Adult Male Scent-Marking in Lemur catta and Eulemur fulvus rufus

Scent-marking and olfactory communication are used extensively by prosimians and can provide spatial and temporal records of group movement and behavior. We compare rates of male scent-marking in relation to reproductive seasons, male dominance rank, and habitat use in two related prosimians: Lemur catta and Eulemur fulvus rufus. We collected scent-marking data on adult male Lemur catta at Beza-Mahafaly Reserve (dry forest), and on Eulemur fulvus rufus at Ranomafana National Park (rainforest), Madagascar. In Lemur, rates of overall scent-marking differed significantly by reproductive season, with higher rates occurring in mating and lactation/migration periods, whereas in Eulemur, reproductive season did not appear to affect scent-marking rates. Dominance rank of male Lemur catta did not affect rates of scent-marking. Among male Eulemur fulvus, dominance relations were not apparent; however, 2 of the 5 focal males scent-marked somewhat more frequently during the mating season and also experienced greater mating success. In Lemur catta, higher rates of scent-marking in the mating season may relate to indirect reproductive competition during a period of high aggression, while such mating competition was not as marked in Eulemur fulvus. Furthermore, higher rates of marking in resident male Lemur catta during male migration may correlate with vigilance toward immigrating males. Greater overall scent-marking rates in ring-tailed lemurs may relate to extensive intergroup home range overlap and no area of exclusive use, whereas the red-fronted lemur groups tended to forage in areas of their home range where little-to-no intergroup overlap occurred.     

Effect of sexual dimorphism in bill length on foraging behavior: an experimental analysis of hummingbirds

We examined whether sexual differences in trophic morphology are associated with sexual differences in foraging behavior through two laboratory experiments on rufous hummingbirds (Selasphorus rufus) designed to compare probing abilities (maximum extraction depths) and handling times of sexes at flowers. Bills of female S. rufus are about 10.5% longer than bills of males, and this difference was associated with sexual differences in foraging abilities. Maximum extraction depths of female S. rufus were significantly greater than those of males, and no overlap between the sexes was observed. Moreover, handling times of females were shorter than handling times of males at flowers having longer corollas (15 mm). Thus, because of their longer bills, female S. rufus have the potential to feed from longer flowers than males, and can do so more quickly. We suggest that no single mechanism is responsible for the evolution of sexual dimorphism in bill lengths of hummingbirds, but rather that the dimorphism probably reflects the combined effects of reproductive role division and intersexual food competition, and possibly, sexual selection.     

Sexual Isolation Between Drosophila Melanogaster, D. Simulans and D. Mauritiana: Sex and Species Specific Discrimination

The sexual isolation among the related species Drosophila melanogaster, D. simulans and D. mauritiana is asymmetrical. While D. mauritiana males mate well with both D. melanogaster and D. simulans females, females of D. mauritiana discriminate strongly against males of these two species. Similarly, D. simulans males mate with D. melanogaster females but the reciprocal cross is difficult. Interspecific crosses between several populations of the three species were performed to determine if (i) males and females of the same species share a common sexual isolation genetic system, and (ii) males (or females) use the same genetic system to discriminate against females (or males) of the other two species. Results indicate that although differences in male and female isolation depend on the populations tested, the isolation behaviour between a pair of species is highly correlated despite the variations. However, the rank order of the isolation level along the populations was not correlated in both sexes, which suggests that different genes act in male and female sexual isolation. Neither for males nor for females, the isolation behaviour of one species was paralleled in the other two species, which indicates that the genetic systems involved in this trait are species-pair specific. The implications of these results are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Differences in male-female interaction betweenLemur fulvus andL. macaco

Interspecific differences were found betweenLemur fulvus andLemur macaco in heterosexual pair-tests.L. fulvus showed more mutual grooming and were more active in exploration thanL. macaco. The absence of a naked anal region inL. macaco females causes a virtual absence of foreheadmarking on this region by males.L. macaco males have a stronger tendency to mark the body of the female with their anogenital region after a nose-anogenital contact thanL. fulvus, indicating that the behaviour is more ritualized inL. macaco males.     

Plants Consumed by Eulemur fulvus in Comoros Islands (Mayotte) and Potential Effects on Intestinal Parasites

The study of self-medication among animals—zoopharmacognosy—is founded on observations that suggest that wild animals use plants with specific biological properties that may be beneficial to them. To verify whether self-vermifugation occurs among Eulemur fulvus in the wild, we studied their feeding behavior in both the dry and humid forests of Mayotte (Comoros Islands). We used the focal individual sampling method over an annual cycle. We conducted a complementary study during the 2-mo mating season, via the scan sampling method (at 10-min intervals). Among the 29 plant species brown lemurs consumed, we tested 16 in vitro as antiparasitic agents on 3 experimental parasite models (Rhabditis pseudoelongata, Trichomonas vaginalis, Entamoeba invadens). We obtained crude extracts to be tested after 2 successive chemical extractions (ethyl acetate and methanol), and 7 of them, belonging to 4 different plant species, showed an antiparasitic property: lemurs consumed Annona squamosa and Mimusops comorensis in large amounts, but ingested Ixora cremixora and Syzygium jambos sporadically. The 4 plants were active on the flagellate but only one of them (Ixora cremixora) also demonstrated antinematode properties. Humans use 2 of the plants as intestinal antiparasitic agents in traditional medicine and include numerous other plants in the diet. The relative lake of amoebas and flagellates in stools of Eulemur fulvus may be related to the consumption of plants with antiprotozoal properties. Nevertheless, in the absence of specific behavior that could be linked to a voluntary therapeutic action during our study, self-vermifugation in Eulemur fulvus remains elusive.     

Sexual behavior in brown capuchins ( Cebus apella )

We observed sexual behavior patterns in two captive groups of Cebus apella.We obtained data on intersexual solicitations and intersexual competition. The length of proceptivity cycles by females averaged 18.8 ± 1.2 days; this corresponds with published reports of physiological measures of ovulatory cycles. Females initiated sexual interactions with males significantly more than males initiated interactions with females, and female solicitations increased in frequency over the duration of displayed periods of proceptivity. In contrast, male solicitations of females were infrequent and did not change significantly throughout female proceptive phases. Each female solicited the same male throughout a given proceptive phase. We observed no evidence of male-male or female-female competition. Males seem to respond to female sexual behavior directed toward them, rather than initiating sexual interactions themselves. Even so, male sexual interactions with females followed only a small proportion of solicitations.     

Female House Mice do not Differ in Their Exploratory Behaviour from Males

Dispersal is an important ecological trait affecting genetic variation and dynamics of populations. Hence, the exploratory behaviour prior to actual dispersal may be crucial for potentially dispersing individuals. In mammals, females are traditionally seen as the more philopatric sex and dispersal as male‐biased behaviour, and so behavioural strategies related to the exploration of novel resources should be differentially expressed in males and females. In addition, due to sexual selection exploratory strategies may be expected to vary according to females’ reproductive phase. We employed a standard open‐field test as an approximation of the first phase of dispersal, using adult house mice representing two subspecies, M. m. musculus and M. m. domesticus. We tested the prediction that exploration of neutral area varies in females during different phases of the oestrus cycle and is different between both sexes and subspecies. We expected to find higher exploration in males, as the more dispersing sex and less pronounced subspecies‐specific differences in females than in males. We found no significant effect of the oestrous phase on any of the parameters of the exploratory behaviour measured. Sexual dimorphism was found only in latency to enter the arena in M. m. domesticus where females hesitated longer to enter a new area than males. Significant subspecies‐specific differences were found in three of four tested exploration parameters, so we conclude that females of both subspecies follow similar strategies to those displayed by males. Musculus mice show shorter latency to enter a new area, but once inside, domesticus mice explore the arena significantly longer, with less frequent retreats to a shelter. Our results thus highlight that the role of female dispersal in interdemic gene flow should not be neglected.     

Female dominance in blue-eyed black lemurs(Eulemur macaco flavifrons)

Female dominance is unusual among mammals and has been described in detail for only a handful of species. Here we present data on the frequency and outcome of dominance interactions in seven semi-free ranging and captive groups of blue-eyed black lemurs (Eulemur macaco flavifrons) housed at the Duke University Primate Center. We collected over 260 hours of focal data during which all occurrences of dominant-subordinate interactions were recorded. We collected data outside the typical breeding and birthing seasons for this species, thus eliminating possible confounding factors and increased aggression associated with these periods. We found that females were dominant over males in all seven groups, with females winning 99% of all dominance interactions.E. m. flavifrons used aggressive dominance (e.g. chase, cuff, bite) in 81% of all interactions, with the remainder of interactions being decided using social dominance (e.g. deference in the form of supplants or cowers). Older females were dominant over younger females in two out of three multi-female groups (in each case, younger females were daughters), and younger males (sons of the dominant female) received less aggression from females than did older males (n = 2 groups). Caging and group size appear to play a minimal role in the expression of female dominance. While confirmation must await further observations on free-ranging groups ofE. m. flavifrons, our data strongly suggest that this subspecies can be characterized as female dominant.     

Paternity Determination in Two Groups of Eulemur fulvus mayottensis: Implications for Understanding Mating Strategies

We used random amplified polymorphic DNA (RAPD) to determine paternity in two groups of brown lemurs (Eulemur fulvus mayottensis). We analyzed the results in relation to behavioral data on observed copulations, dominance relationships among adult males, and female behavior. The association between paternity determination and behavioral sampling shows that paternity determination is a crucial tool for understanding the mating strategies and reproductive success in the studied species. In brown lemurs, dominance relationships between males are correlated with reproductive success, but male social dominance could be altered by female choice as suggested by the ability of subordinate males to sire offspring in the presence of a dominant male.