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Host defense reinforces host-parasite cospeciation
Dale H Clayton1, Sarah E Bush, Brad M Goates
1Department of Biology, University of Utah, Salt Lake City, UT 84112, USA. clayton@biology.utah.edu
Summary
Cospeciation, the synchronized evolution of hosts and parasites, is reinforced by host defense mechanisms. Feather lice cannot survive on new bird hosts if their sizes differ, preventing parasite speciation.
Area of Science:
- Evolutionary biology
- Parasitology
- Ecology
Background:
- Cospeciation describes the parallel speciation of interacting species, like hosts and parasites.
- While often viewed as neutral, adaptive factors in cospeciation remain under-explored.
Purpose of the Study:
- To investigate the adaptive role of host defense in cospeciation using feather lice (Columbicola) and their avian hosts (Columbiformes).
- To determine if body size constraints influence host-parasite cospeciation patterns.
Main Methods:
- Phylogenetic analyses of Columbicola lice and Columbiformes hosts using nuclear and mitochondrial DNA.
- Experimental host-switching trials to assess louse viability on novel hosts.
- Measurement of louse fitness components: attachment, feeding, and evasion of host preening.
Main Results:
- Significant cospeciation and correlated evolution of host and parasite body size were detected.
- Lice failed to establish viable populations on hosts differing in size from their native host.
- Host preening, a defense mechanism, was the primary factor limiting louse survival on novel-sized hosts.
Conclusions:
- Host defense mechanisms, specifically preening, impose adaptive constraints that reinforce cospeciation.
- Body size differences between hosts and parasites prevent host-switching, thereby maintaining congruent phylogenies.