Parental kinship coefficient but not paternal coloration predicts early offspring growth in lake char.

The 'good genes' hypotheses of sexual selection predict that females prefer males with strong ornaments because they are in good health and vigor and can afford the costs of the ornaments. A key assumption of this concept is that male health and vigor are useful predictors of genetic quality and hence offspring performance. We tested this prediction in wild-caught lake char (Salvelinus umbla) whose breeding coloration is known to reveal aspects of male health. We first reanalyzed results from sperm competition trials in which embryos of known parenthood had been raised singly in either a stress- or non-stress environment. Paternal coloration did not correlate with any measures of offspring performance. However, offspring growth was reduced with higher kinship coefficients between the parents. To test the robustness of these first observations, we collected a new sample of wild males and females, used their gametes in a full-factorial in vitro breeding experiment, and singly raised about 3000 embryos in either a stress- or non-stress environment (stress induced by microbes). Again, paternal coloration did not predict offspring performance, while offspring growth was reduced with higher kinship between the parents. We conclude that, in lake char, the genetic benefits of mate choice would be strongest if females could recognize and avoid genetically related males, while male breeding colors may be more relevant in intra-sexual selection.

Sperm of more colourful males are better adapted to ovarian fluids in lake char (Salmonidae).

Fish often spawn eggs with ovarian fluids that have been hypothesized to support the sperm of some males over others (cryptic female choice). Alternatively, sperm reactions to ovarian fluids could reveal male strategies. We used wild-caught lake char (Salvelinus umbla) to experimentally test whether sperm react differently to the presence of ovarian fluid, and whether any differential sperm reaction could be predicted by male breeding coloration, male inbreeding coefficients (based of 4150 SNPs) or the kinship coefficients between males and females. Male coloration was positively linked to body size and current health (based on lymphocytosis and thrombocytosis) but was a poor predictor of inbreeding or kinship coefficients. We found that sperm of more colourful males were faster in diluted ovarian fluids than in water only, while sperm of paler males were faster in water than in ovarian fluids. We then let equal numbers of sperm compete for fertilizations in the presence or absence of ovarian fluids and genetically assigned 1464 embryos (from 70 experimental trials) to their fathers. The presence of ovarian fluids significantly increased the success of the more colourful competitors. Sperm of less inbred competitors were more successful when tested in water only than in diluted ovarian fluids. The kinship coefficients had no significant effects on sperm traits or fertilization success in the presence of ovarian fluids, although parallel stress tests on embryos had revealed that females would profit more from mating with least related males rather than most coloured ones. We conclude that sperm of more colourful males are best adapted to ovarian fluids, and that the observed reaction norms suggest male strategies rather than cryptic female choice.

Host conservation through their parasites: molecular surveillance of vector-borne microorganisms in bats using ectoparasitic bat flies.

Most vertebrates host a wide variety of haematophagous parasites, which may play an important role in the transmission of vector-borne microorganisms to hosts. Surveillance is usually performed by collecting blood and/or tissue samples from vertebrate hosts. There are multiple methods to obtain samples, which can be stored for decades if properly kept. However, blood sampling is considered an invasive method and may possibly be harmful to the sampled individual. In this study, we investigated the use of ectoparasites as a tool to acquire molecular information about the presence and diversity of infectious microorganism in host populations. We tested the presence of three distinct vector-borne microorganisms in both bat blood and bat flies: Bartonella bacteria, malaria-like Polychromophilus sp. (Apicomplexa), and Trypanosoma sp. (Kinetoplastea). We detected the presence of these microorganisms both in bats and in their bat flies, with the exception of Trypanosoma sp. in South African bat flies. Additionally, we found Bartonella sp. in bat flies from one population in Spain, suggesting its presence in the host population even if not detected in bats. Bartonella and Polychromophilus infection showed the highest prevalence in both bat and bat fly populations. Single, co- and triple infections were also frequently present in both. We highlight the use of haematophagous ectoparasites to study the presence of infectious microorganism in host blood and its use as an alternative, less invasive sampling method.

TITLE: Conservation des hôtes grâce à leurs parasites : surveillance moléculaire des microorganismes à transmission vectorielle chez les chauves-souris à l'aide de mouches ectoparasites. ABSTRACT: La plupart des vertébrés hébergent une grande variété de parasites hématophages, qui peuvent jouer un rôle important dans la transmission de microorganismes à transmission vectorielle à leurs hôtes. La surveillance est généralement effectuée en prélevant des échantillons de sang et/ou de tissus sur des hôtes vertébrés. Il existe plusieurs méthodes pour obtenir des échantillons, qui peuvent être conservés pendant des décennies dans des bonnes conditions. Cependant, le prélèvement sanguin est considéré comme une méthode invasive et peut éventuellement être nocif pour l'individu prélevé. Dans cette étude, nous avons étudié l'utilisation d'ectoparasites comme outil pour acquérir des informations moléculaires sur la présence et la diversité des microorganismes infectieux dans les populations hôtes. Nous avons testé la présence de trois microorganismes distincts, transmis par des vecteurs, dans le sang et les mouches des chauves-souris : les bactéries Bartonella, Polychromophilus sp. (Apicomplexa) et Trypanosoma sp. (Kinetoplastea). Nous avons détecté la présence de ces microorganismes à la fois chez les chauves-souris et chez leurs mouches des chauves-souris, à l'exception de Trypanosoma sp. chez les chauves-souris sud-africaines. De plus, nous avons trouvé Bartonella sp. chez les mouches des chauves-souris d'une population en Espagne, ce qui suggère sa présence dans la population hôte même si elle n'est pas détectée chez les chauves-souris elles-mêmes. Les infections à Bartonella et Polychromophilus ont montré la prévalence la plus élevée dans les populations de chauves-souris et de mouches des chauves-souris. Des infections simples, doubles et triples étaient également fréquemment présentes dans les deux cas. Nous mettons en évidence l'utilisation d'ectoparasites hématophages pour étudier la présence de microorganismes infectieux dans le sang de l'hôte et son utilisation comme méthode alternative et moins invasive d'échantillonnage.