We currently study two systems with the aim of working out the ecological and evolutionary impact of these bacteria on the ecology and evolution of their hosts.
Bolly, as she is affectionately termed, is a butterfly that lives in the IndoPacific. Our research has found that each island in the Pacific has a different prevalence of Wolbachia male-killers within bolly; male-killers are absent in some, but present in very high frequency in others. In one case, 99% of females bear the male-killer, producing a population sex ratio of around 100 females per male. Perhaps most remarkably, we know from historical data that these frequencies have been relatively constant in the recent past.
The fact that bolly on different islands carry a different prevalence of male-killer make this species a fantastic place to examine the impact of these parasites, where we can determine the effect on host ecology and evolution at different prevalence levels, and test hypotheses as to their effect with replicated populations.
As well as showing variation in prevalence of the parasite, we have also recently observed variation in the ability of the parasite to kill males. The same ‘strain’ of Wolbachia does not act as a male-killer in many populations in S.E. Asia. We are currently examining the cause of this variation as well.
See Sylvain and Emily’s pages for details
Collaborators: Dr Nina Wedell, Leeds; Dr Neil Davies, GUMP Research Station, UC Berkeley, Moorea, French Polynesia & Prof George Roderick, UC Berkeley; Dr Menno Schilthuizen, University of Malaysia in Sabah.
Sponsors: NERC, NSF, BBSRC.
The second system we are working on uses an experimental evolution approach to examine the effect of female biased sex ratios produced by male-killers on host evolution. This involves maintenance of Drosophila under different sex ratio regimes, as if there were different prevalence of male-killing, and examining the evolutionary consequences of these regimes over 20 generations of selection. We will examine whether male and female reproductive biology changes over this timeframe.
See Max’s page for details.
Collaborators: Dr Tracey Chapman & Dr Kevin Fowler, UCL.
Sponsor: EU
In addition to this, we are using models to develop our ideas about the impact of male-killing parasites on natural populations, and patterns of evolution and incidence of inherited microbes. We are working on interactions between parasites which affect the same process, on the evolution of higher level phenomena such as haplodiploidy, and on the emergence of new phenotypes.
Sponsor: UCL Graduate School.
Collaborators: Dr Arndt Telschow (Kyoto University), Prof Peter Hammerstein (Humboldt University, Berlin), Prof Andrew Pomiankowski (UCL)
