1
|
Fujita MK, Singhal S, Brunes TO, Maldonado JA. Evolutionary Dynamics and Consequences of Parthenogenesis in Vertebrates. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-114900] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Parthenogenesis is asexual reproduction without any required participation from males and, as such, is a null model for sexual reproduction. In a comparative context, we can expand our understanding of the evolution and ecology of sex by investigating the consequences of parthenogenesis. In this review, we examine the theoretical predictions of and empirical results on the evolution of asexual reproduction in vertebrates, focusing on recent studies addressing the origins and geographic spread of parthenogenetic lineages and the genomic consequences of an asexual life history. With advances in computational methods and genome technologies, researchers are poised to make rapid and significant progress in studying the origin and evolution of parthenogenesis in vertebrates, thus providing an important perspective on understanding biodiversity patterns of both asexual and sexual populations.
Collapse
Affiliation(s)
- Matthew K. Fujita
- Amphibian and Reptile Diversity Research Center and Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - Sonal Singhal
- Department of Biology, California State University, Dominguez Hills, Carson, California 90747, USA
| | - Tuliana O. Brunes
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brazil
| | - Jose A. Maldonado
- Amphibian and Reptile Diversity Research Center and Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, USA
| |
Collapse
|
2
|
Nania D, Flecks M, Rödder D. Continuous expansion of the geographic range linked to realized niche expansion in the invasive Mourning gecko Lepidodactylus lugubris (Duméril & Bibron, 1836). PLoS One 2020; 15:e0235060. [PMID: 32628687 PMCID: PMC7337341 DOI: 10.1371/journal.pone.0235060] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 06/07/2020] [Indexed: 12/02/2022] Open
Abstract
Lepidodactylus lugubris is a parthenogenetic gecko which has been increasingly expanding its range during the last century. This invasive species has been reported from multiple tropical and subtropical countries in five continents, most of which were colonized in recent times. In order to understand how the realized niche of the species was affected by this dramatic geographic range expansion, we reconstructed the history of the geographic range expansion. We built models of the realized niche of the species at different points in time during the invasion process. This was achieved through the implementation of modern hypervolume construction methods, based on the Hutchinson's niche concept. The models were then compared to detect possible realized climatic niche expansion over time. Furthermore, we investigated possible pathways used by the species to spread. A progressive expansion of the realized niche was identified. As the species spread into new areas, we observed a tendency to colonize regions with warmer temperatures and higher precipitation rates. Finally, we found evidence for cargo shipping being the major pathway through which the species expands its range. Further studies on this topic should aim to investigate the role of biological interactions, and how they shape the distribution of L. lugubris on a global scale. A deeper understanding of this kind of processes will help us tackle the issue of invasive species, which has become a major challenge in conservation biology.
Collapse
Affiliation(s)
- Dario Nania
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
- Department of Biology and Biotechnology, Sapienza University of Rome, Rome, Italy
| | - Morris Flecks
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| | - Dennis Rödder
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| |
Collapse
|
3
|
Haubrock PJ, Cuthbert RN, Veselý L, Balzani P, Baker NJ, Dick JTA, Kouba A. Predatory functional responses under increasing temperatures of two life stages of an invasive gecko. Sci Rep 2020; 10:10119. [PMID: 32572111 PMCID: PMC7308338 DOI: 10.1038/s41598-020-67194-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 06/01/2020] [Indexed: 11/09/2022] Open
Abstract
The direct effects of temperature increases and differences among life-history might affect the impacts of native and invasive predators on recipient communities. Comparisons of functional responses can improve our understanding of underlying processes involved in altering species interaction strengths and may predict the effect of species invading new communities. Therefore, we investigated the functional responses of the mourning gecko Lepidodactylus lugubris (Duméril & Bibron, 1836) to explore how temperature, body-size and prey density alter gecko predatory impacts in ecosystems. We quantified the functional responses of juvenile and adult geckos in single-predator experiments at 20, 23 and 26 °C. Both displayed saturating Type-II functional responses, but juvenile functional responses and the novel Functional Response Ratio were positively affected by temperature as juvenile attack rates (a) increased as a function of increased temperature. Handling times (h) tended to shorten at higher temperature for both predator stages. We demonstrate that the effects of temperature on functional responses of geckos differ across ontogeny, perhaps reflecting life-history stages prioritising growth and maturation or body maintenance. This indicates that temperature-dependent gecko predatory impacts will be mediated by population demographics. We advocate further comparisons of functional responses to understand the invasiveness and future predatory impacts of geckos, and other invasive species globally, as temperatures change.
Collapse
Affiliation(s)
- Phillip J Haubrock
- Senckenberg Research Institute and Natural History Museum Frankfurt, Department of River Ecology and Conservation, Gelnhausen, Germany.
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25, Vodňany, Czech Republic.
| | - Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, Northern Ireland, UK
- GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, Düsternbrooker Weg 20, Kiel, Germany
| | - Lukáš Veselý
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25, Vodňany, Czech Republic
| | - Paride Balzani
- University of Florence, Department of Biology, Via Romana 17, 50121, Florence, Italy
| | - Nathan Jay Baker
- Senckenberg Research Institute and Natural History Museum Frankfurt, Department of River Ecology and Conservation, Gelnhausen, Germany
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, Northern Ireland, UK
| | - Antonín Kouba
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25, Vodňany, Czech Republic
| |
Collapse
|
4
|
Paczesniak D, Klappert K, Kopp K, Neiman M, Seppälä K, Lively CM, Jokela J. Parasite resistance predicts fitness better than fecundity in a natural population of the freshwater snail
Potamopyrgus antipodarum. Evolution 2019; 73:1634-1646. [DOI: 10.1111/evo.13768] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/17/2019] [Accepted: 04/20/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Dorota Paczesniak
- Department of Aquatic Ecology Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dübendorf Switzerland
- Institute of Integrative Biology ETH‐Zürich Zürich Switzerland
- Global Institute for Food Security University of Saskatchewan Saskatoon Canada
| | - Kirsten Klappert
- Department of Aquatic Ecology Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dübendorf Switzerland
- Institute of Integrative Biology ETH‐Zürich Zürich Switzerland
| | - Kirstin Kopp
- Department of Aquatic Ecology Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dübendorf Switzerland
- Institute of Integrative Biology ETH‐Zürich Zürich Switzerland
- Velux Stiftung Zürich Switzerland
| | - Maurine Neiman
- Department of Biology University of Iowa Iowa City Iowa 52245
| | - Katri Seppälä
- Department of Aquatic Ecology Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dübendorf Switzerland
- Institute of Integrative Biology ETH‐Zürich Zürich Switzerland
| | - Curtis M. Lively
- Department of Biology Indiana University Bloomington Indiana 47405
| | - Jukka Jokela
- Department of Aquatic Ecology Swiss Federal Institute of Aquatic Science and Technology (EAWAG) Dübendorf Switzerland
- Institute of Integrative Biology ETH‐Zürich Zürich Switzerland
| |
Collapse
|
5
|
Murakami Y, Hayashi F. Molecular discrimination and phylogeographic patterns of clones of the parthenogenetic gecko
Lepidodactylus lugubris
in the Japanese Archipelago. POPUL ECOL 2019. [DOI: 10.1002/1438-390x.1030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Yuki Murakami
- Department of BiologyTokyo Metropolitan University Tokyo Japan
| | - Fumio Hayashi
- Department of BiologyTokyo Metropolitan University Tokyo Japan
| |
Collapse
|
6
|
Murakami Y, Hayashi F. Behavioral Interactions for Food among Two Clones of ParthenogeneticLepidodactylus lugubrisand Sexually ReproducingHemidactylus frenatusGeckos. CURRENT HERPETOLOGY 2018. [DOI: 10.5358/hsj.37.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Yuki Murakami
- Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji, Tokyo 192-0397, JAPAN
| | - Fumio Hayashi
- Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji, Tokyo 192-0397, JAPAN
| |
Collapse
|
7
|
Lapwong Y, Juthong W. New Records of Lepidodactylus lugubris (Duméril and Bibron, 1836) (Squamata, Gekkonidae) from Thailand and a Brief Revision of Its Clonal Composition in Southeast Asia. CURRENT HERPETOLOGY 2018. [DOI: 10.5358/hsj.37.143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Yingyod Lapwong
- School of Life Sciences, University of Technology Sydney, Broadway NSW 2007, AUSTRALIA
| | - Watinee Juthong
- Pitchalai Preparatory School, Hat Yai, Songkhla 90110, THAILAND
| |
Collapse
|
8
|
Jokela J, Lively CM, Fox JA, Dybdahl MF. FLAT REACTION NORMS AND "FROZEN" PHENOTYPIC VARIATION IN CLONAL SNAILS (POTAMOPYRGUS ANTIPODARUM). Evolution 2017; 51:1120-1129. [PMID: 28565497 DOI: 10.1111/j.1558-5646.1997.tb03959.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/1996] [Accepted: 04/21/1997] [Indexed: 11/27/2022]
Abstract
The Frozen Niche-Variation hypothesis (FNV) suggests that clones randomly sample and "freeze" the genotypes of their ancestral sexual populations. Hence, each clone expresses only a fraction of the total niche-use variation observed in the sexual population, which may lead to selection for ecological specialization and coexistence of clones. A generalized form of the FNV model suggests that the same is true for life-history (as well as other) traits that have important fitness consequences, but do not relate directly to niche use. We refer to the general form of the model as the Frozen Phenotypic Variation (FPV) model. A mixed population of sexual and parthenogenetic snails (Potamopyrgus antipodarum) in a New Zealand lake allowed us to examine the phenotypic variation expressed by coexisting clones in two benthic habitats, and to compare that variation to the sexual population. Three clones were found primarily in an aquatic macrophyte zone composed of Isoetes kirkii (1.5-3.0 m deep), and three additional clones were found in a deeper macrophyte zone composed of Elodea canadensis (4.0-6.0 m deep). These clones showed significant variation between habitats, which mirrored that observed in the sexual population. Specifically, clones and sexuals from the deeper habitat matured at a larger size and had larger broods. There was also significant among-clone variation within habitats; and as expected under the FPV model, the within-clone coefficients of variation for size at maturity were low in both habitats when compared to the sexual population. In addition, we found four clones that were common in both macrophyte zones. The reaction norms of these clones were flat across habitats, suggesting little phenotypic plasticity for morphology or life-history traits. Flat reaction norms, high among-clone variation, and low coefficients of variation (relative to the sexual population) are in accordance with the FPV model for the origin of clonal lineages. We also measured the prevalence of infection by trematode larvae to determine whether clones are inherently more or less infectable, or whether they are freezing phenotypic variation for resistance from the sexual population. We did this in the deep habitats of the lake where recycling of the parasite by the vertebrate host is unlikely, thereby reducing the complications raised by frequency-dependent responses of parasites to host genotypes. We found no indication that clones are either more or less infectable than the resident sexual population. Taken together, our results suggest that phenotypic variation for both life-history traits and resistance to parasites is frozen by clones from the local sexual population.
Collapse
Affiliation(s)
- Jukka Jokela
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Jennifer A Fox
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Mark F Dybdahl
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| |
Collapse
|
9
|
Hanley KA, Fisher RN, Case TJ. LOWER MITE INFESTATIONS IN AN ASEXUAL GECKO COMPARED WITH ITS SEXUAL ANCESTORS. Evolution 2017; 49:418-426. [PMID: 28565091 DOI: 10.1111/j.1558-5646.1995.tb02274.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/1993] [Accepted: 11/16/1993] [Indexed: 11/28/2022]
Abstract
What advantage do sexually reproducing organisms gain from their mode of reproduction that compensates for their twofold loss in reproductive rate relative to their asexual counterparts? One version of the Red Queen hypothesis suggests that selective pressure from parasites is strongest on the most common genotype in a population, and thus genetically identical clonal lineages are more vulnerable to parasitism over time than genetically diverse sexual lineages. Our surveys of the ectoparasites of an asexual gecko and its two sexual ancestral species show that the sexuals have a higher prevalence, abundance, and mean intensity of mites than asexuals sharing the same habitat. Our experimental data indicate that in one sexual/asexual pair this pattern is at least partly attributable to higher attachment rates of mites to sexuals. Such a difference may occur as a result of exceptionally high susceptibility of the sexuals to mites because of their low genetic diversity (relative to other more-outbred sexual species) and their potentially high stress levels, or as a result of exceptionally low susceptibility of the asexuals to mites because of their high levels of heterozygosity.
Collapse
Affiliation(s)
- Kathryn A Hanley
- Department of Biology-0116, University of California at San Diego, La Jolla, California, 92093-0116
| | - Robert N Fisher
- Department of Biology-0116, University of California at San Diego, La Jolla, California, 92093-0116
| | - Ted J Case
- Department of Biology-0116, University of California at San Diego, La Jolla, California, 92093-0116
| |
Collapse
|
10
|
Fox JA, Dybdahl MF, Jokela J, Lively CM. GENETIC STRUCTURE OF COEXISTING SEXUAL AND CLONAL SUBPOPULATIONS IN A FRESHWATER SNAIL (POTAMOPYRGUS ANTIPODARUM). Evolution 2017; 50:1541-1548. [PMID: 28565708 DOI: 10.1111/j.1558-5646.1996.tb03926.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/1995] [Accepted: 09/19/1995] [Indexed: 11/28/2022]
Abstract
We examined clonal diversity and the distribution of both clonal and sexual genotypes in a single population of freshwater snails (Potamopyrgus antipodarum) in which diploid sexual individuals and triploid parthenogens coexist. A genetic analysis of individuals from three habitat zones in Lake Alexandrina, New Zealand revealed extremely high clonal diversity: 165 genotypes among 605 clonal individuals. The frequency of triploid clonal individuals increased with increasing depth in the lake, and most of the individual clones were habitat specific, suggesting that differences among habitats are important in structuring the clonal subpopulation. There were also high levels of clonal diversity within habitats, suggesting frequent origins of habitat-specific clones. In contrast, diploid sexual individuals were proportionately more common in the shallow regions of the lake (where infection by trematode larvae is highest), and there was no significant spatial structure in the sexual subpopulation. We suggest that habitat specialization by clones, as well as parasite-mediated selection against common clones, are important factors affecting the structure of this mixed population of sexual and clonal snails.
Collapse
Affiliation(s)
- Jennifer A Fox
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Mark F Dybdahl
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - Jukka Jokela
- Department of Biology, Indiana University, Bloomington, Indiana, 47405.,Laboratory of Ecological Zoology, University of Turku, FIN-20500, Finland
| | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| |
Collapse
|
11
|
Vrijenhoek RC, Pfeiler E. DIFFERENTIAL SURVIVAL OF SEXUAL AND ASEXUAL
POECILIOPSIS
DURING ENVIRONMENTAL STRESS. Evolution 2017; 51:1593-1600. [DOI: 10.1111/j.1558-5646.1997.tb01482.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/1997] [Accepted: 06/03/1997] [Indexed: 12/01/2022]
Affiliation(s)
- Robert C. Vrijenhoek
- Center for Theoretical and Applied Genetics Rutgers University New Brunswick New Jersey 08903‐0231
| | - Edward Pfeiler
- Departamento de Ciencias Marinas Instituto Tecnológico y de Estudios Superiores de Monterrey Guaymas Sonora 85400 Mexico
- Department of Biology Arizona State University Tempe Arizona 85287‐1501 Mexico
| |
Collapse
|
12
|
Tarkhnishvili D, Murtskhvaladze M, Anderson CL. Coincidence of genotypes at two loci in two parthenogenetic rock lizards: how backcrosses might trigger adaptive speciation. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
13
|
Population genetic structure and distribution patterns of sexual and asexual gecko species in the Ogasawara Islands. Ecol Res 2015. [DOI: 10.1007/s11284-015-1246-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
14
|
Boldness underlies foraging success of invasive Lepidodactylus lugubris geckos in the human landscape. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2008.04.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
15
|
Jordaens K, Scheirs J, Verhagen R, Backeljau T. Ecogenetic Comparison of the Selfing Terrestrial Slugs Arion Silvaticus and A. Circumscriptus in Belgium (Mollusca: Pulmonata: Arionidae). Hereditas 2004. [DOI: 10.1111/j.1601-5223.1998.00027.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
|
16
|
Negovetic S, Anholt BR, Semlitsch RD, Reyer HU. SPECIFIC RESPONSES OF SEXUAL AND HYBRIDOGENETIC EUROPEAN WATERFROG TADPOLES TO TEMPERATURE. Ecology 2001. [DOI: 10.1890/0012-9658(2001)082[0766:srosah]2.0.co;2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
17
|
Negovetic S, Jokela J. Food choice behaviour may promote habitat specificity in mixed populations of clonal and sexual Potamopyrgus antipodarum. Anim Behav 2000; 60:435-441. [PMID: 11032646 DOI: 10.1006/anbe.2000.1486] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Genetic polymorphism along an environmental gradient may be maintained if disruptive selection on habitat-specific traits leads to a correlated response in traits that reduce gene flow between habitats. We studied a short-distance cline in a population of freshwater snails Potamopyrgus antipodarum in which sexual and clonal snails coexist. Sexuals and clones show a life history cline by depth: snails reproduce at a smaller size in shallower habitats. Clones are also structured genetically across habitats and seem not to mix, even though habitats are within the dispersal distance of the snails and the opportunity for gene flow via migration must be considerable. Because habitat preference may promote divergence in both clones and sexuals along the depth gradient, we investigated whether snails show habitat-specific food choice behaviour that could reduce migration. We tested the food choice behaviour of the snails by exposing them simultaneously to food from their home and adjacent habitats. Both juvenile and adult snails from the shallow shore bank and a mid-water macrophyte habitat preferentially grazed on the vegetation of their original habitats. We suggest that the observed genetic and life history cline may be maintained by food choice behaviour that may promote a partial barrier to gene flow between the habitats. Copyright 2000 The Association for the Study of Animal Behaviour.
Collapse
|
18
|
Abstract
Why sex prevails in nature remains one of the great puzzles of evolution. Sexual reproduction has an immediate cost relative to asexual reproduction, as males only express their contribution to population growth through females. With no males to sustain, an asexual mutant can double its relative representation in the population in successive generations. This is the widely accepted 'twofold cost of males'. Many studies have attempted to explain how sex can recoup this cost from fitness benefits associated with the recombination of parental genotypes, but these require complex biological environments that cycle over evolutionary timescales. In contrast, we have considered the ecological dynamics that govern asexual invasion. Here we show the existence of a threshold growth rate for the sexual population, above which the invasion is halted by intraspecific competition. The asexual population then exerts a weaker inhibitory effect on the carrying capacity of the sexual population than on its own carrying capacity. The stable outcome of this is coexistence on a depleted resource base. Under these ecological circumstances, longer-term benefits of sex may eventually drive out the asexual competitor.
Collapse
Affiliation(s)
- C P Doncaster
- Division of Biodiversity and Ecology, School of Biological Sciences, University of Southampton, UK.
| | | | | |
Collapse
|
19
|
|
20
|
|
21
|
|
22
|
|
23
|
Radtkey RR, Becker B, Miller RD, Riblet R, Case TJ. Variation and evolution of class I Mhc in sexual and parthenogenetic geckos. Proc Biol Sci 1996; 263:1023-32. [PMID: 8805837 DOI: 10.1098/rspb.1996.0151] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We present the first Mhc class I sequences in geckos. We compared Mhc variation in gekkonid species that reproduce sexually (Hemidactylus frenatus, Lepidodactylus aureolineatus, L. moestus, L. sp. Arno, L. sp. Takapoto) to others reproducing parthenogenetically (H. garnotii, L. lugubris). These comparisons include the known maternal (L. moestus) and paternal (L. sp. Arno) ancestors of the asexual L. lugubris. Sequences similar to other vertebrate species were obtained from both nuclear and cDNA templates indicating that these sequences are derived from expressed class I Mhc loci. Southern blot analysis using gecko class I probes, revealed that parthenogenetic clonal lineages of independent evolutionary origin have no within-clone band variation at class I loci and that no detectable recombination between restriction sites had taken place. Variability in the sexual species was similar to mammalian taxa, i.e. class I genes are highly variable in outbreeding sexual populations. Sequence analysis of the alpha-2 domain of class I genes identified point mutations in a clonal lineage of L. lugubris which led to amino acid substitutions. Potential transspecific allelic lineages were also observed. The persistence of asexual lineages with little or no class I diversification over thousands of generations seems to argue against strong selection for Mhc multi-allelism caused by pathogen-Mhc allele specificity. On the other hand, the high level of heterozygosity in the parthenogenetic species (a consequence of their hybrid origin) may provide clonal lineages with adequate antigen presenting diversity to survive and compete with sexual relatives.
Collapse
Affiliation(s)
- R R Radtkey
- Department of Biology-0116, University of California, San Diego, La Jolla 92093-0116, USA
| | | | | | | | | |
Collapse
|