Presentation Detail

Phylogeography

Sorger, Daniela Magdalena [1].

Island-like divergence on Florida's sand ridges - the case of a trap-jaw ant.

Florida's inland ridges originated as sand islands at a time when sea levels were significantly higher than they are now. These ridges (some up to 100 miles long) are home to orange trees, but also endemic animals like the charismatic trap-jaw ant Odontomachus relictus. This ant occurs on only two of these sand ridges and lives in sand hill scrub habitat. Besides its high habitat-specificity, little is known about the life history of this ant or whether and how it differs between ridges. The two ridges have been separated for up to one million years, sufficient time (given isolation) for divergence to occur. Here, I present preliminary data from sampling over 100 populations on both ridges to test the hypothesis of species divergence between ridges using behavioral, genetic, and morphological data. Some early aggression trials showed aggression between ridges but no aggression within ridges. A subset of individuals was used for genetic analysis of the barcoding gene CO1 which revealed a mighty 4.84% divergence between ridges. Such difference suggests that what is now called O. relictus may represent two distinct species, which would be two of America's rarest ants, EACH living in a highly threatened habitat. Measurements of morphological characters yielded no consistent between-ridge differences in visual traits suggesting that molecular divergence has not been accompanied by strong divergence in morphology. Molecular differences within ridges have not yet been considered. However, qualitative morphological differences in color and size have been observed between clusters of populations on each ridge.These variants are consistent within aggression patterns. Next steps include a more in-depth phylogenetic study adding nuclear genes and population genetics using microsatellite markers that are currently being developed. These methods will help shed more light into the evolutionary history and ecology of O. relictus. More specifically, I will be able to answer life history questions about breeding structure (e.g. number of queens and males contributing to the gene pool of a single colony), dispersal (e.g. relatedness within and between colonies, clusters, and ridges), and age of divergence. Similar patterns of divergence (and rarity) are likely in other organisms living on these ridges. For instance, Dorymyrmex elegans, a small dolichoderine ant, exhibits distinct morphological differences between these same ridges. An analysis of the gene CO1 showed a curious genetic divergence of one cluster of populations while others are genetically indistinct from a second species (D. bureni) living in the same habitat.

1 - North Carolina State University, Biology, 127 David Clark Labs, Box 7617, 100 Eugene Brooks Ave., Raleigh, NC, 27695, USA

Keywords:
ants
divergence
islands
habitat isolation
Isolation by distance.

Presentation Type: Regular Oral Presentation
Session: 118
Location: Peruvian B/Snowbird Center
Date: Monday, June 24th, 2013
Time: 10:45 AM
Number: 118002
Abstract ID:448
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation