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Abstract Detail



Macroevolution

Boyko, James [1], Teo, Nakov [1], Alverson, Andrew [1], Beaulieu, Jeremy [1].

Testing the signal of marine versus freshwater origins of photosynthetic eukaryotes.

The evolution of photosynthetic bacteria remains, perhaps, the most significant event in life's history, changing the flow of energy through the biosphere and the geology of earth itself. Similarly, the evolution of autotrophic eukaryotes has proven critical to the development of terrestrial life. The environmental conditions during the course of primary plastid endosymbiosis have recently been examined using phylogenetic comparative techniques. However, previous attempts to address these questions have relied exclusively on an exemplar sampling approach of cyanobacteria and early photosynthetic eukaryotes. At best, it remains unclear whether key events such as the primary endosymbiosis of the chloroplast occurred in low salinity (i.e., freshwater) habitat or in a marine environment, prolonging the debate about the ecological context for the origin of plastids. We expand on this work by compiling an extensive dataset of over 25,000 species for which their salinity environment is known, and combine this information with an additional character that defines whether the lineage was terrestrial or aquatic. We apply recently developed comparative methods that account for both diversification rate differences in the coordinated evolution of multiple binary characters, as well as unmeasured factors that artificially influence the rates of evolution in the observed characters. Additionally, we conduct a series of tests to examine whether the inherent "memory-less" processes underlying essentially all phylogenetically-based comparative frameworks applied solely to extant taxa naturally make it impossible to ever confidently infer ancestral conditions for an event that took place nearly 2.5 billion of years in the past.


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1 - University of Arkansas, Biological Sciences, Fayetteville, AR

Keywords:
Phylogenetic Comparative Methods
Plastid.

Presentation Type: Oral Paper
Session: 42, Macroevolution II
Location: 107/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 2:30 PM
Number: 42005
Abstract ID:930
Candidate for Awards:None


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