Size-assortative Pairing Research Articles

Influence of Microphallus hoffmanni (Trematoda, Microphallidae) on the survival, sexual selection, and fecundity of Gammarus aequicauda (Amphipoda)

We investigated the influence of Microphallus hoffmanni (Trematoda) on the survival, mating success, and fecundity of its intermediate host, Gammarus aequicauda (Amphipoda). Despite the great size of M. hoffmanni metacercariae, the mean parasite abundance and the ratio of the variance to the mean abundance increased with host size, suggesting that accumulation of this parasite had no significant effect on the survival of its host. Size-assortative pairing was significant and we found no evidence of a parasite-mediated reduction in male competitiveness. Fecundity was reduced in infected females. Our results are in contrast to those obtained with helminths that alter the intermediate host's behaviour to favour their transmission to the definitive host.

The influence of prey size and female reproductive state on the courtship of the autumn spider, Metellina segmentata: a field experiment

Abstract. Factors affecting courtship and mating behaviour in the common European orb-weaving autumn spider, Metellina segmentata, were examined in a field experiment. Males of this species wait on the edge of a web for the resident female to capture a prey item before entering the web to initiate courtship. Males on webs provided with large prey items (naturally occurring tipulids) exhibited more courtship behaviour and were more successful in gaining copulations than those on webs provided with small prey items. The differential success of these males was due to differences in female prey capture and retention or removal of the prey item from the web. Female reproductive state also influenced male courtship and mating behaviour. Males courted and copulated with more fecund females, perhaps as a result of these females' willingness to mate. Courtship duration and female egg load were correlated negatively and copulation duration positively with female size. Causal and functional aspects of the use of prey in this species are examined. In addition, size-assortative pairing and aspects of mate choice are discussed.

Predation Risk Affects Mate Choice in a Gobiid Fish

Predation Risk Affects Mate Choice in a Gobiid Fish

Assortative mating in the dune beetle Erodius sauditus (Tenebrionidae: Erodiini) in Kuwait

The dune beetle Erodius sauditus is a common inhabitant of the sand dunes of gullies of the Jal Az Zor escarpment in Kuwait. The mating behaviour of this short-lived, univoltine species was studied between March and May 1989. Females were larger than males but less common in the population. Paired females were larger than average while paired males were not. However, successfully copulating males were larger than those in non-copulating pairs. Copulating pairs were not interrupted by other individuals and positive size assortative mating was only found among copulating pairs for the second of two collections made during the breeding season. No size assortative pairing was found for non-copulating pairs in either collection. The contradictory findings for assortative mating may be explicable in terms of the general population decline and the egg-carrying capacity of the females.

Mate choice and size assortative pairing by the cichlid fishes of Lake Jiloá, Nicaragua

Size‐assortative mating occurs for all six substratum‐spawning cichlids studied in Lake Jiloá, Nicaragua. Mate quality is clearly a dominant consideration for both sexes, as larger pairs had disproportionately more young surviving beyond 3 weeks. Mating with the largest available mate should generally be advantageous to both sexes, since the success of a pair is dependent on their ability to take and defend a territory. A model involving mate discrimination by both partners is developed and contrasted to models involving single sex discrimination with intrasexual competition.

Male breeding behaviour and mate acquisition in the Common toad, Bufo bufo

The breeding behaviour of a Common toad (Bufo bufo) population was studied at a breeding pond on Portland, Dorset. Major toad movements towards the breeding pond occurred on warm, wet nights when the temperature did not fall below 6°C. Males arrived earlier than females resulting in an initially exaggerated sex ratio which then slowly reduced as the breeding season progressed. No size assortative pairing was found although large males were more successful at mating than small males. Although males demonstrated no ESS (evolutionary stable strategy) in searching for a female between sites within the pond evidence suggesting the existence of one between the pond and an undefined area surrounding it was found.