Kinship alters the effects of forced cohabitation on body weight,mate choice and fitness in the rat-like hamster Tscheskia triton

It has been documented that social isolation imparts deleterious effects on gregarious rodents species,but caging in group imparts such effects on solitary rodents. This study was attempted at examining how kinship to affect body weight,behavioral interaction,mate choice and fitness when we caged male and female rat-like hamsters Tscheskia triton in pair,a solitary species. We found that females paired with nonsibling males became heavier than the females paired with sibling males,but both agonistic and amicable behavior between paired males and females did not differ between sibling and nonsibling groups. This indicated that kinship might reduce females' obesity in response to forced cohabitation,and dissociation might exist between physiological and behavioral responses. Furthermore,binary choice tests revealed that social familiarity between either siblings or nonsiblings decreased their investigating time spent in opposite sex conspecific of cage mates and/or their scents as compared with those of non-mates,suggesting effects of social association on mate and kin selection of the hamsters. On the other side,both females and males caged in pair with siblings show a preference between unfamiliar siblings or their scents and the counterparts of nonsiblings after two month separation,indicating that the kin recognition of the hamsters might also rely on phenotype matching. In addition,cohabitation (or permanent presence of fathers) elicited a lower survival of pups in nonsibling pairs than sibling pairs,but did not affect litter size,suggesting that kinship affects fitness when housing male and female ratlike hamsters together. Therefore,inbreeding might be adapted for rare and endangered

Seismic sentinel? An analysis of captive giant panda behavior in response to the Lushan earthquake in China

It is widely believed that various animal species can sense and respond to the geophysical stimuli that precede earthquakes,especially electromagnetic fields,although supporting field evidence is mostly anecdotal.Here we report on the reactions of four female giant pandas under observation over the three days prior to the Lushan(30.1°N,103.0°E)magnitude 7.0 earthquake that occurred in Sichuan province,China,on April 20,2013.We observed no significant generalized behavioral anomalies indicative of them perceiving an impending earthquake.We also observed no startle behaviors in the 5 s prior to tremors commencing,indicating that these pandas either did not detect or did not respond to precursor P-waves.Our findings suggest that although giant pandas have evolved in,and continue to occupy exclusively,a seismically active range in central China,they do not appear to perceive pre-earthquake geophysical warning signs.

Giant panda(Ailuropoda melanoleuca)neonates use broadband calls to communicate with their mothers

Infant call structure should have evolved to elicit maximum maternal attention and investment.Neonates of giant pandas produce three types of vocalizations reported to be vitally important in the context of mother–infant communications.However,how cubs,0–15 days old,communicate with their mothers to elicit maternal care remains unknown.We analyzed 12 different call parameters of 3475 squawks,1355 squalls,and 491 croaks from 11 captive giant panda(Ailuropoda melanoleuca)neonates from age 0 to 15 days.In playback experiments,we also tested whether mothers could detect ultrasound.Our results show that neonates use broadband calls with ultrasonic frequencies up to 65 kHz to convey information about their physiological needs and to attract maternal care.In playback experiments,we tested if mothers reacted differently to broadband calls(BBC)than to artificially altered calls that included only frequencies<20 kHz(AUDC)or calls that included only frequencies>20 kHz(USC).Playback confirmed that,although adult females responded significantly less often to USC,BBC than to or AUDC,they could detect USC,BBC and generally made appropriate behavioral responses,indicating a potential benefit for neonates to utilize ultrasonic and broadband frequencies.Our findings provide a new insight into mother–infant communication in giant pandas and will be helpful for reducing the mortality of cubs,younger than 1 month old,in captivity.

Seasonal and reproductive variation in chemical constituents of scent signals in wild giant pandas

Seasonally reproducing animals show many behavioral and physiological changes during the mating period, including increased signaling for intrasexual competition and mate attraction. We collected 102 anogenital gland secretions(AGS) from marking trees in Foping Nature Reserve, and used gas chromatography mass spectrometry to analyze these chemical composition. Of these marks, all but one were from males, confirmed with DNA analysis. We found that several chemical constituents, especially volatile compounds, were present only during the mating season and that the relative abundance of many compounds changed as a function of breeding season, whereas nonvolatile compounds were lower in the mating season. This seasonal variation in chemical composition of AGS most likely plays an important role in governing giant panda reproduction, including mate location, attraction, and male-male competition. The chemical properties of many of these putative chemosignals—such as volatility and longevity—are suggestive of these roles, and undoubtedly contribute to successful reproduction for this species with a characteristically sophisticated chemical communication system. We also found a number of important differences between the chemical constituents of AGS from wild pandas and those found in previous studies with captive pandas, suggesting that inappropriate chemosignal composition may contribute to poor reproductive success in captive breeding programs.

Vomeronasal organ lesion disrupts social odor recognition, behaviors and fitness in golden hamsters

Most studies support the viewpoint that the vomeronasal organ has a profound effect on conspecific odor recog­nition,scent marking and mating behavior in the golden hamster(Mesocricetus auratus).However,the role of the vomeronasal organ in social odor recognition,social interaction and fitness is not well understood.There­fore,we conducted a series of behavioral and physiological tests to examine the referred points in golden ham­ster.We found that male hamsters with vomeronasal organ lesion showed no preference between a predator odor(the anal gland secretion of the Siberian weasels(Mustela sibirica)and putative female pheromone components(myristic acid and palmitic acid),but were still able to discriminate between these 2 kinds of odors.In behavior­al tests of anxiety,we found that vomeronasal organ removal causes female hamsters to spend much less time in center grids and to cross fewer center grids and males to make fewer crossings between light and dark boxes than sham-operated controls.This indicates that a chronic vomeronasal organ lesion induced anxious responses in females.In aggressive behavioral tests,we found that a chronic vomeronasal organ lesion decreased agonistic behavior in female hamsters but not in males.The pup growth and litter size show no differences between the 2 groups.All together,our data suggested that vomeronasal organ ablation disrupted the olfactory recognition of social chemosignals in males,and induced anxiety-like and aggressive behavior changes in females.However,a vomeronasal organ lesion did not affect the reproductive capacity and fitness of hamsters.Our studies may have important implications concerning the role of the vomeronasal organ in golden hamsters and also in rodents.