Presentation Detail

Species Interactions and Coevolution

Merilo, Mark T [1], Adamowicz, Sarah J [1], Ali, R Ayesha [2].

On patterns of coevolution across cophylogenies.

Symbiotic associations among species are a pervasive, if not universal factor in the evolutionary history of all types of organisms. Further, understanding how mutualistic and parasitic organisms coevolve has implications in diverse systems ranging from agriculture to human health. Due to the interdependence between organisms and their symbionts, studying coevolution provides a better understanding of evolutionary trends in general. By mapping the phylogeny of a group of symbionts onto that of their hosts, a common evolutionary history can be reconstructed, thereby giving an estimate of occurrences of four coevolutionary events types: host switching; cospeciation; duplication,whereby the symbiont speciates but the host does not so both symbionts remain on a single host lineage; and sorting, whereby the host speciates but the symbiont does not so a single host lineage retains the symbiont.
To date, the majority of such analyses have been limited to the study of four or fewer cophylogenies at a time. These analyses have typically tested the degree to which the symbiont phylogeny is dependent on or independent of the host phylogeny. However, no studies consider or quantify how patterns of all four of these coevolutionary events differ across cophylogenies. In this study we take a meta-analysis approach to collect and analyze 127 pairs of published host-symbiont cophylogenies, together with association data (e.g. who eats whom). For each cophylogeny, we use CoRe-PA to reconstruct coevolutionary histories from which we can estimate the proportion of speciation events that fall into the above four categories. We then develop a randomization test to compare patterns of coevolutionary event profiles of symbiotic taxa across latitude zones as well as biological classifications of symbiotic relationship types. This approach presents a novel method of directly comparing groups of multiple reconstructed cophylogenies and testing for differences amongst them.
Evidence of differences in the profiles of coevolutionary event types were found between cophylogenies grouped as adaptive vs. innate host immune system types, between ecto- and endo-symbionts, as well as across latitude zones. No difference was found between parasites vs. mutualists, monoxenous vs. heteroxenous symbionts (parasites with a single vs. multiple hosts), or between symbionts transmitted vertically vs. horizontally.
The implications of our study are two-fold. 1) We present a novel method of statistically comparing historic coevolutionary patterns across large numbers of cophylogenies. 2) Through our preliminary results, we identify potential future directions for an important but under-examined question: What factors influence patterns in coevolution?

1 - University of Guelph, Biodiversity Institute of Ontario & Integrative Biology, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
2 - University of Guelph, Mathematics and Statistics, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada

Keywords:
Coevolution
host shifts
co-divergence
symbiotic relationships.

Presentation Type: Regular Oral Presentation
Session: 99
Location: Cotton B/Snowbird Center
Date: Monday, June 24th, 2013
Time: 8:30 AM
Number: 99001
Abstract ID:861
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation