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211.
Lydia H. Beaudrot Sonya M. Kahlenberg Andrew J. Marshall 《Behavioral ecology and sociobiology》2009,63(11):1549-1562
Infanticide is widespread among mammals, is particularly common in primates, and has been shown to be an adaptive male strategy
under certain conditions. Although no infanticides in wild orangutans have been reported to date, several authors have suggested
that infanticide has been an important selection pressure influencing orangutan behavior and the evolution of orangutan social
systems. In this paper, we critically assess this suggestion. We begin by investigating whether wild orangutans have been
studied for a sufficiently long period that we might reasonably expect to have detected infanticide if it occurs. We consider
whether orangutan females exhibit counterstrategies typically employed by other mammalian females. We also assess the hypothesis
that orangutan females form special bonds with particular “protector males” to guard against infanticide. Lastly, we discuss
socioecological reasons why orangutan males may not benefit from infanticide. We conclude that there is limited evidence for
female counterstrategies and little support for the protector male hypothesis. Aspects of orangutan paternity certainty, lactational
amenorrhea, and ranging behavior may explain why infanticide is not a strategy regularly employed by orangutan males on Sumatra
or Borneo. 相似文献
212.
In the stream-dwelling isopod, Lirceus fontinalis, mating contests between males and females occur prior to pair formation. We examined the relative contribution of male preference
and female resistance to contest outcomes. We first quantified male and female behavior during typical mating interactions
and examined the relationship between time until molt (TTM) and mating outcomes. We then examined the role of male preference
and female resistance in determining mating outcomes when females differed in molt type (growth, egg deposition) and appeared
to differ in TTM (due to hormone applications). Both male preference and female resistance contributed to different components
of the mating sequence but female resistance ultimately determined whether or not pair formation occurred. Males expressed
a preference for females that appeared to be close to molt, using variation in levels of molt hormone as a cue. However, males
did not discriminate between females based on molt type.
Received: 5 March 1999 / Received in revised form: 10 August 1999 / Accepted: 16 October 1999 相似文献
213.
D. J. Green H. L. Osmond M. C. Double A. Cockburn 《Behavioral ecology and sociobiology》2000,48(6):438-446
Empirical and theoretical studies have only recently begun to examine how females use complex multi-component displays when
selecting mates. Superb fairy-wrens are well suited to the study of female choice because females have control over extra-group
paternity and cuckold their mates at high rates, while males possess a variety of sexually selected traits. Available evidence
suggests that females base their extra-group mate choice on the timing of male moult into breeding plumage or the onset of
display. However, males continue to perform elaborate displays throughout the season, and direct most displays to females
during their fertile period. We therefore conducted focal observations on fertile females to quantify the frequency of male
display and used microsatellite genotyping to compare the role of display rate during the breeding season and the timing of
male moult on female mate choice. We show that the addition of data on male display rate does not improve our ability to predict
which males obtain extra-group paternity. The timing of male moult into breeding plumage remains the only predictor of male
extra-group reproductive success. Nevertheless, we found that males displayed more to females that were unable to select extra-group
mates on the basis of the timing of moult or the onset of display. This raises the possibility that there are circumstances
when females use display rate to discriminate between potential extra-group sires. Overall this study supports the theoretical
prediction that females are more likely to base their mate choice on reliable indicators of male quality such as fixed morphological
traits and displays of endurance, in this case an early moult into breeding plumage and the performance of an elaborate display
during the winter, than a flexible behavioural trait such as display rate during the breeding season.
Received: 26 January 2000 / Revised: 1 August 2000 / Accepted: 26 August 2000 相似文献
214.
Females in several sexually dimorphic species with conventional sex roles possess ornamental traits that resemble those found
in males. The evolution of such traits, however, is still poorly understood. Bluethroats (Luscinia s. svecica) are socially monogamous, sexually dichromatic passerine birds, in which female throat patch coloration varies from near
absence to near full expression of male-like coloration. A recent study, demonstrating that male bluethroats prefer colourful
females, suggests that female coloration is subject to sexual selection through male choice. However, the benefits males may
gain from mating with colourful females have not yet been identified. In this study we tested the hypothesis that female coloration
signals parental quality (the good-parent hypothesis). During the course of the same day, we recorded female care both in
the presence and the absence of the male mate. The latter was done to eliminate the confounding effect of variable male care
by removing the male temporarily. Female coloration did not correlate with female feeding rates either in the presence or
in the absence of the male. Female feeding rates in the absence and the presence of the male were positively, although weakly,
correlated. Female coloration did not correlate with female ability to compensate for the loss of male care, or with the change
in brood mass during male removal. Therefore, there is no evidence for the good-parent hypothesis to explain female plumage
coloration in bluethroats.
Received: 4 March 1999 / Received in revised form: 14 October 1999 / Accepted: 23 October 1999 相似文献
215.
The small cichlid fish Neolamprologus multifasciatus is endemic to Lake Tanganyika and is unique among fish because it lives in complex social groups with several reproductive
males and females, all of which participate in defending their territory against neighbors and intruders. Individuals use
empty snail shells for breeding and shelter. Previous parentage analysis using microsatellites suggested occasional exchange
of individuals between groups. In field experiments, we found that females showed a higher tendency than males to migrate
into territories already occupied by a resident pair. The phenomenon and causes of female-biased immigration were further
investigated in aquarium experiments: Nine of 15 females, but only 2 of 15 equally sized males, settled in territories of
established pairs. Territorial males exhibited more aggression toward strange males (potential reproductive competitors) than
toward strange females (potential additional mates); their females were more aggressive toward strange females (probably competitors
for shells) than toward strange males. Apparently, a conflict exists between the sexes regarding the immigration of additional
females. This conflict seems to be the selective basis for observed active male interference in aggressive disputes between
females in the territory. Interfemale tolerance in a group was greater in the male’s presence than in his absence.
Received: 1 February 2000 / Received in revised form: 2 May 2000 / Accepted: 5 May 2000 相似文献
216.
Endocrine disrupting chemical (EDC) effects during early life have the potential to modulate population structure, either directly through increased mortality or by causing inappropriate aggregation events, thus affecting the number of young that will reach adulthood. An alteration in the dispersal and recruitment patterns can also impair the connectivity among geographically distant populations. However, the detection of EDC-induced effects occurring after egg hatch, when newborns increase their chances of contacting with environmentally dispersed contaminants, is not a simple process as effects might be masked by the large natural mortality rates that usually occur during fish early life.Since there is a lack of information regarding the impact of EDCs on fish early life dispersal patterns, particularly on vertical migrations patterns, the effects of environmentally relevant concentrations of EE2 on the vertical distribution of newborn fish was assessed through an ex situ exposure experiment. Syngnathus abaster newborns were exposed to EE2 (nominal concentrations of 8, 12 and 36 ng L−1) and the dynamics of their vertical distribution was monitored for up to 40 d. No significant differences in overall mortality were observed between treatments or in the dynamics of the registered death curves. Nevertheless, an alteration in the distribution patterns was observed. The commonly benthic newborn tended to shift their vertical distribution towards the surface, in a dose-dependent manner. Curiously, a follow up of the exposed pipefish confirmed that EE2 effects were also noticeable upon sexual maturity, namely by the alteration of several primary and secondary sexual characters. The observation that vertical distributional patterns, at least in pipefish, are clearly altered at environmentally relevant EE2 concentrations indicates that EDC’s impact in fish larvae behaviour should be considered when addressing the effects of contaminants, given the obvious implications on population connectivity, stability and persistence. 相似文献
217.
Sperm competition and sexual selection: a meta-analysis of paternity studies of birds 总被引:8,自引:0,他引:8
Sperm competition (the competition among the sperm of different males for fertilization of the eggs of a female) has been
suggested to be an important component of sexual selection, but no general assessment has been made of this proposition. We
used a meta-analytic approach to assess the extensive literature on paternity (the proportion of offspring in a focal nest
sired by an attending male) in birds based on allozyme and molecular techniques. The relative variance in male mating success
was on average increased by a factor of 4.6 over the variance in apparent male success. Males with more extravagant secondary
sexual characters had higher paternity in their own nests than less adorned males. There was a weak effect of male age being
positively associated with paternity in own nests. Male body size measured as the length of wing and tarsus was weakly positively
associated with paternity in own nests. Male survival prospect was positively associated with paternity in own nests. Polygynous
males generally had decreased paternity of their broods compared to monogamous males. Paternity of the resident male decreased
with increasing population density and breeding asynchrony. The intensity of paternity guards such as within-pair copulation
rate and mate guarding were not significantly related to extra-pair paternity. Sperm competition was thus an important component
of sexual selection by increasing the variance in male mating success, and by being associated with the expression of secondary
sexual characters, in particular in dense and asynchronously breeding populations of birds.
Received: 12 February 1998 / Accepted after revision: 31 May 1998 相似文献
218.
Peter B. S. Spencer Alan B. Horsup Helene D. Marsh 《Behavioral ecology and sociobiology》1998,43(1):1-9
The reason why a female who is socially paired to one particular male seeks extra-pair copulations (EPCs) with others has
important implications in life history models and to the study of behaviour. The Allied rock-wallaby, Petrogale assimilis, lives in spatially isolated colonies in tropical north Queensland, Australia. Extensive observations of a colony at Black
Rock showed that intense behavioural bonding occurs between pairs of adult males and females; about two-thirds of males paired
with one female, the remainder paired with two females simultaneously. Single-locus microsatellite profiling determined the
paternity of 63 offspring from 21 females for which long-term behavioural data were available. One-third of the young were
fathered by males which were not paired socially with the mother. The mating system was heterogeneous: (1) all offspring of
11 females were fathered by the mother's partner, (2) all young of 5 females were fathered by extra-pair males, and (3) only
some of the young of 5 females were fathered by their regular consort. Analysis of individual longitudinal demographic records
showed that females whose young were always fathered by their consort had higher reproductive success than those whose young
were always fathered as a result of (EPCs). However, females with some offspring fathered by their regular consort and others
via EPCs had the highest probability of raising young to independence. These females were significantly more likely to have
an offspring fathered as a result of an EPC if their previous young had failed to survive to pouch emergence. These results
are consistent with the hypothesis that females choose mates for their genetic quality. Comparison of the males with which
these females sought EPCs and the regular consorts suggested that arm length rather than body weight or testes size was used
as the index of genetic quality. Results from a second colony of rock-wallabies in which the reproductive rate was accelerated
were also consistent with the genetic-quality hypothesis. These results imply that by choosing better-quality fathers irrespective
of social pairing, females are able to maximise their overall lifetime reproductive success, and presumably, those of their
offspring.
Received: 8 June 1997 / Accepted after revision: 28 February 1998 相似文献
219.
Mate choice games, context-dependent good genes, and genetic cycles in the side-blotched lizard, Uta stansburiana 总被引:4,自引:0,他引:4
According to mate choice models, a female should prefer males with traits that are reliable indicators of genetic quality
which the sire can pass on to their progeny. However, good genes may depend on the social environment, and female choice for
good genes should be context dependent. The side-blotched lizard, Uta stansburiana, exhibits genetically based throat colors (orange, blue, or yellow) that could be used as a sexually selected signal since
they reliably predict the genetic quality of mates. The frequencies of male and female morphs cycle between years, and both
male and female morphs have an advantage when rare; thus genetic quality will depend on morph frequency. A female should choose
a sire that maximizes the reproductive success of both male and female progeny. We examine a game theoretical model that predicts
female mate choice as a function of morph frequency and population density. The model predicts the following flexible mate
choice rule: both female morphs should prefer rare males in ’boom years’ of the female cycle (e.g., ’rarest-of-N rule’), but
prefer orange males in ’crash years’ of the female cycle (’orange-male rule’). Cues from the current social environment should
be used by females to choose a mate that maximizes the future reproductive success of progeny, given the social environment
of the next generation. We predict that the cue is the density of aggressive orange females. In the side-blotched lizard,
cycling mate choice games and context-dependent mate choice are predicted to maintain genetic variation in the presence of
choice for good genes.
Received: 8 March 2000 / Revised: 26 August 2000 / Accepted: 4 September 2000 相似文献
220.
A 45,X/46,Xder(Y) mosaicism detected prenatally was shown to have a rare Y inversion- duplication or Y/Y translocation which can only be identified by a combination of high resolution cytogenetics and fluorescence in situ hybridization. The present data indicate the usefulness and importance of chromosome-specific probes in the identification and characterization of chromosome rearrangements. 相似文献