Date of Completion


Embargo Period



Dr. David E. Avery, Dr. George B. McManus

Field of Study



Master of Science

Open Access

Open Access


To predict the response of the biota to environmental change requires information on intrapopulation variation in life history traits and the proportion of phenotypic variation attributable to genes, heritability. Yet, knowledge of these parameters in marine populations is very limited. In the present study, I consider phenotypic plasticity and heritability of temperature-dependent, fitness-related life history traits in two coastal copepod species, Acartia tonsa and Acartia hudsonica, from Long Island Sound, a temperate estuary on the east coast of the USA. Acartia hudsonica is a purportedly cold-adapted species and A. tonsa a warm-adapted one. I used a full-sibling, split family design to measure egg production rate, adult longevity, and estimated lifetime fecundity at 16oC and 18oC (Acartia hudsonica) and 22oCand 24oC (Acartia tonsa). Treatment temperatures represent projected increases of +2oC and +4oC by the end of the century relative to mean temperature values experienced by these species, respectively, in Long island Sound. In A. tonsa, egg production, adult life span, and lifetime fecundity displayed significant sibship-environment interaction (pA. hudsonica. Selection differentials, the expected change in fitness with a change in phenotype, for traits of A. tonsa were positive. Evolutionary rates in A. tonsa were moderate, ranging from 0.13 (lifetime fecundity) to 0.23 haldanes (egg production). These results indicate that A. tonsa in Long Island Sound has the potential to evolutionarily cope with predicted increases in global temperature whereas A. hudsonica does not.

Major Advisor

Dr. Hans G. Dam