosses, and such heterozygous asexuals frequently are more abundant than their sexual relatives in marginal habitats. Although asexual species have been reported in various macroalgal taxa, detailed information regarding their distribution, heterozygosity, and origin is limited. Because many asexual tetrasporophyte strains of Caloglossa vieillardii have been isolated from South Australia, far from their core tropical habitats, we re-examined the distribution range of asexual C. vieillardii and genotyped these and other western Pacific strains using an actin gene marker. We confirmed the marginal distribution of the asexuals; however, a small patch of sexual thalli was newly discovered 450 km further west from asexual populations in South Australia. Three heterozygous genotypes and one homozygous genotypes were detected from nine asexual populations; 21 heterozygous strains were obligately asexual, but one homozygous strain suddenly produced sexual gametophytes after several years of culture. We hypothesized that the most abundant heterozygous genotype (defined as type 3/4) in asexual populations occurred by a cross between type 3 and type 4 allele gametophytes, both of which were isolated from the Australian coasts. In the crossing experiments, certain combinations between type 3 females and type 4 males produced tetrasporophytes, which recycled successive tetrasporophytes. In the culture experiments, whereas both sexual and asexual strains successfully produced tetraspores at 12°C, no sexual strains released carpospores below 14°C. However, it is uncertain whether this slight difference of maturation temperature was related to the marginal distribution of asexual C. vieillardii.
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Affiliation(s)
- Mitsunobu Kamiya
- Faculty of Marine Bioscience, Fukui Prefectural University, 1-1, Gakuen-cho, Obama, Fukui, 917-0003, Japan
| | - Erika Saba
- Graduate School of Bioscience and Biotechnology, Fukui Prefectural University, 1-1, Gakuen-cho, Obama, Fukui, 917-0003, Japan
| | - John A West
- School of Biosciences 2, University of Melbourne, Parkville, Victoria, 3010, Australia
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26
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Dagg JL. How counterfactuals of Red-Queen theory shed light on science and its historiography. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2017; 64:53-64. [PMID: 28683340 DOI: 10.1016/j.shpsc.2017.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 06/02/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
A historical episode of evolutionary theory, which has lead to the Red Queen theory of the evolutionary maintenance of sex, includes two striking contingencies. These are used to explore alternative what-if scenarios, in order to test some common opinions about such counterfactuals. This sheds new light on the nature of science and its historiography. One counterfactual leads to an unexpected convergence of its result to that of the actual science but, nevertheless, differs in its causal structure. The other diverges towards an incompatible alternative, but this requires further contingent choices that also diverge from actual science. The convergence in the first counterfactual is due to a horizontal transfer of knowledge. Similar transfers of knowledge are typical for innovations of actual science. This suggests that contingent choices can merge as well as fork research traditions both in actual research and counterfactual history. Neither the paths of the actual history of science nor those of its counterfactual alternatives will form a tree of exclusively diverging bifurcations, but a network instead. Convergencies in counterfactuals may, therefore, be due to the web-structure of science as much as to the aims of the historians in question. Furthermore, the difference in causal structure between the actual science and its convergent counterfactual might become diagnostic for external factors rather than internal aims forcing a historian towards convergence.
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27
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Lomax JL, Carlson RE, Wells JW, Crawford PM, Earley RL. Factors affecting egg production in the selfing mangrove rivulus (Kryptolebias marmoratus). ZOOLOGY 2017; 122:38-45. [PMID: 28268048 DOI: 10.1016/j.zool.2017.02.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/13/2017] [Accepted: 02/15/2017] [Indexed: 02/03/2023]
Abstract
The mangrove rivulus, Kryptolebias marmoratus, is one of two known vertebrate species with preferentially self-fertilizing hermaphrodites. Males also exist, and can outcross with hermaphrodites. Outcrossing events vary across wild populations and occur infrequently in laboratory settings. This study sought to add dimension to our understanding of mangrove rivulus reproductive habits by probing the effects of male presence on hermaphroditic unfertilized egg production. Specifically, we quantified egg production of solitary hermaphrodites compared to hermaphrodites exposed to males and exposed to other hermaphrodites. Hermaphrodites tended to produce more fertilized eggs in the presence of males but unfertilized eggs were produced relatively rarely and did not vary significantly among treatments. The probability that hermaphrodites would produce eggs changed as a function of genetic dissimilarity with their partner and in a season-dependent manner. In the fall, the probability of laying eggs decreased as a function of increased genetic dissimilarity, regardless of the sex of the partner. In the winter/spring, however, the probability of laying eggs increased markedly with increased genetic dissimilarity, regardless of the sex of the partner. Our findings indicate that reproductive decisions are modulated by factors beyond male presence, and we discuss a number of alternative hypotheses that should be tested in future studies.
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Affiliation(s)
- Justin L Lomax
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Rachel E Carlson
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Judson W Wells
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Patrice M Crawford
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Ryan L Earley
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA.
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28
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Slowinski SP, Morran LT, Parrish RC, Cui ER, Bhattacharya A, Lively CM, Phillips PC. Coevolutionary interactions with parasites constrain the spread of self-fertilization into outcrossing host populations. Evolution 2016; 70:2632-2639. [PMID: 27593534 DOI: 10.1111/evo.13048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 08/20/2016] [Accepted: 08/26/2016] [Indexed: 11/26/2022]
Abstract
Given the cost of sex, outcrossing populations should be susceptible to invasion and replacement by self-fertilization or parthenogenesis. However, biparental sex is common in nature, suggesting that cross-fertilization has substantial short-term benefits. The Red Queen hypothesis (RQH) suggests that coevolution with parasites can generate persistent selection favoring both recombination and outcrossing in host populations. We tested the prediction that coevolving parasites can constrain the spread of self-fertilization relative to outcrossing. We introduced wild-type Caenorhabditis elegans hermaphrodites, capable of both self-fertilization, and outcrossing, into C. elegans populations that were fixed for a mutant allele conferring obligate outcrossing. Replicate C. elegans populations were exposed to the parasite Serratia marcescens for 33 generations under three treatments: a control (avirulent) parasite treatment, a fixed (nonevolving) parasite treatment, and a copassaged (potentially coevolving) parasite treatment. Self-fertilization rapidly invaded C. elegans host populations in the control and the fixed-parasite treatments, but remained rare throughout the entire experiment in the copassaged treatment. Further, the frequency of the wild-type allele (which permits selfing) was strongly positively correlated with the frequency of self-fertilization across host populations at the end of the experiment. Hence, consistent with the RQH, coevolving parasites can limit the spread of self-fertilization in outcrossing populations.
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Affiliation(s)
| | - Levi T Morran
- Department of Biology, Emory University, Atlanta, Georgia 30322
| | | | - Eric R Cui
- Department of Biology, Indiana University, Bloomington, IN 47401
| | | | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, IN 47401
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403
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29
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Gibson AK, Xu JY, Lively CM. Within-population covariation between sexual reproduction and susceptibility to local parasites. Evolution 2016; 70:2049-60. [PMID: 27402345 DOI: 10.1111/evo.13001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/08/2016] [Accepted: 06/16/2016] [Indexed: 01/30/2023]
Abstract
Evolutionary biology has yet to reconcile the ubiquity of sex with its costs relative to asexual reproduction. Here, we test the hypothesis that coevolving parasites maintain sex in their hosts. Specifically, we examined the distributions of sexual reproduction and susceptibility to local parasites within a single population of freshwater snails (Potamopyrgus antipodarum). Susceptibility to local trematode parasites (Microphallus sp.) is a relative measure of the strength of coevolutionary selection in this system. Thus, if coevolving parasites maintain sex, sexual snails should be common where susceptibility is high. We tested this prediction in a mixed population of sexual and asexual snails by measuring the susceptibility of snails from multiple sites in a lake. Consistent with the prediction, the frequency of sexual snails was tightly and positively correlated with susceptibility to local parasites. Strikingly, in just two years, asexual females increased in frequency at sites where susceptibility declined. We also found that the frequency of sexual females covaries more strongly with susceptibility than with the prevalence of Microphallus infection in the field. In linking susceptibility to the frequency of sexual hosts, our results directly implicate spatial variation in coevolutionary selection in driving the geographic mosaic of sex.
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Affiliation(s)
- Amanda K Gibson
- Department of Biology, Indiana University, Bloomington, Indiana, 47405.
| | - Julie Y Xu
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
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30
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Parrish RC, Penley MJ, Morran LT. The Integral Role of Genetic Variation in the Evolution of Outcrossing in the Caenorhabditis elegans-Serratia marcescens Host-Parasite System. PLoS One 2016; 11:e0154463. [PMID: 27119159 PMCID: PMC4847799 DOI: 10.1371/journal.pone.0154463] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 04/13/2016] [Indexed: 12/05/2022] Open
Abstract
Outcrossing is predicted to facilitate more rapid adaptation than self-fertilization as a result of genetic exchange between genetically variable individuals. Such genetic exchange may increase the efficacy of selection by breaking down Hill-Robertson interference, as well as promoting the maintenance of within-lineage genetic diversity. Experimental studies have demonstrated the selective advantage of outcrossing in novel environments. Here, we assess the specific role of genetic variation in the evolution of outcrossing. We experimentally evolved genetically variable and inbred populations of mixed mating (outcrossing and self-fertilizing) Caenorhabditis elegans nematodes under novel ecological conditions—specifically the presence of the virulent parasite Serratia marcescens. Outcrossing rates increased in genetically variable host populations evolved in the presence of the parasite, whereas parasite exposure in inbred populations resulted in reduced rates of host outcrossing. The host populations with genetic variation also exhibited increased fitness in the presence of the parasite over eight generations, whereas inbred populations did not. This increase in fitness was primarily the result of adaptation to the parasite, rather than recovery from initial inbreeding depression. Therefore, the benefits of outcrossing were only manifested in the presence of genetic variation, and outcrossing was favored over self-fertilization as a result. As predicted, the benefits of outcrossing under novel ecological conditions are a product of genetic exchange between genetically diverse lineages.
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Affiliation(s)
- Raymond C. Parrish
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - McKenna J. Penley
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Levi T. Morran
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
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31
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Ashby B, King KC. Diversity and the maintenance of sex by parasites. J Evol Biol 2015; 28:511-20. [PMID: 25676723 DOI: 10.1111/jeb.12590] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 01/12/2015] [Indexed: 01/21/2023]
Abstract
The Red Queen hypothesis (RQH) predicts that parasite-mediated selection will maintain sexual individuals in the face of competition from asexual lineages. The prediction is that sexual individuals will be difficult targets for coevolving parasites if they give rise to more genetically diverse offspring than asexual lineages. However, increasing host genetic diversity is known to suppress parasite spread, which could provide a short-term advantage to clonal lineages and lead to the extinction of sex. We test these ideas using a stochastic individual-based model. We find that if parasites are readily transmissible, then sex is most likely to be maintained when host diversity is high, in agreement with the RQH. If transmission rates are lower, however, we find that sexual populations are most likely to persist for intermediate levels of diversity. Our findings thus highlight the importance of genetic diversity and its impact on epidemiological dynamics for the maintenance of sex by parasites.
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Affiliation(s)
- B Ashby
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, UK
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Lively CM, Morran LT. The ecology of sexual reproduction. J Evol Biol 2014; 27:1292-303. [PMID: 24617324 PMCID: PMC4077903 DOI: 10.1111/jeb.12354] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/28/2014] [Accepted: 01/29/2014] [Indexed: 11/28/2022]
Abstract
Sexual reproduction is widely regarded as one of the major unexplained phenomena in biology. Nonetheless, while a general answer may remain elusive, considerable progress has been made in the last few decades. Here, we first review the genesis of, and support for, the major ecological hypotheses for biparental sexual reproduction. We then focus on the idea that host-parasite coevolution can favour cross-fertilization over uniparental forms of reproduction, as this hypothesis currently has the most support from natural populations. We also review the results from experimental evolution studies, which tend to show that exposure to novel environments can select for higher levels of sexual reproduction, but that sex decreases in frequency after populations become adapted to the previously novel conditions. In contrast, experimental coevolution studies suggest that host-parasite interactions can lead to the long-term persistence of sex. Taken together, the evidence from natural populations and from laboratory experiments point to antagonistic coevolution as a potent and possibly ubiquitous force of selection favouring cross-fertilization and recombination.
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Affiliation(s)
- C M Lively
- Department of Biology, Indiana University, Bloomington, IN, USA
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