BIOL 1602 Lecture : mortality rates
Document Summary
In populations where mortality rates are high, individuals tend to breed earlier in life. Read example on mainland and island opossums. Populations have not evolved longer life spans because the power of natural selection declines with age. Deleterious mutations whose effects occur late in life can accumulate in populations. The more offspring a parent (or pair of parents) attempts to raise at once, the less time and energy the parent can devote to caring for each one. Selection will favour the clutch size that produces the most surviving offspring. Any individual offspring will survive decreases with increasing clutch size. The abiliiity of the parents to feed any individual offspring declines as the number of offspring increases. In an experiment, the mean clutch size was 8. 53: the average number of surviving offspring from clutches of each size was also determined. This number was highest for clutches of 12 eggs.
