Pair Formation in California Condors

SYNOPSIS. Pair formation is a prerequisite for reproductionin California condors and exploring the process has been centralto the captive breeding program for this endangered species.Observations show that once birds reach sexual maturity theycan form pairs within a matter of months; even birds who havelost or been separated from their mates will successfully bondwith others. However, some adults who are housed together showlittle indication of pairing. When such birds are placed withother potential mates they frequently successfully pair andproduce young, suggesting that individual differences play arole in pair formation. We recommend that adults who have notbonded within two years be housed with different potential mates. Condors raised together may or may not form pair bonds uponreaching sexual maturity; unfamiliar condors introduced at fouryears of age or older will form pair bonds. In the four caseswhere pairings have been successful the male initiates moreintrapair interactions with aggressive behavior than does thefemale. Unpaired condors housed in groups do show courtshipand the most dominant birds, usually males, are the most activein giving wings-out/head-down displays. Displays may be directedto males or females and may signal dominance and/or interest.Displays may be followed by mounts and one female may crowdin front of the bird to whom a male is displaying, increasingthe chances that she will receive the display and be mounted.Displaying and the response to displaying birds may be mechanismswhich influence mate selection.     

Reassessment of age of sexual maturity in gibbons (hylobates spp.)

From studies of both wild and captive animals, gibbons are thought to reach sexual maturity at about 6 to 8 years of age, and the siamang (Hylobates syndactylus) at about 8 to 9 years. However, a review of the literature reveals that in most cases the exact age of the maturing animals was not known and had to be estimated. This study presents seven case reports on captive gibbons of known age. Captive males of the white-cheeked crested gibbon (H. leucogenys leucogenys) and of the siamang (H. syndactylus) can breed at the age of 4 and 4.3 years, respectively. Similarly, hybrid females (H. lar × H. moloch) and siamang females can breed at 5.1 and 5.2 years, respectively. This finding may help to improve the breeding success of captive gibbon populations. It is not clear whether gibbons reach sexual maturity earlier in captivity or whether sexual maturity is also reached by 5 years of age in the wild. Possible implications for the interpretation of group size regulation and of reproductive strategies of wild gibbons are discussed.     

Early reproductive investment,senescence and lifetime reproductive success in female Asian elephants

The evolutionary theory of senescence posits that as the probability of extrinsic mortality increases with age, selection should favour early‐life over late‐life reproduction. Studies on natural vertebrate populations show early reproduction may impair later‐life performance, but the consequences for lifetime fitness have rarely been determined, and little is known of whether similar patterns apply to mammals which typically live for several decades. We used a longitudinal dataset on Asian elephants (Elephas maximus) to investigate associations between early‐life reproduction and female age‐specific survival, fecundity and offspring survival to independence, as well as lifetime breeding success (lifetime number of calves produced). Females showed low fecundity following sexual maturity, followed by a rapid increase to a peak at age 19 and a subsequent decline. High early life reproductive output (before the peak of performance) was positively associated with subsequent age‐specific fecundity and offspring survival, but significantly impaired a female's own later‐life survival. Despite the negative effects of early reproduction on late‐life survival, early reproduction is under positive selection through a positive association with lifetime breeding success. Our results suggest a trade‐off between early reproduction and later survival which is maintained by strong selection for high early fecundity, and thus support the prediction from life history theory that high investment in reproductive success in early life is favoured by selection through lifetime fitness despite costs to later‐life survival. That maternal survival in elephants depends on previous reproductive investment also has implications for the success of (semi‐)captive breeding programmes of this endangered species.     

Female reproductive parameters in the Javan gibbon (Hylobates moloch)

Javan gibbons (Hylobates moloch) are one of the most endangered gibbon species in the world. Data on the reproductive biology of the species are almost nonexistent, and a general understanding of the female reproductive biology of this species is important for both ex situ and in situ conservation. Using 18 years of data from 11 captive individuals, we provide new information on the reproductive biology of Javan gibbons based on sexual swelling and menstrual bleeding, including reproductive development, interbirth intervals, and ovarian cycle lengths. Menarche and the onset of sexual swelling occurred at 6.2 and 6.5 years respectively, followed by a period of adolescent sterility of about 1.5 years. Average age at first birth was 8.8 years, and interbirth intervals were about 2.3 years, decreasing to 1.0 year during cases of infant mortality at or shortly after birth. Ovarian cyclicity was measured through periods between menstrual bleeding and sexual swelling. Menstrual bleeding indicates the start of a new ovarian cycle, while sexual swelling normally occurs near the time of ovulation. Menstrual bleeding intervals gave a cycle length of 25.6 days, while sexual swelling intervals gave a cycle length of 27.3 days. These both correspond closely to cycle lengths in other gibbon species, as well as hormonal studies in Javan gibbons. In particular, observing the presence/absence of swellings was found to be a useful and easy method to monitor female ovarian cycles, and could be a practical noninvasive technique for caretakers and researchers. Zoo Biol 29:449–456, 2010. © 2009 Wiley‐Liss, Inc.     

Is gibbon ape leukaemia virus still a threat?

相似文献   

Fecal Glucocorticoid Measurements and Their Relation to Rearing,Behavior, and Environmental Factors in the Population of Pileated Gibbons (<Emphasis Type="Italic">Hylobates pileatus</Emphasis>) Held in European Zoos

Pileated gibbons (Hylobates pileatus) are rated as endangered according to the International Union of Conservation of Nature (IUCN) Red List. The captive population suffers from poor breeding success and is threatened to become overaged. Although several factors are likely to contribute to the poor breeding success, one in particular may be chronic stress associated with prolonged periods of high glucocorticoid (GC) output. We investigated fecal GC levels of pileated gibbons (Hylobates pileatus) and their relationship to specific life-history variables and environmental factors. After validation of an enzyme immunoassay for the measurement of 5-reduced 3α,11β-dihydroxy cortisol metabolites to assess GC output reliably in pileated gibbons, we collected fecal samples over several days from all 36 European adult pileated gibbons located in 11 institutions and compared GC levels to intrinsic individual parameters, husbandry, behavior, and breeding history. Age, sex, and origin (wild vs. captive born) had no effect on GC levels. However, unnaturally reared gibbons had higher GC levels and showed more behavioral abnormalities than parent-reared individuals. Further, nonreproducing gibbons living in a pair without infants had higher GC concentrations than gibbons living in a family, bachelor group, or as singletons. With respect to environmental factors, a large size of the inside enclosure and the existence of visual protection from visitors was associated with lower fecal GC output. The data indicate that rearing and housing conditions appear to correlate to GC levels in pileated gibbons housed under captive conditions. It is hoped this knowledge will support the future management of the species in captivity and thus lead to a more successful breeding of this endangered primate.     

Sexually extravagant males age more rapidly

Evolutionary theories of ageing posit that increased reproductive investment occurs at the expense of physiological declines in later life. Males typically invest heavily in costly sexual ornaments and behaviour, but evidence that the expression of these traits can cause senescence is lacking. Long-lived houbara bustards (Chlamydotis undulata) engage in extravagant sexual displays to attract mates and here we show that males investing most in these displays experience a rapid senescent deterioration of spermatogenic function at a younger age. This effect is sufficiently large that the expected links between male 'showiness' and fertility reverse in later life, despite 'showy' males continuing to display at near maximal levels. We show that our results cannot be explained by the selective disappearance of competitive phenotypes and that they are instead consistent with an early vs. late life trade-off in male reproductive competence, highlighting the potential significance of sexual selection in explaining rates of ageing.     

Effect of ambient temperature on serum prolactin and luteinizing hormone levels during the reproductive life cycle of the female turkey (Meleagris gallopavo)

An ambient temperature of 30 degrees C compared to 18 degrees C accelerated the increase in serum prolactin (Prl) level induced by photostimulation of female turkeys. The contribution of reproductive stage and nesting behavior to this serum Prl elevation was assessed by housing adult female turkeys in individual wire cages while allowing other females free access to nests on the floor. Birds of both groups were exposed to 10 degrees C, 24 degrees C or 30 degrees C beginning 4 wk prior to photostimulation and continuing throughout the reproductive phase. Lapsed time between the onset of photostimulation and onset of sexual maturity, and between the onset of sexual maturity and onset of incubation behavior was shorter in birds housed at 30 degrees C with access to nests than in corresponding birds housed at 24 degrees C and 10 degrees C. The increases in serum Prl associated with sexual maturity or incubation behavior occurred at a greater rate in the birds maintained at 30 degrees C. Cage-reared birds had the same lapsed time between onset of photostimulation and onset of sexual maturity and the same sustained low Prl level regardless of ambient temperature exposure. All groups exhibited similar luteinizing hormone profiles. These findings indicate that the accelerated increase in Prl under elevated temperature in floor-reared turkeys is related to accelerated development of reproductive function, and not the direct effect of ambient temperature on mechanisms controlling Prl.     

Correlates of sexual and maternal competence in captive gorillas

The captive gorilla population may not be self-sustaining, in part because the overall birth rate is low and because many potential founders have failed to reproduce. We used questionnaires to collect standardized biographies of every gorilla held in North America. These biographies were searched for factors associated with reproductive success or failure. Captive-born gorillas are reproducing at least as well as wild-borns, when reproductive success is expressed as number of infants per year of reproductive opportunity. Mother-reared females are reproductively more successful than hand-reared females, but there is no difference in the reproductive success of mother-reared and hand-reared males. Social access to conspecifics in the 1st year is associated with higher reproductive success, at least for females. Reproductively successful and unsuccessful gorillas of both sexes have had equal access to potential mates, but unsuccessful animals are less likely than successful ones to exhibit normal sexual behavior. We conclude that many cases of reproductive failure are due to deficits in sexual behavior, which in turn may result from lack of early social experience with conspecifics. Some reproductive failure involves medical problems; interventive diagnostic techniques continue to be useful, if only to identify healthy individuals that can be managed intensively. The probability that a female will be a competent mother is not affected by her being wild-born or captive-born, or mother-reared or hand-reared.     

Mortality rates among wild chimpanzees

In order to compare evolved human and chimpanzees' life histories we present a synthetic life table for free-living chimpanzees, derived from data collected in five study populations (Gombe, Ta?, Kibale, Mahale, Bossou). The combined data from all populations represent 3711 chimpanzee years at risk and 278 deaths. Males show higher mortality than females and data suggest some inter-site variation in mortality. Despite this variation, however, wild chimpanzees generally have a life expectancy at birth of less than 15 years and mean adult lifespan (after sexual maturity) is only about 15 years. This is considerably lower survival than that reported for chimpanzees in zoos or captive breeding colonies, or that measured among modern human hunter-gatherers. The low mortality rate of human foragers relative to chimpanzees in the early adult years may partially explain why humans have evolved to senesce later than chimpanzees, and have a longer juvenile period.     

Influence of housing conditions on pregnancy outcome in cynomolgus monkeys (Macaca fascicularis)

Female cynomolgus monkeys (Macaca fascicularis) were kept under 3 different housing conditions: individually in type A cages (45 X 45 X 60 cm), individually in type B cages (70 X 70 X 100 cm) and as couples in type B cages. Primigravida did not show early embryonic mortality, differing significantly from 11.5% early losses in multigravida. Early embryonic mortality was not affected by housing condition. Further reproductive failure rates did not differ significantly for primigravid (18.5%) and multigravid females (24.0%), though abortion tended to occur more frequently in primigravida. Perinatal mortality (16.1%) accounted for most of the losses under each housing condition. More successful pregnancies (90%) were recorded for females housed individually in type B cages than for females housed in type A cages (68%). About 50% of the couples originally established remained until weaning of their infants, yielding 77% viable offspring. For multigravid females statistical evaluation showed a significant effect of housing conditions on reproductive outcome (X2-test 0.01 less than P less than 0.05) that could be entirely attributed to low losses in females housed individually in type B cages. It is concluded that housing conditions can have a profound influence on reproductive success in cynomolgus monkeys.     

Alternative life histories in the Atlantic salmon: genetic covariances within the sneaker sexual tactic in males

Alternative reproductive tactics are ubiquitous in many species. Tactic expression often depends on whether an individual's condition surpasses thresholds that are responsible for activating particular developmental pathways. Two central goals in understanding the evolution of reproductive tactics are quantifying the extent to which thresholds are explained by additive genetic effects, and describing their covariation with condition-related traits. We monitored the development of early sexual maturation that leads to the sneaker reproductive tactic in Atlantic salmon (Salmo salar L.). We found evidence for additive genetic variance in the timing of sexual maturity (which is a measure of the surpassing of threshold values) and body-size traits. This suggests that selection can affect the patterns of sexual development by changing the timing of this event and/or body size. Significant levels of covariation between these traits also occurred, implying a potential for correlated responses to selection. Closer examination of genetic covariances suggests that the detected genetic variation is distributed along at least five directions of phenotypic variation. Our results show that the potential for evolution of the life-history traits constituting this reproductive phenotype is greatly influenced by their patterns of genetic covariance.     

Male and female mate choice affects offspring quality in a sex-role-reversed pipefish.

Where both sexes invest substantially in offspring, both females and males should discriminate between potential partners when choosing mates. The degree of choosiness should relate to the costs of choice and to the potential benefits to be gained. We measured offspring quality from experimentally staged matings with preferred and non-preferred partners in a sex-role-reversed pipefish, Syngnathus typhle L. Here, a substantial male investment in offspring results in a lower potential reproductive rate in males than in females, and access to males limits female reproductive success rather than vice versa. Thus, males are choosier than females and females compete more intensely over mates than do males. Broods from preferred matings were superior at escaping predation, when either males or females were allowed to choose a partner. However, only 'choosing' females benefited in terms of faster-growing offspring. Our results have important implications for mate-choice research: here we show that even the more competitive and less choosy sex may contribute significantly to sexual selection through mate choice.     

Immature male gibbons produce female-specific songs

Gibbons are apes that are well known to produce characteristic species-specific loud calls, referred to as “songs.” Of particular interest is the sex specificity of the “great calls” heard in gibbon songs. However, little is known about the development of such calls. While great calls are given by female gibbons of various ages, they have never been recorded from males. Here, we report two observations of immature male gibbons from two different species, wild Hylobates agilis and captive H. lar, which spontaneously sang female-specific great calls. Based on the video clips, we conclude that immature males also have the potential to produce great calls. Our observations led us to propose a new hypothesis for the development of sexual differentiation in the songs of gibbons, and its implications for the general issue of sex-specific behavior in primates.     

Home-range characteristics and the influence of seasonality on female reproduction in white-handed gibbons (Hylobates lar) at Khao Yai National Park, Thailand

A three-year (2001-2003) study was carried out on the home range characteristics of seven wild white-handed gibbon (Hylobates lar) groups focusing on the spatio-temporal distribution of food resources at Khao Yai National Park in northeastern Thailand. These results were combined with 23 years (1980-2003) of reproductive performance data on seven females from the same focal groups. Reproductive performance was equal among females with regard to birth, weaning and maturation ratios, and independent of variation in food availability. Offspring mortality, however, was significantly positively correlated with home-range size. In addition, there was an increase in offspring mortality just after weaning, suggesting that the increase in the daily distance traveled by juveniles contributed to this mortality. Conceptions clustered during the first half of the year when food production was at its peak, which presumably allowed females to accumulate sufficient body reserves to resume ovarian cycling. Our results place Khao Yai gibbons closer to Cercopithecidae than great apes in terms of the temporal pattern of reproductive events, though gestation, lactation, inter-birth interval, and offspring maturation are considerably longer in gibbons, placing them closer to the other apes. Our findings underline the unique phylogenetic position of these small-bodied apes in terms of reproductive patterns in primates.     

Preliminary study on hand preference in captive northern white-cheeked gibbons (<Emphasis Type="Italic">Nomascus leucogenys</Emphasis>)

The postural origin hypothesis and the task complexity hypothesis propose that hand preference in non-human primates evolved in association with body posture and task complexity, respectively. The results of previous studies testing these two hypotheses, however, vary greatly with the different primate species and methods used. To investigate the effect of body posture and task complexity on hand preference, we recorded bouts of hand usage in nine captive northern white-cheeked gibbons (Nomascus leucogenys) housed at Beijing Zoo as they reached for food items in a ground-reaching task, a box task, and a tube task. The results showed that four to seven of the nine gibbons displayed a hand preference at the individual level in different tasks, and that hand preference in individuals was task-specific; there was no group-level hand preference in any task. The box task seemed to elicit a greater strength of hand preference than the ground-reaching task at the individual level. Although the small sample size rules out drawing any strong conclusions concerning hand preference at the group level, our results suggest that the suspensory reaching posture might increase the expression of hand preference at the individual level. This study provides preliminary information on hand preference in captive northern white-cheeked gibbons, and will be helpful for future studies addressing the origin and evolution of hand preference in small apes.     

Adaptive male effects on female ageing in seed beetles

Selection can favour the evolution of a high reproductive rate early in life even when this results in a subsequent increase in the rate of mortality, because selection is relatively weak late in life. However, the optimal reproductive schedule of a female may be suboptimal to any one of her mates, and males may thus be selected to modulate female reproductive rate. Owing to such sexual conflict, coevolution between males and females may contribute to the evolution of senescence. By using replicated beetle populations selected for reproduction at an early or late age, we show that males evolve to affect senescence in females in a manner consistent with the genetic interests of males. 'Late' males evolved to decelerate senescence and increase the lifespan of control females, relative to 'early' males. Our findings demonstrate that adaptive evolution in one sex may involve its effects on senescence in the other, showing that the evolution of optimal life histories in one sex may be either facilitated or constrained by genes expressed in the other.     

Assessment of lifetime performance of small ruminants under different feeding systems

Evaluation of lifetime productivity of individual animals in response to various interventions allows assessment of long-term investment opportunities for farmers. In order to gain a better understanding of promising feed interventions for improvement of small ruminant production in Southwestern Nigeria, a dynamic modelling approach was used to explore the effect of different feeding strategies on the lifetime productivity of West African Dwarf (WAD) goats. Modifications were made to the current version of Livestock Simulator developed for cattle production to simulate goat production systems particularly for WAD goats. Effects of changes in input parameters (quality of feed and potential adult weight) confirmed the sensitivity of the modelled weight development and reproductive performance. The values of simulated model outputs corresponded well with observed values for most of the variables, except for the pre-weaning mortality rate in the cut-and-carry system where a wide discrepancy between simulated (2.1%) and observed (23%) data was found. The scenario analysis showed that simulated goats in the free grazing system attained sexual maturity and kidded much later than those in the grazing with supplementation and the cut-and-carry systems. The simulated results suggested that goats require supplementation with protein and energy sources, in order to promote lifetime productivity, early sexual maturity and higher birth weight. In terms of economic returns based on feed cost alone, the moderately intense system produced the most profit. We therefore conclude that grazing with adequate supplementation using farm-generated feed resources offers an opportunity for improving smallholder goat production systems in West Africa.     

Unusual behaviour of captive-raised gibbons: implications for welfare

Unusual behaviours not normally seen in the wild were studied in 52 captive agile (Hylobates agilis albibarbis) and 23 Müllers gibbons (H. muelleri spp) at three locations within the Kalaweit Gibbon Rehabilitation Project. Unusual behaviours included stereotypic behaviour (SB), human-directed masturbation and posterior presenting. These data were collected over 18 months as part of an ongoing study into behavioural adaptation of gibbons in a rehabilitation programme. Data were also collected on the unusual behaviours observed, for example, SB, human-directed masturbation and posterior presenting. I suggest causes of the abnormal behaviours and propose solutions to reduce their incidence in order to improve the gibbon’s progress in rehabilitation. From this study I conclude that most gibbons can be rehabilitated from the point of view of acquiring and maintaining a normal behavioural repertoire once in suitable housing. Encouraging the gibbons to reduce and/or stop these unusual behaviours is key to the welfare of the gibbons while in the rehabilitation programme and to successful release into a forest habitat. An erratum to this article can be found at     

Female competition and its evolutionary consequences in mammals

Following Darwin's original insights regarding sexual selection, studies of intrasexual competition have mainly focused on male competition for mates; by contrast, female reproductive competition has received less attention. Here, we review evidence that female mammals compete for both resources and mates in order to secure reproductive benefits. We describe how females compete for resources such as food, nest sites, and protection by means of dominance relationships, territoriality and inter‐group aggression, and by inhibiting the reproduction of other females. We also describe evidence that female mammals compete for mates and consider the ultimate causes of such behaviour, including competition for access to resources provided by mates, sperm limitation and prevention of future resource competition. Our review reveals female competition to be a potentially widespread and significant evolutionary selection pressure among mammals, particularly competition for resources among social species for which most evidence is currently available. We report that female competition is associated with many diverse adaptations, from overtly aggressive behaviour, weaponry, and conspicuous sexual signals to subtle and often complex social behaviour involving olfactory signalling, alliance formation, altruism and spite, and even cases where individuals appear to inhibit their own reproduction. Overall, despite some obvious parallels with male phenotypic traits favoured under sexual selection, it appears that fundamental differences in the reproductive strategies of the sexes (ultimately related to parental investment) commonly lead to contrasting competitive goals and adaptations. Because female adaptations for intrasexual competition are often less conspicuous than those of males, they are generally more challenging to study. In particular, since females often employ competitive strategies that directly influence not only the number but also the quality (survival and reproductive success) of their own offspring, as well as the relative reproductive success of others, a multigenerational view ideally is required to quantify the full extent of variation in female fitness resulting from intrasexual competition. Nonetheless, current evidence indicates that the reproductive success of female mammals can also be highly variable over shorter time scales, with significant reproductive skew related to competitive ability. Whether we choose to describe the outcome of female reproductive competition (competition for mates, for mates controlling resources, or for resources per se) as sexual selection depends on how sexual selection is defined. Considering sexual selection strictly as resulting from differential mating or fertilisation success, the role of female competition for the sperm of preferred (or competitively successful) males appears particularly worthy of more detailed investigation. Broader definitions of sexual selection have recently been proposed to encompass the impact on reproduction of competition for resources other than mates. Although the merits of such definitions are a matter of ongoing debate, our review highlights that understanding the evolutionary causes and consequences of female reproductive competition indeed requires a broader perspective than has traditionally been assumed. We conclude that future research in this field offers much exciting potential to address new and fundamentally important questions relating to social and mating‐system evolution.