Description from NSF award abstract:
The marine communities of the northern and southern hemispheres are kept distinct by warm water and strong currents near the equator. Nevertheless, many taxa have established "antitropical" distributions, occurring in temperate zones on either side of the tropics but not within the warmest tropical regions. Although paleontological studies and molecular phylogenies provide information about the timing and direction of trans-tropical colonization, the existence of single species with antitropical distributions provides an opportunity to begin to investigate several fundamental questions about the recent history of and future prospects for biological connectivity between the northern and southern hemispheres. This project focuses on characterizing connectivity across the tropics in the antitropical gooseneck barnacle Pollicipes elegans. This eastern Pacific species is found in both hemispheres but is absent from the warmest waters immediately to the north of the equator. Previously-collected data show that mtDNA haplotype lineages are shared between northern and southern hemisphere populations, and that the separation between north and south has been relatively recent, within the last 160,000 years. This research has two main goals. First, the investigators will use multi-locus sequence data and microsatellite loci to estimate the time of separation of northern and southern populations and how much gene flow has occurred since that split, both over evolutionary timescales and across recent generations. The second goal is to characterize larval thermal tolerance and performance as a means to test the hypothesis that temperature is a barrier to larval dispersal across the warmest tropical regions in P. elegans. Although several other hypotheses can potentially explain what keeps P. elegans out of the tropics, such as the isolating effects of the equatorial boundary currents or post-settlement processes, assessing the temperature sensitivity of the dispersive larval stage will provide the first important physiological test of how temperature limits connectivity. Understanding the history of gene flow and the temperature tolerance of dispersive larvae will provide insight into the impacts of recent and projected increases in tropical sea surface temperatures on recent and future patterns of connectivity between the hemispheres.
Dataset | Latest Version Date | Current State |
---|---|---|
Microsatellite primer sequences from Pollicipes elegans collected at the University of Hawaii during 2015 (Gene flow across the tropics project) | 2015-12-18 | Final no updates expected |
Larval genotype data for Pollicipes elegans collected at the Universtiy of Hawaii in 2013 (Gene flow across the tropics project) | 2015-12-18 | Final no updates expected |
Cytochrome oxidase I DNA sequences from Pollicipes elegans collected at the University of Hawaii in 2015 (Gene flow across the tropics project) | 2015-12-17 | Final no updates expected |
Genotype data for the three adult barnacle aggregations collected at the University of Hawaii in 2015 (Gene flow across the tropics project) | 2015-12-17 | Final no updates expected |
Principal Investigator: Peter B. Marko
University of Hawai'i (UH)
Co-Principal Investigator: Amy L. Moran
University of Hawai'i (UH)
Contact: Peter B. Marko
University of Hawai'i (UH)