Category Archives: Article

Evolution of infection-induced host sterility

Harmful effects of parasitism include reduction of host reproductive abilities and increased host mortality. Whereas the former effect is commonly caused by sexually transmitted infections, increased mortality is typically due to other infection types. The initial models of the evolution of sterility virulence predicted development of fully sterilizing parasites, that is, infertility of the infected hosts. However, empirical observations agree with this prediction only partially. Therefore, the current effort is to reveal and understand mechanisms that prevent evolution of full sterilization and allow for evolution of only partial sterilization. This question I address also in my research. The actual study of this topic is the following one:

Janouskova, E., Berec, L. (2020) Fecundity-longevity trade-off, vertical transmission and evolution of virulence in sterilizing pathogens. American Naturalist 195: 95-106.

Allee effects under climate change

Understanding how climate change affects population dynamics is crucial for assessing future of biodiversity. Here I ask how can Allee effects, occurring when mean individual fitness is reduced in rare populations, respond to increasing temperature. Despite the role Allee effects play in ecology of invasive, threatened and harvested populations, impacts of climate change on Allee effects are practically unknown. Analysis of two population models reveals that whereas the Allee effect driven by predation generally weakens as temperature increases, the Allee effect due to need of finding mates is predicted to become stronger when warming occurs. For the former model, the metabolic theory suggests that with increasing temperature prey growth rate should increase faster than predator attack rate. Increasing temperature thus weakens the Allee effect. In the latter, gypsy moth population model, mating rate increases with warming due to enhanced female−male encounter rate and temperature-induced modifications in female and male adult emergence distributions. However, male and female mortality rates increase, too and the net effect is strengthening of the Allee effect. These results have repercussions also for pest control, indicating that augmentation of biocontrol agents may perhaps be not as effective as using pesticides or disrupting mating.

Berec L (2019) Allee effects under climate change. Oikos XX, XX-XX; doi: 10.1111/oik.05941