摘要:

The spatial organization of capercaillie (Tetrao urogallus) cocks on a lek was studied in the French Central Pyrenees from 1979 to 1983 by mapping territory boundaries. Between 1980 and 1982 more detailed data were obtained on the movements of 14 cocks that could be individually identified by their plumage. The objectives were to determine if the boundaries of the lek varied from year to year and to study changes in size and location of areas defended by individual males on the lek, both within and between years. The spatial boundaries of the lek showed a certain plasticity from year to year owing to population turnover. Within the lek each individual male defended a restricted area corresponding to the definition of a territory. Each year I observed a spatial reorganization of these territories. Thus the capercaillie lek system is characterized by a certain individual plasticity which provides an explanation for the ability of this species to cope with different environments even though it cannot resist brutal modifications of large areas of its habitat.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523098

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A recent controversy has arisen over the relative advantage of the hymenopteran sting as a defensive weapon against vertebrates or invertebrates as this relates to the origin of insect sociality (STARR 1985a, KUKUK et al. 1989, and reply by STARR 1989). These studies emphasize the value of the sting as an antipredator device, but minimize its offensive potential. Concomitant with the evolution of cooperation among hymenopteran insects has been extensive exploitation by parasitic individuals of the reproductive efforts of others. Use of the sting is a common feature of both facultative and obligate nest usurpation in the social Hymenoptera. Increases in sting size and venom gland size have occurred, presumably as a result of arms races arising out of the competing selective forces of cooperation and parasitism which underly hymenopteran sociality.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523099

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The behavioral tactics and mating behavior of male fox squirrels (Sciurus niger) were studied in a small population of uniquely marked, free-ranging individuals during the winter breeding season in 1986 to 1990. Twelve mating bouts were observed with an average of 5.83 males. Two alternative male reproductive tactics were active pursuit and satellite. Active-pursuit males were the most dominant squirrels that fought for and defended proximity to the estrous female. Satellite males were subordinates that remained dispersed in the estrous female's home range but avoided interaction with active-pursuit males. Active pursuit accounted for more copulations than the satellite tactic (0.83 vs 0.23 copulations/male/bout) with the copulations distributed more evenly among active-pursuit males (CV = 133.7) than among satellite males (CV = 191.3). Satellite males copulated with a female after she avoided the contest competition among active-pursuit males. Although the tactics were dominance-based, dominance rank was not directly correlated with mating success. However, highranking, dominant males gained access to and mounted more females than lower ranking males. The alternative mating tactics of male fox squirrels may be important in mediating intermale mating success.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523100

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The Fan-tailed WarblerCisticola juncidisis a polygynous and territorial passerine. Eleven territories were established at an edge habitat over the 3 years of study. All of the owners which were adjacent to only one neighbouring territory attempted to hold secondary territories and four males succeeded in establishing secondary territories. On the contrary, five males adjacent to two neighbours did not attempt to leave their primary territories. The probability of establishing a secondary territory in the Fan-tailed Warbler seems to depend on the risk of intrusion by neighbours.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523101

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Although a variety of behavioural mechanisms are known to inhibit infanticide in male house mice, the potential for social subordination to inhibit infanticide has not been widely investigated. Sixty male CF-1 stock house mice (Mus domesticus) were grouped five per cage from weaning until 5 months of age. Each male was then isolated and tested for infanticide at 1-day and 25-days after being singly housed. Only 13% were infanticidal after 1-day of isolation, but after 25-days of isolation, 44% were infanticidal (P < 0.0001). Thus, being group-housed with other males inhibits infanticide in most CF-1 male mice. From an ecological perspective, the cage-by-cage data suggest that subordination is a behavioural counterstrategy by which a dominant breeding male can inhibit his rivals from killing pups, thus maintaining social stability and reproductive success in a typical house mouse microdeme.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523102

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In some populations, female threespine sticklebacks (Gasterosteus aculeatusL.) frequently eat conspecific eggs, even when other food is abundant. We tested the hypothesis that egg-eaters have a fitness advantage relative to non-egg eaters by manipulating diet. Our results indicate a clear reproductive advantage for the cannibals. Females that were fed conspecific eggs and a mixture of other foods produced 1.8 times as many eggs over the breeding season as those fed a non-egg diet. Furthermore the cannibals were in better condition at the end of the breeding season than the non-cannibals. We suggest that egg-eating females gain access to nutrients that are lacking or rare in other foods items and/or that eggs are more easily digested than other food.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523103

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Different opinions exist about mantelline relationships. Major causes are differences in observations on tarsals and carpals, and the fact that no consensus has been reached concerning the systematics of the other ranoid frogs, so making it difficult to determine the polarity of character states. Therefore a series of osteological characters was investigated in several ranoids, especially in the Mantellinae, and a cladogram of the “firmisternal” frogs was constructed. This cladogram splits into two main branches; the Microhyloidea containing the Sooglossidae, Dendrobatidae, Microhylidae and Hemisotidae (including the Brevicipitinae) and the Ranoidea comprising the Arthroleptidae, Hyperoliidae and Ranidae, including the Mantellinae and Rhacophorinae.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523105

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Dart-poison frogs (family Dendrobatidae) are well known for the bright colors and toxic skin alkaloids of some members. These small inhabitants of tropical forests comprise 157 named species placed in six genera. Despite the growing interest in all aspects of dendrobatid biology, the placement of the family in relation to other anurans remains controversial because of differing views concerning the identity of its sister group. The dendrobatids are hypothesized to be derived from within either the Leptodactylidae or the Ranidae, which are classified in the superfamilies Bufonoidea and Ranoidea, respectively. These extremely divergent hypotheses of relationships were derived traditionally from limited numbers of characters. Examples of a few characters that support the leptodactylid hypothesis include aspects of cranial morphology and procoelous vertebrae, and those that support the ranid hypothesis include round sacral diapophyses and the presence of bursa angularis oris. Interestingly, some characters were used to support both hypotheses, owing to different interpretations of the same characters (e.g., pectoral girdle, thigh musculature). In reviewing the hypotheses and characters, it is evident that many complications concerning the placement of the Dendrobatidae reflect inherent problems with most of the characters, including homoplasy, ambiguous and erroneous reporting of characters, and a priori assumptions concerning character evolution.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523106

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The most morphologically primitive of all frogs are those with amphicoelous vertebrae. These frogs areAscaphusfrom North America, the six known fossil and Recent species ofLeiopelmafrom New Zealand, and the Jurassic fossilsNolobatrachusandVieraellafrom South America. Previous consideration of the evolutionary importance of these frogs has been almost exclusively concerned with their primitive characteristics relative to other frogs. Yet virtually no shared derived characters have been found among the genera. Genetic and cytogenetic divergence is extremely high. Present biochemical estimates of genetic divergence are at or beyond the limits of many of the techniques used. Although the living genera are very plesiomorphic,Ascaphushas such unique characteristics as an intromittent organ, high chromosome number (2n= 46), and oocyte gene amplification via eight endomitotic germinal vesicles. Derived features of RecentLeiopelmainclude inscriptional ribs, a reduced or absent tadpole stage, and low chromosome numbers (2n= 18 or 2n= 22 male/23 female).NotobatrachusandVieraellamay be difficult to assign to either Ascaphidae or Leiopelmatidae.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523107

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In early anuran larvae the posterior wall of the nasal capsule is not developed. The olfactory nerves are exposed dorsally. Later paired, transversely located elements roof these nerves. They fuse and, later, produce, by downward growth, the walls of the olfactory canals. Laterally, the first functional partition between the future nasal capsule and orbit is the commissura quadratocranialis anterior. The ophthalmicus nerve runs across the dorsal surface of the commissura. In the course of further development, a new element (called the lamina orbitonasalis), arises anterolaterally to the commissura; consequently, the above mentioned nerve is enclosed in a canal betweeo the lamina orbitonasalis and the braincase. Meanwhile, the commissura becomes detached from the braincase and fixed to the lamina. Later another element, the epipraemandibulare, arises anterodorsally to the lamina; it encloses a branch of the ophthalmicus nerve in a canal. On the lateral end of the lamina orbitonasalis a further element arises: the processus maxillaris posterior. As the commissura later becomes detached even from the lamina, the processus ultimately represents the only connection of the palatoquadrate with the postnasal wall. Thus the postnasal wall, and adjacent parts of the palatoquadrate are of complex origin, though in adults they are a single unit. Comparison with those labyrinthodonts in which corresponding data are available reveals that the structure of their postnasal wall corresponds to certain larval stages of anurans. Thus the structure in adult anurans represents an evolutionary addition lacking in labyrinthodonts. For this reason, in the search for anuran ancestors one may compare adult labyrinthodonts not only with adult but also larval anurans.

ISSN:0394-9370    

DOI:10.1080/08927014.1993.9523108

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor