Host–parasite local adaptation after experimental coevolution of Caenorhabditis elegans and its microparasite Bacillus thuringiensis

Abstract

Coevolving hosts and parasites can adapt to their local antagonist. In studies on natural populations, the observation of local adaptation patterns is thus often taken as indirect evidence for coevolution. Based on this approach, coevolution was previously inferred from an overall pattern of either parasite or host local adaptation. Many studies, however, failed to detect such a pattern. One explanation is that the studied system was not subject to coevolution. Alternatively, coevolution occurred, but remained undetected because it took different routes in different populations. In some populations, it is the host that is locally adapted, whereas in others it is the parasite, leading to the absence of an overall local adaptation pattern. Here, we test for overall as well as population-specific patterns of local adaptation using experimentally coevolved populations of the nematode Caenorhabditis elegans and its bacterial microparasite Bacillus thuringiensis. Furthermore, we assessed the importance of random interaction effects using control populations that evolved in the absence of the respective antagonist. Our results demonstrate that experimental coevolution produces distinct local adaptation patterns in different replicate populations, including host, parasite or absence of local adaptation. Our study thus provides experimental evidence of the predictions of the geographical mosaic theory of coevolution, i.e. that the interaction between parasite and host varies across populations.

MainstreamingCaenorhabditis elegansin experimental evolution

“…This fact has been exploited to test models of host-pathogen dynamics by tracking coevolution between worm host and bacterial pathogen, and then quantifying responses to selection imposed on each of them. For example, trade-offs evolve between worm growth rates and resistance to pathogens [29,48], local adaptation occurs between pathogens and hosts [49,50], and outcrossing sex increases during host -pathogen coevolution [51][52][53]. With the recent discovery of viruses that infect natural populations of C. elegans and C. briggsae [54], viral coevolution experiments provide a further dimension to test these and related hypotheses.…”

“…The diverse reproductive strategies have already been exploited for mutation studies, and adaptive evolution is an obvious next direction to explore in detail. ecological theory Host -parasite coevolution is, and will be, a prosperous area for C. elegans experimental evolution [49,52]. But this is just one possible ecosystem.…”

Increased responsiveness in feeding behaviour ofCaenorhabditis elegansafter experimental coevolution with its microparasiteBacillus thuringiensis

“…Our analysis also revealed a significant effect of replicate within host-selection regime. This effect is probably a consequence of independent evolutionary trajectories in the replicate populations within the same evolution treatment, as already shown for these populations previously [15,20].…”

“…We previously demonstrated multiple phenotypic and genetic changes for exactly the same coevolved host populations [15,20]. The increased responsiveness in feeding behaviour adds another trait of relevance for the interaction with parasites that is directly influenced by coevolutionary adaptations.…”

Metazoan endoparasites diversity of Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) as an indicator of environmental alterations on a tropical aquatic system

“…The environmental conditions are of great importance to the parasites development phases, as the infective forms of many parasites may be susceptible to the hosts' external conditions (Schulte et al 2011). That's the reason why the modifications of the Paraná River hydrological system may also be an important factor for the parasite richness reduction.…”