Seasonality and the scheduling of life history at different latitudes

Abstract

For many ectotherms, the annual cycle is partitioned into ' growing ' (summer) and ' nongrowing ' (winter) seasons, and the lengths of these seasons are inversely related across a latitudinal gradient. This pattern of variation has the potential to affect diverse life-history traits profoundly. A key selective agent is size-dependent winter mortality which, with increasing latitude, places an increasing premium on attainment of large body size before the first winter of life. Winter body size is determined primarily by two factors: ( I ) birth date, which defines the beginning of the first growing season and (2) somatic growth rate within the first season. Using examples drawn from the Atlantic silverside, Menidiu menidiu (L.), and other fishes, I show how latitudinal variation in the scheduling of the spawning season, countergradient variation in the capacity for growth and reproduction, and mode of sex determination (environmental v. genetic) represent adaptations to seasonality.

Movements of Marine Fish and Decapod Crustaceans: Process, Theory and Application

“…equatorial gyres) are known to influence the distribution of those species with an extensive planktonic duration (Scheltema, 1986) (Figure 3). Many of these broad-scale physical hydrodynamics are cyclical and animals have evolved behavioural interactions such as the scheduling of spawning to coincide with lunar phases, seasonal winds and tidal currents (Norcross and Shaw, 1984;Morgan and Christy, 1994;Botsford et al, 2001), or to place the juvenile 'growing season' in the warmer, more productive months of the year (Conover, 1992). For example, in Chesapeake Bay, USA, hatching of blue crab larvae (Callinectes sapidus) mainly coincides with night-time ebb tides, which distribute progeny offshore in spring and summer when planktonic food resources for larvae are most abundant (Hines et al, 1995).…”

Sub-populations of coastal cod with different behaviour and life-history strategies

“…An example is size-dependent winter mortality in juvenile fish. Due to a shorter growth season at high latitudes, selection for rapid growth is strong to counteract the negative effect of the environment (Conover & Present 1990, Conover 1992. Despite environmental stress at high latitudes, the potential growth rate evolves to a level beyond what local stress conditions dictate (Arendt 1997).…”

Links between climate variation and the year class strength of New Zealand hoki (Macruronus novaezelandiae) Hector

“…Another important aspect of food supply is that there needs to be enough available to allow postlarvae and juvenile fish to grow to a minimum size before their first winter, as this can have a major effect on their ability to survive this period of low food supply (Conover 1992). Thresher et al (1988) Table 5 Eastern stock stepwise and best subset regression of hoki (Macruronus novaezelandiae) year class strength (YCS) and correlated climate variables.…”