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Many mammals warn conspecifics with alarm calls about detected predators. These alarm calls are either functionally referential,
urgency based, or they can have multiple functions, including predator deterrence. The taxonomic distribution of these alarm
call systems is uneven, with primates providing the best-known examples for a functionally referential system and rodents
most examples of an urgency-based system. Reports of different alarm call systems in lemurid primates prompted us to examine
the anti-predator behavior of two additional lemur species. In an experimental field study we exposed adult redfronted lemurs
(Eulemur fulvus rufus) and white sifakas (Propithecus verreauxi verreauxi) to playbacks of vocalizations of their main aerial and terrestrial predators, as well as to their own alarm calls given
in response to the presentation of these predators. We scored the subjects' immediate behavioral responses, including alarm
calls, from video recordings made during the first minute following a playback. We found that both species gave specific alarm
calls only in response to raptor playbacks and the corresponding alarm calls, whereas calls given in response to carnivores
and the corresponding alarm calls were also observed in other situations characterized by high arousal. Other behavioral responses,
such as gaze and escape directions, corresponded to the hunting strategies of the two predator classes, suggesting that the
corresponding vocalizations were categorized correctly. These two lemur species, which represent different families, have
therefore independently evolved a mixed alarm call system, characterized by functionally referential calls for diurnal raptors,
but not for carnivores. Electronic supplementary material to this paper can be obtained by using the Springer LINK server
located at http://dx.doi.org/10.1007/s00265-001-0436-0
Electronic Publication 相似文献
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The aim of this study was to investigate reproductive strategies and their consequences in gray mouse lemurs (Microcebus murinus), small solitary nocturnal primates endemic to Madagascar. Previous reports of sexual dimorphism in favor of males and females,
respectively, a high potential for sperm competition and pheromonal suppression of mating activity among captive males, led
us to investigate mechanisms of intrasexual competition in a wild population. Based on 3 years of mark-recapture data, we
demonstrate that sexual dimorphism in this species fluctuated annually as a result of independent changes in male and female
body mass. Male body mass increased significantly prior to the short annual mating season. Because their testes increased
by 100% in the same period and because their canines are not larger than those of females, we suggest that large male size
may be advantageous in searching for estrous females and in enabling them to sustain periods of short-term torpor. In contrast
to reports from captive colonies, we found no evidence for two morphologically distinct classes of males. Finally, we also
show that most adult males are active throughout the cool dry season that precedes the mating season, whereas most adult females
hibernate for several months. This is in contrast to other solitary hibernating mammals, where males typically emerge 1–2
weeks before females. Thus, this first extended field study of M.␣murinus clarified previous conflicting reports on sexual dimorphism and male reproductive strategies in this primitive primate by
showing that their apparent deviation from predictions of sexual selection theory is brought about by specific environmental
conditions which result in sex-specific life history tactics not previously described for mammals. A general conclusion is
that sexual selection can operate more strongly on males without resulting in sexual dimorphism because of independent selection
on the same traits in females.
Received: 6 July 1997 / Accepted after revision: 28 March 1998 相似文献
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Peter?M.?KappelerEmail author Hans?G.?Erkert 《Behavioral ecology and sociobiology》2003,54(4):359-369
Whether animals are active at night or during the day has profound consequences for many aspects of their behavioral ecology. Because of ecological and physiological trade-offs, most animals, including primates, are either strictly nocturnal or diurnal. However, a few primate species exhibit cathemeral activity, i.e., their activity is irregularly distributed throughout the 24-h cycle. Details and determinants of this unusual activity pattern are poorly understood because long-term 24-h observations are not feasible in the field. We therefore used small data loggers to record the activity of cathemeral redfronted lemurs (Eulemur fulvus rufus) from several neighboring groups quantitatively and continuously over a complete annual cycle in order to evaluate various proposed proximate and ultimate determinants of cathemeral activity. Activity data were examined for variation as a function of ambient temperature, time of day, lunar phase, and season. We found that cathemeral activity occurred year-round and that, on average, 3.5 times more activity occurred during the day. Total and diurnal activity increased during the long days of the austral summer. Nocturnal activity increased during the longer nights of the cool dry season. Irrespective of season, lunar phase had a significant effect on the distribution of activity across the 24-h cycle, with most nocturnal activity recorded during parts of the night with greatest brightness. These data indicate that light availability is the primary proximate determinant for the patterning of cathemeral activity. Several lines of evidence suggest that cathemerality in lemurs has evolved from nocturnal ancestors and that it represents a transitory state on the way to the diurnal niche.Communicated by F. Trillmich 相似文献
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