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Nuptial Gifts (nuptial + gift)
Selected AbstractsNUPTIAL GIFTS AND THE EVOLUTION OF MALE BODY SIZEEVOLUTION, Issue 3 2002Kenneth M. Fedorka Abstract In many insect systems, males donate nuptial gifts to insure an effective copulation or as a form of paternal investment. However, if gift magnitude is both body size-limited and positively related to fitness, then the opportunity exists for the gift to promote the evolution of large male size. In the striped ground cricket, Allonemobius socius, males transfer a body size-limited, somatic nuptial gift that is comprised primarily of hemolymph. To address the implications of this gift on male size evolution, we quantified the intensity and direction of natural (fecundity) and sexual (mating success) selection over multiple generations. We found that male size was under strong positive sexual selection throughout the breeding season. This pattern of selection was similar in successive generations spanning multiple years. Male size was also under strong natural selection, with the largest males siring the most offspring. However, multivariate selection gradients indicated that gift size, and not male size, was the best predictor of female fecundity. In other words, direct fecundity selection for larger gifts placed indirect positive selection on male body size, supporting the hypothesis that nuptial gifts can influence the evolution of male body size in this system. Although female size was also under strong selection due to a size related fecundity advantage, it did not exceed selection on male size. The implications of these results with regard to the maintenance of the female-biased size dimorphic system are discussed. [source] Sexual dimorphism in chelicerae size in three species of nuptial-gift spiders: a discussion of possible functions and driving selective forcesJOURNAL OF ZOOLOGY, Issue 3 2008L. E. Costa-Schmidt Abstract Positive allometric patterns observed for intersexual signalling characters are related to directional sexual selection, and supported by theoretical and empirical data. Recent models have shown that positive allometry may not hold as a rule if the influence of natural selection is added to the model. Here we tested these models applying traditional morphometrical techniques for the analysis of chelicerae sexual dimorphism and allometric patterns within the genus Paratrechalea: Paratrechalea azul, Paratrechalea galianoae and Paratrechalea ornata. Spider chelicerae are basically used for prey capture, but males of Paratrechalea also use the chelicerae to offer a nuptial gift during courtship, also presenting a clear size and colour sexual dimorphism supporting a possible role as a signal. Chelicerae size was male biased for all the variables studied and showed an isometric pattern, while females showed a higher variation. Our findings are in accordance with models of viability-related function for prey capture, questioning some statements proposed by the positive allometry model. [source] Nuptial food gifts influence female egg production in the scorpionfly Panorpa cognataECOLOGICAL ENTOMOLOGY, Issue 3 2007LEIF ENGQVIST Abstract 1.,Before copulation, male Panorpa cognata scorpionflies offer females a salivary secretion, which is consumed by the female during copulation. It has previously been demonstrated that this nuptial food gift functions as mating effort by increasing male attractiveness and by increasing ejaculate transfer during copulation. 2.,In this study, the effect of saliva consumption on female reproductive output was investigated, and thus the possibility that nuptial food gifts also serve as paternal investment. The experimental design enabled the effect of nuptial gift consumption to be disentangled from other possible effects of multiple mating or increased copula duration. 3.,The results showed that saliva consumption increases female egg production by on average 8% (4.5 eggs) per consumed salivary mass, whereas mean egg weight was not influenced.4. These results have important implications for the evolution and maintenance of both male nuptial gifts and female polyandry in this and other species. [source] GENETIC VARIATION IN MALE EFFECTS ON FEMALE REPRODUCTION AND THE GENETIC COVARIANCE BETWEEN THE SEXESEVOLUTION, Issue 6 2003MARY ELLEN CZESAK Abstract., Males of many insect species increase the fecundity and/or egg size of their mates through the amount or composition of their nuptial gifts or ejaculate. The genetic bases of such male effects on fecundity or egg size are generally unknown, and thus their ability to evolve remains speculative. Likewise, the genetic relationship between male and female investment into reproduction in dioecious species, which is expected to be positive if effects on fecundity are controlled by at least some of the same genes in males and females, is also unknown. Males of the seed beetle Stator limbatus contribute large ejaculates to females during mating, and the amount of donated ejaculate is positively correlated with male body mass. Females mated to large males lay more eggs in their lifetime than females mated to small males. We describe an experiment in which we quantify genetic variation in the number of eggs sired by males (mated to a single female) and found that a significant proportion of the phenotypic variance in the number of eggs sired by males was explained by their genotype. Additionally, the number of eggs sired by a male was highly positively genetically correlated with his body mass. The between-sex genetic correlation, that is, the genetic correlation between the number of eggs sired by males and the number of eggs laid by females, was highly positive when eggs were laid on Acacia greggii seeds. This indicates that males that sire many eggs have sisters that lay many eggs. Thus, some of the genes that control male ejaculate size (or some other fecundity-enhancing factor) when expressed in males appear to control fecundity when expressed in females. We found no significant interaction between male and female genotype on fecundity. [source] NUPTIAL GIFTS AND THE EVOLUTION OF MALE BODY SIZEEVOLUTION, Issue 3 2002Kenneth M. Fedorka Abstract In many insect systems, males donate nuptial gifts to insure an effective copulation or as a form of paternal investment. However, if gift magnitude is both body size-limited and positively related to fitness, then the opportunity exists for the gift to promote the evolution of large male size. In the striped ground cricket, Allonemobius socius, males transfer a body size-limited, somatic nuptial gift that is comprised primarily of hemolymph. To address the implications of this gift on male size evolution, we quantified the intensity and direction of natural (fecundity) and sexual (mating success) selection over multiple generations. We found that male size was under strong positive sexual selection throughout the breeding season. This pattern of selection was similar in successive generations spanning multiple years. Male size was also under strong natural selection, with the largest males siring the most offspring. However, multivariate selection gradients indicated that gift size, and not male size, was the best predictor of female fecundity. In other words, direct fecundity selection for larger gifts placed indirect positive selection on male body size, supporting the hypothesis that nuptial gifts can influence the evolution of male body size in this system. Although female size was also under strong selection due to a size related fecundity advantage, it did not exceed selection on male size. The implications of these results with regard to the maintenance of the female-biased size dimorphic system are discussed. [source] Temperature and host species affect nuptial gift size in a seed-feeding beetleFUNCTIONAL ECOLOGY, Issue 6 2006C. W. FOX Summary 1In many insects species, males contribute large nutritional gifts to females during mating, generally as seminal fluids (ejaculates) or spermatophores. These nuptial gifts can affect both male and female fitness, and can mediate selection on male body size. However, it is unclear how environmental variables, such as temperature and diet, affect gift size and the consequences of gift size for male and female fitness. 2We examine how temperature and rearing host affect male nuptial gift size (both total ejaculate size and the proportion of a male's mass allocated to his seminal fluids), and the relationship between gift size and female reproduction, in two populations of the seed-feeding beetle Callosobruchus maculatus. 3Males reared at lower temperature (20 °C) produced substantially larger ejaculates than males reared at higher temperatures (25, 30 and 35 °C). However, males allocated a smaller proportion of their body mass to their ejaculate at the lowest temperature compared with other temperatures. This effect of temperature on male allocation to their ejaculates mirrored the effect of temperature on female body size , male ejaculate size remained a relatively constant proportion of their mate's body mass across temperatures. 4Rearing host also affected male ejaculate size but the magnitude and direction of the host effect differed between populations. 5Rearing temperature affected the relationship between male body mass and ejaculate size. Temperature also affected the relationship between female body mass and fecundity. The relationship between male body mass and ejaculate size was significantly lower when beetles were reared on cowpea than when beetles were reared on azuki or mung. 6We found no evidence that male body size or nuptial gift size affected female fecundity in either population of C. maculatus. We thus propose that the effect of nuptial gift size on male fitness is through a reduction in female mating frequency and thus increased paternity for males producing larger nuptial gifts. [source] | ||||||||||