Dispersal evolution in a population infected with a male-killing endosymbiont

Area of Science:

• Evolutionary Biology
• Ecology
• Microbial Genetics

Background:

• Host dispersal is a key factor in parasite transmission dynamics, creating potential conflicts between host and parasite interests.
• Vertically transmitted parasites, like male-killing Spiroplasma in the African monarch butterfly, face unique challenges and opportunities related to host dispersal.
• The ability of parasites to manipulate host dispersal and the resulting evolutionary consequences are not well understood.

Purpose of the Study:

• To investigate the potential for parasites to manipulate host dispersal for their own benefit.
• To explore how parasite-driven manipulation of dispersal influences host population structure and parasite spread.
• To examine the evolutionary responses of both infected and uninfected hosts to parasite-induced dispersal manipulation.

Main Methods:

• Theoretical modeling was used to simulate host-parasite interactions.
• A comparative approach contrasted parasite spread with and without dispersal manipulation.
• The model focused on the African monarch butterfly (Danaus chrysippus) and male-killing Spiroplasma endosymbionts.

Main Results:

• A dispersal-manipulating male-killing parasite can shift the host population's dispersal pattern from male-biased to female-biased.
• Infected females exhibit the highest dispersal rates.
• Uninfected females show the strongest evolutionary response, evolving towards philopatry (reduced dispersal) compared to a non-manipulating scenario.

Conclusions:

• Parasite manipulation of host dispersal can significantly alter host population dynamics and parasite transmission.
• This study reveals a novel evolutionary context where the phenotypic effects of parasitism are most pronounced in uninfected individuals.
• The findings highlight the complex interplay between host behavior, parasite evolution, and population ecology.