ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522807

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Sparrows have colonized areas modified by humans since the onset of agriculture and seed storage. In fact, present day distributions of the sparrow populations are directly related to urban areas, farms and villages. Consequently the sedentary behaviour of sparrows, in pristine areas, with low densities of specimens, can act as a barrier to gene flow among populations. We analyzed the genetic variability and gene flow rates in four Italian sparrow populations sampled in areas affected by different levels of human activity. Population variability was analyzed by DNA fingerprinting with M13 multilocus minisatellite probe, which yielded multibanded fingerprints (the average number of bands was 25, ranging in size from 23 kb to 0.3 kb). The population located within the pristine area of the Cilento-Vallo di Diano National Park (San Marco) showed the higher value of within-population similarity (Sw = 0.73). This suggests a probable higher level of inbreeding in comparison with the other localities. The genetic isolation of the San Marco population is also imputable to the between-populations similarity values (Sb), that seem to be related with a preferential direction of gene circulation along urbanised corridors. The results show that population variability and gene flow rate in the Italian sparrow are directly related to the presence of urbanised areas. The results also show that the M13 multilocus fingerprinting probe represents a advantageous marker for the detection of genetic variability within a small geographical scale in passerine birds.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522808

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Among patterns of naturally occurring infanticide, one of the most interesting is the killing of young by lactating adult females in several mammalian species. In different species, the litters of either distantly related mothers or of close relatives have been documented as victims. We examined possible genetic benefits of infanticide by adult females using models of inclusive fitness and coancestry. Infanticide is viewed as a form of nepotism, in which offspring that are closer relatives of the infanticidal marauder have a greater chance of recruiting into a breeding group following infanticide. In this context, the genetic relationship of marauders and the young they kill is based upon the competitive social environment within breeding groups of adults. Two models were developed, based on linear and curvilinear changes in the fitness of mothers that either protect their litters or leave their litters unprotected while they maraud the litters of other adult females. Forms of these models that describe genetic polymorphisms of infanticide and ESS (evolutionary stable strategy) frequencies of infanticide yield quantitatively similar results. The models suggest that a balance should occur within populations between marauding and protection of young. At equilibrium, infanticide appears to be a spiteful behavior because it lowers the reproductive success of both the marauder (due to leaving their litters unattended and thus subject to other marauders) and mothers that try to protect their litters (because at least some maraudings are successful). Further, high levels of coancestry among females in a social breeding group should not change the frequency of infanticide when the population is at the equilibrium frequencies of marauding and protecting. Thus, in breeding groups made up of matrilines of highly philopatric females, infanticide of young genetically related to the marauder might be expected. Conclusions drawn from the models are supported by patterns of infanticide in ground-dwelling squirrels, where extensive information on infanticide exists and the social structure of breeding groups varies among species.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522809

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The infanticidal behaviour of wild-caught male and femaleMicrotus pennsylvanicuswas studied in captivity to examine the hypothesis that nonparental infanticide provides perpetrators with nutritional gains after cannibalizing their victims. Voles of different breeding condition, age, and sex were tested for their behaviour toward unfamiliar vole and house-mouse pups in a neutral arena. Infanticide on unfamiliar vole pups was relatively frequent among pregnant, less frequent among reproductively active (nonpregnant-nonlactating) and immature females, and almost absent in lactating females. Most infanticidal females, particularly non-breeding and immature females, did not cannibalize the pups. Pregnant females often attacked and cannibalized vole and house-mouse pups. A majority of breeding male voles were infanticidal when exposed to an unfamiliar pup in an unfamiliar place, and at least half of them cannibalized their victims. Taken together, these results suggest that nutritional gains are an occasional but not the main motivation of pupkilling behaviour in female meadow voles. In contrast, the attainment of nutritional benefits could be one main benefit of infanticide by male meadow voles.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522810

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Studies of within-colony genetic conflicts have revealed that worker interests sometimes prevail even when they conflict with the queens' interests. Male production is one area where worker's and queens' interests may conflict. A worker is most closely related to her own sons; however, queens often monopolize male production even when outnumbered by the workers. A possible explanation is that workers prevent each other from reproducing when they are more highly related to queen's sons than to other worker's sons. We investigated male production inParachartergus colobopterus, using DNA microsatellite loci to determine withincolony relatedness and who produced the males. Males were only produced in colonies where collective worker interests and queen interests both favored queens' sons. Analyses of the male genotypes showed that males were produced by the queens. Queen production of males could also be favored if worker reproduction reduced colony efficiency. This is an example of a situation where potential within-colony conflict is resolved by limiting male production to those colonies where the genetic interests of workers collectively, queens, and the interests of colony efficiency coincide. If this kind of conflict resolution is general, withincolony conflict may have played a larger role in social evolution than is currently apparent.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522811

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The ability of an insectivorous scincid lizard,Mabuya maculariato discriminate among prey chemicals and control substances and its responses to chemical cues from several plant species eaten by herbivorous and omnivorous lizards were examined experimentally using the swab method. We presented cotton swabs bearing chemical cues to the lizards and recorded the numbers of tongue-flicks directed to swabs in 60 sec and whether or not they bit the swab. The lizards exhibited much stronger responses to prey chemicals (cricket) than to stimuli from romaine lettuce, diluted cologne (pungency control), and deionized water (odorless control). Responses to romaine lettuce stimuli did not differ from those to the two control stimuli. In further observations, there were no significant differences in response strength between deionized water and chemical stimuli from strawberry, red grape, and dandelion flower. These findings support the hypothesis that insectivorous lizards do not exhibit strong chemosensory investigation of plants that are palatable and do induce high rates of tongue-flicking and/or biting in herbivorous lizards. Although insufficient comparative data are available to test the hypothesis that plant chemical discrimination evolves in response to dietary shifts from insectivory to omnivory or herbivory, the present data and all published data are consistent with the hypothesis. The data forM. maculariasuggest that plant chemical discriminations may have been absent in basal lygosomine skinks and derived in the herbivorous lygosomineCorucia zebrata.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522812

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper we investigated if the contact of a mother-pups unit with different partners may affect pup survival and growth inCalomys musculinusandC. laucha. Mother-pups units were housed with either a virgin female, a familiar male or a strange male, and the effect of these partners on the litter was measured from birth through weaning. InC. lauchaboth the presence of a strange male or a virgin female was deleterious for pup survival and growth. InC. musculinus, however, the presence of any partner, even the siring male, decreased pup survival and growth (the strange male was the most deleterious for pup growth). In both species the virgin female partner was killed in approximately half of the cases, while there was a differential response to the strange male, C. laucha females appeared less tolerant to strange males than theirC. musculinuscounterpart, which is consistent with the idea thatC. musculinusfemales interact in nature with more than one male in their home range. All of the familiar males survived. This study provides evidence thatC. lauchapups grow better in the presence of either the mother alone or in the partnership of the familiar male, while inC. musculinus, the presence of any partner, even the siring male, is deleterious for litter survival and growth under laboratory conditions. In the context of previous evidence, the current results are interpreted to mean that C. laucha is closer thanC. musculinusto the monogamy end of a three-dimensional system for the definiton of monogamy.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522813

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Ophryotrocha diademais a simultaneous hermaphroditic worm whose peculiar mating system involves forming pairs within which partners exchange eggs repeatedly in a kind of serial monogamy. To test whether direct recognition of the former partner exists in this species we checked whether two familiar partners, after a short separation, spawned again without engaging in a new courtship. In contrast, non-familiar partners were expected to invest a longer time in courtship before spawning again. Results indicate that no direct individual recognition of a former mate exists and that only indirect cues are used to identify former partners.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522814

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Savalli & Fox (1999) have recently shown that in the bruchid beetleCallosobruchus maculatus, females inseminated by large males lay more eggs than those inseminated by small males. Here we report the results of a very similar experiment, on the same species, which yielded the opposite result; females inseminated by small males laid more eggs than those inseminated by large males. On analysing the methods and results, two differences in experimental design become apparent; male age at first copulation and population origin. We suggest these two differences may have produced the contrasting results and believe they offer important evolutionary and developmental insights into ejaculate composition.

ISSN:0394-9370    

DOI:10.1080/08927014.2000.9522815

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor