UNUSUAL GENETIC VARIATION IN BODY SIZE, DEVELOPMENT TIMES, OIL STORAGE, AND SURVIVORSHIP IN THE MARINE COPEPODPSEUDOCALANUS

Abstract

The techniques of quantitative genetics have long been applied to animal breed ing and agriculture, but seldom to studies of natural populations, and even more sel dom to marine organisms. Yet they are the only techniques that can be used to study inheritance of most traits of interest to ecologists and evolutionary biologists. The best introduction remains the book by Falconer (1960). A previous study of the heritability of demographic traits in the marine copepod Eurytemora herdmani, although evidently the first of its kind, produced few sur prises ( McLaren, 1976a) . It was found that traits of such obvious demographic importance as body size (influencing fecundity) , age of maturity, and mortality had low heritabilities at laboratory temperatures experienced in nature. As McLaren ( 1976a) notes, such low heritabilities are expected for traits involved in determin ing fitness. The results of the present study are very different and not so easy to understand. In what follows it will be clear that we may be dealing with a genetically com plex population of animals, and possibly with cryptic or sibling species. Therefore, we refer throughout only to the genus name, Pseudocalanus. The genus is among the most widespread and numerically abundant metazoans in the world (Corkett and McLaren, 1978).