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.

摘要: Despite growing interest in female ornament evolution, we still have a rudimentary understanding of female display traits relative to similar traits in males. Under one popular adaptive scenario, female ornaments are hypothesized to function in female-female competition and serve as badges of status, such that their expression is linked with elevated aggression in some cases. In this study, we investigated the relationship between 2 female ornaments-male-like red throat color and red spine coloration-and female aggression in 2 independently derived stream-resident populations of three-spined stickleback Gasterosteus aculeatus. Using simulated intrusions, we tested whether females with redder ornaments were generally more aggressive, and for variation in aggressive and social behaviors between the 2 populations. We found that the red intensity of the throat and spine did not predict aggression levels in either population, suggesting a limited role for both female ornaments during female-female interaction. The 2 populations exhibited different levels of aggressive behaviors, unrelated to the color patches. Our results suggest that variation in selective pressures between populations may promote interpopulation variance in aggressive behavior but not the correlation between female ornamentation and aggression, and raise the possibility that red coloration may have evolved through different mechanisms or processes in the 2 populations.

摘要: Parasites generally have a negative influence on the color expression of their hosts. Sexual selection theory predicts resistant high-quality individuals should show intense coloration, whereas susceptible low-quality individuals would show poor coloration. However, intensely colored males of different species of Old and New World lizards were more often infected by hemoparasites. These results suggest that high-quality males, with intense coloration, would suffer higher susceptibility to hemoparasites. This hypothesis remains poorly understood and contradicts general theories on sexual selection. We surveyed a population of Sceloporus occidentalis for parasites and found infections by the parasite genera Lankesterella and Acroeimeria. In this population, both males and females express ventral blue and yellow color patches. Lankesterella was almost exclusively infecting males. The body size of the males significantly predicted the coloration of both blue and yellow patches. Larger males showed darker (lower lightness) blue ventral patches and more saturated yellow patches that were also orange-skewed. Moreover, these males were more often infected by Lankesterella than smaller males. The intestinal parasite Acroeimeria infected both males and females. The infection by intestinal parasites of the genus Acroeimeria was the best predictor for the chroma in the blue patch of the males and for hue in the yellow patch of the females. Those males infected by Acroeimeria expressed blue patches with significantly lower chroma than the uninfected males. However, the hue of the yellow patch was not significantly different between infected and uninfected females. These results suggest a different effect of Lankesterella and Acroeimeria on the lizards. On the one hand, the intense coloration of male lizards infected by Lankesterella suggested high-quality male lizards may tolerate it. On the other hand, the low chroma of the blue coloration of the infected males suggested that this coloration could honestly express the infection by Acroeimeria.

摘要: Sugar beet root maggot (SBRM, Tetanops myopaeformis von Roder) is a major but poorly understood insect pest of sugar beet (Beta vulgaris L.). The molecular mechanisms underlying plant defense responses are well documented, however, little information is available about complementary mechanisms for insect adaptive responses to overcome host resistance. To date, no studies have been published on SBRM gene expression profiling. Suppressive subtractive hybridization (SSH) generated more than 300 SBRM ESTs differentially expressed in the interaction of the pest with a moderately resistant (F1016) and a susceptible (F1010) sugar beet line. Blast2GO v. 3.2 search indicated that over 40% of the differentially expressed genes had known functions, primarily driven by fruit fly D. melanogaster genes. Expression patterns of 18 selected EST clones were confirmed by RT-PCR analysis. Gene Ontology (GO) analysis predicted a dominance of metabolic and catalytic genes involved in the interaction of SBRM with its host. SBRM genes functioning during development, regulation, cellular process, signaling and under stress conditions were annotated. SBRM genes that were common or unique in response to resistant or susceptible interactions with the host were identified and their possible roles in insect responses to the host are discussed.

摘要: Sexual ornaments contribute substantially to phenotypic diversity and it is particularly relevant to understand their evolution. Ornaments can assume the function of signals-of-quality that the choosy sex uses to evaluate potential mating partners. Often there are no obvious direct benefits and investment into mate choice is primarily rewarded by beneficial alleles that are inherited to the offspring. Inter-sexual communication via sexual ornaments requires honesty of the sexual signal, yet the question of what maintains honesty remains only partially solved. One solution is that honesty is maintained by trait expression being dependent on individual condition, since condition-dependent trait expression offers an effectively inexhaustible source of genetic variability. Here we test in the highly sexually dimorphic club-legged grasshopper Gomphocerus sibiricus if putative sexual ornaments, in particular the striking front-leg clubs, are more strongly affected by a lipopolysaccharide (LPS) immune challenge than putatively not sexually selected traits. Our results show overall little condition-dependent expression of morphological and song traits, with sexually selected traits exhibiting effects comparable to nonsexually selected traits (with the possible exception of stridulatory file length and syllable-to-pause ratio in advertisement songs). Interestingly, field observations of individuals of lethally parasitized individuals suggest that a very strong environmental challenge can specifically affect the expression of the front-leg clubs. The presence of 1% of males in natural populations with missing or heavily deformed clubs plus 5% with minor club deformations furthermore indicate that there are risks associated with club development during final ecdysis and this might act as a filter against deleterious alleles.