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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 308 (1984), S. 181-184 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The primary social unit of the vampire bat is the female group. During a 26-month (September 1978-February 1983) study in northwestern Costa Rica, 184 of the estimated 200 D. rotundus encountered inside 14 hollow tree day roosts at one site were netted and uniquely marked with wing bands. Infants ...
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 391 (1998), S. 276-279 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In some species, females choose mates possessing ornaments that predict offspring survival. However, sexual selection by female preference for male genetic quality remains controversial because conventional genetic mechanisms maintain insufficient variation in male quality to account for costly ...
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 32 (1993), S. 303-311 
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By means of field observations and laboratory experiments on the Malaysian stalk-eyed fly Cyrtodiopsis whitei we examined the consequences of variation in copulation duration for sperm competition. In this sexually dimorphic species over 90% of all copulations occur in nocturnal aggregations with from one to four males and up to 24 females. Copulation duration observed in both the field and the laboratory exhibited a bimodal distribution with peaks at 10 and 50 s. In the field short copulations less than 30 s long occurred frequently when more than one male was present in an aggregation but most were not the direct result of male interference. Sperm counts from female spermathecae after artificial interruptions indicated sperm are not transferred during the first 40 s of a copulation. When solitary males mated up to five times in succession to virgin females, short copulations did not occur, nor was the number of sperm transferred reduced. However, short copulations did occur when we mated isolated females within 6 min of a previous copulation. By mating irradiated and non-irradiated males in reciprocal pairs we discovered that C. whitei exhibits both first-male sperm precedence and sperm mixing. More than half of the females mated first to sterile and then to fertile males failed to produce offspring. Such variation in copulation duration and sperm precedence is consistent with male placement and detection of a spermatophore that acts as a temporary mating plug. Our data suggest that those male C. whitei which successfully defend large aggregations of females reduce sperm waste and competition by preferentially transferring sperm to females that have not mated recently.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 17 (1985), S. 123-134 
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Variability at seven polymorphic allozyme loci and observations of dispersal and mating provide evidence for nonrandom genetic structure among adult female groups of the highly social bat, Desmodus rotundus. The average degree of relatedness, estimated by allelic correlations at each locus, within three and six groups of females is 0.018 (SE=0.013) and 0.032 (SE=0.023), respectively. Even though these estimates do not differ significantly from zero, a multivariate analysis of variance of individual allele frequencies reveals that three of six pairwise comparisons of groups reach significance. This genetic heterogeneity within a population does not lead to increased genetic subdivision between populations. Mean classificatory ability of the discriminant functions drops from 84% for assignment to group to 56% for assignment to population. This pattern of genetic variability is due to recruitment of female offspring into their natal groups and forced male dispersal. Occasional movements of unrelated females between groups lead to the formation of multiple matrilines within groups. Although males fight viciously for access to the top of preferred female roosting sites and top males mate preferentially with females in that roost, mean maximum paternity for top males is only 46%. Consequently, male mating success is sufficiently random to maintain gametic equilibria among all pairs of loci. Given an infant mortality of 54%, mean male tenure of 17 months, and a birth interval of 10 months, females are unlikely to be related through common male ancestors. In one group, the average degree of relatedness, derived from matrilineal pedigrees, is 0.11 (SD=0.17). Computer simulations of the growth of a group of female D. routundus show that the low level of relatedness within groups is expected even if the proportion of unrelated females allowed into a group decreases. This pattern holds for any animal which recruits one sex into its social group and has relatively high juvenile mortality followed by low adult mortality.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 17 (1985), S. 111-121 
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At a site in Costa Rica, three groups of 8–12 adult female vampire bats, Desmodus rotundus, utilize group-specific sets of hollow trees as day roosts. Long-term nonrandom associations between pairs of females, as measured by the proportion of time one bat spends roosting in the same tree with another bat over a 3 year period, occur even when preferences for particular trees are removed. Significant associations exist between both related and unrelated adult females. Adult male bats, however, show few associations with females or other males. By observing bats within trees and while foraging, and by monitoring feeding flights with radiotelemetry, the following potential benefits of association could be tested. Females roost together to (1) share a suitable microclimate, (2) avoid predators, (3) avoid ectoparasite infestations, (4) minimize travel to mobile prey animals, (5) respond to coercive males, (6) feed simultaneously from a bite, (7) remove ectoparasites by allogrooming, and (8) share food by regurgitating blood to other bats within roosts. The data do not indicate that any of the first five hypotheses provide significant benefits for long-term associations although predators and ectoparasite levels may cause occasional changes in roost sites. Simultaneous feeding was uncommon and apparently confined to females and their recent offspring. Allogrooming, although common, occurred independently of the presence of ectoparasites. Food sharing, however, occurred between both related and unrelated adult females with high levels of association and provides at least one selective advantage for maintaining cohesive female groups.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 46 (1999), S. 221-227 
    ISSN: 1432-0762
    Keywords: Key words Assessment ; Intraspecific competition ; Sexual selection ; Diopsidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolution of male weapons or status signals has been hypothesized to precede evolution of female mating preferences for those traits. We used staged male fights among three species of Malaysian stalk-eyed flies (Diptera: Diopsidae) to determine if elongated eye span, which is preferred by females in two sexually dimorphic species, influences contest outcome. Extreme sexual dimorphism, with large males possessing longer eye span than females, is shared by Cyrtodiopsis whitei and C. dalmanni. In contrast, C. quinqueguttata exhibits a more ancestral condition – short, sexually monomorphic eye stalks. Videotape analysis of 20-min paired contests revealed that males with larger eye span and body size won more fights in the dimorphic, but not monomorphic, species. To determine if males from the dimorphic species use eye span directly to resolve contests, we competed male C. dalmanni from lines that had undergone artificial selection for 30 generations to increase or decrease eye span. We found that eye span, independently of body size, determines contest outcome in selected-line males. Furthermore, in both dimorphic species, the average encounter duration declined as the eye span difference between contestants increased, as expected if males use eye span to assess opponent size. The number of encounters also increased with age in dimorphic, but not monomorphic, species. Selected-line males did not differ from outbred males in either fight duration or number of encounters. We conclude that exaggerated male eye stalks evolved to influence both competitive interactions and female mating preferences in these spectacular flies.
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  • 7
    Publication Date: 1990-02-01
    Print ISSN: 0036-8733
    Electronic ISSN: 1946-7087
    Topics: Biology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 8
  • 9
    Publication Date: 1998-09-01
    Print ISSN: 0018-067X
    Electronic ISSN: 1365-2540
    Topics: Biology
    Published by Springer Nature
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  • 10
    Publication Date: 2001-01-01
    Print ISSN: 0018-067X
    Electronic ISSN: 1365-2540
    Topics: Biology
    Published by Springer Nature
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