ADAPTATIONS AND EVOLLUTION OF SPECIES. What is evolution? The change in the genetic make-up of a species over time. How does evolution occur?. GRADUALISM gradual process that goes on all the time PUNCTUATED EQUILIBRIUM periods of rapid change are separated by periods of little or no change.
The allele for sickle cell anemia affects the population in opposing ways:
(1) tends to eliminate the allele in homozygous individuals because sickle cell anemia is lethal for these individuals
(2) tends to preserve the allele because the heterozygote is resistant to malaria
1. Birth weight in offspring
2. Seed size