In many species, a proportion of males opts out of the conventional trials of strength that are commonly associated with holding or attracting resources such as females.

These males frequently engage in behaviours and express morphologies that help them avoid conflict with other males. The co-existence of alternative male tactics has stimulated our interest in both the evolution of divergent adaptive optima within species and the quantitative and ecological genetics of life-history decisions in general.

Where alternative male reproductive tactics occur within a sex, there is a rare opportunity to understand adaptation to divergent sexual roles – guards versus sneaks – within a species. This opportunity is all the more valuable because phylogenetic and population effects are controlled. We have used this approach to study the costs of secondary sexual traits, immunity, sperm competition and parental care.

Where males adopt alternative reproductive tactics, this phenotypic plasticity is frequently a threshold response to an environmental cue. Our interest in the biology of the alternative phenotypes has spread to the evolution of the switch between phenotypes as an adaptation in itself. We are interested in the genetic basis to switching between phenotypes, how selection acts on alternative phenotypes and thus on switches, how sexual and male dimorphism co-evolve and how ecology shapes the genetic architecture of switching.

We study the co-existence of alternative phenotypes in a range of species in the laboratory and the field, including people, guppy fish, crickets, dung beetles, seed beetles, earwigs, harvestmen, native bees, mites, ticks, and algae. In so doing we study traits such as mate-finding behaviour, male morphology, host-searching behaviour, sexual reproduction, sex ratio, multiple mating and plague forming, as environmentally cued threshold traits.