摘要:

The environment can modulate the reproductive pattern of many arthropods by abiotic factors (e.g. temperature, photoperiod, moisture) or by biotic factors (e.g. male-effect, population structure). In the terrestrial isopodArmadillidium vulgare, reproduction is stimulated by environmental factors (e.g. photoperiod) and by the male's behaviour which plays two roles: first accelerating the onset of female reproduction by stimulating vitellogenesis, then mating with a female before the parturial molting. This study is focussed on the influence of male or female presence on the initiation of reproduction. We conclude that the intermittent presence of a male (1 day in 3, or 1 day a week) was as efficient as a permanent contact. The 4th week of the female preparturial inter-molt was the most sensitive time, since the presence of a male during this week only had as much effect as permanent contact. This particular sensitivity can be explained by the vitellogenesis cycle: a male present when the female is beginning the «D» period of its inter-molt (appearance of white plates) accelerates vitellogenesis. Another main conclusion is that female-female intermittent crowding (1 day in 3) also showed a significant acceleration of vitellogenesis. In conclusionArmadillidium vulgareshows various biotic triggers of reproduction, which co-exist with classical abiotic ones. We discuss the relevance of these findings for natural populations, especially when the sex-ratio of the population is highly female-biased because of a parasitic distortion of sex-ratio.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522853

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Female territoriality (defined here as defense of exclusive space with respect to conspecific females) among mammals typically has been considered a mechanism to defend food resources. We propose an alternative hypothesis that the primary function of territoriality in solitary and semi-social female mammals is to protect vulnerable young from infanticidal conspecific females. Female territoriality is prominent among rodents, carnivores, insectivores, and some lagomorphs, but occurs rarely in bats, ungulates, marine mammals, marsupials, and most primates. A common trait of species with female territoriality is that they have nonmobile altricial young that are deposited in a burrow or protected den site. In contrast, female territoriality does not occur in species with precocial young or species with altricial young that are carried with the mother or that are reared communally. The timing of female aggression and territoriality appears to be more closely associated with lactation than with food habits or the distribution and abundance of food. Hence, we hypothesize that vulnerability of altricial young to infanticide, is a pervasive factor in the evolution of territoriality in female mammals. Territoriality for defense of food appears to be relatively uncommon and restricted to those situations in which food is centrally located or can be stored in a defensible cache.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522854

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Fiddler crabs present an accentuated sexual dimorphism wherein males have one of the chelipeds greatly enlarged, compared to the other chela or to the two small feeding chelipeds of females. Available observational data in the literature suggest a dual function for this trait both as an armament to fight other males and as an ornament to court females by claw waving. We experimentally tested femaleUca tangerifor possible preferences based on the size and elevation (waving posture) of the male large cheliped and on male handedness. Dead, resin-coated males were used as test objects. Females significantly more often approached males with larger claws and males with raised claws. Male handedness had no effect on female responses. These results are consistent with a female mating preference based on claw size and position and hence with the evolution of claw size and the waving display as a result of sexual selection by female choice.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522855

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The Cooperative Breeding Hypothesis (CBH) for the evolution of heterospecific brood parasitism (HBP) in birds, states that brood parasites evolved from a cooperatively breeding ancestor, presumably after a process involving conspecific brood parasitism as an initial evolutionary step. I tested this hypothesis by means of comparative analyses of the altricial parasitic taxa. The CBH was not supported, although some statistically not significant trends support the hypotheses which indicate conspecific brood parasitism as the initial step towards HBP.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522856

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Infanticide has been reported in a wide range of taxa. Although recent work suggests that infanticide may be present in managed populations of ungulate species, it has not been documented in wild ungulates. Here, I present qualitative evidence of infanticide in a wild ungulate, the hippopotamus (Hippopotamus amphibius) and suggest that infanticide in the hippopotamus may be a strategy by which males increase reproductive success. I present a conceptual model in which infanticide by males occurs within approximately 50 days post parturition and acts as a means to shorten the interbirth interval, particularly when water resources are scarce, and territory takeovers or changes in dominance hierarchy are likely.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522857

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Interspecific brood parasitism, in which females lay eggs in the nests of other species, has been observed in many altricial birds. In addition, nestling aggression, in which parasite nestlings attempt to out compete or kill host eggs or nestlings, occurs in many species of interspecific brood parasites. We examine the relationship traits for nestling aggression potentially have to the evolution of obligate brood parasitism. We propose the following: (1) under conditions in which a low number of extra eggs is made possible by being freed from parental care, a stable facultative stage could arise; (2) if aggression arose in a stable facultative parasite, aggression would be selected for if the ratio of the increase in success conferred on young in host nests to the decrease in success suffered by young in the home nest was above some threshold; and (3) once aggression had arisen in the facultative parasite, it could produce strong selection for the evolution of an obligate strategy.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522858

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The classical methods of cuticular hydrocarbon extraction in insects involve the use of solvents and therefore the killing of specimens. We describe here a simple and inexpensive method that allows for the sampling of cuticular hydrocarbons from live social insects in the field. We compare the results of our method with those of the classical solvent extraction method, as well as those of solid phase micro-extraction (SPME), and show that the method is both reliable and suitable for use in the natural environment. We describe for the first time the cuticular compounds of the social waspPolistes nimphus.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522859

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor