Female preferences for male golden snub-nosed monkeys vary with male age and social context

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 monkeys 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 one-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 lower-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 vs. male senescence. This study lays the groundwork for future studies that examine possible direct and indirect benefits of such strategies.

A behavioral logic underlying aggression in an African cichlid fish

Social rank in a hierarchy determines which individuals have access to important resources such as food, shelter, and mates. In the African cichlid fish Astatotilapia burtoni, rank is under social control, such that larger males are more likely than smaller males to be dominant in rank. Although it is well known that the relative size of A. burtoni males is critical in controlling social rank, the specific behavioral strategies underlying responses to males of different sizes are not well understood. In this research, our goal was to characterize these responses by performing resident-intruder assays, in which aggressive behaviors were measured in territorial males in response to the introduction of unfamiliar males that differed in relative standard length (SL). We found that the relative SL of intruders played an important role in determining behavioral performance. Resident males exposed to larger (>5% larger in SL) or matched (between 0 and 5% larger or smaller in SL) intruder males performed more lateral displays, a type of non-physical aggression, compared to resident males exposed to smaller (>5% smaller in SL) intruder males. However, physical aggression, such as chases and bites, did not differ as a function of relative SL. Our results suggest that A. burtoni males amplify non-physical aggression to settle territorial disputes in response to differences in relative SL that were not previously considered to be behaviorally relevant.HighlightsRelative size determines social rank in the African cichlid Astatotilapia burtoniResident male A. burtoni respond differently to small size differences in intruder malesResidents perform more non-physical aggression against larger intrudersResidents do not alter physical aggression as a function of differently sized intrudersDistinct behavioral strategies are used against different intruders

Breeding patterns of female prairie voles (Microtus ochrogaster) displaying alternative reproductive tactics

Individuals of either sex may display alternative behaviors to obtain copulations, but few studies have examined the breeding patterns of females and males in populations where individuals of both sexes exhibit alternative reproductive tactics (ARTs). In prairie voles (Microtus ochrogaster), most adults are territorial, residing at a single nest site either as male–female pairs or as solitary individuals. However, some adults adopt nonterritorial, wandering tactics. During two field seasons monitoring prairie vole populations maintained in seminatural enclosures, we found evidence that females exhibiting different ARTs bred differentially with resident and wandering males. Females residing at a nest with a male bred significantly more often with a paired resident male, primarily their social partner, and significantly less often with male wanderers compared to single resident females or wandering females. These patterns were not due to chance, because paired resident females produced offspring with paired resident males significantly more than expected based on the relative abundance of these males in the population, whereas single resident females produced offspring with male wanderers significantly more than expected based on the proportion of male wanderers in the population. We did not find any evidence that multiple paternity was greater in the litters of single resident females and wanderer females even though these females lacked a male social partner to limit mating access by multiple males. This suggests that mate guarding by a female’s male social partner was not the primary determinant of multiple paternity in the litters of females exhibiting different reproductive tactics. However, male ART did affect the likelihood of multiple paternity. Females that produced offspring with single resident or wanderer males had an increased likelihood of multiple paternity relative to females producing offspring with paired resident males. The results of this study show that female and male ARTs can affect breeding patterns.

Report of agonistic interaction in Malagasy frogs of the genus Gephyromantis (Anura, Mantellidae)

Territorial behaviour has been recorded in several amphibian families but rarely in frogs from Madagascar, despite the extremely high species diversity in the country. Here we describe the agonistic encounter of two male frogs of the Malagasy-endemic genus Gephyromantis. The physical combat was preceded by a switch from the advertisement call to a more aggressive tone of the resident male upon the intruder approaching. Although no physical interaction has been reported before, the change in call type is similar to that observed in other Gephyromantis. The combat lasted for about one minute with both males trying to subdue each other, until the intruder retreated.

Knowledge of heart attack and stroke symptoms among US Native American Adults: a cross-sectional population-based study analyzing a multi-year BRFSS database

Background Heart disease and stroke are among the leading causes of death in Native Americans. Knowledge of heart attack and stroke symptomology are essential for prompt identification of symptoms and for appropriate action in seeking care. Knowledge of heart attack and stroke symptoms among US Native American adults was this study’s focus. Methods Multivariate techniques were used to analyze national surveillance data. Native American adults comprised the study population. Low heart attack and stroke knowledge score was the dependent variable. Results Logistic regression analysis yielded that Native American adults with low heart attack and stroke composite knowledge scores were more likely to be: older, less educated, poorer, uninsured, a rural resident, male, without a primary health care provider, and lacking a recent medical checkup. Conclusions The identified characteristics of Native American adults with heart attack and stroke knowledge deficits or disparities should guide educational initiatives by health care providers focusing on improving such knowledge.

Behavioral and Endocrine Alterations to Partner Interactions and Offspring Care during Periods of Conflict

Biparental care has evolved to ensure successful rearing of offspring. However, separation during periods of care can lead to conflicts that might negatively impact pair bonds and offspring care. In this study, pair-bonded convict cichlids (Amatitlania nigrofasciata) were observed for changes in behavior toward their partners and offspring before and after a period of separation. Males and females were designated either as a Resident (remain with offspring) or Removed (separated from partner and offspring for 5 days) individual. Behaviors between partners and toward offspring were measured before and after separation, and compared to the levels of behavior of control pairs (never separated), as well as individuals introduced to a novel partner instead. Cortisol levels of Resident male and female A. nigrofasciata were assayed using water-borne hormone collection before and after separation. Aggression between pair bond members did increase following reintroduction, but did not lead to the termination of pair bonds. Resident females showed more aggression to novel partners than Resident males. Offspring care decreased in both Resident and Removed females. Experimental pairs decreased the amount of time spent interacting with intruders. Cortisol levels were significantly higher among experimental pairs compared with control pairs that did not experience a separation. Females (both control and experimental) showed small, yet significant increases in cortisol levels, while both control and experimental males did not. These results suggest that while pair bonds appear resilient, prolonged separations influence pair bond and parental care dynamics, both behaviorally and hormonally, and require pairs to re-establish roles, resulting in less time caring for offspring.

Resource competition and apparent competition in declining mule deer (Odocoileus hemionus)

Resource competition and apparent competition have both been suggested as the cause of mule deer (Odocoileus hemionus (Rafinesque, 1817)) decline concurrent with white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) increase. I tested for both hypotheses by conducting a “press” and “release” experiment in a mule deer, white-tailed deer, and cougar (Puma concolor (L., 1771)) community. If resource competition is causal, then predation should decrease, but other sources of mortality should increase following increased mortality of cougars and release of competing white-tailed deer. If apparent competition is causal, then predation should decrease and mule deer should increase following increased mortality of cougars and release of white-tailed deer. I accepted the apparent competition hypothesis because high mortality of female cougars and cougar population decline was associated with both white-tailed deer and mule deer population growth. Very high mortality of female cougars appeared to result in mule deer population recovery. However, high mortality of male cougars (with increased male immigration) preceding high female mortality appeared to result in sexually segregated prey-switching by females with cubs from abundant white-tailed deer to rare mule deer to avoid sexually selected infanticide. High mortality of resident male cougars may have precipitated the mule deer decline in the first place.

The relationship between perch type and aggressive behavior in the lizard Norops polylepis (Squamata: Dactyloidae)

The intensity of aggression against intruders by owners of a territory has been related to the type of resources available to an individual within its territory. The influence of perch-site characteristics on aggressive behavior of resident male Norops polylepis in presence of an intruder male was investigated in this study. At each perch site, pairwise encounters were conducted in which the aggressive behavior of resident males was recorded, along with the diameter of the perch and the number of nearby perches. Aggressive behavior of resident males increased on larger perches and to some extent in areas having greater density of nearby saplings. Potential explanations for the high aggressive behavior of N. polylepis on broad perches with high number of neighboring saplings are explored.

Gradient Evolution of Body Colouration in Surface- and Cave-DwellingPoecilia mexicanaand the Role of Phenotype-Assortative Female Mate Choice

Ecological speciation assumes reproductive isolation to be the product of ecologically based divergent selection. Beside natural selection, sexual selection via phenotype-assortative mating is thought to promote reproductive isolation. Using the neotropical fishPoecilia mexicanafrom a system that has been described to undergo incipient ecological speciation in adjacent, but ecologically divergent habitats characterized by the presence or absence of toxic H2S and darkness in cave habitats, we demonstrate a gradual change in male body colouration along the gradient of light/darkness, including a reduction of ornaments that are under both inter- and intrasexual selection in surface populations. In dichotomous choice tests using video-animated stimuli, we found surface females to prefer males from their own population over the cave phenotype. However, female cave fish, observed on site via infrared techniques, preferred to associate with surface males rather than size-matched cave males, likely reflecting the female preference for better-nourished (in this case: surface) males. Hence, divergent selection on body colouration indeed translates into phenotype-assortative mating in the surface ecotype, by selecting against potential migrant males. Female cave fish, by contrast, do not have a preference for the resident male phenotype, identifying natural selection against migrants imposed by the cave environment as the major driver of the observed reproductive isolation.