查看更多>>摘要：Age is a key factor affecting sexual selection,as many physical and social traits are age-related.Although studies of primate mate choice often consider particular age-related traits,few consider the collective effects of male age.We tested the hypothesis that female golden snub-nosed mon-keys Rhinopithecus roxellana prefer prime aged males(10-15 years)over younger and older males.We examined a habituated,provisioned troop during a 3-year study in the Qinling Mountains,China.Prime age males were more likely to be resident males of 1-male units(OMUs)than males of other ages.Since females are free to transfer between OMUs,the number of females per OMU can be indicative of female preferences.We examined the number of females per OMU,and found that it increased with resident male age up to 7-8 years,and declined after 12 years,such that prime age resident males had more females than other resident males.Females also initiated extra-unit copulations with high-ranking prime age males at significantly higher rates than with other males.Nevertheless,females tended to transfer from OMUs with high-ranking,older resident males to those with low-ranking,younger resident males.Thus,females appear to use different strategies when choosing social mates and extra-unit mates(i.e.,different social contexts).We speculate that females may perceive early signs of aging in males and trade off the benefits and costs of high rank versus male senescence.This study lays the groundwork for future studies that examine pos-sible direct and indirect benefits of such strategies.
查看更多>>摘要：Conspicuous coloration in animals serves many functions such as anti-predation.Anti-predation strategies include motion dazzle and flash behavior.Motion dazzle markings can reduce the prob-ability of being preyed on because the predators misjudge their movement.In flash behavior,prey demonstrate conspicuous cue while fleeing;the predators follow them;however,the prey hide their markings and the predators assume that the prey has vanished.To investigate whether bovids use conspicuous hindquarter markings as an anti-predatory behavior,we undertook phylogenetically controlled analyses to explore under what physiological characteristics and envir-onmental factors bovids might have this color pattern.The results suggested that rump patches and tail markings were more prevalent in bovids living in larger-sized groups,which supports the hypothesis of intraspecific communication.Moreover,we observed the occurrence of conspicuous white hindquarter markings in bovids having smaller body size and living in larger groups,sug-gesting a motion dazzle function.However,the feature of facultative exposing color patterns(flash markings)was not associated with body size,which was inconsistent with predictions and implied that bovids may not adopt this as an anti-predator strategy.It was concluded that species in bovids with conspicuous white hindquarter markings adopt motion dazzle as an anti-predation strategy while fleeing and escaping from being prey on.
查看更多>>摘要：Predation is an important ecological constraint that influences communication in animals.Fish re-spond to predators by adjusting their visual signaling behavior,but the responses in calling behav-ior in the presence of a visually detected predator are largely unknown.We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator.To test this we investigated dyadic contests in female croaking gouramis(Trichopsis vittata,Osphronemidae)in the presence and absence of a predator(Astronotus ocella-tus,Cichlidae)in an adjoining tank.Agonistic behavior in T.vittata consists of lateral(visual)dis-plays,antiparallel circling,and production of croaking sounds and may escalate to frontal displays.We analyzed the number and duration of lateral display bouts,the number,duration,sound pres-sure level,and dominant frequency of croaking sounds as well as contest outcomes.The number and duration of lateral displays decreased significantly in predator when compared with no-predator trials.Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics.In the presence of a predator,dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays.The gouramis showed approaching behavior toward the predator between lateral displays.This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish.Sound properties,in contrast,did not change.Decreased signaling and the lack of escalating con-tests reduce the fish's conspicuousness and thus predation threat.
查看更多>>摘要：Rescue behavior is observed when 1 individual provides help to another individual in danger.Most reports of rescue behavior concern ants(Formicidae),in which workers rescue each other from various types of entrapment.Many of these entrapment situations can be simulated in the labora-tory using an entrapment bioassay,in which ants confront a single endangered nest mate entrapped on a sandy arena by means of an artificial snare.Here,we compared numerous charac-teristics of rescue actions(contact between individuals,digging around the entrapped individual,pulling at its body parts,transport of the sand covering it,and biting the snare entrapping it)in Formica cinerea ants.We performed entrapment tests in the field and in the laboratory,with the lat-ter under varying conditions in terms of the number of ants potentially engaged in rescue actions and the arena substrate(marked or unmarked by ants'pheromones).Rescue actions were more probable and pronounced in the field than in the laboratory,regardless of the type of test.Moreover,different test types in the laboratory yielded inconsistent results and showed note-worthy variability depending on the tested characteristic of rescue.Our results illustrate the specif-ics of ant rescue actions elicited in the natural setting,which is especially important considering the scarcity of field data.Furthermore,our results underline the challenges related to the compari-son of results from different types of entrapment tests reported in the available literature.Additionally,our study shows how animal behavior differs in differing experimental setups used to answer the same questions.
查看更多>>摘要：An increase in ecotourism adversely impacts many animals and contributes to biodiversity loss.To mitigate these impacts,we illustrate the application of a conservation behavior framework toward the development of a sustainable ecotourism management plan.In Ubon Ratchathani,Thailand,thousands of tourists annually come to see a unique mass migration of shrimps on land(referred to as"shrimp parading").Preliminary work suggests that this tourism has negatively impacted the shrimps.To reduce tourism-related impacts we studied:1)the decisions shrimps make when para-ding and 2)how shrimps respond to different light intensities and colors.We created an artificial stream and tested the conditions that influence parading by experimentally varying the presence of light and systematically manipulating water velocity(10,60,and 100 cm/s).Additionally,we con-ducted an in situ experiment to study how shrimps respond to tourists'lights under three inten-sities(50,400,and 9,000 lux)and five colors(white,blue,green,orange,and red).We found most shrimps prefer to leave the river when it is dark and there is low water flow.Shrimps responded the least to red(λmax=630nm)and orange(λmax=625nm)light at 50 lux.These findings were used to develop a management plan by creating three different tourist zones,which maximize tour-ist needs and minimize the anthropogenic impacts on the shrimps.This work could be used as an example of the application of conservation behavior framework in developing management plan for sustainable ecotourism for other invertebrate taxa.
查看更多>>摘要：Consistent inter-individual differences in daily activity rhythms(i.e.,chronotypes)can have eco-logical consequences in determining access to food resources and avoidance of predators.The most common measure to characterize chronotypes in animals as well as humans is the onset of activity(i.e.,early or late chronotypes).However,daily activity rhythms may also differ in the rela-tive amount of activity displayed at particular time periods.Moreover,chronotypes may also be linked to other consistent inter-individual differences in behavior(i.e.,personality),such as the pro-pensity to take risks.Here,we used the signal crayfish Pacifastacus leniusculus to test the presence of chronotypes and risk-taking personality traits and a potential behavioral syndrome between these traits.We first exposed crayfish to 5 days of light-darkness to measure daily activity rhythms and then we applied a visual predator-simulating stimulus in 2 different contexts(neutral and food).Our results showed consistent(i.e.,across 5 days)inter-individual differences in the relative nocturnal activity displayed in the early and middle,but not in the late part of darkness hours.Moreover,while crayfish displayed inter-individual differences in risk-taking behavior,these were not found to be consistent across 2 contexts.Therefore,we were not able to formally test a behav-ioral syndrome between these 2 traits.In conclusion,our study provides the first evidence of chronotypes in the relative amount of activity displayed at particular time periods.This could be a valuable information for applied ecological aspects related to the signal crayfish,which is a major invasive species of freshwater ecosystems.
查看更多>>摘要：The study of the recent colonization of a symbiont and its interaction with host communities in new locations is an opportunity to understand how they interact.The use of isotopic ratios in trophic ecol-ogy can provide measurements of a species'isotopic niche,as well as knowledge about how the iso-topic niches between symbiont and host species overlap.Stable isotope measurements were used to assess the sources of carbon assimilated by the host species(the bivalves Mytilus galloprovincialis and Scrobicularia plana)and their associated symbiont pea crab Afropinnotheres monodi,which occurs within these bivalves'mantle cavities.The mixing model estimates suggest that all of them as-similate carbon from similar sources,particularly from pseudofaeces and particulate organic matter in this symbiotic system based on filter feeding.The symbiotic species occupy comparable trophic levels and its association seems to be commensal or parasitic depending on the duration of such association.The pea crab A.monodi reflects a sex-specific diet,where males are more generalist than the soft females because the latter's habitat is restricted to the host bivalve.The high isotopic overlap between soft females and M.galloprovincialis may reflect a good commensal relationship with the host.
查看更多>>摘要：Maximum and minimum metabolic rates in birds are flexible traits and such flexibility can be ad-vantageous in variable climates.The climatic variability hypothesis(CVH)posits that more variable climates should result in greater metabolic flexibility for geographically distinct populations.Whether the CVH applies to sympatric species occupying microclimates differing in variability is unknown.Microclimates of open habitats are likely more variable than those of sheltered habitats.If the CVH extends to microclimates,we expect birds from open habitats to show greater flexibility than those from sheltered habitats.To test this extension of the CVH,we compared seasonal vari-ation in microclimates and metabolic rates for sympatric horned larks Eremophila alpestris,which occupy open habitats,and house sparrows Passer domesticus,which occupy sheltered habitats.We measured operative temperature(Te,an integrative measure of the thermal environment),summit metabolic rate(Msum,maximal cold-induced metabolic rate),and basal metabolic rate(BMR,minimal maintenance metabolic rate)in summer and winter.For both winter and summer,daily minimum Te was similar between open and sheltered habitats but maximum Te was higher for open habitats.Winter microclimates,however,were colder for open than for sheltered habitats after accounting for convective differences.Both species increased Msum in winter,but seasonal Msum flexibility was greater for larks(43％)than for sparrows(31％).Winter increases in BMR were 92.5％and 11％for larks and sparrows,respectively,with only the former attaining statistical sig-nificance.Moreover,species * season interactions in general linear models for whole-organism metabolic rates were significant for BMR and showed a similar,although not significant,pattern for Msum,with greater seasonal metabolic flexibility in horned larks than in house sparrows.These results suggest that extending the CVH to sympatric bird species occupying different microclimates may be valid.
Sara F.NUNESMário MOTA-FERREIRAMarta SAMPAIOJoana ANDRADE...
211-219页
查看更多>>摘要：Invasive species are a major threat to island biodiversity,and their eradications have substantially contributed to the conservation of island endemics.However,the consequences of eradications on the trophic ecology of native taxa are largely unexplored.Here,we used the eradication of invasive black rats Rattus rattus and European rabbits Oryctolagus cuniculus from the Berlenga Island,in the western coast of Portugal,as a whole-ecosystem experiment to investigate the effects of the eradication of invasive mammals on the trophic niche and body dimensions of the island-restricted Berlenga wall lizard Podarcis carbonelli berlengensis over a 2-year period.Our results suggest an expansion of the isotopic niche and an intensification of the sexual dimorphism of the lizard following mammal eradication.Additionally,we found considerable variability in isotopic niche across the island and detected evidence of sex-specific and season-modulated nutritional requirements of this threatened reptile.Our findings support that the eradication of 2 of the planets most problematic invasive vertebrates led to changes in the lizard trophic niche and sexual dimorphism in just 2 years.This suggests that the ecological pressuresfor example,prey availability and habitat structureto which lizards are exposed have substantially changed post-eradication.Our study emphasizes the scientific value of island eradications as experiments to address a wide range of ecological questions and adds to the increasing body of evidence supporting substantial conservation gains associated with these restoration interventions.
查看更多>>摘要：The demographic trend of a species depends on the dynamics of its local populations,which can be compromised by local or by global phenomena.However,the relevance of local and global phe-nomena has rarely been investigated simultaneously.Here,we tested whether local phenomena compromised a species'demographic trend using the Eurasian common lizard Zootoca vivipara,the terrestrial reptile exhibiting the widest geographic distribution,as a model species.We ana-lyzed the species'ancient demographic trend using genetic data from its 6 allopatric genetic clades and tested whether its demographic trend mainly depended on single clades or on global phenom-ena.Zootoca vivipara's effective population size increased since 2.3 million years ago and started to increase steeply and continuously from 0.531 million years ago.Population growth rate exhib-ited 2 maxima,both occurring during global climatic changes and important vegetation changes on the northern hemisphere.Effective population size and growth rate were negatively correlated with global surface temperatures,in line with global parameters driving long-term demographic trends.Zootoca vivipara's ancient demography was neither driven by a single clade,nor by the 2 clades that colonized huge geographic areas after the last glaciation.The low importance of local phenomena,suggests that the experimentally demonstrated high sensitivity of this species to short-term ecological changes is a response in order to cope with short-term and local changes.This suggests that what affected its long-term demographic trend the most,were not these local changes/responses,but rather the important and prolonged global climatic changes and important vegetation changes on the northern hemisphere,including the opening up of the forest by humans.
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