Gymnotus, the banded electric knifefish, is a diverse genus with a range that extends from Argentina to southern Mexico and includes species distributed both east (cis-Andean) and west (trans-Andean) of the Andes. Each Gymnotus species exhibits a distinctive electric organ discharge (EOD), used for communication and navigation. Here, I present a new molecular phylogenetic hypothesis for 35 Gymnotus species based on two mitochondrial (cyt b and 16S) and two nuclear genes (RAG2 and Zic1). I found that the trans-Andean species are distributed in four distinct lineages with varying amounts of divergence from their closest cis-Andean sister taxa. I suggest that not all trans-Andean species evolved as a result of the orogeny of the Andes. I evaluate EOD phase number evolution in Gymnotus and find a trend for reduced phase numbers in both cis- and trans-Andean regions. Finally, I suggest hypotheses to account for the patterns of EOD phase number diversification.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/30525 |
| Date | 05 December 2011 |
| Creators | Brochu, Kristen |
| Contributors | Lovejoy, Nathan |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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