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Moran NA. PHENOTYPE FIXATION AND GENOTYPIC DIVERSITY IN THE COMPLEX LIFE CYCLE OF THE APHID
PEMPHIGUS BETAE. Evolution 2017; 45:957-970. [DOI: 10.1111/j.1558-5646.1991.tb04363.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/1990] [Accepted: 11/14/1990] [Indexed: 11/29/2022]
Affiliation(s)
- Nancy A. Moran
- Department of Ecology and Evolutionary Biology University of Arizona Tucson AZ 85721 USA
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2
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Lynch M, Pfrender M, Spitze K, Lehman N, Hicks J, Allen D, Latta L, Ottene M, Bogue F, Colbourne J. THE QUANTITATIVE AND MOLECULAR GENETIC ARCHITECTURE OF A SUBDIVIDED SPECIES. Evolution 2017; 53:100-110. [DOI: 10.1111/j.1558-5646.1999.tb05336.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/1998] [Accepted: 10/19/1998] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Lynch
- Department of Biology University of Oregon Eugene Oregon 97403
| | | | - Ken Spitze
- Department of Biology University of Miami Coral Gables Florida 33124
| | - Niles Lehman
- Department of Biological Sciences University at Albany, State University of New York Albany New York 12222
| | - Justin Hicks
- Department of Biology University of Oregon Eugene Oregon 97403
| | - Deborah Allen
- Department of Biology University of Oregon Eugene Oregon 97403
| | - Leigh Latta
- Department of Biology University of Oregon Eugene Oregon 97403
| | - Marcos Ottene
- Department of Biology University of Miami Coral Gables Florida 33124
| | - Farris Bogue
- Department of Biology University of Oregon Eugene Oregon 97403
| | - John Colbourne
- Department of Zoology University of Guelph Guelph Ontario N1G 2W1 Canada
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3
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Spitze K, Burnson J, Lynch M. THE COVARIANCE STRUCTURE OF LIFE-HISTORY CHARACTERS IN DAPHNIA PULEX. Evolution 2017; 45:1081-1090. [PMID: 28564186 DOI: 10.1111/j.1558-5646.1991.tb04376.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/1990] [Accepted: 01/24/1991] [Indexed: 11/27/2022]
Abstract
The genetic covariance structure for life-history characters in two populations of cyclically parthenogenetic Daphnia pulex indicates considerable positive correlation among important fitness components, apparently at odds with the expectation if antagonistic pleiotropy is the dominant cause of the maintanence of genetic variation. Although there is no genetic correlation between offspring size and offspring number, present growth and present reproduction are both strongly positively correlated genetically with future reproduction, and early maturity is genetically correlated with larger clutch size. Although the ubiquity of antagonistic pleiotropy has been recently questioned, there are peculiarities of cyclical parthenogenesis that could lead to positive life-history covariance even when negative covariance would be expected in a similar sexual species. These include the influence of nonadditive gene action on evolution in clonally reproducing organisms, and the periodic release of hidden genetic variance within populations of cyclical parthenogens. Examination of matrix similarity, using the bootstrap for distribution-free hypothesis testing, reveals no evidence to suggest that the genetic covariance matrices differ between the populations. However, there is considerable evidence that the phenotypic and environmental covariance matrices differ between populations. These results indicate approximate stability of the genetic covariance matrix within species, an important assumption of many phenotypic evolution models, but should caution against the use of phenotypic in place of genetic covariance matrices.
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Affiliation(s)
- Ken Spitze
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA
| | - John Burnson
- Department of Ecology, Ethology, and Evolution, University of Illinois at Urbana-Champaign, Urbana, IL, 61820, USA
| | - Michael Lynch
- Department of Biology, University of Oregon, Eugene, OR, 97403, USA
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Spitze K. CHAOBORUS PREDATION AND LIFE-HISTORY EVOLUTION IN DAPHNIA PULEX: TEMPORAL PATTERN OF POPULATION DIVERSITY, FITNESS, AND MEAN LIFE HISTORY. Evolution 2017; 45:82-92. [PMID: 28564082 DOI: 10.1111/j.1558-5646.1991.tb05268.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/1989] [Accepted: 04/23/1990] [Indexed: 12/01/2022]
Abstract
The effect of predation by the aquatic dipteran larva Chaoborus americanus on genetic diversity and life-history evolution in the cladoceran Daphnia pulex was investigated in large replicate laboratory populations. Instantaneous daily loss rates of clonal diversity and genetic variance for fitness indicate that 93-99% of initial genetic diversity can be removed from populations during the 8-12 generations of clonal reproduction that occur each year in natural populations. In the absence of predation, the principal evolved changes in mean population life history were smaller immature body size and increased and earlier fecundity. In the presence of size-selective Chaoborus predation, populations evolved toward larger body size and increased and earlier reproduction. The difference between these two trajectories is an estimate of the direct additive effect of Chaoborus predation. This effect was manifested as evolution toward larger body size with a trend toward earlier and increased reproduction.
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Affiliation(s)
- Ken Spitze
- Department of Ecology, Ethology, and Evolution, University of Illinois, Victor E. Shelford Vivarium, 606 E. Healey, Champaign, IL, 61820, USA
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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.
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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
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6
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Scheiner SM, Berrigan D. THE GENETICS OF PHENOTYPIC PLASTICITY. VIII. THE COST OF PLASTICITY IN DAPHNIA PULEX. Evolution 2017; 52:368-378. [PMID: 28568340 DOI: 10.1111/j.1558-5646.1998.tb01638.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/1997] [Accepted: 01/28/1998] [Indexed: 12/01/2022]
Abstract
In a heterogeneous world, the optimal strategy for an individual is to continually change its phenotype to match the optimal type. However, in the real world, organisms do not behave in this fashion. One potential reason why is that phenotypic plasticity is costly. We measured production and maintenance costs of plasticity in the freshwater crustacean Daphnia pulex (Cladocera: Crustacea) in response to the presence of chemical signals from a predator, the insect Chaoborus americanus. We looked at three changes in juvenile body size and shape: body length, body depth, and tailspine length. Fitness costs were measured as changes in adult growth and fecundity, and summarized as the intrinsic rate of increase (r) for individuals reared in the presence or absence of Chaoborus extract. The cost of plasticity was measured as a multiple regression of mean clone fitness against trait and trait plasticity. We found scant evidence for either production or maintenance costs of plasticity. We also failed to find direct costs of these juvenile structures, which is surprising, as others have found such costs. We attribute the lack of measurable direct or plasticity costs to a decrease in metabolic rates in the presence of the Chaoborus extract. This decrease in metabolic rate may have compensated for any cost increases. We call for more extensive measures of the costs of plasticity, especially under natural conditions, and the incorporation of costs into evolutionary models.
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Affiliation(s)
- Samuel M Scheiner
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, 60115
| | - David Berrigan
- Department of Zoology, University of Washington, Seattle, Washington, 98195
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Weider LJ. A TEST OF THE "GENERAL-PURPOSE" GENOTYPE HYPOTHESIS: DIFFERENTIAL TOLERANCE TO THERMAL AND SALINITY STRESS AMONG DAPHNIA CLONES. Evolution 2017; 47:965-969. [PMID: 28567908 DOI: 10.1111/j.1558-5646.1993.tb01251.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1992] [Accepted: 10/13/1992] [Indexed: 11/29/2022]
Affiliation(s)
- Lawrence J Weider
- Abteilung Ökophysiologie, Max-Planck-Institut für Limnologie, Postfach 165, 24302, Plön, Federal Republic of Germany
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8
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Raborn RT, Spitze K, Brendel VP, Lynch M. Promoter Architecture and Sex-Specific Gene Expression in Daphnia pulex. Genetics 2016; 204:593-612. [PMID: 27585846 PMCID: PMC5068849 DOI: 10.1534/genetics.116.193334] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 07/29/2016] [Indexed: 11/18/2022] Open
Abstract
Large-scale transcription start site (TSS) profiling produces a high-resolution, quantitative picture of transcription initiation and core promoter locations within a genome. However, application of TSS profiling to date has largely been restricted to a small set of prominent model systems. We sought to characterize the cis-regulatory landscape of the water flea Daphnia pulex, an emerging model arthropod that reproduces both asexually (via parthenogenesis) and sexually (via meiosis). We performed Cap Analysis of Gene Expression (CAGE) with RNA isolated from D. pulex within three developmental states: sexual females, asexual females, and males. Identified TSSs were utilized to generate a "Daphnia Promoter Atlas," i.e., a catalog of active promoters across the surveyed states. Analysis of the distribution of promoters revealed evidence for widespread alternative promoter usage in D. pulex, in addition to a prominent fraction of compactly-arranged promoters in divergent orientations. We carried out de novo motif discovery using CAGE-defined TSSs and identified eight candidate core promoter motifs; this collection includes canonical promoter elements (e.g., TATA and Initiator) in addition to others lacking obvious orthologs. A comparison of promoter activities found evidence for considerable state-specific differential gene expression between states. Our work represents the first global definition of transcription initiation and promoter architecture in crustaceans. The Daphnia Promoter Atlas presented here provides a valuable resource for comparative study of cis-regulatory regions in metazoans, as well as for investigations into the circuitries that underpin meiosis and parthenogenesis.
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Affiliation(s)
- R Taylor Raborn
- Department of Biology, Indiana University, Bloomington, Indiana 47405 School of Informatics and Computing, Indiana University, Bloomington, Indiana 47405
| | - Ken Spitze
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Volker P Brendel
- Department of Biology, Indiana University, Bloomington, Indiana 47405 School of Informatics and Computing, Indiana University, Bloomington, Indiana 47405
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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Dudycha JL, Snoke-Smith M, Alía R. Correlated responses to clonal selection in populations of Daphnia pulicaria: mechanisms of genetic correlation and the creative power of sex. Ecol Evol 2013; 3:204-16. [PMID: 23467851 PMCID: PMC3586631 DOI: 10.1002/ece3.444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 10/26/2012] [Accepted: 11/01/2012] [Indexed: 11/10/2022] Open
Abstract
Genetic correlations among traits alter evolutionary trajectories due to indirect selection. Pleiotropy, chance linkage, and selection can all lead to genetic correlations, but have different consequences for phenotypic evolution. We sought to assess the mechanisms contributing to correlations with size at maturity in the cyclic parthenogen Daphnia pulicaria. We selected on size in each of four populations that differ in the frequency of sex, and evaluated correlated responses in a life table. Size at advanced adulthood, reproductive output, and adult growth rate clearly showed greater responses in high-sex populations, with a similar pattern in neonate size and r. This pattern is expected only when trait correlations are favored by selection and the frequency of sex favors the creation and demographic expansion of highly fit clones. Juvenile growth and age at maturity did not diverge consistently. The inter-clutch interval appeared to respond more strongly in low-sex populations, but this was not statistically significant. Our data support the hypothesis that correlated selection is the strongest driver of genetic correlations, and suggest that in organisms with both sexual and asexual reproduction, adaptation can be enhanced by recombination.
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Affiliation(s)
- Jeffry L Dudycha
- Department of Biological Sciences, University of South Carolina Columbia, SC, 29208
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Allen DE, Lynch M. The effect of variable frequency of sexual reproduction on the genetic structure of natural populations of a cyclical parthenogen. Evolution 2012; 66:919-926. [PMID: 22380451 PMCID: PMC4521562 DOI: 10.1111/j.1558-5646.2011.01488.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclical parthenogens are a valuable system in which to empirically test theoretical predictions as to the genetic consequences of sexual reproduction in natural populations, particularly if the frequency of sexual relative to asexual reproduction can be quantified. In this study, we used a series of lake populations of the cyclical parthenogen, Daphnia pulicaria, that vary consistently in their investment in sexual reproduction, to address the questions of whether the ecological variation in investment in sex is detectable at the genetic level, and if so, whether the genetic patterns seen are consistent with theoretical predictions. We show that there is variation in the genetic structure of these populations in a manner consistent with their investment in sexual reproduction. Populations engaging in a high frequency of sex were in Hardy-Weinberg and gametic phase equilibrium, and showed little genotypic differentiation across sampled years. In contrast, populations with a lower frequency of sex deviated widely from equilibrium, had reduced multilocus clonal diversity, and showed significant temporal genotypic deviation.
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Affiliation(s)
- Desiree E Allen
- Department of Biology, Indiana University, Bloomington, Indiana 47405 E-mail:
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana 47405 E-mail:
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11
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Thomas MA, Schötz EM. SAPling: a Scan-Add-Print barcoding database system to label and track asexual organisms. ACTA ACUST UNITED AC 2012; 214:3518-23. [PMID: 21993779 DOI: 10.1242/jeb.059048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have developed a 'Scan-Add-Print' database system, SAPling, to track and monitor asexually reproducing organisms. Using barcodes to uniquely identify each animal, we can record information on the life of the individual in a computerized database containing its entire family tree. SAPling has enabled us to carry out large-scale population dynamics experiments with thousands of planarians and keep track of each individual. The database stores information such as family connections, birth date, division date and generation. We show that SAPling can be easily adapted to other asexually reproducing organisms and has a strong potential for use in large-scale and/or long-term population and senescence studies as well as studies of clonal diversity. The software is platform-independent, designed for reliability and ease of use, and provided open source from our webpage to allow project-specific customization.
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Affiliation(s)
- Michael A Thomas
- 170 Carl Icahn Laboratory, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
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12
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VANOVERBEKE J, DE MEESTER L. Clonal erosion and genetic drift in cyclical parthenogens - the interplay between neutral and selective processes. J Evol Biol 2010; 23:997-1012. [DOI: 10.1111/j.1420-9101.2010.01970.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Cáceres CE, Hartway C, Paczolt KA. Inbreeding depression varies with investment in sex in a facultative parthenogen. Evolution 2009; 63:2474-80. [PMID: 19473400 DOI: 10.1111/j.1558-5646.2009.00707.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reproductive mode of facultative parthenogens allows recessive mutations that accumulate during the asexual phase to be unmasked following sexual reproduction. Longer periods of asexual reproduction should increase the accumulation of deleterious mutations within individuals, reduce population-level genetic diversity via competition and increase the probability of mating among close relatives. Having documented that the investment in sexual reproduction differs among populations and clones of Daphnia pulicaria, we ask if this variation is predictive of the level of inbreeding depression across populations. In four lake populations that vary in sex investment, we raised multiple families (mother, field-produced daughter, laboratory-produced daughter) on high food and estimated the fitness reduction in both sexually produced offspring relative to the maternal genotype. Inbred individuals had lower fitness than their field-produced siblings. The magnitude of fitness reduction in inbred offspring increased as population-level investment in sex decreased. However, there was less of a fitness reduction following sex in the field-produced daughters, suggesting that many field-collected mothers were involved in outcross mating.
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Affiliation(s)
- Carla E Cáceres
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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15
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16
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Wolinska J, Lively CM. The cost of males in Daphnia pulex. OIKOS 2008. [DOI: 10.1111/j.0030-1299.2008.16760.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Both costs and benefits of sex correlate with relative frequency of asexual reproduction in cyclically parthenogenic Daphnia pulicaria populations. Genetics 2008; 179:1497-502. [PMID: 18562659 DOI: 10.1534/genetics.107.082479] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sexual reproduction is generally believed to yield beneficial effects via the expansion of expressed genetic variation, which increases the efficiency of selection and the adaptive potential of a population. However, when nonadditive gene action is involved, sex can actually impede the adaptive progress of a population. If selection promotes coupling disequilibria between genes of similar effect, recombination and segregation can result in a decrease in expressed genetic variance in the offspring population. In addition, when nonadditive gene action underlies a quantitative trait, sex can produce a change in trait means in a direction opposite to that favored by selection. In this study we measured the change in genotypic trait means and genetic variances across a sexual generation in four populations of the cyclical parthenogen Daphnia pulicaria, which vary predictably in their incidence of sexual reproduction. We show that both the costs and benefits of sex, as measured by changes in means and variances in life-history traits, increase substantially with decreasing frequency of sex.
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18
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TAGG NIKKI, DONCASTER CPATRICK, INNES DAVIDJ. Resource competition between genetically varied and genetically uniform populations of Daphnia pulex (Leydig): does sexual reproduction confer a short-term ecological advantage? Biol J Linn Soc Lond 2005. [DOI: 10.1111/j.1095-8312.2005.00475.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tagg N, Innes DJ, Doncaster CP. Outcomes of reciprocal invasions between genetically diverse and genetically uniform populations of Daphnia obtusa (Kurz). Oecologia 2005; 143:527-36. [PMID: 15909133 DOI: 10.1007/s00442-005-0016-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Accepted: 01/19/2005] [Indexed: 10/25/2022]
Abstract
Ecological theory predicts that genetic variation produced by sexual reproduction results in niche diversification and provides a competitive advantage both to facilitate invasion into genetically uniform asexual populations and to withstand invasion by asexual competitors. We tested the hypothesis that a large group of diverse clones of Daphnia obtusa has greater competitive advantage when invading into genetically uniform populations of this species than a smaller group with inherently less genetic diversity. We compared competitive outcomes to those of genetically uniform groups of small and large size invading into genetically diverse populations. Genetically diverse invaders of initially large group size increased their representation by more than those of initially small size; in contrast, genetically uniform invaders of initially large group size diminished on average by more than those of initially small size. These results demonstrate an advantage to the genetic variation produced by sexual reproduction, both in invasion and resisting invasion, which we attribute to competitive release experienced by individuals in genetically diverse populations.
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Affiliation(s)
- N Tagg
- School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, UK
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20
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Van Doninck K, Schön I, Martens K, Backeljau T. Clonal diversity in the ancient asexual ostracod Darwinula stevensoni assessed by RAPD-PCR. Heredity (Edinb) 2005; 93:154-60. [PMID: 15241465 DOI: 10.1038/sj.hdy.6800486] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
As Darwinulidae (Ostracoda) are considered to be ancient asexuals with a wide geographical and ecological distribution, they are expected to have accumulated mutations during a long timeframe. However, previous studies on genetic variability suggested a low genetic divergence within the darwinulid species Darwinula stevensoni. Here, overall genotopic diversity of D. stevensoni is estimated with the Random Amplified Polymorphic DNA (RAPD) technique. Using six primers revealing 47 consistently scorable polymorphic loci, substantial clonal diversity within this species is detected. Five of the seven surveyed populations are multiclonal. Moreover, the seven populations have a different clonal composition with almost all of the observed clonal genotypes being restricted to single populations, indicating the absence of a single widespread 'clone'. The observed clonal diversity seems to refute the existence of a widespread general purpose genotype for D. stevensoni. However, in light of previously detected uniformity at functional loci, we reconsider the definition of a GPG. We suggest that it need not imply a genome-wide fixed genotype, but rather consists of a set of ecologically relevant genes.
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Affiliation(s)
- K Van Doninck
- Freshwater Biology and Malacology Sections, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium.
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21
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Sadler TD, Spitze K. Genetic Variation in Subtropical Populations of Simocephalus (Crustacea:Cladocera). Hereditas 2004. [DOI: 10.1111/j.1601-5223.1995.t01-1-00001.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Jones AG, Arnold SJ, Burger R. EVOLUTION AND STABILITY OF THE G-MATRIX ON A LANDSCAPE WITH A MOVING OPTIMUM. Evolution 2004. [DOI: 10.1554/03-651] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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JOKELA JUKKA, LIVELY CURTISM, DYBDAHL MARKF, FOX JENNIFERA. Genetic variation in sexual and clonal lineages of a freshwater snail. Biol J Linn Soc Lond 2003. [DOI: 10.1046/j.1095-8312.2003.00181.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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SHUFRAN KEVINA, MAYO ZB, CREASE TERESAJ. Genetic changes within an aphid clone: homogenization of rDNA intergenic spacers after insecticide selection. Biol J Linn Soc Lond 2003. [DOI: 10.1046/j.1095-8312.2003.00184.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Sasaki A, Hamilton WD, Ubeda F. Clone mixtures and a pacemaker: new facets of Red-Queen theory and ecology. Proc Biol Sci 2002; 269:761-72. [PMID: 11958707 PMCID: PMC1690956 DOI: 10.1098/rspb.2001.1837] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Host-parasite antagonistic interaction has been proposed as a potential agent to promote genetic polymorphism and to favour sex against asex, despite its twofold cost in reproduction. However, the host-parasite gene-for-gene dynamics often produce unstable cycles that tend to destroy genetic diversity. Here, we examine such diversity destroying coevolutionary dynamics of host and parasite, which is coupled through local or global migration, or both, between demes in a metapopulation structure. We show that, with global migration in the island model, peculiar out-of-phase islands spontaneously arise in the cluster of islands converging to a global synchrony. Such asynchrony induced by the 'pacemaker islands' serves to restore genetic variation. With increasing fraction of local migration, spots of asynchrony are converted into loci or foci of spiral and target patterns, whose rotating arms then cover the majority of demes. A multi-locus analogue of the model reproduces the same tendency toward asynchrony, and the condition arises for an advantage of asexual clones over their sexual counterpart when enough genetic diversity is maintained through metapopulation storage-migration serves as a cheap alternative to sex.
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Affiliation(s)
- A Sasaki
- Department of Biology, Kyushu University, Fukuoka, 812-81 Japan.
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26
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Morgan KK, Hicks J, Spitze K, Latta L, Pfrender ME, Weaver CS, Ottone M, Lynch M. Patterns of genetic architecture for life-history traits and molecular markers in a subdivided species. Evolution 2001; 55:1753-61. [PMID: 11681731 DOI: 10.1111/j.0014-3820.2001.tb00825.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Understanding the utility and limitations of molecular markers for predicting the evolutionary potential of natural populations is important for both evolutionary and conservation genetics. To address this issue, the distribution of genetic variation for quantitative traits and molecular markers is estimated within and among 14 permanent lake populations of Daphnia pulicaria representing two regional groups from Oregon. Estimates of population subdivision for molecular and quantitative traits are concordant, with QST generally exceeding GST. There is no evidence that microsatellites loci are less informative about subdivision for quantitative traits than are allozyme loci. Character-specific comparison of QST and GST support divergent selection pressures among populations for the majority of life-history traits in both coast and mountain regions. The level of within-population variation for molecular markers is uninformative as to the genetic variation maintained for quantitative traits. In D. pulicaria, regional differences in the frequency of sex may contribute to variation in the maintenance of expressed within-population quantitative-genetic variation without substantially impacting diversity at the genic level. These data are compared to an identical dataset for 17 populations of the temporary-pond species, D. pulex.
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Affiliation(s)
- K K Morgan
- Department of Biology, University of Oregon, Eugene 97403, USA.
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Morgan KK, Hicks J, Spitze K, Latta L, Pfrender ME, Weaver CS, Ottone M, Lynch M. PATTERNS OF GENETIC ARCHITECTURE FOR LIFE-HISTORY TRAITS AND MOLECULAR MARKERS IN A SUBDIVIDED SPECIES. Evolution 2001. [DOI: 10.1554/0014-3820(2001)055[1753:pogafl]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Nonadditive genetic variation and genetic disequilibrium are two important factors that influence the evolutionary trajectory of natural populations. We assayed quantitative genetic variation in a temporary-pond-dwelling population of Daphnia pulex over a full season to examine the role of nonadditive genetic variation and genetic disequilibrium in determining the short-term evolutionary trajectory of a cyclic parthenogen. Quantitative traits were influenced by three factors: (1) clonal selection significantly changed the population mean phenotype during the course of the growing season; (2) sexual reproduction and recombination led to significant changes in life-history trait means and the levels of expressed genetic variation, implying the presence of substantial nonadditive genetic variation and genetic disequilibrium; and (3) Egg-bank effects were found to be an important component of the realized year-to-year change. Additionally, we examined the impact of genetic disequilibria induced by clonal selection on the genetic (co)variance structure with a common principal components model. Clonal selection caused significant changes in the (co)variance structure that were eliminated by a single bout of random mating, suggesting that a build-up of disequilibria was the primary source of changes in the (co)variance structure. The results of this study highlight the complexity of natural selection operating on populations that undergo alternating phases of sexual and asexual reproduction.
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Affiliation(s)
- M E Pfrender
- Department of Biology, University of Oregon, Eugene 97403, USA.
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Innes DJ, Fox CJ, Winsor GL. Avoiding the cost of males in obligately asexual Daphnia pulex (Leydig). Proc Biol Sci 2000; 267:991-7. [PMID: 10874748 PMCID: PMC1690637 DOI: 10.1098/rspb.2000.1101] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Asexual organisms are thought to gain an advantage by avoiding the cost of producing males. In the cladoceran Daphnia pulex (Leydig), male production is determined by the environment and is independent of the origin of the asexual obligate parthenogens from the sexual cyclical parthenogens. If there is a cost to producing males, successful obligate parthenogens should have reduced or eliminated male production. Field and laboratory observations showed that obligate parthenogens have much-reduced male production compared to cyclical parthenogens. Although the reduction or elimination of males in the obligate parthenogens suggests that the cost of males is avoided, the coexistence of sexual and asexual forms of D. pulex may be partially explained by cyclical parthenogens compensating for the cost of males by having greater fecundity. In addition, the absence of a mating constraint for the obligate parthenogens may favour an increased allocation to asexual diapausing eggs earlier in the season compared to the cyclical parthenogens which require mating with males to produce sexual diapausing eggs. No difference in the production of diapausing eggs was observed, probably because males were abundant in populations of cyclical parthenogens and do not appear to limit the production of sexual diapausing eggs. D. pulex is a useful system for determining the ecological consequences of abandoning sexual reproduction and explaining the coexistence of sexual and asexual forms of a species.
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Affiliation(s)
- D J Innes
- Department of Biology, Memorial University of Newfoundland, St John's, Canada
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Deng HW. Inferring Deleterious-Mutation Parameters in Natural Daphnia Populations. Biol Proced Online 1998; 1:1-9. [PMID: 12734593 PMCID: PMC140119 DOI: 10.1251/bpo3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/1998] [Revised: 05/07/1998] [Accepted: 05/09/1998] [Indexed: 12/02/2022] Open
Abstract
Deng and Lynch (1, 2) proposed to characterize deleterious genomic mutations from changes in the mean and genetic variance of fitness traits upon selfing in outcrossing populations. Such observations can be readily acquired in cyclical parthenogens. Selfing and life-table experiments were performed for two such Daphnia populations. A significant inbreeding depression and an increase of genetic variance for all traits analyzed were observed. Deng and Lynch's (2) procedures were employed to estimate the genomic mutation rate (U), mean dominance coefficient (), mean selection coefficient (), and scaled genomic mutational variance (). On average, and (^ indicates an estimate) are 0.84, 0.30, 0.14 and 4.6E-4 respectively. For the true values, the and are lower bounds, and and upper bounds.
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Affiliation(s)
- Hong-Wen Deng
- Osteoporosis Research Center and Dept. of Biomedical Sciences, Creighton University. 601 N. 30th St., Suite 6787, Omaha, NE 68131. USA.
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Deng HW. Environmental and genetic control of sexual reproduction in Daphnia. Heredity (Edinb) 1996. [DOI: 10.1038/hdy.1996.67] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Ueno H. Genetic estimations for body size characters, development period and development rate in a coccinelid beetle,Harmonia axyridis. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf02515093] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Genetic diversity and breeding system variation in Daphnia pulicaria from North American lakes. Heredity (Edinb) 1993. [DOI: 10.1038/hdy.1993.168] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Mort MA. Bridging the gap between ecology and genetics: The case of freshwater zooplankton. Trends Ecol Evol 1991; 6:41-5. [DOI: 10.1016/0169-5347(91)90120-m] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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