Research

The Hollis lab is interested in sexual selection and conflict and our research links aspects of behavioral ecology, evolutionary genetics, and computational biology. We study the spectrum of synergistic and antagonistic interactions that occur between males and females over reproduction. Some of these interactions (e.g. female mate choice) may provide benefits at the population level, while others (e.g. male harm to females) impose a conflict load. There is also antagonism occurring at another level in the genome, where variation that contributes to female fitness may harm male fitness, or vice versa, a dilemma which can be resolved by the evolution of sexual dimorphism. With this in mind, we work on several fundamental and interconnected questions:

(1) What is the extent and evolutionary impact of conflict between the sexes?
(2) What are the molecules involved in post-mating interactions between the sexes and what evolutionary forces rule their fate?
(3) How does sexual selection regulate the process of adaptation?
(4) How are differences between the sexes built (and constrained) in the genome?
(5) How does pre- and post-copulatory isolation arise and harden?

To address these questions we use a variety of approaches, but chief among these is experimental evolution. With experimental evolution, replicated populations evolve in manipulated environments and are tracked in real time. Our experimental work mostly uses the fruit fly Drosophila melanogaster, which is easily maintained in the lab and allows us to employ a well-developed genetic toolkit. Most important of all for our purposes, fruit flies have separate sexes and complex behavior and mating interactions.

The evolutionary change we explore occurs across multiple levels—phenotypes are the most straightforward to assess, but as it has become more tractable our work has increasingly focused on sequence-level changes in the genome and gene expression changes across the transcriptome. We therefore use a combination of genetic tools, genomic and transcriptomic data, and bioinformatic approaches to better understand genetic variation and its relationship to phenotypes and fitness.

We have also worked with several other model systems, including:
– Pseudomonas entomophila, a generalist insect pathogen, in order to ask questions about the sex-specificity of pathogen resistance and how resistance evolves.
– Aedes aegypti, the yellow fever mosquito, to gain an understanding of the components of male mating success and improve insect reproductive control programs.
– Camponotus fellah, the carpenter ant, to ask how social isolation impacts fitness.
– Dictyostelium discoideum, a social amoeba, looking at cycles of antagonistic coevolution.