摘要: In this study, we identified the current distribution of five globally distributed invasive Hemidactylus species and predicted their potential and future distribution using species distribution models based on climate and elevation data. These species included H. brookii, H. frenatus, H. garnotii, H. mabouia, and H. turcicus. We show that many regions with tropical and Mediterranean climates are suitable for most of these species. However, their current and potential distributions suggest that climate is not the only limiting factor. We hypothesize that climatic conditions may affect competition and other interactions resulting in a segregated distribution of the studied Hemidactylus species. As an effect of global climate change it is likely that H. brookii will expand its range to areas that are currently colonized by H. mabouia and/or H. frenatus, while H. turcicus is likely to expand its range to areas that are not yet invaded by any Hemidactylus species. The role of species interactions in the range expansion of these five Hemidactylus species still remains poorly understood, but could be of major importance in understanding and managing these invasive species.

摘要: High male mating effort and high variation in female quality select for male mate choice, which may be expressed as differential investment of reproductive effort based on female value. Male reproductive effort includes investment in direct contest competition with rival males for access to females, yet variation in male-male contest behavior is rarely examined in the context of male mate choice. We examine such male response to variation in female body size, reproductive state, and female-specific ornamentation in the striped plateau lizard, Sceloporus virgatus. We housed lizards in trios of 2 size-matched males and one female for 5 days, such that all 3 lizards were physically isolated and the males could see the female but not each other. We then placed males simultaneously into the female's cage and scored the interaction. Male-male aggression was not significantly affected by female body size, reproductive state, nor ornament color, but was influenced by ornament size which reliably signals the phenotypic quality of the female and her offspring. In the presence of larger-ornamented females, males engaged in more male-male aggressive display behavior more quickly, and performed fewer high-intensity contact behaviors but were equally likely to escalate to this riskier level of fighting. Our data suggest that males adjust their energetic investment during intrasexual competitive interactions in response to variation in the contested female which, assuming males gain direct or indirect benefits from their strategic allocation of reproductive effort, fits the modern understanding of male mate choice.

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摘要: Sexual selection is considered the major cause of sexual dimorphism, but recent observations suggest that natural selection may play a more important role in the evolution of sex differentiation than previously recognized. Therefore, studying the trade-offs between natural selection and sexual selection is crucial to a better understanding of the ecology underlying the evolution of sexual dimorphism. The freshwater blenny Salaria fluviatilis, a fish inhabiting lakes and rivers around the Mediterranean Sea, displays strong sexual dimorphism in size, shape, and behavior (i.e., larger body and head size for males and higher swimming requirements for females during the reproductive period). We tested for differences in sexual dimorphism in size and shape between the populations from lake and river habitats with the goal of identifying the trade-offs between natural and sexual selection that underlie variations in sexual dimorphism in this species. Our results show i) differences in sexual size dimorphism (SSizeD) in accordance to Rensch's rule (i.e., larger individuals in rivers associated with higher SSizeD), and ii) a decrease in shape differentiation between males and females in lake populations. Together, this suggests that the different environmental conditions between lake and river habitats (e.g., resource limitations, predation pressure, water velocity) affect the relative importance of sexual selection in the display of sexual dimorphism within the species. This study highlights the importance of considering the environmental conditions to which populations are exposed to better understand the ecology underlying the evolution of sexual dimorphism.

摘要: The genus Sinocyclocheilus (golden-line barbel) includes 25 species of cave-dwelling blind fish (cavefish) and more than 30 surface-dwelling species with normal vision. Cave environments are dark and generally nutrient-poor with few predators. Cavefish of several genera evolved convergent morphological adaptations in visual, pigmentation, brain, olfactory, and digestive systems. We compared brain morphology and gene expression patterns in a cavefish Sinocyclocheilus anophthalmus with those of a closely related surface-dwelling species S. angustiporus. Results showed that cavefish have a longer olfactory tract and a much smaller optic tectum than surface fish. Transcriptomics by RNA-seq revealed that many genes upregulated in cavefish are related to lysosomes and the degradation and metabolism of proteins, amino acids, and lipids. Genes downregulated in cavefish tended to involve activation of gene expression in cholesterol biosynthesis and cholesterol degradation in the brain. Genes encoding Srebfs (sterol regulatory element-binding transcription factors) and Srebf targets, including enzymes in cholesterol synthesis, were downregulated in cavefish brains compared with surface fish brains. The gene encoding Cyp46a1, which eliminates cholesterol from the brain, was also downregulated in cavefish brains, while the total level of cholesterol in the brain remained unchanged. Cavefish brains misexpressed several genes encoding proteins in the hypothalamus-pituitary axis, including Trh, Sst, Crh, Pomc, and Mc4r. These results suggest that the rate of lipid biosynthesis and breakdown may both be depressed in golden-line cavefish brains but that the lysosome recycling rate may be increased in cavefish; properties that might be related to differences in nutrient availability in caves.