Early constraints in sexual dimorphism: survival benefits of feminized phenotypes.

Sexual dimorphism (SD) has evolved in response to selection pressures that differ between sexes. Since such pressures change across an individual's life, SD may vary within age classes. Yet, little is known about how selection on early phenotypes may drive the final SD observed in adults. In many dimorphic species, juveniles resemble adult females rather than adult males, meaning that out of the selective pressures established by sexual selection feminized phenotypes may be adaptive. If true, fitness benefits of early female-like phenotypes may constrain the expression of male phenotypes in adulthood. Using the common kestrel Falco tinnunculus as a study model, we evaluated the fitness advantages of expressing more feminized phenotypes at youth. Although more similar to adult females than to adult males, common kestrel fledglings are still sexually dimorphic in size and coloration. Integrating morphological and chromatic variables, we analysed the phenotypic divergence between sexes as a measure of how much each individual looks like the sex to which it belongs (phenotypic sexual resemblance, PSR). We then tested the fitness benefits associated with PSR by means of the probability of recruitment in the population. We found a significant interaction between PSR and sex, showing that in both sexes more feminized phenotypes recruited more into the population than less feminized phenotypes. Moreover, males showed lower PSR than females and a higher proportion of incorrect sex classifications. These findings suggest that the mechanisms in males devoted to resembling female phenotypes in youth, due to a trend to increase fitness through more feminized phenotypes, may provide a mechanism to constrain the SD in adulthood.

Genetic basis and fitness correlates of dynamic carotenoid-based ornamental coloration in male and female common kestrels Falco tinnunculus.

Knowledge of the genetic basis of sexual ornaments is essential to understand their evolution through sexual selection. Although carotenoid-based ornaments have been instrumental in the study of sexual selection, given the inability of animals to synthesize carotenoids de novo, they are generally assumed to be influenced solely by environmental variation. However, very few studies have directly estimated the role of genes and the environment in shaping variation in carotenoid-based traits. Using long-term individual-based data, we here explore the evolutionary potential of a dynamic, carotenoid-based ornament (namely skin coloration), in male and female common kestrels. We first estimate the amount of genetic variation underlying variation in hue, chroma and brightness. After correcting for sex differences, the chroma of the orange-yellow eye ring coloration was significantly heritable (h2±SE=0.40±0.17), whereas neither hue (h2=0) nor brightness (h2=0.02) was heritable. Second, we estimate the strength and shape of selection acting upon chromatic (hue and chroma) and achromatic (brightness) variation and show positive and negative directional selection on female but not male chroma and hue, respectively, whereas brightness was unrelated to fitness in both sexes. This suggests that different components of carotenoid-based signals traits may show different evolutionary dynamics. Overall, we show that carotenoid-based coloration is a complex and multifaceted trait. If we are to gain a better understanding of the processes responsible for the generation and maintenance of variation in carotenoid-based coloration, these complexities need to be taken into account.

Multivariate heredity of melanin-based coloration, body mass and immunity.

The genetic covariation among different traits may cause the appearance of correlated response to selection on multivariate phenotypes. Genes responsible for the expression of melanin-based color traits are also involved in other important physiological functions such as immunity and metabolism by pleiotropy, suggesting the possibility of multivariate evolution. However, little is known about the relationship between melanin coloration and these functions at the additive genetic level in wild vertebrates. From a multivariate perspective, we simultaneously explored inheritance and selection of melanin coloration, body mass and phytohemagglutinin (PHA)-mediated immune response by using long-term data over an 18-year period collected in a wild population of the common kestrel Falco tinnunculus. Pedigree-based quantitative genetic analyses showed negative genetic covariance between melanin-based coloration and body mass in male adults and positive genetic covariance between body mass and PHA-mediated immune response in fledglings as predicted by pleiotropic effects of melanocortin receptor activity. Multiple selection analyses showed an increased fitness in male adults with intermediate phenotypic values for melanin color and body mass. In male fledglings, there was evidence for a disruptive selection on rump gray color, but a stabilizing selection on PHA-mediated immune response. Our results provide an insight into the evolution of multivariate traits genetically related with melanin-based coloration. The differences in multivariate inheritance and selection between male and female kestrels might have resulted in sexual dimorphism in size and color. When pleiotropic effects are present, coloration can evolve through a complex pathway involving correlated response to selection on multivariate traits.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 May 2009-31 July 2009.

This article documents the addition of 512 microsatellite marker loci and nine pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Alcippe morrisonia morrisonia, Bashania fangiana, Bashania fargesii, Chaetodon vagabundus, Colletes floralis, Coluber constrictor flaviventris, Coptotermes gestroi, Crotophaga major, Cyprinella lutrensis, Danaus plexippus, Fagus grandifolia, Falco tinnunculus, Fletcherimyia fletcheri, Hydrilla verticillata, Laterallus jamaicensis coturniculus, Leavenworthia alabamica, Marmosops incanus, Miichthys miiuy, Nasua nasua, Noturus exilis, Odontesthes bonariensis, Quadrula fragosa, Pinctada maxima, Pseudaletia separata, Pseudoperonospora cubensis, Podocarpus elatus, Portunus trituberculatus, Rhagoletis cerasi, Rhinella schneideri, Sarracenia alata, Skeletonema marinoi, Sminthurus viridis, Syngnathus abaster, Uroteuthis (Photololigo) chinensis, Verticillium dahliae, Wasmannia auropunctata, and Zygochlamys patagonica. These loci were cross-tested on the following species: Chaetodon baronessa, Falco columbarius, Falco eleonorae, Falco naumanni, Falco peregrinus, Falco subbuteo, Didelphis aurita, Gracilinanus microtarsus, Marmosops paulensis, Monodelphis Americana, Odontesthes hatcheri, Podocarpus grayi, Podocarpus lawrencei, Podocarpus smithii, Portunus pelagicus, Syngnathus acus, Syngnathus typhle,Uroteuthis (Photololigo) edulis, Uroteuthis (Photololigo) duvauceli and Verticillium albo-atrum. This article also documents the addition of nine sequencing primer pairs and sixteen allele specific primers or probes for Oncorhynchus mykiss and Oncorhynchus tshawytscha; these primers and assays were cross-tested in both species.

Prevalence and intensity of blood and intestinal parasites in a field population of a Mediterranean lizard, Lacerta lepida.

We describe the blood and intestinal parasites in the Ocellated lizard, Lacerta lepida, examining the factors that determine the prevalence and intensity of infection of haemogregarines, and the prevalence of coccidia and nematodes. In relation to haemogregarines, no juveniles were detected as being infected, whereas 71.7 % of adults were infected. The prevalence of infection was positively related to the size of the adults. There were no differences between seasons or sexes in the prevalence or intensity of infection in adults. There were no significant differences in the prevalence of infection by nematodes between ages or sexes, nor in relation to the size of adult lizards, but adult lizards excreting coccidian oocysts tend to be smaller. During the mating period, reproductive activities lead to a decrease in the body condition. However, neither the intensity of haemogregarine's infection nor the prevalence of intestinal parasites was related to the lizards' body condition.

Breeding time, health and immune response in the chinstrap penguin Pygoscelis antarctica.

Health status and immunocompetence have been proposed as important factors affecting individual variation in the attainment of breeding condition in birds. We studied individual variation in serological variables indicating health status (blood sedimentation rate, haematocrit, `buffy coat' layer, proportions of different types of leucocytes) in two groups of breeding chinstrap penguins Pygoscelis antarctica with breeding dates 9 days apart. We sampled these individuals shortly after hatching of their young and at the end of the chick-raising period. A group of failed breeders was also sampled. Birds of both sexes were included. We also measured the T-cell-mediated immune response as indicated by an in vivo hypersensitivity response to an intradermal injection of a mitogen (phytohaemagglutinin) in early and late breeders. Sex had no significant effect on most variables. Late breeders had poorer health (more leucocytes, especially heterophils and lymphocytes) and a lower T-cell-mediated immune response than early breeders. Failed breeders were more similar to late than to early breeders. Early breeders suffered a decline in health status throughout the chick-raising period. The impact of pathogens on variation in life history traits in avian populations may be important even in extreme Antarctic environments.

Blood parasites of passerine birds from central Spain.

Sixteen species of passerine birds captured during a 2.5 yr period in Central Spain were examined for hematozoa. Haemoproteus spp., Leucocytozoon spp., Trypanosoma spp., Plasmodium spp., and microfilariae were observed. The most prevalent species were in the genus Leucocytozoon. The majority of the records are new for Spain and some represent new host records. More than one-half of the birds examined were infected with at least one parasite species. These records are similar to those reported from other areas in northern Europe and the Iberian Peninsula.

Hematozoa in two populations of the threatened red-billed chough in Spain.

The prevalence of hematozoa in two populations of red-billed choughs (Pyrrhocorax pyrrhocorax) was sampled in 1992 and 1994 in Spain. Two blood parasites infected red-billed choughs. A species of Plasmodium, possibly Plasmodium relictum, and the piroplasm Babesia frugilegica, are described for the first time from this host. Low prevalence (1/178, < 1%) of hematozoa in these populations, was evidence for a lack of effects of blood parasites on the life history and conservation of this threatened species in at least the two populations studied.