Biomedical subjects

C Kvarnemo

Publications and source records attributed to C Kvarnemo.

6 recordsLinked to original sources

PubMed2001

How cuckoldry can decrease the opportunity for sexual selection: data and theory from a genetic parentage analysis of the sand goby, Pomatoschistus minutus.

Alternative mating strategies are common in nature and are generally thought to increase the intensity of sexual selection. However, cuckoldry can theoretically decrease the opportunity for sexual selection, particularly in highly polygamous species. We address here the influence of sneaking (fertilization thievery) on the opportunity for sexual selection in the sand goby Pomatoschistus minutus, a marine fish species in which males build and defend nests. Our microsatellite-based analysis of the mating system in a natural sand goby population shows high rates of sneaking and multiple mating by males. Sneaker males had fertilized eggs in approximately 50% of the assayed nests, and multiple sneakers sometimes fertilized eggs from a single female. Successful males had received eggs from 2 to 6 females per nest (mean = 3.4). We developed a simple mathematical model showing that sneaking in this polygynous sand goby population almost certainly decreases the opportunity for sexual selection, an outcome that contrasts with the usual effects of cuckoldry in socially monogamous animals. These results highlight a more complex and interesting relationship between cuckoldry rates and the intensity of sexual selection than previously assumed in much of the literature on animal mating systems.

Animals↗

PubMed2001

Surprising similarity of sneaking rates and genetic mating patterns in two populations of sand goby experiencing disparate sexual selection regimes.

Molecular markers have proved extremely useful in resolving mating patterns within individual populations of a number of species, but little is known about how genetic mating systems might vary geographically within a species. Here we use microsatellite markers to compare patterns of sneaked fertilization and mating success in two populations of sand goby (Pomatoschistus minutus) that differ dramatically with respect to nest-site density and the documented nature and intensity of sexual selection. At the Tvärminne site in the Baltic Sea, the microsatellite genotypes of 17 nest-tending males and mean samples of more than 50 progeny per nest indicated that approximately 35% of the nests contained eggs that had been fertilized by sneaker males. Successful nest holders mated with an average of 3.0 females, and the distribution of mate numbers for these males did not differ significantly from the Poisson expectation. These genetically deduced mating-system parameters in the Tvärminne population are remarkably similar to those in sand gobies at a distant site adjoining the North Sea. Thus, pronounced differences in the ecological setting and sexual selection regimes in these two populations have not translated into evident differences in cuckoldry rates or other monitored patterns of male mating success. In this case, the ecological setting appears not to be predictive of alternative male mating strategies, a finding of relevance to sexual selection theory.

Animals↗

PubMed1998

Male potential reproductive rate influences mate choice in a bushcricket.

Male bushcrickets, Requena verticalis, provide their mates with a proteinaceous nuptial gift, which functions both as paternal investment in offspring and to ensure sperm transfer. When nutrients are limited, males have a lower potential reproductive rate than females, so the operational sex ratio becomes female biased. Males are then expected to discriminate more in their choice of mate for two reasons: (1) the relatively higher female potential reproductive rate should reduce the costs of rejecting a female; (2) multiple mating by females should increase variance in female mate quality, because of first male sperm precedence. Males are known to discriminate against old females, which are more likely to have mated previously. Our objective in this study was to partition experimentally the influences of male potential reproductive rate (manipulated by diet) and variance in female quality (estimated by age) and to assess their relative influence on the level of mate choice of male bushcrickets. The potential reproductive rate of males had a great impact on their choosiness, whereas variance in female age had no effect. These results support recent theoretical models that predict costs, rather than benefits, will primarily influence the level of mate choice. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1998

Parental behaviour in relation to the occurrence of sneaking in the common goby.

To investigate whether male common gobies, Pomatoschistus microps (Pisces, Gobiidae), treat their offspring differently depending on confidence of paternity, we conducted an experiment in which randomly chosen males either spawned alone with a female, or with a sneaking male present. Males did not treat their brood differently whether they had experienced sneaking or not. Our estimates of parental care, nest defence against potential egg predators and fanning rate were the same for the two treatments. Furthermore, there was no difference in filial cannibalism (eating their own progeny) between males that had been sneaked upon and males that had not. However, nest-guarding males that ate some of their brood had a smaller original brood area than other males. This suggests either an increase in paternal expenditure with increased brood size or a threshold value (absolute brood size or proportion of nest space covered) above which males do not cannibalize eggs. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1998

Parental behaviour in relation to food availability in the common goby.

In the common goby, Pomatoschistus microps (Pisces, Gobiidae), males build nests under mussel shells where they care for the eggs until hatching. To investigate why male common gobies cannibalize their own eggs (filial cannibalism), we conducted a feeding experiment. Males given little food ate from their eggs more often than males given food in excess. However, males given mussel meat in excess did not eat more of their eggs than males fed with both mussel meat in excess and goby eggs. This may suggest that male common gobies cannibalize their eggs to obtain energy rather than essential nutrients lacking in other diets. Moreover, males ate their whole clutch if it was exceptionally small regardless of food treatment, suggesting that males stop investing in their clutch if its reproductive value is less than the cost of guarding it. Thus, whole clutch cannibalism and partial clutch cannibalism seem to be governed by different factors. Furthermore, poorly built nests were associated with starved males, suggesting that nest concealing is costly. There was an association between how well the nest was built and partial clutch filial cannibalism, suggesting that the appearance of the nest may indicate the condition of the male, and thus the risk of filial cannibalism. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1998

Microsatellite evidence for monogamy and sex-biased recombination in the Western Australian seahorse Hippocampus angustus.

Four polymorphic microsatellite loci were used to assess biological parentage of 453 offspring from 15 pregnant males from a natural population of the Western Australian seahorse Hippocampus angustus. Microsatellite genotypes in the progeny arrays were consistent with a monogamous mating system in which both females and males had a single mate during a male brooding period. Multilocus genotypes implicated four females in the adult population sample as contributors of eggs to the broods of collected males, but there was no evidence for multiple mating by females. Based on genotypic data from the progeny arrays, two loci were linked tightly and the recombination rate appeared to be approximately 10-fold higher in females than in males. The utility of linked loci for parentage analyses is discussed.

Animals↗