Papers by Kirsten Klappert
Evolution, Jun 17, 2019
The cost of males should give asexual females an advantage when in competition with sexual female... more The cost of males should give asexual females an advantage when in competition with sexual females. In addition, high-fecundity asexual genotypes should have an advantage over low-fecundity clones, leading to reduction in clonal diversity over time. To evaluate fitness components in a natural population, we measured the annual reproductive rate of individual sexual and asexual female Potamopyrgus antipodarum, a New Zealand freshwater snail, in field enclosures that excluded competitors and predators. We used allozyme genotyping to assign the asexual females to particular clonal genotypes. We found that the most fecund asexual clones had similar or higher fecundity as the top 10 % of sexual families, suggesting that fecundity selection, even without the cost of males, would lead to replacement of the sexual population by clones. Consequently, we expected that the clones with the highest fecundity would dominate the natural population. Counter to this prediction, we found that high annual reproductive rates did not correlate with the frequency of clones in the natural population. When we exposed the same clones to parasites in the laboratory, we found that resistance to infection was positively correlated with the frequency of clones in the population. The correlation between fecundity and parasite resistance was negative, suggesting a trade-off between these two traits. Our results thus suggest that parasite resistance is an important short-term predictor of the success of asexual P. antipodarum in this population.
Behaviour, 2009
Drosophila montana males produce a courtship song that is a prerequisite for mating to occur and ... more Drosophila montana males produce a courtship song that is a prerequisite for mating to occur and which females use to select mates. Here we show that D. montana female responses to courtship song decreased in the presence of high levels of noise within the same frequency band as the courtship song, but not in equivalent noise levels in an adjacent higher frequency band. This suggests that high noise levels overlapping the frequency band of the song impair signal detection, but that a mechanism for frequency filtering exists that reduces the influence of noise in adjacent frequency bands. Although the acoustic environment of this species in the wild is not known, some potential sources of noise are discussed. Nevertheless, our findings show that background noise (biotic or abiotic) within the same frequency band as the courtship song of D. montana can mask it, suggesting that environmental noise might affect mate choice and thereby may influence the evolution of this courtship signalling system.
Evolution, Jun 1, 2007
Understanding the variation within and between populations in important male mating traits and fe... more Understanding the variation within and between populations in important male mating traits and female preferences is crucial to theories concerning the origin of sexual isolation by coevolution or other processes. There have been surprisingly few studies on the extent of variation and covariation within and between populations, especially where the evolutionary relationships between populations are understood. Here we examine variation in female preferences and a sexually selected male song trait, the carrier frequency of the song, within and between populations from different phylogeographic clusters of Drosophila montana. Song is obligatory for successful mating in this species, and both playback and field studies implicate song carrier frequency as the most important parameter in male song. Carrier frequency varied among three recently collected populations from Oulanka (Finland), Vancouver (Canada), and Colorado (central United States), which represent the main phylogeographic groups in D. montana. Males from Colorado had the most distinct song frequency, which did not follow patterns of genetic differentiation. There was considerable variation in preference functions within, and some variation between, populations. Surprisingly, females from three lines from Colorado seem to have preferences disfavoring the extreme male trait found in this population. We discuss sources of selection on male song and female preference.
Journal of Helminthology, Nov 29, 2019
The adult and metacercaria life stages of a new species of the microphallid genus Atriophallophor... more The adult and metacercaria life stages of a new species of the microphallid genus Atriophallophorus Deblock & Rosé, 1964 are described from specimens collected at Lake Alexandrina (South Island, New Zealand). In addition to molecular analyses of ribosomal and mitochondrial genes, metacercariae of Atriophallophorus winterbourni n. sp. from the snail host Potamopyrgus antipodarum (Gray) were grown in vitro to characterise internal and external morphology of adults using light and scanning electron microscopy and histological techniques. A. winterbourni n. sp. is readily distinguishable from A. coxiellae Smith, 1973 by having a different structure of the prostatic chamber, sub-circular and dorsal to genital atrium, rather than cylindrical, fibrous, elongate and placed between the seminal vesicle and the genital atrium. The new species is most similar to A. minutus (Price, 1934) with regards to the prostatic chamber and the morphometric data, but possesses elongate-oval testes and subtriangular ovary rather than oval and transversely-oval in A. minutus. Phylogenetic analyses including sequence data for A. winterbourni n. sp. suggested a congeneric relationship of the new species to a hitherto undescribed metacercariae reported from Australia, both forming a strongly supported clade closely related to Microphallus and Levinseniella. In addition, we provide an amended diagnosis of Atriophallophorus to accommodate the new species and confirm the sinistral interruption of the outer rim of the ventral sucker caused by the protrusion of the dextral parietal atrial scale at the base of the phallus.
Journal of Evolutionary Biology, Mar 1, 2010
Current advances in genetic analysis are opening up our knowledge of the genetics of species diff... more Current advances in genetic analysis are opening up our knowledge of the genetics of species differences, but challenges remain, particularly for out‐bred natural populations. We constructed a microsatellite‐based linkage map for two out‐bred lines of Drosophila montana derived from divergent populations by taking advantage of the Drosophila virilis genome and available cytological maps of both species. Although the placement of markers was quite consistent with cytological predictions, the map indicated large heterogeneity in recombination rates along chromosomes. We also performed a quantitative trait locus (QTL) analysis on a courtship song character (carrier frequency), which differs between populations and is subject to strong sexual selection. Linkage mapping yielded two significant QTLs, which explained 3% and 14% of the variation in carrier frequency, respectively. Interestingly, as in other recent studies of traits which can influence speciation, the strongest QTL mapped to a genomic region partly covered by an inversion polymorphism.
Journal of Evolutionary Biology, Jan 13, 2014
According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones ... more According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones counterbalances the reproductive advantage of asexual lineages, which would otherwise outcompete sexual conspecifics. Such selection on the clonal population is expected to lead to a faster clonal turnover in habitats where selection by parasites is stronger. We tested this prediction by comparing the genetic structure of clonal and sexual populations of freshwater snail Potamopyrgus antipodarum between years 2003 and 2007 in three depth-specific habitats in Lake Alexandrina (South Island, New Zealand). These habitats differ in the risk of infection by castrating trematodes and in the relative proportion of sexual individuals. As predicted, we found that the clonal structure changed significantly in shallow and mid-water habitats, where prevalence of infection was high, but not in the deep habitat, where parasite prevalence was low. Additionally, we found that both clonal diversity and evenness of the asexual population declined in the shallow habitat. In contrast, the genetic structure (based on F-statistics) of the coexisting sexual population did not change, which suggests that the change in the clonal structure cannot be related to genetic changes in the sexual population. Finally, the frequency of sexuals had no effect on the diversity of the sympatric clonal population. Taken together, our results show a more rapid clonal turnover in high-infection habitats, which gives support for the Red Queen hypothesis for sex.
Ecology and Evolution, May 1, 2023
Parasite species that use two or more host species during their life cycle depend on successful t... more Parasite species that use two or more host species during their life cycle depend on successful transmission between these species. These successive host species may have different habitat requirements. For example, one host species may be aquatic while the other is terrestrial. To overcome this complicating factor in transmission, a wide diversity of parasite species have adaptations that alter the habitat preference in one host species to facilitate transmission to the next host species. Two common trematode parasites in New Zealand, Atriophallophorus winterbourni and Notocotylus spp., both have a life cycle with two host species. The aquatic snail Potamopyrgus antipodarum is the intermediate host, from which the parasites require transmission to dabbling ducks or other waterfowl. Of these parasites, A. winterbourni is most frequently found in snails from the shallow‐water margin. This may indicate parasite‐induced movement of infected snails into the foraging habitat of dabbling ducks. To test whether the parasites manipulate the snails to move into shallow water, we stretched tubular mesh cages across depth‐specific ecological habitat zones in a lake. Both infected and healthy snails were released into the cages. After 11 days, significantly higher infection frequencies of A. winterbourni were retrieved from the shallowest end of the cages, while Notocotylus spp. frequencies did not vary with depth. The hypothesis that A. winterbourni induces its snail host to move into the shallow‐water habitat cannot be rejected based on the experimental results. Although further research is needed to address alternative explanations, the depth preference of infected snails may be due to a parasite adaptation that facilitates trophic transmission of parasites to dabbling ducks.
Current Topics in Developmental Biology, 2005
D. montana (a species of the D. virilis group) has spread over the northern hemisphere, populatio... more D. montana (a species of the D. virilis group) has spread over the northern hemisphere, populations from different areas showing both genetic and phenotypic divergence. The males of this species produce an elaborate courtship song, which plays a major role both in species recognition and in intraspecific mate choice. The genetic architecture and physical constraints, as well as the importance of the signal for species recognition, set boundaries within which this signal can vary. Within these limits, courtship song parameters may change, depending on the males&amp;amp;amp;amp;amp;amp;amp;amp;#39; physical condition and on the environment they inhabit. Females are likely to affect song evolution by exerting directional selection toward higher carrier frequencies. Given this complexity, only a comprehensive, multidisciplinary approach, starting with traditional field observation and combining controlled behavioral experiments, biometric measurements, and sophisticated molecular techniques, has the potential of shedding light on the past history and the evolution of this signal, and, eventually, adding to our understanding of the mechanisms, functions, and outcomes of sexual selection in acoustic communication systems.
BMC Evolutionary Biology, 2009
Background: Conflicts of interest between the sexes are increasingly recognized as an engine driv... more Background: Conflicts of interest between the sexes are increasingly recognized as an engine driving the (co-)evolution of reproductive traits. The reproductive behaviour of Drosophila montana suggests the occurrence of sexual conflict over the duration of copulation. During the last stages of copulation, females vigorously attempt to dislodge the mounting male, while males struggle to maintain genital contact and often successfully extend copulations far beyond the females' preferred duration. Results: By preventing female resistance, we show that females make a substantial contribution towards shortening copulations. We staged matings under different sex ratio conditions, and provide evidence that copulation duration is a form of male reproductive investment that responds to the perceived intensity of sperm competition as predicted by game theoretical models. Further, we investigated potential benefits to persistent males, and costs to females coerced into longer matings. While males did not benefit in terms of increased progeny production by protracting copulation, female remating was delayed after long first copulations. Conclusion: Copulation time is a trait subject to sexual conflict. Mating durations exceeding female optima serve males as a form of 'extended mate guarding': by inducing mating refractoriness in the female, a male extends the time over which its sperm is exclusively used to sire progeny and reduces the likelihood of the female being reinseminated by a competitor.
This dataset contains measurements of song traits (means from 3 measurements per individual) for ... more This dataset contains measurements of song traits (means from 3 measurements per individual) for 3 generations of experimental crosses
Acoustic signals often play a significant role in pair formation and in species recognition. Dete... more Acoustic signals often play a significant role in pair formation and in species recognition. Determining the genetic basis of signal divergence will help to understand signal evolution by sexual selection and its role in the speciation process. An earlier study investigated QTL for male courtship song carrier frequency in Drosophila montana using microsatellite markers. We refined this study by adding to the linkage map markers for ten candidate genes known to affect song production in D. melanogaster. We also extended the analyses to additional song characters (pulse train length, pulse number, interpulse interval, pulse length and cycle number). Our results indicate that loci in two different regions of the genome control distinct features of the courtship song. Pulse train traits (pulse train length and pulse number) mapped to the X chromosome, showing significant linkage with the period gene. In contrast, characters related to song pulse properties (pulse length, cycle number and carrier frequency) mapped to the region of chromosome 2 near the candidate gene fruitless, identifying these genes as suitable loci for further investigations. In previous studies, the pulse train traits have been found to vary substantially between Drosophila species, and so are potential species recognition signals, while the pulse traits may be more important in intra-specific mate choice
Allozyme genotypes at 9 loci and ploidy information for Potamopyrgus antipodarum snails from Lake... more Allozyme genotypes at 9 loci and ploidy information for Potamopyrgus antipodarum snails from Lake Alexandrina, New Zealand. Genotypes were obtained with celulose acetate electrophoresis. Ploidy level was assigned based on asymetric banding pattern in heterozygotes. Loci used for assigning ploidy level include: 6PGD, MPI, IDH2, PGM1 and PGM2 (ploidy assignment based on AAT1, AAT2, IDH1 and PEP-D was not reliable). Description of the column headings and abbreviations uded: Data in columns A, B, C, D was not used in the analyses, but can be used to track the sample back to one of the original celulose acetate gels that are stored at the department of Aquatic Ecology, Eawag, Switzerland. A-SNAIL - snail number per sample B-TUBE - eppendorf tube code C-RUN - allozyme genotyping run D-POSITION - position on gel E-YEAR - year sampled F-SITE - sampling site G-HABITAT - habitat where sample was taken (3 depth-related habitats: shallow, mid-water and deep) H-PLOIDY - ploidy level (NA - not available, 0 - homozygote, 2-diploid, 3-triploid) I- SEX_COMMON_RARE - reproductive mode, for clones common or rare (S- sexuals, C-common clones, R-rare clones). A clone was defined as ‘common’ if its frequency among triploid asexuals was above 1.5% in any of the samples (year/site/habitat combination) J-CLONE_ID - Unique clone number K-S - column names are allozyme loci names. Genotypes are coded with a single digit. Loci for which the banding pattern is unreliable for asigning ploidy level are left with 2 alleles for triploid heterozygotes
According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones ... more According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones counterbalances the reproductive advantage of asexual lineages, which would otherwise outcompete sexual conspecifics. Such selection on the clonal population is expected to lead to a faster clonal turnover in habitats where selection by parasites is stronger. We tested this prediction by comparing the genetic structure of clonal and sexual populations of freshwater snail Potamopyrgus antipodarum between years 2003 and 2007 in three depth-specific habitats in Lake Alexandrina (South Island, New Zealand). These habitats differ in the risk of infection by castrating trematodes and in the relative proportion of sexual individuals. As predicted, we found that the clonal structure changed significantly in shallow and mid-water habitats, where prevalence of infection was high, but not in the deep habitat, where parasite prevalence was low. Additionally, we found that both clonal diversity and evenness of the asexual population declined in the shallow habitat. In contrast, the genetic structure (based on F–statistics) of the coexisting sexual population did not change, which suggests that the change in the clonal structure cannot be related to genetic changes in the sexual population. Finally, the frequency of sexuals had no effect on the diversity of the sympatric clonal population. Taken together, our results show a more rapid clonal turnover in high-infection habitats, which gives support for the Red Queen hypothesis for sex
Allozyme genotypes at 9 loci and ploidy information for the 200 Potamopyrgus antipodarum snails f... more Allozyme genotypes at 9 loci and ploidy information for the 200 Potamopyrgus antipodarum snails from Lake Alexandrina, New Zealand, of the random sample collected in 2010 (“background sample”). Genotypes were obtained with cellulose acetate electrophoresis. Ploidy level was assigned based on asymmetric banding pattern in heterozygotes. Loci used for assigning ploidy level include: 6PGD, MPI, IDH2, PGM1 and PGM2 (ploidy assignment based on AAT1, AAT2, IDH1 and PEP-D was not reliable). Descriptions of column headings and abbreviations used: A: SNAIL - snail number. B: PLOIDY - ploidy level (0-homozygote, 2-diploid, 3-triploid, 4-tetraploid). Diploid snails are sexual, and polyploid snails are asexual; homozygotes were included in the sexual group. C: GENOTYPE_ID - The numbers above zero are unique clone numbers. Zeroes indicate genotypes for which unique clone number could not be assigned. Sexual snails are marked as "S". D-L: column names are allozyme loci names. Genotypes are coded with a single digit. Loci for which the banding pattern is unreliable for assigning ploidy level are left with 2 alleles for triploid heterozygotes
The cost of males should give asexual females an advantage when in competition with sexual female... more The cost of males should give asexual females an advantage when in competition with sexual females. In addition, high-fecundity asexual genotypes should have an advantage over low-fecundity clones, leading to reduction in clonal diversity over time. To evaluate fitness components in a natural population, we measured the annual reproductive rate of individual sexual and asexual female Potamopyrgus antipodarum, a New Zealand freshwater snail, in field enclosures that excluded competitors and predators. We used allozyme genotyping to assign the asexual females to particular clonal genotypes. We found that the most fecund asexual clones had similar or higher fecundity as the top 10 % of sexual families, suggesting that fecundity selection, even without the cost of males, would lead to replacement of the sexual population by clones. Consequently, we expected that the clones with the highest fecundity would dominate the natural population. Counter to this prediction, we found that high annual reproductive rates did not correlate with the frequency of clones in the natural population. When we exposed the same clones to parasites in the laboratory, we found that resistance to infection was positively correlated with the frequency of clones in the population. The correlation between fecundity and parasite resistance was negative, suggesting a trade-off between these two traits. Our results thus suggest that parasite resistance is an important short-term predictor of the success of asexual P. antipodarum in this population
Journal of Helminthology, 2019
The adult and metacercaria life stages of a new species of the microphallid genusAtriophallophoru... more The adult and metacercaria life stages of a new species of the microphallid genusAtriophallophorusDeblock & Rosé, 1964 are described from specimens collected at Lake Alexandrina (South Island, New Zealand). In addition to molecular analyses of ribosomal and mitochondrial genes, metacercariae ofAtriophallophorus winterbournin. sp. from the snail hostPotamopyrgus antipodarum(Gray) were grownin vitroto characterize internal and external morphology of adults using light and scanning electron microscopy and histological techniques.Atriophallophorus winterbournin. sp. is readily distinguishable fromAtriophallophorus coxiellaeSmith, 1973 by having a different structure of the prostatic chamber, sub-circular and dorsal to genital atrium, rather than cylindrical, fibrous, elongate and placed between the seminal vesicle and the genital atrium. The new species is most similar toAtriophallophorus minutus(Price, 1934) with regards to the prostatic chamber and the morphometric data, but possesses...
Journal of Evolutionary Biology, 2014
According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones ... more According to the Red Queen hypothesis for sex, parasite-mediated selection against common clones counterbalances the reproductive advantage of asexual lineages, which would otherwise outcompete sexual conspecifics. Such selection on the clonal population is expected to lead to a faster clonal turnover in habitats where selection by parasites is stronger. We tested this prediction by comparing the genetic structure of clonal and sexual populations of freshwater snail Potamopyrgus antipodarum between years 2003 and 2007 in three depth-specific habitats in Lake Alexandrina (South Island, New Zealand). These habitats differ in the risk of infection by castrating trematodes and in the relative proportion of sexual individuals. As predicted, we found that the clonal structure changed significantly in shallow and mid-water habitats, where prevalence of infection was high, but not in the deep habitat, where parasite prevalence was low. Additionally, we found that both clonal diversity and evenness of the asexual population declined in the shallow habitat. In contrast, the genetic structure (based on F-statistics) of the coexisting sexual population did not change, which suggests that the change in the clonal structure cannot be related to genetic changes in the sexual population. Finally, the frequency of sexuals had no effect on the diversity of the sympatric clonal population. Taken together, our results show a more rapid clonal turnover in high-infection habitats, which gives support for the Red Queen hypothesis for sex.
Infection status of individual Potamopyrgus antipodarum snails in the laboratory infection experi... more Infection status of individual Potamopyrgus antipodarum snails in the laboratory infection experiments of 2009 and 2011. Descriptions of column headings and abbreviations used: A: SNAIL - individual snail number. B: DATASET - "I2009"- infection experiment of 2009, "I2011"- infection experiment of 2011. C: YEAR - 2009, 2011. D: TREATMENT: "alex" - parasite source from Lake Alexandrina, "control" - control for parasite exposure. E: HABITAT: Lake Alexandrina habitat zone from which the snails were sampled. F: REP: Replicate number. In 2009 the experimental snails were exposed in 2 trays, and control snails in 2 trays. In 2011 the experimental snails were exposed in 6 trays and control snails in 2 trays; the control snails were combined into one tray before terminating the experiment. G: LENGTH: Snail length [mm]. H: SEX: Snail sex: "F"- female, "M"- male. I: MIC: Microphallus sp. infection: "1"- present, "0"- absent. J: PLOIDY - 2- diploid, 3- triploid. K: GENOTYPE_ID - The numbers above zero are unique clone numbers. Zeroes indicate genotypes for which unique clone number could not be assigned. Sexual snails are marked as "S"
Evolutionary Ecology Research, 2002
To determine the influence of dispersal on the expression of immune traits, we conducted a recipr... more To determine the influence of dispersal on the expression of immune traits, we conducted a reciprocal transfer experiment. Chorthippus biguttulus grasshoppers from two populations were released as juveniles into their native and transfer environments. After recapture as adults, we found that an immune trait, the amount of phagocytically active cells, was significantly reduced in the transfer environments. In contrast, adult body mass differed between the two habitats, but was not reduced in the transfer environments. The results suggest that dispersal to a new environment can reduce the expression of immune traits, while otherwise not influencing body condition. One reason for such an effect could be that the parasite community in the foreign environment might be relatively maladapted, which would lead to reduced demands for resource allocation to immune traits.
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Papers by Kirsten Klappert