Biogeography Explains Cophylogenetic Patterns in Toucan Chewing Lice

Abstract

Historically, comparisons of host and parasite phylogenies have concentrated on cospeciation. However, many of these comparisons have demonstrated that the phylogenies of hosts and parasites are seldom completely congruent, suggesting that phenomena other than cospeciation play an important role in the evolution of host-parasite assemblages. Other coevolutionary phenomena, such as host switching, parasite duplication (speciation on the host), sorting (extinction), and failure to speciate can also influence host-parasite assemblages. Using mitochondrial and nuclear protein-coding DNA sequences, I reconstructed the phylogeny of ectoparasitic toucan chewing lice in the Austrophilopterus cancellosus subspecies complex and compared this phylogeny with the phylogeny of the hosts, the Ramphastos toucans, to reconstruct the history of coevolutionary events in this host-parasite assemblage. Three salient findings emerged. First, reconstructions of host and louse phylogenies indicate that they do not branch in parallel, and their cophylogenetic history shows little or no significant cospeciation. Second, members of monophyletic Austrophilopterus toucan louse lineages are not necessarily restricted to monophyletic host lineages. Often, closely related lice are found on more distantly related but sympatric toucan hosts. Third, the geographic distribution of the hosts apparently plays a role in the speciation of these lice. These results suggest that for some louse lineages biogeography may be more important than host associations in structuring louse populations and species, particularly when host life history (e.g., hole nesting) or parasite life history (e.g., phoresis) might promote frequent host switching events between syntopic host species. These findings highlight the importance of integrating biogeographic information into cophylogenetic studies.

Geography and host biogeography matter for understanding the phylogeography of a parasite

“…Yet, this study suggests that co-speciation might not be observed at a higher phylogenetic scale (i.e., over a longer time period) if host specificity is not limited to a single host species. Indeed, regional codifferentiation with different closely related host species might rather ultimately mix the co-differentiation signal if the different host species overlap partially in their distribu-tion ranges and if the parasite life history traits, such as in Heligmosomoides, authorize host switching events between syntopic host species (Weckstein, 2004). In addition, the signal of regional co-differentiation, if generated by differences in the regional abundance of the different hosts, might also be lost if the relative regional host abundance changes over evolutionary time.…”

Do fly parasites of bats and their hosts coevolve?speciation in Trichobius phyllostomae group (Diptera, Streblidae) and their hosts (Chiroptera, Phyllostomidae) suggests that they do not

“…The second is that most common among these flies. Historical associations of lice and some mites with their hosts may have many cospeciation/codivergent events, exceptions to which may be explained by phoresia (Weckstein 2004). Cophylogenetic analyses of other, second-group, ectoparasitic arthropods (fleas and ticks) with preparasitic stages in the roost or environment of their mammal hosts, find a low probability of cospeciation.…”

A phylogenetic test of the parasite-host associations between Maculinea butterflies (Lepidoptera: Lycaenidae) and Myrmica ants (Hymenoptera: Formicidae)

“…Other studies report a partial or no fit between the parasite and host phylogenies in more complex situations, involving parasites infecting multiple hosts. This is the case for Monogenea and fish , lice and passerine birds (Johnson et al, 2002), chewing lice and toucans (Weckstein, 2004), and chewing lice and penguins (Banks et al, 2006).…”