Characterization of 13 microsatellite marker loci in Verreaux's sifaka (Propithecus verreauxi)

The Verreaux's sifaka (Propithecus verreauxi) is one of the species of Propithecus, living in the dry forest of southwest Madagascar. This species is endangered due to the loss and fragmentation of its natural habitat, a consequence of deforestation. Thirteen novel nuclear microsatellite loci were isolated and characterized in three populations of Verreaux's sifaka. The marker suite proved informative with an average of 8.9 alleles per locus and observed heterozygosity across the three populations of 0.675.     

Intrasexual selection in Verreaux's sifaka (Propithecus verreauxi verreauxi)

Studies of sexual selection show that both female choice and male-male competition can influence the evolution and expression of male phenotypes. In this regard, it is important to determine the functional basis through which male traits influence variation in male reproductive success. In this study, we estimate the strength and type of sexual selection acting on adult males in a population of wild lemur, Verreaux's sifaka (Propithecus verreauxi verreauxi). The data used in this study were collected at Beza Mahafaly Special Reserve, southwest Madagascar. We conducted paternity analyses on 70 males in order to estimate the distribution of reproductive success in this population. Paternity data were combined with morphometric data in order to determine which morphological traits covary with male fitness. Five morphological traits were defined in this analysis: body size, canine size, torso shape, arm shape, and leg shape. We utilized phenotypic selection models in order to determine the strength and type of selection acting directly on each trait. Our results show that directional selection acts on leg shape (a trait that is functionally related to locomotor performance), stabilizing selection acts on body mass and torso shape, and negative correlational selection acts on body mass and leg shape. We draw from biomechanical and kinematic studies of sifaka locomotion to provide a functional context for how these traits influence male mating competition within an arboreal environment. Verreaux's sifaka and many other gregarious lemurs are sexually monomorphic in body mass and canine size, despite a high frequency and intensity of male-male aggressive competition. Our results provide some insight into this paradox: in our population, there is no directional selection acting on body mass or canine size in males. The total pattern of selection implicates that behaviors relating to locomotor performance are more important than behaviors relating to fighting ability during intrasexual contests.     

Patterns of seasonality and group membership characterize the gut microbiota in a longitudinal study of wild Verreaux's sifakas (Propithecus verreauxi)

The intestinal microbiota plays a major role in host development, metabolism, and health. To date, few longitudinal studies have investigated the causes and consequences of microbiota variation in wildlife, although such studies provide a comparative context for interpreting the adaptive significance of findings from studies on humans or captive animals. Here, we investigate the impact of seasonality, diet, group membership, sex, age, and reproductive state on gut microbiota composition in a wild population of group‐living, frugi‐folivorous primates, Verreaux's sifakas (Propithecus verreauxi). We repeatedly sampled 32 individually recognizable animals from eight adjacent groups over the course of two different climatic seasons. We used high‐throughput sequencing of the 16S rRNA gene to determine the microbiota composition of 187 fecal samples. We demonstrate a clear pattern of seasonal variation in the intestinal microbiota, especially affecting the Firmicutes‐Bacteroidetes ratio, which may be driven by seasonal differences in diet. The relative abundances of certain polysaccharide‐fermenting taxa, for example, Lachnospiraceae, were correlated with fruit and fiber consumption. Additionally, group membership influenced microbiota composition independent of season, but further studies are needed to determine whether this pattern is driven by group divergences in diet, social contacts, or genetic factors. In accordance with findings in other wild mammals and primates with seasonally fluctuating food availability, we demonstrate seasonal variation in the microbiota of wild Verreaux's sifakas, which may be driven by food availability. This study adds to mounting evidence that variation in the intestinal microbiota may play an important role in the ability of primates to cope with seasonal variation in food availability.     

Influence of reproductive season and rank on fecal glucocorticoid levels in free-ranging male Verreaux's sifakas (Propithecus verreauxi)

Studies in anthropoid primates and other mammals suggest that reproductive season, rank, reproductive skew, aggression received, and social support are the major factors influencing glucocorticoid output. In which way these are also affecting adrenal function in lemurid primates has been studied rarely. Here, we examine the influence of reproductive season and rank on glucocorticoid output in male sifakas (Propithecus verreauxi), a species characterized by high breeding seasonality, a hierarchy among males and extreme reproductive skew towards dominant males. We established a fecal assay for non-invasively monitoring adrenal activity and collected 315 fecal samples during the reproductive and birth season from 10 male sifakas living in 5 groups in Western Madagascar. We found a significant effect of season on glucocorticoid output, with males exhibiting higher fecal glucocorticoid levels during the reproductive compared to the birth season in conjunction with an increase in overall aggression rates during the former period. Moreover, our data indicate a significant effect of rank on adrenocortical activity with dominant males exhibiting higher glucocorticoid levels than subordinate males in the reproductive season. However, dominant males did not differ significantly in rates of initiated or received aggression and rates of affiliative behavior from subordinates but showed significantly lower rates of submission. Given their highly formalized dominance relationships, we conclude that higher glucocorticoid output in dominant males during the 4-month reproductive season is likely related to higher energetic demands necessary to cope with the challenges of male reproduction rather than to physical demands of increased fighting frequency to maintain dominance status. High rank in sifakas may thus carry high costs, which, however, may be outweighed by monopolization of almost all paternities. In sum, our data generally support the findings on the relationship between environmental and social factors and glucocorticoid output found in non-lemurid primates.     

Testing for a historical population bottleneck in wild Verreaux's sifaka (Propithecus verreauxi verreauxi) using microsatellite data

The degree to which historical human activities negatively impacted past and present lemur species is a long-standing question in primatology. At present, most evidence addressing this issue comes from archaeology, paleontology, and behavioral studies. Genetic data provide another source of evidence. In this study, six microsatellite loci, genotyped on more than 360 wild Verreaux's sifaka, are used in order to test the hypothesis that this population experienced a population bottleneck in the last 2000 years. Excess heterozygosity is compared with the heterozygosity expected under mutation-drift equilibrium in order to test for the genetic signature of a rapid population contraction in the past. The results indicate that the sifaka population did not experience a population bottleneck. Various methodological and conceptual implications of this result are discussed.     

Detection of conspecific and heterospecific alarm signals by juvenile pumpkinseed under weak acidic conditions

Under neutral (pH 7·0) conditions, juvenile pumpkinseed Lepomis gibbosus exhibited significant antipredator responses, of similar intensities, to the chemical alarm cues of conspecifics, an allopatric congener the green sunfish Lepomis cyanellus and the artificial alarm cue of a sympatric prey guild member (Cyprinidae, hypoxanthine-3- N -oxide). Under weakly acidic conditions (pH 6·0), however, no increase in antipredator behaviour was seen in response to hypoxanthine-3- N -oxide and a quantitatively weaker response was found in response to conspecific and congener cues, suggesting that the use of chemical alarm cues by some prey fishes may be impaired by acid precipitation.     

Intergroup relations and home range use in Verreaux's sifaka (Propithecus verreauxi)

Relationships between neighboring groups feature prominently in socioecological theory, but few empirical studies have focused on the effects of neighbors on the behavior of primates. Interactions between neighboring groups are most conspicuous during intergroup encounters, but the likelihood of encounters with neighbors can also affect ranging and activity patterns indirectly, and, as a result, behavioral patterns in areas of exclusive use may differ from those in overlap areas of adjacent home ranges. The aim of this study was to examine intergroup relations and spatial variation in home range use in Verreaux's sifaka (Propithecus verreauxi) during the annual mating season. Based on 230 hr of focal animal data collected from ten members of five adjacent groups, we found that behavioral patterns and patterns of resource utilization were not markedly different between areas of exclusive use and overlap areas of adjacent home ranges. Group cohesion tended to be higher in overlap than in core areas, but the proportion of time spent resting and foraging did not differ between these two areas. However, dominant males exhibited a higher scent-marking rate in overlap areas. Observations during intergroup encounters revealed that chases between males occurred frequently, whereas fights involving physical contact were not observed. We also found that the intergroup dominance hierarchy depended on the relative group size or the number of males in each group, with groups of lower dominance rank exhibiting a tendency to sleep proportionally more often in their core areas. The results of this study suggest that in primate species with a moderate level of intergroup aggression, such as Verreaux's sifaka, the possibility of encountering neighbors in areas of home range overlap does not exert strong influence on their behavior and resource utilization.     

Effects of housing differences upon activity budgets in captive sifakas (Propithecus verreauxi)

Activity budgets of captive sifakas (Propithecus verreauxi coquereli and Propithecus verreauxi verreauxi) were assessed from 500 hours of observational data obtained at the Duke University Primate Center (Durham, NC). Data were examined for behavioral differences according to gender, availability of intergroup contact, subspecies, indoor/outdoor housing, and enclosure size. Results showed few differences between the activity budgets of males and females. Several differences found in conjunction with availability of intergroup contact appeared to relate more to subspecific, than to contact, differences. Sifakas housed outdoors were more active, spending less time resting and more time in locomotion, feeding, and playing than sifakas housed indoors. The findings of this study implicate outdoor housing as a primary factor in stimulating activity in these rare prosimian primates.     

No evidence of eavesdropping on heterospecific alarm calls by captive zebra finches recently descended from wild birds

Alarm calls are vocalisations animals give in response to predators which mainly function to alert conspecifics of danger. Studies show that numerous species eavesdrop on heterospecific calls to gain information about predator presence. Responding to heterospecific calls may be a learned or innate response, determined by whether the response occurs with or without prior exposure to the call. In this study, we investigated the presence of eavesdropping behaviour in zebra finches Taeniopygia guttata. This species is not known to possess a distinct alarm call to warn adult conspecifics of a threat, and could be relying on alarm calls of nearby heterospecifics for predator information. We used a playback experiment to expose captive zebra finches to three heterospecific sounds: an unfamiliar alarm call (from the chestnut‐rumped thornbill Acanthiza uropygialis), a familiar alarm call, and a familiar control (both from the noisy miner Manorina melanocephala). These calls were chosen to test if the birds had learnt to distinguish between the function of the two familiar calls, and if the acoustic properties of the unfamiliar alarm indicated presence of a threat to the finches. Our results showed that in response to the thornbill alarm, the birds reduced the rate of production of short calls. However, this decrease was also seen when considering both short and distance calls in response to the control sound. An increase in latency to call was also seen after the control stimulus when compared to the miner alarm. The time spent scanning increased in response to all three stimuli, but this did not differ between stimuli. There were no significant differences when considering the stimulus by time interaction for any of the three vigilance measures. Overall, no strong evidence was found to indicate that the captive zebra finches were responding to the heterospecific alarm stimuli with anti‐predator behaviour.     

Innate responses to conspecific and heterospecific alarm cues in the endangered eastern cape redfin Pseudobarbus afer

We examined innate responses to conspecific and heterospecific alarm cues in a small cyprinid minnow, the Eastern Cape redfin Pseudobarbus afer. We found that redfins respond to conspecific skin extract, which contains alarm chemicals, and showed that their preferred response is to hide in refugia. Redfins also respond to skin extract from an allopatric, distantly related minnow species, the chubbyhead barb Enteromius anoplus indicating that neither sympatry nor close phylogenetic relationships are necessary for recognition of heterospecific alarm cues. Although both conspecific and heterospecific alarm cues induced similar responses, the response to heterospecific cues was less intense. This may be explained by a trade-off between selection to maximise threat recognition and selection to avoid the costs of responding to irrelevant cues, or by differences in chemical structures of alarm cues between species. These findings have implications for the conservation of this Endangered fish species and for freshwater fishes throughout Africa.     

Application of fecal steroid techniques to the reproductive endocrinology of female verreaux's Sifaka (Propithecus verreauxi)

Solid phase extraction, high performance liquid chromatography, and radioimmunoassay were used to test the validity of fecal steroid analysis for assessing ovarian function in sifaka (Propithecus verreauxi). Daily fecal samples were collected over a 4 month period from two cycling female sifaka, and single samples were collected from females during normal gestation and males while housed at the Duke University Primate Center. Tests of radioimmunoassay validity indicated that solid phase extraction and microradioimmunoassay techniques were reliable and accurate methods for quantifying ovarian steroids in sifaka feces. The progesterone (P₄) antibody specifically quantitated only P₄, while several estrogen metabolites made small contributions to immunoreactive measures of estradiol (E₂). A 1:10 dilution reduced these contributions to 3–15% of the estimated E₂ concentration. Although the spectral data suggested that E₂ was not the major metabolite present, it accounted for the majority of the immunoreactivity at normal assay dilutions. Fecal profiles of immunoreactive E₂ and P₄ in the conceptive female resembled serum profiles of other strepsirhines. E₂ and P₄ were elevated at the end of the conceptive cycle and were more markedly increased in late pregnancy in the two pregnant females. Mating behavior and indices of sexual interest were observed in conjunction with E₂ peaks, although not all peaks were accompanied by observations of sexual behavior. © 1995 Wiley-Liss, Inc.     

Birth season glucocorticoids are related to the presence of infants in sifaka (Propithecus verreauxi)

The responses of plural breeding mammals to environmental stressors are little understood in free-ranging populations, but recent studies of singular breeders suggest that ecological factors and social milieu influence the variable physiological stress responses observed among individuals. Our previous studies examining faecal glucocorticoid (fGC)–behaviour interactions in plural breeding male sifaka (Propithecus verreauxi) show that fGC elevations coincide with specific dispersal events, particularly the eviction of subordinates by resident alpha males. This study examined the utility of fGC assays for assessing the stress responses of male sifaka to demographic changes in the population during the birth season. Analyses were based on 889 faecal samples collected over five birth seasons from 124 adult males residing in 55 different groups at Beza Mahafaly, Madagascar. Results show that fGC levels in males are unrelated to age, residence, group stability or rank, but are significantly and positively correlated with the presence of infants, annual elevations in weekly mean fGC concentrations in males paralleling increasing numbers of infants born annually in the population. These data are the first to show that in seasonal plural breeding species such as sifaka, elevated fGC in males reflects specific events related to reproduction rather than states or social context during the birth season.     

Response to conspecific and heterospecific alarm cues by pumpkinseeds in simple and complex habitats: field verification of an ontogenetic shift

Three focal size classes [small (<40 mm, standard length, L _S), medium (40–80 mm L _S) and large (>80 mm L _S)] of pumpkinseed Lepomis gibbosus were exposed to conspecific or one of three heterospecific chemical alarm cues under one of three levels of habitat complexity (low, intermediate and high). Under low and intermediate habitat complexities, pumpkinseeds <80 mm L _S exhibited a significant antipredator response when exposed to the chemical alarm cues of heterospecific prey guild members (largemouth bass Micropterus salmonides and hypoxanthine‐3‐ N ‐oxide, the putative Ostariophysan alarm 'pheromone'), while pumpkinseeds >80 mm L _S exhibited a foraging response. Under highly complex habitats, pumpkinseeds of all three size classes exhibited an antipredator response. Moreover, under all three habitat conditions, pumpkinseeds of all size classes exhibited an antipredator response to conspecific alarm cues. There was no change in behaviour under any treatment combination in response to an allopatric heterospecific control (swordtails Xiphophorus helleri ). These results provide the first field verification of the size dependent use of chemical alarm cues by centrarchids and demonstrate that microhabitat complexity significantly influences the threat‐sensitive use of these cues.     

Reproduction in free-ranging male Propithecus verreauxi: The hormonal correlates of mating and aggression

Endocrine studies of captive strepsirrhine primates suggest that physical environment and social factors mediate inter-individual variations in testicular function and serum testosterone (sT) in males. While these studies have made major contributions to our understanding of the individual proximate mechanisms influencing androgen activity in male strepsirrhines, none have investigated how these mechanisms work coincidentally in free-ranging populations. In this study we used fecal steroid analysis to examine androgen-behavior interactions associated with reproduction in free-ranging male Propithecus verreauxi. Behavioral and hormone data were collected from two social groups during the 1990–91 and 1991–92 breeding seasons at Beza Mahafaly, Madagascar. Solid phase and radioimmunoassay techniques were used to quantify testosterone (T) in 105 desiccated fecal samples collected weekly from seven males. Results suggest that 1) solid phase extraction and radioimmunoassay techniques were reliable and accurate methods for quantifying T in sifaka feces; 2) fecal T (fT) elevations spanned a minimum of 4 months, peak levels occurring 1 month prior to the January onset of the breeding season; 3) fecal T concentrations were influenced by developmental factors and, among mature males, social factors associated with rank, intergroup aggression, and group instability. Am J Phys Anthropol 105:137–151, 1998. © 1998 Wiley-Liss, Inc.     

Morphological integration and natural selection in the postcranium of wild verreaux's sifaka (Propithecus verreauxi verreauxi)

Morphological integration manifests as strong phenotypic covariation among interacting traits. In this study, a graph-theory approach is used to analyze patterns of morphological integration in a wild population of Verreaux's sifaka (Propithecus verreauxi verreauxi). The motivation for this study is to determine the relative roles of development versus function in shaping patterns of morphological integration in the sifaka postcranium. A developmental and a functional hypothesis of integration are compared with the observed pattern of integration and the fit of these hypotheses is assessed using information theoretic statistics. Correlational selection is also estimated on limb elements. Information theoretic statistics indicate that the developmental hypothesis fits the observed pattern of integration slightly better than the functional hypothesis. Only two pairs of traits experience correlational selection but neither of the traits within each pair are morphologically integrated. The observed pattern of integration contains several trait-trait associations that are specified by both the functional and developmental hypotheses. These results likely reflect the nested covariation structure in which a novel locomotor mode, vertical clinging and leaping, is derived from a primitive quadrupedal morphotype.     

Embryonic substances induce alarm response in adult zebrafish (Danio rerio)

Many aquatic animals rely on chemicals released by injured individuals of the same species to assess predation risk. Among these chemical cues, alarm substances released from the injured skin of ostariophysan fishes have been extensively examined. In most fish species examined, these cues appear to be released by all injured individuals (including larvae, juveniles and adults) and elicit alarm responses in conspecifics. Adult alarm cues also affect development and physiology of embryos. Nonetheless, whether embryos produce alarm cues that affect adults is not known. This study reports that extracts of zebrafish (Danio rerio) embryos at 36 h post-fertilization or later induce antipredator behaviours reminiscent of those induced by skin alarm substances. At an equivalent of 10⁻⁶ g embryo per millilitre, the extract induced bottom-dwelling and freezing in adults. These behaviours are consistent with those induced by adult alarm substances. This study concludes that zebrafish embryos produce alarm substances.     

Characterization and screening of microsatellite loci in a wild lemur population (Propithecus verreauxi verreauxi).

Sixteen dinucleotide microsatellite loci were isolated from the genome of Propithecus verreauxi verreauxi. All loci were polymorphic when genotyped on a minimum of 16 animals. The number of alleles across these loci ranges from two to 11. Additionally, seven of these loci were genotyped across a minimum of 200 animals in order to estimate heterozygosity and their potential for parentage assignment in this population. Using these seven loci, the mean heterozygosity in this population is 0.705, and the combined probability of these seven loci to exclude a random individual from parentage, when one parent is known, is 0.996. These data suggest that these loci will be useful for estimating a variety of population genetic and genealogical parameters in P. v. verreauxi populations.