Michel Saint Jalme

Multiple sexual advertisements honestly reflect health status in peacocks (Pavo cristatus)

The evolution of multiple sexual traits remains controversial and poorly understood in evolutionary biology. In many bird species, males exhibit complex courtships involving feather ornaments and behavioral display. Multiple traits may convey information on the genetic and phenotypic quality of males. In particular, fixed characters, such as feather ornaments (produced once a year during the annual molt in many bird species) might convey information about past male condition (at the time of trait development); whereas flexible traits such as behavioral displays should be sensitive to present condition. Here we show that both flexible behavioral displays and fixed feather ornaments of peacocks, used by females to choose a mate, honestly reflect health status. Correlative data showed that peacocks with high display rate (the number of behavioral displays per hour) and a large number of tail eyespots had low levels of circulating heterophils, suggesting better health status. Experimental activation of the immune system, through LPS injection, significantly reduced display rate compared to a control group. However, the sensitivity of a male display rate to the immune challenge was dependent on the number of tail eyespots: males with higher number of tail eyespots were better able to cope with the experimental immune challenge, and maintained their display rate at levels closer to the levels performed before the immune activation. These results are consistent with the idea that multiple signaling might enhance information reliability.

Male sexual attractiveness affects the investment of maternal resources into the eggs in peafowl (Pavo cristatus)

According to the differential investment hypothesis, females paired with attractive mates are expected to invest more in the current reproduction relative to females paired with unattractive males. We experimentally tested this hypothesis in the peafowl (Pavo cristatus) by providing females with males that differed in sexual attractiveness. In agreement with the differential allocation hypothesis, females paired with more ornamented males laid larger eggs, and deposited higher amounts of testosterone into the egg yolk, independently of the sex of the embryo. These results show that the association between paternal phenotype and offspring quality could arise via a differential maternal investment. They also suggest that, if ornamented males do transmit good genes to the progeny, the maternal differential investment can amplify the effect of such good genes on the offspring fitness.

Male health status, signalled by courtship display, reveals ejaculate quality and hatching success in a lekking species

1. The information content of secondary sexual traits and the benefits gathered by choosy females are at the heart of sexual selection theory. Indicator models of sexual selection assume that secondary sexual traits reflect the phenotypic/genetic quality of their bearers and that females gather benefits from choosing these high-quality males. 2. Here, we tested the idea that courtship display reflects the health status in a bird species with a lek-based mating system, the houbara bustard (Chlamydotis undulata undulata). A group of males was treated with the lipopolysaccharide (LPS) of the cell wall of the bacterium Escherichia coli during the seasonal peak of courtship display, while another group of males was injected with a phosphate-buffered saline solution (PBS) as a control. We then monitored the effect of the treatment on both courtship display and ejaculate quality. Finally, females were artificially inseminated with semen from LPS and PBS males, which allowed us to assess the effect of the immunological treatment on reproduction. 3. We found that the inflammatory challenge reduced courtship display and semen quality compared to controls. Interestingly, males that better resisted to the immune challenge in terms of courtship display also better resisted in terms of ejaculate quality. Early reproductive failure was increased when females were artificially inseminated with semen from immune-activated males. Failure of eggs laid by females inseminated with LPS semen was due to a reduced fertilization power of sperm of LPS males or to increased embryo mortality in the very early stage of embryo development. As a consequence, hatching rate was reduced for females inseminated with semen collected from LPS males. 4. These results show that by assessing male courtship display, females may gain insight into the current phenotypic/genetic quality of mates and gather fitness benefits in terms of reproductive success.

Habitat use and mating system of the houbara bustard (Chlamydotis undulata undulata) in a semi-desertic area of North Africa: implications for conservation

Studies of the movements and home-ranges of houbara bustards (Chlamydotis undulata undulata) showed sexual and seasonal differences in the use of space, with a polygynous mating system similar to an ‘exploded-lek’ or a ‘resource-defence-polygyny’, that remains undefined. We used the arthropod biomass as an index of the trophic quality of six defined habitats and we radio-tracked 7 females and 13 males to test whether sexual and seasonal variations in habitat use were related to resource availability, and to verify if critical resources for breeding females were monopolised by males. We analysed habitat selection in both sexes separately. We used the habitat type composition of buffer zones around radio-locations to study annual and seasonal habitat selection and to identify preferred habitats, using the chi-square goodness-of-fit test. Habitat use between sexes and between seasons were compared using MANOVA based on log-ratios of habitat proportions. During the year, and in each season, both sexes appeared to be significantly selective for habitats in comparison to their availability. But males avoided esparto grass, while females used all habitats. Habitat use differed between sexes in the breeding season, but not in the non-breeding season. In spring, when food resources were abundant and uniformly distributed in space, males preferred ‘temporarily flooded areas’ and females preferred ‘reg with tall perennials’ that offered both food and cover for brooding. Critical resources were not monopolised by males and the mating system fulfilled the definition of the ‘exploded-lek’. Leks are key sites for reproduction and should be considered as priority areas in further conservation plans.

Do peahens not prefer peacocks with more elaborate trains

Ever since Darwin (1871), the peacock’s train has been cited as the icon of an extravagant conspicuous secondary sexual trait that has evolved through female mate choice. However, Takahashi et al. (2008) recently challenged this idea. They monitored female mate choice during 7 years in a feral peafowl, Pavo cristatus, population in Japan and found no correlation between male mating success and three morphological train traits. They concluded that ‘combined with previous results, our findings indicate that the peacock’s train is not currently the universal target of female choice’ and proposed ‘that the peacock’s train is an obsolete signal for which female preference has already been lost or weakened’ (Takahashi et al. 2008, page 1216). We feel that their conclusions are far too strong, particularly since three independent studies have found a relationship between train features and mating success (Petrie et al. 1991; Petrie & Halliday 1994; Yasmin & Yahya 1996; Loyau et al. 2005a). The purpose of this article is therefore to draw attention to alternative explanations and conclusions that are essential for the understanding of the complexity of mate choice. We first suggest some possible nonadaptive and adaptive explanations for the reported differences in female preferences in the peafowl. We then show that plasticity in mate choice is a widespread phenomenon across a large spectrum of species. Therefore, we suggest that findings based on a single

Does recognized genetic management in supportive breeding prevent genetic changes in life‐history traits?

Supportive breeding is one of the last resort conservation strategies to avoid species extinction. Management of captive populations is challenging because several harmful genetic processes need to be avoided. Several recommendations have been proposed to limit these deleterious effects, but empirical assessments of these strategies remain scarce. We investigated the outcome of a genetic management in a supportive breeding for the Houbara Bustard. At the phenotypic level, we found an increase over generations in the mean values of gamete production, body mass and courtship display rate. Using an animal model, we found that phenotypic changes reflected genetic changes as evidenced by an increase in breeding values for all traits. These changes resulted from selection acting on gamete production and to a lesser extent on courtship display. Selection decreased over years for female gametes, emphasizing the effort of managers to increase the contribution of poor breeders to offspring recruited in the captive breeding. Our results shed light on very fast genetic changes in an exemplary captive programme that follows worldwide used recommendations and emphasizes the need of more empirical evidence of the effects of genetic guidelines on the prevention of genetic changes in supportive breeding.

Assessing habitat and resource availability for an endangered desert bird species in eastern Morocco: the Houbara Bustard

In Morocco we tested the consistency between an a priori habitat classification based on topography, hydrology, vegetation structure and composition, and an a posteriori classification based on arthropod assemblages, in a plain supporting wild endangered Houbara Bustards. According to vegetation structure, we defined seven a priori habitats that differed significantly in perennial cover and height. A multivariate multiple regression analysis showed a significant relationship between arthropod assemblages and vegetation structure. Canonical Analyses of Principal Coordinates, conducted simultaneously on direct searches of arthropods and trapping data, showed significant differences between assemblages in both cases, and produced two similar constrained ordinations of six a posteriori habitats: esparto grass (Stipa tenacissima), temporarily flooded areas, fields, “reg” with short perennials, “reg” with tall perennials and wadis. The two sampling methods reflected a dominance of ants and beetles. Arthropod biomasses increased significantly in spring and then decreased significantly in summer for beetles, and in autumn for ants. No strong differences appeared between habitats within seasons, especially in spring, indicating a uniform distribution of food resources during the Houbara breeding season. The “reg” with short perennials had the highest ant biomass in summer. This “reg” and fields also supported the highest arthropod biomass in autumn. Variation in arthropod biomass was a pertinent factor that should be integrated into Houbara habitat selection studies. The definition of habitat availability based on easily identifiable landscape units, combined with empirical tests on arthropod communities provided an accurate classification for habitat selection studies and conservation planning.

Conservation genetics of Houbara Bustard (Chlamydotis undulata undulata): population structure and its implications for the reinforcement of wild populations

The major decline of Houbara Bustards—sensu lato—throughout their range has led to their classification as ‘vulnerable’ on the IUCN Red List. Within this context, a captive breeding program was established in Morocco to restock North African wild populations of Houbara Bustard (Chlamydotis undulata undulata). At present, founders originate from locations that are currently being reinforced through the addition of captive bred individuals. However, it is planned to restock others areas of the species’ range. Before this could be considered, an accurate knowledge of the genetic structure of the wild recipient population is essential to delineate potential conservation units. We therefore sampled populations throughout most of the remaining range, and used several methods to evaluate their genetic differentiation by means of both mtDNA and microsatellite markers. Very little genetic differentiation was found for both genetic markers (Φst ranged from −0.181 to 0.118 and Fst ranged from −0.004 to 0.019). This suggests that C. u.undulata populations could be managed as a single Conservation Unit.

Quantitative genetics of sexual display, ejaculate quality and size in a lekking species

The investment into extravagant sexual display and competitive sperm are two essential components of pre- and post-copulatory sexual selection. Even though the selective forces acting on sexual display and sperm characteristics have been extensively studied in recent years, the genetic architecture underlying the expression of these traits has been rarely explored. Here, we estimated the genetic variances and covariances of traits linked with ejaculate size and quality, and sexual display in the houbara bustard (Chlamydotis undulata undulata, Jacquin 1784). Using a very large pedigree-based data set, we show that sexual signalling and ejaculate size (but not ejaculate quality) are heritable and genetically positively correlated. The matrix of genetic covariances also provided support for some across-sex correlations: male and female gamete numbers are positively correlated, and more surprisingly, male display and female gamete numbers are also positively correlated. These results can have important implications for the understanding of the evolution of sperm traits and sexual display in animals.

Pigeons discriminate between human feeders

Considered as plague in many cities, pigeons in urban areas live close to human activities and exploit this proximity to find food which is often directly delivered by people. In this study, we explored the capacity of feral pigeons to take advantage of this human-based food resource and discriminate between friendly and hostile people. Our study was conducted in an urban park. Pigeons were fed by two experimenters of approximately the same age and skin colour but wearing coats of different colours. During the training sessions, the two human feeders displayed different attitudes: one of the feeders was neutral and the second was hostile and chased away the pigeons. During the two test phases subsequent to the training phase, both feeders became neutral. Two experiments were conducted, one with one male and one female feeder and the second with two female feeders. In both experiments, the pigeons learned to quickly (six to nine sessions) discriminate between the feeders and maintained this discrimination during the test phases. The pigeons avoided the hostile feeder even when the two feeders exchanged their coats, suggesting that they used stable individual characteristics to differentiate between the experimenter feeders. Thus, pigeons are able to learn quickly from their interactions with human feeders and use this knowledge to maximize the profitability of the urban environment. This study provides the first experimental evidence in feral pigeons for this level of human discrimination.