Overview. Marine zooplankton show strong ecological responses to climate change, but little is known about their capacity for evolutionary response. Many authors have assumed that the evolutionary potential of zooplankton is limited. However, recent studies indicate broad circumstantial evidence for the idea that selection is a dominant evolutionary force acting on these species, and that genetic isolation often is achieved at regional spatial scales in pelagic habitats. The proposed research will use a combination of population genetic, ecological, and oceanographic techniques to test two central hypotheses regarding how the pelagic environment controls genetic variation within zooplankton species.
This RAPID project will take advantage of a unique opportunity for basin-scale transect sampling across boreal-temperate, subtropical and tropical waters of the Atlantic Ocean (> 90° latitude) through the Atlantic Meridional Transect (AMT) cruise in 2014. Population genomic studies on this material will use RADSeq-derived SNP markers to identify the geographic location of strong genetic breaks within three copepod species, and Bayesian and coalescent analytical techniques will test if these regions act as dispersal barriers. The physiological condition of animals collected in distinct ocean habitats will be assessed by measurements of egg production as well as body size (condition index), dry weight, and carbon and nitrogen content. We will test the prediction that ocean regions that serve as dispersal barriers for marine holoplankton are areas of poor-quality habitat for the target species. We hypothesize that this is a dominant mechanism driving population genetic structure in oceanic zooplankton.
EAGER: New molecular methods for studying copepod nauplii in the field
Investigators: Erica Goetze (PI), Petra Lenz (co-PI), and Karen Selph (co-PI).
The most abundant metazoans in the open sea are often the earliest developmental stages of copepods, their nauplii. Nauplii remain under-studied due to the limitations of conventional techniques and an historical emphasis on studying the larger mesozooplankton. However, there is increasing recognition that nauplii play important roles in food web dynamics, and considerable evidence suggests that nauplii may be important trophic intermediaries between microbial and classical food webs, due to their high abundance, high weight-specific ingestion rates, and ability to feed on relatively small particles. This team of investigators is developing a novel molecular approach to studying diverse populations of nauplii in mixed field samples based on quantitative PCR (qPCR). Here we propose to complete development and validation of this qPCR-based technique for enumeration of nauplii, and demonstrate its utility in the field. The specific objectives of this research are to identify and reduce technical and biological sources of error, determine the accuracy of the method across a range of environmental conditions, and complete one paired field experiment that compares the grazing impact of naupliar and protozoan micro-grazers in a model subtropical coastal ecosystem, in order to demonstrate the utility of this new method.