摘要:

Surveys of eight radiotracked polecats (Mustela putorius) showed that they caught mainly male terrestrial anurans at spawning sites. Agile frogsRana dalmatinaformed 77.5%, whereas common toadsBufo buforepresented only 14.6% of preyed anurans. Throughout the breeding period, male anurans were found to be predominant, representing 64.8% of available agile frog and 60.7% of common toad populations in the four ponds studied. The number of male frogs was significantly higher in two ponds which were not exploited by polecats in 1990. Polecats preyed selectively on anuran males (electivity indexD= 0.34 in agile frogs andD= 0.50 in toads). Thus, the intensive predation of polecats at spawning sites can influence the sex-ratio of anuran populations.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522922

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The reproductive strategy of the folivorous Indian green frog (Rana hexadactyla) was studied at a seasonal locality in south India. The reproductive tracts of adult females, and the liver and abdominal fat masses of adult males and females, were examined monthly. Mature eggs were recovered from females at all months of the year, although monthly variation in relative clutch mass suggests seasonality in reproduction. Egg masses increase prior to the seasonal rains, and drop sharply during or just after the wet seasons. The size of visceral lipid deposits shows seasonal peaks that are correlated to feeding peaks. The decline in fat body mass is associated with spawning peaks, suggesting their mobilization for reproduction. The liver mass of adult males also shows seasonal variation, being greatest prior to the peak spawning periods, indicating the mobilization of lipid for courtship and spermatogenesis. The liver mass of adult females does not show month-to-month variation.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522923

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The relationships between group size, activity patterns, and time of day were studied during a mild winter in a protected population of Isard or Pyrenean chamois (Rupicapra pyrenaica pyrenaica) in open montane pastures in the bottom of a central valley, bordered by a beech forest. The size and the total number of groups increased progressively from dawn to the middle of the afternoon. Nearly half of the animals foraged early in the morning, while about two out of five were moving. As the day proceeded, the allocation of time for foraging increased regularly until approximately 3/4 of the animals were observed foraging at about 17:00. Foraging increased initially at the expense of moving, and later to both moving and standing. Then, just before dusk, both group size and time devoted to foraging decreased, as individuals returned to the beech forest to rest during the night in a sheltered habitat. The relative influence of weather conditions and of the digestive physiology of Pyrenean chamois on this spatiotemporal process is discussed.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522924

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Colonies of the queenless ponerineDiacammasp. have females with three types of functions with respect to reproductive status: a mated worker (gamergate), egg-laying unmated dominant workers, and non-reproductive unmated subordinate workers. In the laboratory, several dominant workers oviposited but most eggs were eaten by the gamergate. However, some eggs, which may have resulted in the production of males, were overlooked and escaped from oophagy by the gamergate.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522925

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Understanding the relative costs of different forms of ornamental displays is fundamental to research on the evolution of such traits. For traits such as elongated tails, assessing the degree of exaggeration is straight-forward: bigger is more exaggerated and more costly. In contrast, assignment of such a hierarchical ranking of costliness and exaggeration to color displays has not been possible. In this paper, I consider whether red carotenoid displays represent a more energetically costly form of ornamentation than yellow or orange carotenoid displays. Several lines of evidence support the idea that red carotenoid pigmentation is particularly costly. Red carotenoid pigments are less abundant than yellow pigments in the diet of virtually all vertebrates. Although many vertebrates can convert some yellow carotenes and xanthophylls to red pigments, all species appear to be restricted in the types of metabolic conversions of which they are capable as well as by the costs of such conversions. In virtually all avian taxa with carotenoid-based coloration, when females and juvenile males show plumage hue that is different than that of adult males, their plumage is less red (more orange or yellow). Finally, in a comparative study of cardueline finches, there was a significant positive relationship between the degree of sexual dichromatism and the redness of male plumage, suggesting that red is a particularly costly color display. The finding that red is a more costly color display than yellow or orange has important implications for comparative studies of the evolution of ornamental plumage.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522926

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Whether an animal lives alone or in a group may have fitness consequences. Among yellow-bellied marmots (Marmota flaviventris), fitness is thought to be lower for noncolonial than for colonial females because juvenile survival, as indicated by trapping, is lower. Trapping, however, may not be an accurate estimate of survival. Low recapture rates of noncolonial juveniles may result from early dispersal due to maternal behavior, or higher mortality due to predation or inadequate resources for overwinter survival. Our objective was to determine if survival was lower for noncolonial than for colonial juveniles, and to determine the cause of the low recapture rate of noncolonial juveniles. Our results show that survival of noncolonial juveniles was not lower than that of colonial juveniles. Noncolonial juveniles were not more vulnerable to predation during the active season, nor was overwinter mortality higher. Some noncolonial juveniles did disperse early, and most moved away from the natal burrow to hibernate, thereby explaining the low recapture rate reported previously. Early dispersal was not related to maternal behavior. Noncolonial females do not enjoy the benefits of group-living, especially the opportunity to form matrilines; but they also do not suffer the costs, such as competition for resources.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522927

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The number of matings by social insect queens is an important determinant of the kinship structure of their colonies, and it is therefore expected to affect a variety of kin-selected worker strategies. Here we report mate number data forParachartergus colobopterus, the first such data for any member of the polygynous epiponine wasps. Mate number is assessed by microsatellite genotyping of the sperm stored in queen spermathecae. Queens of this species mate only once. This finding is consistent with a prediction of several theories positing that multiple mating functions to increase genetic diversity and is therefore less necessary in multiple-queen species. The finding of single mating, together with earlier data, allows estimation of effective queen numbers for all colonies, 4.40 queens, for male-producing colonies, 4.16 queens, and for queen-producing colonies, 1.18.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522928

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Storing food items is considered an alternative to fat storage in many species of ground squirrels. In a comparative study in the laboratory, we hypothesized that two closely-related ground squirrels,Spermophilus tridecemlineatusandS. spilosoma(subgenusIctidomys, Rodentia Sciuridae), could hoard food and that the highest proportion of individuals displaying hoarding should be observed in the species with the greatest changes in body masses over both active and hibernation periods. Moreover, food hoarding is often displayed when a resource is temporarily available. Hoarding should be more frequent when the feeding conditions change and stable feeding conditions over several tests should decrease hoarding. Contrary to thepredictions, S. spilosomararely hoarded food, whereas manyS. tridecemlineatusdid it. As predicted, the number of animals hoarding food was maximum for new feeding conditions and decreased with repetitive trials.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522929

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The behavioural events constituting a nesting cycle were documented and compared with the results of homing experiments. Homing times of displaced wasps decreased as the nesting cycle progressed and as provisioning increased.

ISSN:0394-9370    

DOI:10.1080/08927014.1996.9522930

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor