101
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Lo EYY. Testing hybridization hypotheses and evaluating the evolutionary potential of hybrids in mangrove plant species. J Evol Biol 2010; 23:2249-2261. [PMID: 20796134 DOI: 10.1111/j.1420-9101.2010.02087.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Natural hybridization is of marked importance from global to local biological diversity. In mangroves, species ranges overlap extensively with one another and species share a long overlap of flowering time. Although hybridization has been suggested, patterns of hybridization and the evolutionary potential of hybrids are not yet fully understood. This study provides molecular evidence for the parental origins and status of hybrids in the dominant mangrove genus Rhizophora based on comparisons of chloroplast and nuclear phylogenies and estimations of genetic relatedness and structure from inter-simple sequence repeat (ISSR) markers. Phylogenetic analyses indicate that almost all species can act as maternal parents to hybrids and that hybridization can be bidirectional. Bayesian analyses indicate that hybrids are simple F(1) s, and no trace of backcrossing was detected within populations. Hybridization, for the most part, occurs almost only locally and dispersal of hybrid individuals is limited beyond the hybrid sites.
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Affiliation(s)
- E Y Y Lo
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA.
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102
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Fricke C, Andersson C, Arnqvist G. Natural selection hampers divergence of reproductive traits in a seed beetle. J Evol Biol 2010; 23:1857-67. [PMID: 20646133 DOI: 10.1111/j.1420-9101.2010.02050.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Speciation is thought to often result from indirect selection for reproductive isolation. This will occur when reproductive traits that cause reproductive isolation evolve (i) as a by-product of natural selection on traits with which they are genetically correlated or (ii) as an indirect result of diversifying sexual selection. Here, we use experimental evolution to study the degree of divergent evolution of reproductive traits by manipulating the intensity of natural and sexual selection in replicated selection lines of seed beetles. Following 40 generations of selection, we assayed the degree of divergent evolution of reproductive traits between replicate selection lines experiencing the same selection regime. The evolution of reproductive traits was significantly divergent across selection lines within treatments. The evolution of reproductive traits was both slower and, more importantly, significantly less divergent among lines experiencing stronger directional natural selection. This suggests that reproductive traits did not evolve as an indirect by-product of adaptation. We discuss several ways in which natural selection may hamper divergent evolution among allopatric populations.
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Affiliation(s)
- C Fricke
- Evolutionary Biology Centre, Department of Ecology and Evolution, Animal Ecology, Uppsala University, Norbyvägen 18D, Uppsala, Sweden.
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103
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Rugman-Jones PF, Hoddle MS, Stouthamer R. Nuclear-mitochondrial barcoding exposes the global pest Western flower thrips (Thysanoptera: Thripidae) as two sympatric cryptic species in its native California. JOURNAL OF ECONOMIC ENTOMOLOGY 2010; 103:877-886. [PMID: 20568635 DOI: 10.1603/ec09300] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Over the past three decades, Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), has become a major worldwide pest of many agricultural and horticultural crops. In response, much time, money, and effort have been put into pure and applied research focusing on the biology and control of this pest. Western flower thrips is native to Western North America and widespread in California. High levels of variation in basic biology, pest status, and resistance to insecticides bring into question the specific status of Western flower thrips. We used nuclear-mitochondrial barcoding to compare DNA sequences of nuclear and mitochondrial genes between Western flower thrips populations across California, looking for association between these unlinked loci. Sequences of D2 domain of 28S and cytochrome c oxidase I gene revealed the existence of two distinct but sympatric genetic entities, and we describe a simple polymerase chain reaction-based method for diagnosing these entities. The complete association of these nuclear and mitochondrial loci in areas of sympatry is indicative of reproductive isolation and the existence of two cryptic species, both of which key out to Western flower thrips by using morphological characters. The finding that Western flower thrips is a complex of two species has important implications for past, current, and most importantly future research on these pests.
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Affiliation(s)
- Paul F Rugman-Jones
- Department of Entomology, University of California, Riverside, CA 92521, USA.
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104
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Miranda MBB, Innes DJ, Thompson RJ. Incomplete reproductive isolation in the blue mussel (Mytilus edulis and M. trossulus) hybrid zone in the Northwest Atlantic: role of gamete interactions and larval viability. THE BIOLOGICAL BULLETIN 2010; 218:266-281. [PMID: 20570850 DOI: 10.1086/bblv218n3p266] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Reproductive isolation in free-spawning organisms may involve only small changes in the gamete surface molecules that control fertilization, linking gamete incompatibility and speciation. Most studies have focused on species in which natural hybrids are absent and reproductive isolation is complete, but how gamete incompatibility evolves remains unclear. Reproductive isolation is incomplete between two sympatric mussel species (Mytilus edulis, M. trossulus) that hybridize in nature. In this study prezygotic and postzygotic components of reproductive incompatibility were examined in laboratory crosses. Conspecific crosses showed significantly greater rates of fertilization than heterospecific crosses, although some females of both species showed heterospecific gamete compatibility. The proportion of fertilized eggs developing into normal larvae was not significantly different between conspecific and heterospecific crosses, but survival of normal larvae was greater for conspecific crosses. Mixed-species sperm experiments suggested that conspecific sperm preference may further limit hybridization. The different components of reproductive incompatibility and total incompatibility varied among females of both species. Although our study has shown that partial reproductive isolation between M. edulis and M. trossulus involves both prezygotic gamete interactions and postzygotic larval survival, further research is required to determine the potential role of gamete incompatibility in the evolution of complete reproductive isolation between these species.
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Affiliation(s)
- Marcelo B B Miranda
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland A1B3X9, Canada
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105
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Montgomery BR, Soper DM, Delph LF. Asymmetrical conspecific seed-siring advantage between Silene latifolia and S. dioica. ANNALS OF BOTANY 2010; 105:595-605. [PMID: 20147372 PMCID: PMC2850797 DOI: 10.1093/aob/mcq013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 12/04/2009] [Accepted: 12/22/2009] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS Silene dioica and S. latifolia experience only limited introgression despite overlapping flowering phenologies, geographical distributions, and some pollinator sharing. Conspecific pollen precedence and other reproductive barriers operating between pollination and seed germination may limit hybridization. This study investigates whether barriers at this stage contribute to reproductive isolation between these species and, if so, which mechanisms are responsible. METHODS Pollen-tube lengths for pollen of both species in styles of both species were compared. Additionally, both species were pollinated with majority S. latifolia and majority S. dioica pollen mixes; then seed set, seed germination rates and hybridity of the resulting seedlings were determined using species-specific molecular markers. KEY RESULTS The longest pollen tubes were significantly longer for conspecific than heterospecific pollen in both species, indicating conspecific pollen precedence. Seed set but not seed germination was lower for flowers pollinated with pure heterospecific versus pure conspecific pollen. Mixed-species pollinations resulted in disproportionately high representation of nonhybrid offspring for pollinations of S. latifolia but not S. dioica flowers. CONCLUSIONS The finding of conspecific pollen precedence for pollen-tube growth but not seed siring in S. dioica flowers may be explained by variation in pollen-tube growth rates, either at different locations in the style or between leading and trailing pollen tubes. Additionally, this study finds a barrier to hybridization operating between pollination and seed germination against S. dioica but not S. latifolia pollen. The results are consistent with the underlying cause of this barrier being attrition of S. dioica pollen tubes or reduced success of heterospecifically fertilized ovules, rather than time-variant mechanisms. Post-pollination, pre-germination barriers to hybridization thus play a partial role in limiting introgression between these species.
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106
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Abstract
Reinforcement, a process by which natural selection increases reproductive isolation between populations, has been suggested to be an important force in the formation of new species. However, all existing cases of reinforcement involve an increase in mate discrimination between species. Here, I report the first case of reinforcement of postmating prezygotic isolation (i.e., barriers that act after mating but before fertilization) in animals. On the slopes of the African island of São Tomé, Drosophila yakuba and its endemic sister species D. santomea hybridize within a well-demarcated hybrid zone. I find that D. yakuba females from within this zone, but not from outside it, show an increase in gametic isolation from males of D. santomea, an apparent result of natural selection acting to reduce maladaptive hybridization between species. To determine whether such a barrier could evolve under laboratory conditions, I exposed D. yakuba lines derived from allopatric populations to experimental sympatry with D. santomea, and found that both behavioral and gametic isolation become stronger after only four generations. Reinforcement thus appears to be the best explanation for the heightened gametic isolation seen in sympatry. This appears to be the first example in animals in which natural selection has promoted the evolution of stronger interspecific genetic barriers that act after mating but before fertilization. This suggests that many other genetic barriers between species have been increased by natural selection but have been overlooked because they are difficult to study.
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Affiliation(s)
- Daniel R. Matute
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
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107
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Fisher HS, Hoekstra HE. Competition drives cooperation among closely related sperm of deer mice. Nature 2010; 463:801-3. [PMID: 20090679 PMCID: PMC2824558 DOI: 10.1038/nature08736] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 12/07/2009] [Indexed: 11/09/2022]
Abstract
Among the extraordinary adaptations driven by sperm competition is the cooperative behaviour of spermatozoa. By forming cooperative groups, sperm can increase their swimming velocity and thereby gain an advantage in intermale sperm competition. Accordingly, selection should favour cooperation of the most closely related sperm to maximize fitness. Here we show that sperm of deer mice (genus Peromyscus) form motile aggregations, then we use this system to test predictions of sperm cooperation. We find that sperm aggregate more often with conspecific than heterospecific sperm, suggesting that individual sperm can discriminate on the basis of genetic relatedness. Next, we provide evidence that the cooperative behaviour of closely related sperm is driven by sperm competition. In a monogamous species lacking sperm competition, Peromyscus polionotus, sperm indiscriminately group with unrelated conspecific sperm. In contrast, in the highly promiscuous deer mouse, Peromyscus maniculatus, sperm are significantly more likely to aggregate with those obtained from the same male than with sperm from an unrelated conspecific donor. Even when we test sperm from sibling males, we continue to see preferential aggregations of related sperm in P. maniculatus. These results suggest that sperm from promiscuous deer mice discriminate among relatives and thereby cooperate with the most closely related sperm, an adaptation likely to have been driven by sperm competition.
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Affiliation(s)
- Heidi S Fisher
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Cambridge, Massachusetts 02138, USA.
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108
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Chapman T. WONDERFUL AND JUST PLAIN WEIRD: THE GLORIOUS BIOLOGY OF SPERM. Evolution 2009. [DOI: 10.1111/j.1558-5646.2009.00930.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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109
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The genetics of postmating, prezygotic reproductive isolation between Drosophila virilis and D. americana. Genetics 2009; 184:401-10. [PMID: 19917764 DOI: 10.1534/genetics.109.111245] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many studies have demonstrated the rapid diversification of reproductive genes that function after mating but before fertilization. This process might lead to the evolution of postmating, prezygotic barriers between species. Here, I investigate the phenotypic and genetic basis of postmating, prezygotic isolation between two closely related species of Drosophila, Drosophila virilis and D. americana. I show that a strong barrier to interspecific fertilization results in a 99% reduction in progeny production. A genetic interaction among maternal and paternal alleles at only a few loci prevents the fertilization of D. virilis females by D. americana males. These loci are autosomal and isolation acts recessively; the fertilization incompatibility is caused by at least two loci in the maternal D. virilis parent in combination with at least three loci in the paternal D. americana parent. These findings, together with results from classical experiments, suggest that male-female coevolution within D. americana may have driven postmating, prezygotic isolation between species.
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110
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The evolution of postpollination reproductive isolation in Costus. ACTA ACUST UNITED AC 2009; 22:247-55. [PMID: 20033446 PMCID: PMC2796120 DOI: 10.1007/s00497-009-0113-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 08/14/2009] [Indexed: 12/03/2022]
Abstract
Reproductive isolation is critical to the diversification of species. Postpollination barriers may be important in limiting gene flow between closely related species, but they are relatively cryptic and their evolution is poorly understood. Here, we review the role of postpollination reproductive isolation in plants, including the various stages at which it operates and the hypotheses for how it may evolve. We then review empirical studies in the plant genus Costus, evaluating documented postpollination barriers in light of these hypotheses. We summarize isolation due to parental style length differences and present evidence supporting the hypothesis that the differences are in part a by-product of selection on floral morphology. Additionally, we show that reduced pollen adhesion, germination, and tube growth contribute to reproductive isolation between two closely related sympatric species of Costus. Geographic variation in the strength of these crossing barriers supports the hypothesis that they evolved under reinforcement, or direct natural selection to strengthen isolation.
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111
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RAHMÉ J, WIDMER A, KARRENBERG S. Pollen competition as an asymmetric reproductive barrier between two closely relatedSilenespecies. J Evol Biol 2009; 22:1937-43. [DOI: 10.1111/j.1420-9101.2009.01803.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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112
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Waelti MO, Page PA, Widmer A, Schiestl FP. How to be an attractive male: floral dimorphism and attractiveness to pollinators in a dioecious plant. BMC Evol Biol 2009; 9:190. [PMID: 19660122 PMCID: PMC2738674 DOI: 10.1186/1471-2148-9-190] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 08/06/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sexual selection theory predicts that males are limited in their reproductive success by access to mates, whereas females are more limited by resources. In animal-pollinated plants, attraction of pollinators and successful pollination is crucial for reproductive success. In dioecious plant species, males should thus be selected to increase their attractiveness to pollinators by investing more than females in floral traits that enhance pollinator visitation. We tested the prediction of higher attractiveness of male flowers in the dioecious, moth-pollinated herb Silene latifolia, by investigating floral signals (floral display and fragrance) and conducting behavioral experiments with the pollinator-moth, Hadena bicruris. RESULTS As found in previous studies, male plants produced more but smaller flowers. Male flowers, however, emitted significantly larger amounts of scent than female flowers, especially of the pollinator-attracting compounds. In behavioral tests we showed that naïve pollinator-moths preferred male over female flowers, but this preference was only significant for male moths. CONCLUSION Our data suggest the evolution of dimorphic floral signals is shaped by sexual selection and pollinator preferences, causing sexual conflict in both plants and pollinators.
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Affiliation(s)
- Marc O Waelti
- Plant Ecological Genetics, Institute of Systematic Botany, ETH Zürich, Zürich, Switzerland.
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113
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114
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Matsubayashi KW, Katakura H. Contribution of multiple isolating barriers to reproductive isolation between a pair of phytophagous ladybird beetles. Evolution 2009; 63:2563-80. [PMID: 19490076 DOI: 10.1111/j.1558-5646.2009.00738.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Reproductive isolation between species may often be attained by multiple isolating barriers, but the components are rarely studied in animal taxa. To elucidate the nature of multiple isolating barriers, we quantified the strength of three premating barriers, including ecologically based ones (seasonal, habitat, and sexual), two postmating-prehatching barriers (reduced egg hatchability and conspecific sperm precedence [CSP]), and one posthatching barrier, including four components of F(1) hybrid reduced fitness, between two phytophagous ladybird beetles, Henosepilachna vigintioctomaculata and H. pustulosa. We detected five positive barriers (habitat isolation, sexual isolation, reduced egg hatchability, CSP, and reduced egg hatchability in backcrosses of F(1) hybrids). None of these barriers entirely prevents gene exchange when it acts alone, but jointly they generate nearly complete reproductive isolation even between sympatric populations. Host fidelity contributed most strongly to reproductive isolation by reducing interspecific hybridization through several important types of ecological isolation, including microspatial, habitat, and seasonal isolation. The existence of multiple isolating barriers likely helps keep reproductive isolation stable and robust, by complementing changes in the strength of leaky barriers. This complementarity of multiple isolating barriers yields the concept of robustness of reproductive isolation, which is important when considering the long-term maintenance of species boundaries in coexisting species pairs.
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115
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Seki K, Wiwegweaw A, Asami T. Fluorescent pigment distinguishes between sibling snail species. Zoolog Sci 2009; 25:1212-9. [PMID: 19267648 DOI: 10.2108/zsj.25.1212] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Traditional taxonomy of shell-bearing molluscs does not generally use soft-body coloration. However, the land snails Bradybaena pellucida and B. similaris have been distinguished only on the basis of the color of the soft-body visible through the shell. Thus, the taxonomic status of the two species has traditionally been questionable. We found that dense spots of pigments embedded in the dorsal mantle are responsible for the yellow coloration of B. pellucida . Similar spots in B. similaris are white and less densely aggregated in whorls further from the apex, and the brown color of the hepatopancreas is visible through the shell. The yellow pigments of B. pellucida seep out with mucus from the body in natural and laboratory conditions. The two species became externally indistinguishable after 30 days of laboratory feeding, because the yellow spots disappeared in B. pellucida and the color of the hepatopancreas changed from dark brown to pale brown in both species. Irradiation with ultraviolet A demonstrated that the yellow pigment of B. pellucida fluoresces. Adult specimens of the two species were distinct in penial microsculpture, with F(1) hybrids intermediate in form. Populations of the two species differed significantly in allelic frequencies at four allozyme loci. Therefore, B. pellucida and B. similaris are morphologically and genetically distinct. The fluorescent yellow pigment distinguishes B. pellucida from B. similaris under natural conditions despite its environmental dependence.
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Affiliation(s)
- Keiichi Seki
- Department of Biology, Shinshu University, Matsumoto 390-8621, Japan
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116
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Devaux C, Lande R. Displacement of flowering phenologies among plant species by competition for generalist pollinators. J Evol Biol 2009; 22:1460-70. [PMID: 19467129 DOI: 10.1111/j.1420-9101.2009.01762.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We model the evolution of allochronic isolation between sympatric animal-pollinated plant species via displacement of their flowering times. The plant species share generalist pollinators and either produce inviable hybrid seeds or do not hybridize at all. Displacement of flowering times between reproductively isolated species reduces competition for pollinators and the formation of inviable hybrid seeds. Under strong pollen limitation, competition for pollinators causes rapid evolution of allochronic isolation both for hybridizing and nonhybridizing species. Under weak pollen limitation, allochronic isolation evolves rapidly for hybridizing species but more slowly for nonhybridizing species. Positive density-dependent pollinator visitation rate at low flower densities facilitates allochronic isolation under weak pollen limitation. Allochronic isolation among sympatric species sharing generalist pollinators could be common under any intensity of pollen limitation if the flowering season is sufficiently long.
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Affiliation(s)
- Céline Devaux
- Division of Biological Sciences, University of California - San Diego, La Jolla, CA, USA.
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117
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Aluja M, Rull J, Pérez-Staples D, Díaz-Fleischer F, Sivinski J. Random mating among Anastrepha ludens (Diptera: Tephritidae) adults of geographically distant and ecologically distinct populations in Mexico. BULLETIN OF ENTOMOLOGICAL RESEARCH 2009; 99:207-214. [PMID: 19063753 DOI: 10.1017/s0007485308006299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Mexican fruit fly Anastrepha ludens (Loew) (Diptera: Tephritidae) is a polyphagous pestiferous insect with a geographical range encompassing highly variable environmental conditions. Considering that cryptic species have been recently found among South American representatives of the same taxonomic group as A. ludens, we tested whether or not some populations of A. ludens have evolved assortative mating as an isolating mechanism that maintains intrapopulation genetic differences and behavioral adaptations to local conditions. Males and females stemming from widely separated locations with similar environmental conditions and males and females stemming from populations within individual-flight range, but collected in different hosts (a native and an exotic one), mated randomly amongst themselves when placed in a field cage. Despite the fact that sibling males and females from two distinct populations also mated randomly amongst themselves, siblings engaged in significantly longer copulations than non-siblings, indicating that perhaps adults discriminated mates with similar genetic compositions. Our results have important practical implications as A. ludens is the most devastating pest of citrus in Mexico and Central America, and large-scale releases of sterile flies are used to control it.
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Affiliation(s)
- M Aluja
- Instituto de Ecología, A.C., C.P. 91000 Xalapa, Veracruz, Mexico.
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118
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Characterization of the sperm molecule bindin in the sea urchin genus Paracentrotus. J Mol Evol 2009; 68:366-76. [PMID: 19330367 DOI: 10.1007/s00239-009-9219-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 02/12/2009] [Accepted: 02/19/2009] [Indexed: 10/21/2022]
Abstract
Bindin is a sea urchin gamete-recognition protein that plays an essential role in the specificity of egg-sperm interactions and thus may be evolving under sexual selection and be related to speciation. Bindin has been found to evolve under strong selection in some sea urchin genera and neutrally in others. In this study, we characterized bindin in the two extant species of the genus Paracentrotus: P. lividus from the Atlanto-Mediterranean region and P. gaimardi from Brazil. The structure of the bindin molecule in Paracentrotus is similar to that of other genera studied thus far, consisting of a conserved core flanked by two variable regions and an intron of variable length located at the same conserved position as in other genera. Polymorphism in P. lividus is caused mainly by point substitutions and insertions/deletions, and length variations are caused mainly by the number of repeated motifs in the flanking regions. There is no evidence of recombination. Positive selection is acting on amino acid sites located in two regions flanking the conserved core.
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119
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Martín-Coello J, Benavent-Corai J, Roldan ERS, Gomendio M. SPERM COMPETITION PROMOTES ASYMMETRIES IN REPRODUCTIVE BARRIERS BETWEEN CLOSELY RELATED SPECIES. Evolution 2009; 63:613-23. [DOI: 10.1111/j.1558-5646.2008.00585.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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120
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Tregenza T, Attia F, Bushaiba SS. Repeatability and heritability of sperm competition outcomes in males and females of Tribolium castaneum. Behav Ecol Sociobiol 2009. [DOI: 10.1007/s00265-009-0716-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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121
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Wiwegweaw A, Seki K, Mori H, Asami T. Asymmetric reproductive isolation during simultaneous reciprocal mating in pulmonates. Biol Lett 2009; 5:240-3. [PMID: 19141413 DOI: 10.1098/rsbl.2008.0714] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The generality of asymmetric reproductive isolation between reciprocal crosses suggests that the evolution of isolation mechanisms often proceeds in reciprocal asymmetry. In hermaphroditic snails that copulate simultaneously and reciprocally, asymmetry in premating isolation may not be readily detectable because the failure of the symmetric performance of courtship would prevent copulation from occurring. On the other hand, through their prolonged copulation, snails discriminate among mates when exchanging spermatophores for their benefit and thus may exhibit asymmetric reproductive isolation during interspecific mating. However, no clear case of reciprocal asymmetry has been found in reproductive isolation between snail species. Here we show a discrete difference in hybridization success between simultaneous reciprocal copulations between two species of pulmonate snails. Premating isolation of Bradybaena pellucida (BP) and Bradybaena similaris (BS) is incomplete in captivity. In interspecific copulation, BP removes its penis without transferring a spermatophore, while BS sires hybrids by inseminating BP. Thus, 'male' BP or 'female' BS rejects the other individual, while female BP and male BS accept each other, so that the two sexes of either BP or BS oppose each other in mate discrimination. Our results are a clear example of asymmetry in reproductive isolation during simultaneous reciprocal mating between hermaphroditic animals.
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Affiliation(s)
- Amporn Wiwegweaw
- Department of Biology, Shinshu University, Matsumoto 390-8621, Japan
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122
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Abstract
Barriers to gene flow can arise at any stage in the reproductive sequence. Most studies of reproductive isolation focus on premating or postzygotic phenotypes, leaving the importance of differences in fertilization rate overlooked. Two closely related species of house mice, Mus domesticus and M. musculus, form a narrow hybrid zone in Europe, suggesting that one or more isolating factors operate in the face of ongoing gene flow. Here, we test for differences in fertilization rate using laboratory matings as well as in vitro sperm competition assays. In noncompetitive matings, we show that fertilization occurs significantly faster in conspecific versus heterospecific matings and that this difference arises after mating and before zygotes form. To further explore the mechanisms underlying this conspecific advantage, we used competitive in vitro assays to isolate gamete interactions. Surprisingly, we discovered that M. musculus sperm consistently outcompeted M. domesticus sperm regardless of which species donated ova. These results suggest that in vivo fertilization rate is mediated by interactions between sperm, the internal female environment, and/or contributions from male seminal fluid. We discuss the implications of faster conspecific fertilization in terms of reproductive isolation among these two naturally hybridizing species.
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Affiliation(s)
- Matthew D Dean
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
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123
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Hochkirch A, Bücker A, Gröning J. Reproductive interference between the common ground-hopper Tetrix undulata and the slender ground-hopper Tetrix subulata (Orthoptera, Tetrigidae). BULLETIN OF ENTOMOLOGICAL RESEARCH 2008; 98:605-612. [PMID: 19012803 DOI: 10.1017/s0007485308005907] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The coexistence of closely related species is often hampered by resource competition or reproductive interference (interspecific sexual interactions). Species utilising similar signal channels might face substantial problems when they co-occur. It has, therefore, been suggested that reinforcement might drive signal evolution in narrow suture zones of secondary contact. However, species with large overlapping ranges are usually not believed to interact sexually. The Slender Ground-hopper, Tetrix subulata, and the Common Ground-hopper, Tetrix undulata (Orthoptera: Tetrigidae) are sister species, which occur sympatrically in large parts of western and Central Europe, but rarely share the same habitat. It has been hypothesized that reproductive interference might account for their missing coexistence. Here, we test experimentally whether these two species interact sexually. Our results suggest an incomplete premating isolation of these ground-hoppers, as we recorded heterospecific courtship, mating attempts and mating. The number of conspecific copulations and mating attempts of T. subulata decreased substantially in the presence of T. undulata, whereas the latter species was not negatively affected. Males of both species preferred to approach females of T. undulata, whereas females of both species did not discriminate against heterospecific males. Further studies on the reproductive success are needed to clarify whether reproductive interference might influence habitat partitioning between these species.
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Affiliation(s)
- A Hochkirch
- University of Osnabrück, Department of Biology/Chemistry, Division of Ecology, Barbarastrasse 13, D-49076 Osnabrück, Germany.
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124
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Fishman L, Aagaard J, Tuthill JC. TOWARD THE EVOLUTIONARY GENOMICS OF GAMETOPHYTIC DIVERGENCE: PATTERNS OF TRANSMISSION RATIO DISTORTION IN MONKEYFLOWER (MIMULUS) HYBRIDS REVEAL A COMPLEX GENETIC BASIS FOR CONSPECIFIC POLLEN PRECEDENCE. Evolution 2008; 62:2958-70. [DOI: 10.1111/j.1558-5646.2008.00475.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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125
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Palumbi SR. Speciation and the evolution of gamete recognition genes: pattern and process. Heredity (Edinb) 2008; 102:66-76. [PMID: 19018273 DOI: 10.1038/hdy.2008.104] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Proteins on gamete surfaces are major determinants of fertilization success, particularly in free-spawning animals. Molecular analyses of these simple genetic systems show rapid evolution, positive selection, accelerated coalescence and, sometimes, extensive polymorphism. Careful analysis of the behavior of sperm produced by males with different gamete alleles shows that these alleles can deliver significant functional differences. Three forms of allele-specific fertilization advantage have been shown: assortative mating based on gamete type, rare allele advantage and heterozygote superiority. Models suggest that sperm and egg proteins may be coevolutionary partners that can alternate between directional selection for high fertilization ability and cyclic adaptation of eggs and sperm driven by sexual conflict. These processes act within allopatric populations and may accelerate their divergence if gamete adaptations in separate demes reduce cross-fertilization. Reproductive character displacement by reinforcement may play a diversifying role when previously allopatric populations rejoin. In circumstance that might prove to be common, divergence in sympatry can be driven by sexual conflict or by association of mating types with ecological differences. The ecology of fertilization, especially the degree of sperm competition and egg death via polyspermy, are important determinants of the strength and direction of selection on gametes. Free-spawning animals allow careful analysis of gamete recognition -from the behavior of adults and interactions of gametes, to molecular patterns of allele divergence. Future research efforts on the evolutionary consequences of fertilization ecology, and the interaction between extensive variation in egg surface proteins and sperm fertilization ability, are particularly needed.
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Affiliation(s)
- S R Palumbi
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA.
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126
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Rugman-Jones PF, Eady PE. Co-evolution of male and female reproductive traits across the Bruchidae (Coleoptera). Funct Ecol 2008. [DOI: 10.1111/j.1365-2435.2008.01446.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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127
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Kay KM, Schemske DW. Natural selection reinforces speciation in a radiation of neotropical rainforest plants. Evolution 2008; 62:2628-42. [PMID: 18637960 DOI: 10.1111/j.1558-5646.2008.00463.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The importance of reinforcement, that is, natural selection that strengthens reproductive isolation between incipient species, remains controversial. We used two approaches to test for reinforcement in a species radiation of Neotropical gingers in the genus Costus. First, we conducted an intensive study of Costus pulverulentus and Costus scaber, two recently diverged species that co-occur and share hummingbird pollinators. The hummingbird pollinators transfer pollen between these Costus species, but hybrids are rarely found in nature. By performing pollinations between populations of C. pulverulentus and C. scaber from three sites across the species' geographic ranges, we find that pollen-pistil incompatibilities acting prior to fertilization have evolved only between locally sympatric populations, whereas geographically distant populations within the region of sympatry and allopatric populations remain fully interfertile. Second, we conducted a comparative study of isolating mechanisms across the genus. We find lower seed set due to pollen-pistil incompatibility between species pairs that co-occur and experience pollen transfer in nature compared to species pairs that are otherwise isolated, regardless of genetic distance. Taken together, these studies indicate that crossing barriers prevent potentially maladaptive hybridization and effectively reinforce the speciation process. Our results add to mounting evidence for reinforcement from animal studies and show that plant speciation may also involve complex mate recognition systems. Reinforcement may be particularly important in rapidly diverging lineages where ecological factors play a primary role in reproductive isolation, as may often be the case in tropical communities.
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Affiliation(s)
- Kathleen M Kay
- Department of Plant Biology, 166 Plant Biology Building, Michigan State University, East Lansing, Michigan 48824, USA.
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128
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Andrés JA, Maroja LS, Harrison RG. Searching for candidate speciation genes using a proteomic approach: seminal proteins in field crickets. Proc Biol Sci 2008; 275:1975-83. [PMID: 18495616 PMCID: PMC2596363 DOI: 10.1098/rspb.2008.0423] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 04/22/2008] [Accepted: 04/24/2008] [Indexed: 11/12/2022] Open
Abstract
In many animals, male seminal proteins influence gamete interactions and fertilization ability and are probably involved in barriers to gene flow between diverging lineages. Here we use a proteomic approach to identify seminal proteins that are transferred to females during copulation and that may be involved in fertilization barriers between two hybridizing field crickets (Gryllus firmus and Gryllus pennsylvanicus). Analyses of patterns of divergence suggest that much of the field cricket genome has remained undifferentiated following the evolution of reproductive isolation. By contrast, seminal protein genes are highly differentiated. Tests of selection reveal that positive selection is likely to be responsible for patterns of differentiation. Together, our observations suggest that some of the loci encoding seminal proteins may indeed play a role in fertilization barriers in field crickets.
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Affiliation(s)
- Jose A Andrés
- Department of Ecology and Evolutionary Biology, Cornell UniversityIthaca, NY 14853, USA
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129
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Gröning J, Hochkirch A. Reproductive Interference Between Animal Species. QUARTERLY REVIEW OF BIOLOGY 2008; 83:257-82. [PMID: 18792662 DOI: 10.1086/590510] [Citation(s) in RCA: 358] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Julia Gröning
- University of Osnabrück, Department of Biology/Chemistry, Division of Ecology, D-49076 Osnabrück, Germany.
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130
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Prokupek A, Hoffmann F, Eyun SI, Moriyama E, Zhou M, Harshman L. An evolutionary expressed sequence tag analysis of Drosophila spermatheca genes. Evolution 2008; 62:2936-47. [PMID: 18752616 DOI: 10.1111/j.1558-5646.2008.00493.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study investigates genes enriched for expression in the spermatheca, the long-term sperm storage organ (SSO) of female Drosophila. SSO genes are likely to play an important role in processes of sexual selection such as sperm competition and cryptic female choice. Although there is keen interest in the mechanisms of sexual selection at the molecular level, very little is known about the female genes that are involved. In the present study, a high proportion of genes enriched for expression in the spermatheca are evolving rapidly. Most of the rapidly evolving genes are proteases and genes of unknown function that could play a specialized role in the spermatheca. A high percentage of the rapidly evolving genes have secretion signals and thus could encode proteins that directly interact with ejaculate proteins and coevolve with them. In addition to identifying rapidly evolving genes, the present study documents categories of genes that could play a role in spermatheca function such as storing, maintaining, and utilizing sperm. In general, candidate genes discovered in this study could play a key role in sperm competition, cryptic female choice of sperm, and sexually antagonistic coevolution, and ultimately speciation.
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Affiliation(s)
- Adrianne Prokupek
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA.
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131
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Lee CB, Page LE, McClure BA, Holtsford TP. Post-pollination hybridization barriers in Nicotiana section Alatae. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-008-0077-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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132
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Civetta A, Rosing KR, Fisher JH. Differences in sperm competition and sperm competition avoidance in Drosophila melanogaster. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2007.10.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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133
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SHERMAN CRAIGDH, WAPSTRA ERIK, ULLER TOBIAS, OLSSON MATS. Male and female effects on fertilization success and offspring viability in the Peron's tree frog, Litoria peronii. AUSTRAL ECOL 2008. [DOI: 10.1111/j.1442-9993.2007.01823.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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134
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Bjork A, Starmer WT, Higginson DM, Rhodes CJ, Pitnick S. Complex interactions with females and rival males limit the evolution of sperm offence and defence. Proc Biol Sci 2008; 274:1779-88. [PMID: 17507332 PMCID: PMC2493577 DOI: 10.1098/rspb.2007.0293] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Postcopulatory sexual selection favours males which are strong offensive and defensive sperm competitors. As a means of identifying component traits comprising each strategy, we used an experimental evolution approach. Separate populations of Drosophila melanogaster were selected for enhanced sperm offence and defence. Despite using a large outbred population and evidence of substantive genetic variation for each strategy, neither trait responded to selection in the two replicates of this experiment. Recent work with fixed chromosome lines of D. melanogaster suggests that complex genotypic interactions between females and competing males contribute to the maintenance of this variation. To determine whether such interactions could explain our lack of response to selection on sperm offence and defence, we quantified sperm precedence across multiple sperm competition bouts using an outbred D. melanogaster population exhibiting continuous genetic variation. Both offensive and defensive sperm competitive abilities were found to be significantly repeatable only across matings involving ejaculates of the same pair of males competing within the same female. These repeatabilities decreased when the rival male stayed the same but the female changed, and they disappeared when both the rival male and the female changed. Our results are discussed with a focus on the complex nature of sperm precedence and the maintenance of genetic variation in ejaculate characteristics.
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Affiliation(s)
- Adam Bjork
- Department of Biology, Syracuse University, 108 College Place, Syracuse, NY 13244-1270, USA.
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135
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Slaughter C, McCartney MA, Yund PO. Comparison of gamete compatibility between two blue mussel species in sympatry and in allopatry. THE BIOLOGICAL BULLETIN 2008; 214:57-66. [PMID: 18258776 DOI: 10.2307/25066660] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Recent demonstrations of positive selection on genes controlling gamete compatibility have resulted in a proliferation of hypotheses concerning the sources of selection. We tested a prediction of one prominent hypothesis, selection to avoid hybridization (i.e., reinforcement), by comparing heterospecific gamete compatibility in two Mytilus edulis populations: one population in Cobscook Bay, Maine, in which the close congener, M. trossulus, is abundant (a region of sympatry), and one population in Kittery, Maine, in which M. trossulus is absent (a region of allopatry). Three diagnostic nuclear DNA markers were used to identify mussels to species and to estimate the frequency of both species and their hybrids in the two populations. Controlled crosses were then conducted by combining eggs of M. edulis females with a range of M.edulis and M. trossulus sperm concentrations. Results were not consistent with the reinforcement hypothesis. M. edulis females collected from the region of sympatry were no more incompatible with M. trossulus males than were M. edulis females collected from the region of allopatry. A trend in the opposite direction, toward greater compatibility in sympatry, suggests that introgression of M. trossulus genes that control egg compatibility, such as those encoding receptors for sperm, may influence evolution of gametic isolation in hybridizing populations.
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Affiliation(s)
- Christin Slaughter
- Department of Biological Sciences, Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin Moss Lane, Wilmington, North Carolina 28409, USA.
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136
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Interspecific and intraspecific comparisons of ejaculates in the cotton bollworm Helicoverpa armigera and the tobacco budworm H. assulta. J ETHOL 2008. [DOI: 10.1007/s10164-007-0076-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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137
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138
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Zeh JA, Zeh DW. Mate Choice by Non-Virgin Females Contributes to Reproductive Isolation between Populations of the Harlequin Beetle-Riding Pseudoscorpion. Ethology 2007. [DOI: 10.1111/j.1439-0310.2007.01432.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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139
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140
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DOWLING DK, FRIBERG U, ARNQVIST G. A comparison of nuclear and cytoplasmic genetic effects on sperm competitiveness and female remating in a seed beetle. J Evol Biol 2007; 20:2113-25. [DOI: 10.1111/j.1420-9101.2007.01433.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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141
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Svensson EI, Karlsson K, Friberg M, Eroukhmanoff F. Gender Differences in Species Recognition and the Evolution of Asymmetric Sexual Isolation. Curr Biol 2007; 17:1943-7. [DOI: 10.1016/j.cub.2007.09.038] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 08/16/2007] [Accepted: 09/17/2007] [Indexed: 10/22/2022]
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142
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Snook RR, Chapman T, Moore PJ, Wedell N, Crudgington HS. Interactions between the sexes: new perspectives on sexual selection and reproductive isolation. Evol Ecol 2007. [DOI: 10.1007/s10682-007-9215-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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143
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Mendelson TC, Imhoff VE, Venditti JJ. The accumulation of reproductive barriers during speciation: postmating barriers in two behaviorally isolated species of darters (Percidae: Etheostoma). Evolution 2007; 61:2596-606. [PMID: 17894811 DOI: 10.1111/j.1558-5646.2007.00220.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Identifying the manner in which reproductive barriers accumulate during lineage divergence is central to establishing general principles of species formation. One outstanding question is which isolating mechanisms form the first complete barrier to gene flow in a given lineage or under a particular set of conditions. To identify these initial reproductive barriers requires examining lineages in very early stages of divergence, before multiple reproductive barriers have evolved to completion. We quantified the strength of three postmating barriers in a pair of darter species and compared these estimates to each other and to the strength of behavioral isolation (BI) reported in a previous study. Results reveal no evidence of gametic incompatibility but intermediate levels of conspecific sperm precedence and hybrid inviability. As BI is nearly complete, our analysis comparing the strength of multiple reproductive barriers implicates the evolution of mate choice as central to both the origin and maintenance of these species. Further examination of ecological isolation and hybrid sterility is necessary to determine the role of these barriers in darter speciation.
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Affiliation(s)
- Tamra C Mendelson
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA.
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144
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ENGQVIST L. Genetic variance and genotype reaction norms in response to larval food manipulation for a trait important in scorpionfly sperm competition. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01336.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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145
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Abstract
Conspecific gamete precedence, the usage of conspecific sperm by a female that mates with both a conspecific and a heterospecific male, has been found in many taxa. We construct a population genetic model to examine the evolution of conspecific gamete precedence and its coevolution with premating isolation in the process of reinforcement. Our findings suggest that conspecific gamete precedence can evolve via a process very similar to reinforcement. We explore the nature of the selection against hybridization necessary to drive this evolution. Moreover, our results confirm the prediction of Marshall et al. (Trends Ecol. Evol. 2002;17:558-563) that conspecific gamete precedence will inhibit the evolution of reinforcement between two species. We further find that reinforcement will inhibit the evolution of conspecific gamete precedence. Both reinforcement and conspecific gamete precedence increase reproductive isolation and contribute to the process of speciation. We discuss factors that may affect which of these phenomena are likely to become predominant between incipient species.
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Affiliation(s)
- P D Lorch
- Biology Department, University of North Carolina, Chapel Hill, NC, USA.
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146
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Rugman-Jones PF, Eady PE. Conspecific sperm precedence in Callosobruchus subinnotatus (Coleoptera: Bruchidae): mechanisms and consequences. Proc Biol Sci 2007; 274:983-8. [PMID: 17251102 PMCID: PMC2141677 DOI: 10.1098/rspb.2006.0343] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Conspecific sperm precedence (CSP) has been identified as an important post-copulatory, pre-zygotic mechanism that can act to reduce gene flow between populations. The evolution of CSP is thought to have arisen as a by-product of male and female coevolution in response to intraspecific post-copulatory sexual selection. However, little is known about the mechanisms that generate CSP. When Callosobruchus subinnotatus females copulate with both C. subinnotatus and Callosobruchus maculatus males, regardless of mating order, the majority of eggs are fertilized by conspecific sperm. The low number of heterospecific fertilizations does not result from general differences in the viability of sperm in the female reproductive tract, as heterospecific sperm fertilized equivalent numbers of eggs as conspecific sperm in the absence of sperm competition. Instead, CSP results from disadvantages to heterospecific sperm that are manifest only when in competition with conspecific sperm. CSP in C. subinnotatus appears to result from two, not mutually exclusive, mechanisms. First, conspecific sperm are better able to displace heterospecific sperm from female storage. Second, conspecific sperm achieve disproportionately higher numbers of fertilizations relative to their proportional representation in the fertilization set. Thus, we provide evidence of differential sperm use from the female spermatheca.
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147
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Levitan DR, Fukami H, Jara J, Kline D, McGovern TM, McGhee KE, Swanson CA, Knowlton N. MECHANISMS OF REPRODUCTIVE ISOLATION AMONG SYMPATRIC BROADCAST-SPAWNING CORALS OF THE MONTASTRAEA ANNULARIS SPECIES COMPLEX. Evolution 2007. [DOI: 10.1111/j.0014-3820.2004.tb01647.x] [Citation(s) in RCA: 176] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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148
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Britch SC, Swartout EJ, Hampton DD, Draney ML, Chu J, Marshall JL, Howard DJ. Genetic architecture of conspecific sperm precedence in Allonemobius fasciatus and A. socius. Genetics 2007; 176:1209-22. [PMID: 17435237 PMCID: PMC1894585 DOI: 10.1534/genetics.106.064949] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The evolution of barriers to gene exchange is centrally important to speciation. We used the crickets Allonemobius fasciatus and A. socius to investigate the genetic architecture of conspecific sperm precedence (CSP), a postinsemination prezygotic reproductive barrier. With amplified fragment-length polymorphism (AFLP) markers and controlled crosses we constructed linkage maps and estimated positions of QTL associated with CSP. The majority of QTL have low to moderate effects, although a few QTL exist in A. socius with large effects, and the numbers of QTL are comparable to numbers of genes accounting for species differences in other studies. The QTL are spread across many unlinked markers, yet QTL placed with linked markers are on a small number of linkage groups that could reflect the role of the large Allonemobius sex chromosome in prezygotic isolation. Although many QTL had positive effects on conspecific sperm utilization several QTL also exerted negative effects, which could be explained by intraspecific sexual conflict, sperm competition, or epistasis of introgressed genes on novel backgrounds. One unexpected outcome was that A. socius CSP alleles have a stronger effect than those from A. fasciatus in hybrid females, causing hybrids to behave like A. socius with regard to sperm utilization. Implications of this asymmetry in the Allonemobius hybrid zone are discussed.
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Affiliation(s)
- Seth C Britch
- Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003, USA.
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149
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Kempenaers B. Mate Choice and Genetic Quality: A Review of the Heterozygosity Theory. ADVANCES IN THE STUDY OF BEHAVIOR 2007. [DOI: 10.1016/s0065-3454(07)37005-8] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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150
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Sinervo B, Calsbeek R. The Developmental, Physiological, Neural, and Genetical Causes and Consequences of Frequency-Dependent Selection in the Wild. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2006. [DOI: 10.1146/annurev.ecolsys.37.091305.110128] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We outline roles of frequency-dependent selection (FDS) in coadaptation and coevolutionary change. Coadaptation and coevolution occur because correlational selection (CS) and correlated evolution couple many traits. CS arises from causal interactions between traits expressed in two or more interactors, which invariably involve different traits (signalers-receivers). Thus, the causes of CS are due to FDS acting on trait interactions. Negative FDS, a rare advantage, is often coupled to positive FDS generating complex dynamics and FD cycles. Neural mechanisms of learning and perception create analogous routes by which traits are reinforced in cognitive and perceptual systems of interactors, substituting for positive FDS. FDS across all levels of biological organization is thus best understood as proximate causes that link interactors and shape genetic correlations within and among interactors on long timescales, or cognitive trait correlations within interactors on short timescales. We find rock-paper-scissors dynamics are common in nature.
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Affiliation(s)
- Barry Sinervo
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95064
| | - Ryan Calsbeek
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, 03755
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