Members of the same species share a common genome, the same set of genes and regulatory networks that build the proteins responsible for phenotypic diversity. However, that means that both of the sexes share a common genome, and that is an issue when males of a species are sensitive to their own environmental stimuli, and when females are required to invest a lot of their energy towards reproduction and rearing offspring. Species are often sexually dimorphic as well, where either the male or the female will be larger than their inter-sex counterpart, and this has to do with what ecological tasks each sex is responsible for. Do you have to defend a territory? You better be big! Do you want to create a lot of high-quality offspring? You better not invest that much energy into your own growth! It’s an interesting question in biology today: what happens genetically when a sexually-dimorphic species develops to adulthood?

To answer this question Albert Chung, a graduate student at Georgia Southern University, and his colleagues Robert Cox and Christian Cox designed an experiment to quantify changes in gene regulation in brown anoles throughout ontogeny and quantify how changes in gene regulation produce sexual dimorphism. They quantified gene expression at four different time points until adulthood across three different tissue types (brain, liver, and muscle) using RNA sequencing (RNAseq). Chung and colleagues found that sex-biased gene expression exhibits age specificity, with different age classes exhibiting different patterns of sexual dimorphism in gene expression. They also found that the number of sex-biased genes increases throughout development, important for a species to be able to develop both a larger sex and a smaller sex. In addition, sex-biased gene expression also varies among the different tissue types, with the liver exhibiting an increase in sex-biased genes throughout development, potentially to increase growth in male brown anoles compared to females! Chung spoke in the Raymond Huey Best Student Paper Award session for the Division of Ecology and Evolution and delivered a fantastic presentation. We look forward to learning more about the development of sexual dimorphism (especially in anoles!) from Albert and his co-authors.

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