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Male genitalia are rapidly evolving structures, often driven sexual selection to increase fertilization success. Although sexual selection on females can be strong in systems where males provide offspring care or feed their mates, sometimes resulting in the evolution of female ornamentation, there are no actual estimates of direct sexual selection on female genitalia. In a New Zealand ground weta, Hemiandrus pallitarsis (Orthoptera: Ensifera, Anostostomatidae), females possess a genitalic device (the accessory organ) that is necessary for successful copulation and the acquisition of glandular food-gifts from males. These nutritious gifts are known to result in sexual competition among females in other ensiferan species. In ground weta, the gifts are probably important in avoiding starvation during a months-long period when caring for (their lifetime production of) eggs and offspring. Here, we test the hypothesis that the accessory organ is a sexually selected device in H. pallitarsis by measuring the female Bateman gradient and directional sexual selection on the accessory organ. Using newly developed and characterized microsatellite loci, we analyze offspring and/or stored sperm to estimate female mating frequency for the rst time in ground weta. As predicted, we found positive Bateman gradients for females, and some evidence of directional sexual selection on accessory organ length. Although organ length does not correlate well with female fecundity, it may increase mating success by indicating her condition and thus quality of her offspring care. Signi cance StatementFemale genitalia have largely been studied in the context of exerting selection on males, while the potential for selection on females via mate acquisition or manipulation of males is virtually unstudied.Such selection may be relevant in systems where males make investments in reproduction (offspringcare; mate-feeding), and females are subject to strong sexual selection, occasionally possessing sexual ornaments. Using microsatellite analysis of offspring and stored sperm to estimate mating frequency, we provide the rst evidence of directional sexual selection on a female genital device (accessory organ) found in species of maternal care-providing ground weta. In our focal species, Hemiandrus pallitarsis, we found that females with more mates produced more offspring and females with longer accessory organs obtained more mates. These ndings suggest that the female genital device is a secondary sexual trait, although may have additional mechanical functions.
Male genitalia are rapidly evolving structures, often driven sexual selection to increase fertilization success. Although sexual selection on females can be strong in systems where males provide offspring care or feed their mates, sometimes resulting in the evolution of female ornamentation, there are no actual estimates of direct sexual selection on female genitalia. In a New Zealand ground weta, Hemiandrus pallitarsis (Orthoptera: Ensifera, Anostostomatidae), females possess a genitalic device (the accessory organ) that is necessary for successful copulation and the acquisition of glandular food-gifts from males. These nutritious gifts are known to result in sexual competition among females in other ensiferan species. In ground weta, the gifts are probably important in avoiding starvation during a months-long period when caring for (their lifetime production of) eggs and offspring. Here, we test the hypothesis that the accessory organ is a sexually selected device in H. pallitarsis by measuring the female Bateman gradient and directional sexual selection on the accessory organ. Using newly developed and characterized microsatellite loci, we analyze offspring and/or stored sperm to estimate female mating frequency for the rst time in ground weta. As predicted, we found positive Bateman gradients for females, and some evidence of directional sexual selection on accessory organ length. Although organ length does not correlate well with female fecundity, it may increase mating success by indicating her condition and thus quality of her offspring care. Signi cance StatementFemale genitalia have largely been studied in the context of exerting selection on males, while the potential for selection on females via mate acquisition or manipulation of males is virtually unstudied.Such selection may be relevant in systems where males make investments in reproduction (offspringcare; mate-feeding), and females are subject to strong sexual selection, occasionally possessing sexual ornaments. Using microsatellite analysis of offspring and stored sperm to estimate mating frequency, we provide the rst evidence of directional sexual selection on a female genital device (accessory organ) found in species of maternal care-providing ground weta. In our focal species, Hemiandrus pallitarsis, we found that females with more mates produced more offspring and females with longer accessory organs obtained more mates. These ndings suggest that the female genital device is a secondary sexual trait, although may have additional mechanical functions.
Genitalia are rapidly evolving structures, often driven by sexual conflict and/or sexual selection (especially in males) for coercive, attractive, or stimulatory traits that increase fertilization success. In systems where males make large investments in offspring (i.e., paternal care or nuptial gifts) females may be subject to strong sexual selection, sometimes resulting in the evolution of female ornaments or genital adaptations that increase acquisition of mates and/or male goods and services. In Hemiandrus, short-tailed (reduced ovipositor) ground weta, where males feed their mates spermatophylax gifts, females possess a secondary genitalic device (the accessory organ) that is necessary for successful copulation. Females may compete for access to these gifts in order to avoid starvation because following the mating season, they enter a months-long maternal care period without eating. Thus, the accessory organ may be a sexually selected device involved in the acquisition of spermatophylax meals. Here, we test this hypothesis in female ground weta Hemiandrus pallitarsis by determining whether an increase in mating frequency (estimated from microsatellite analysis of stored sperm) increases lifetime reproductive success (the Bateman gradient). Additionally, we test if the accessory organ is under directional sexual selection by measuring its relationship with female mating success. As predicted, there was both positive Bateman gradients for females, suggestive of sexual selection, and evidence of directional sexual selection on accessory organ length. Although organ length did not correlate well with female fecundity (eggs in abdomen), it may increase mating success by indicating maternal condition and thus quality of her offspring care.
Ladybird beetles like many other organisms show developmental rate polymorphism in response to various abiotic and biotic factors. Since mating disruption acts as a stressor, we decided to study its impact on the occurrence of developmental rate polymorphs in ladybird beetle, Propylea dissecta Mulsant, 1850 (Coleoptera: Coccinellidae). Ten-day-old females were subjected to mating disruptions at 120, 180 minutes and complete mating (211 + 8.1 minutes) and then provided with optimum diet of Aphis craccivora Koch. Larvae in each treatment were reared individually and newly emerged adults were assessed on the basis of their developmental durations. They were separated into two lines: Slow and Fast developers. Extended mating duration was found to be correlated to increased immature survival and reduced offspring development times. Also, in complete mating treatment percentage of fast developers were more in numbers, thus mating duration increased the availability of sperm for females and seminal fluid may have boosted maternal protein reserves which can then be used to produce offspring of better quality. Mating disruption might be a factor reducing the chances of fertilization success and offspring development in P. dissecta.
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