For next week's EXEB-meeting, I am pleased to welcome one of our most beloved and loyal co-workers: Hanna Bensch. Hanna has been working for many summers now with us in the damselfly project, and she also participated in our recent field sampling expedition to Cameroon in Central Africa, during January and February 2017. Hanna's skills as a field assistant are amazing, and we are so happy that she has been working with us for so long time.
Hanna will give a presentation of her Master's-thesis work that she has done under the supervision of Charlie Cornwallis on ostriches (Struthio camelus) in South Africa. The title is:
The monoculture effect: a meta-analysis and experiment on ostrich chicks
Increased genetic diversity of a population can decrease pathogen and parasite transmission and prevalence within the population, a phenomenon known as the monoculture effect. This diversity-disease hypothesis has been studied within many different host systems. However, the overall generality of the monoculture effect has been debated and not systematically investigated. I therefore tested the strength and generality of the monoculture effect by conducting a meta-analysis on the relationship between within group genetic diversity and pathogen prevalence or mortality. My meta-analysis confirmed the monoculture effect to be a general phenomenon, finding a significant negative relationship between group genetic diversity and rates of host infection and mortality. However, a majority of the studies included were on insects and further studies on a broader range of taxa is of interest to increase the understanding of the monoculture effect. To complement my meta-analysis, I therefore conducted an experimental study on ostrich chicks, testing group genetic diversity’s effect on growth and survival.
If you want to know if chicks from groups of high diversity did better than chicks from groups of low diversity, then you have to come to my presentation! :)
Along the same topic as Hanna's presentation above, I suggest that we also have a discussion about a recent paper in Science about the relationship between resistance and tolerance evolution, that challenges the common view that these two forms of defense are redundant to each other. You can find the paper here, and the Abstract is below:
- Irit Levin-Reisman1,
- Irine Ronin1,
- Orit Gefen1,
- Ilan Braniss1,
- Noam Shoresh2,
- Nathalie Q. Balaban1,*
Controlled experimental evolution during antibiotic treatment can help to explain the processes leading to antibiotic resistance in bacteria. Recently, intermittent antibiotic exposures have been shown to lead rapidly to the evolution of tolerance—that is, the ability to survive under treatment without developing resistance. However, whether tolerance delays or promotes the eventual emergence of resistance is unclear. Here we used in vitro evolution experiments to explore this question. We found that in all cases, tolerance preceded resistance. A mathematical population-genetics model showed how tolerance boosts the chances for resistance mutations to spread in the population. Thus, tolerance mutations pave the way for the rapid subsequent evolution of resistance. Preventing the evolution of tolerance may offer a new strategy for delaying the emergence of resistance.