Ross L, Davies NG, Gardner A. 2019. How to make a haploid male. Evolution Letters doi: 10.1002/evl3.107.
About 12% of all animal species are haplodiploid, meaning that mothers give birth to sons without the involvement of a father. Why do these fatherless babies develop as males and not females? And could it be a strategy to get more granddaughters?
Davies NG, Flasche S, Jit M, Atkins KE. 2019. Within-host dynamics shape antibiotic resistance in commensal bacteria. Nature Ecology & Evolution doi: 10.1038/s41559-018-0786-x.
Since antibiotic-resistant bacteria have a fitness advantage in this era of widespread antibiotic use, why haven’t they completely replaced antibiotic-sensitive bacteria? We suggest that within-host competition could help to explain the coexistence of sensitive and resistant strains of commensal bacteria by promoting frequency-dependent selection for resistance. We develop a model that captures patterns of antibiotic resistance across 30 European countries.
Davies NG, Gardner A. 2018. Monogamy promotes altruistic sterility in insect societies. Royal Society Open Science 5: 172190.
Inclusive-fitness theory holds that parental monogamy should promote altruism between siblings, since it ensures that siblings are highly related to each other. In insect societies, a striking example of sibling altruism is when workers give up their own reproduction to focus on enhancing their sibs’ welfare. But a recent mathematical analysis (Olejarz et al. 2015, eLife) could not find a consistent effect of monogamy on the evolution of such worker sterility. We revisit this analysis, making less-restrictive genetic, evolutionary, and ecological assumptions, and find that monogamy clearly promotes worker sterility.
Atkins KE, Lafferty EI, Deeny SR, Davies NG, Robotham JV, Jit M. 2018. Use of mathematical modelling to assess the impact of vaccines on antibiotic resistance. The Lancet Infectious Diseases 18: e204–e213.
Antibiotic resistance (ABR) is a major threat to global heath. Vaccines have been proposed as a means of managing ABR, and mathematical modelling can help us to predict how vaccination may impact upon resistance. We review existing work, highlight important gaps in our understanding, and propose a new framework for understanding the various pathways through which vaccination can promote or inhibit resistance in bacterial pathogens.
Davies NG, Ross L, Gardner A. 2016. The ecology of sex explains patterns of helping in arthropod societies. Ecology Letters 19: 862–872.
Social arthropods (insects, arachnids, and crustaceans) show tremendous variation in the sex of helpers (nurses and soldiers): in some societies, only females help; in others, only males help; and in others still, both sexes help. In this paper, we build a mathematical model that explains these patterns in terms of these species’ sexual ecology, finding that (i) sex-specific preadaptation, (ii) the evolvability of the sex ratio, (iii) mating between siblings, (iv) promiscuity, and (v) whether individuals have reproductive autonomy all impact upon the sex of helpers and how much helping evolves. We test our predictions with an empirical survey.
Davies NG, Gardner A. 2014. Evolution of paternal care in diploid and haplodiploid populations. Journal of Evolutionary Biology 27: 1012–1019.
Workers in the social Hymenoptera (wasps, bees, and ants) are always female. This is probably because, in the solitary ancestors of these insect societies, parental care is provided by females, not males, and so hymenopteran females are preadapted to care for juveniles. In this paper, we ask if the Hymenoptera’s unusual genetics (haplodiploidy) inhibits paternal care, which could explain why it is so rare in this clade. This paper was the Journal of Evolutionary Biology Editor’s Choice article for the June 2014 issue, was a featured article on Faculty of 1000 Prime and was shortlisted for the JEB Graduate Student Prize.