Upon the completion of the textbook readings in Chapters 22-26 you should be able to:
Chapter 22 1. Explain how the principle of gradualism and Charles Lyell's theory of uniformitarianism influenced Darwin's ideas about evolution.
The basic idea of natural selection is that a population of organisms can change over the generations if individuals having certain heritable traits leave more offspring than other individuals. The result of natural selection is evolutionary adaptation, a prevalence of inherited characteristics that enhance organisms’ survival and reproduction in specific environments.
-gradualism, which holds that profound change is the cumulative product of slow but continuous …show more content…
Today, biologists distinguish between intra sexual selection and inter sexual selection. Meaning selection "within the same sex,"intrasexual selection is a direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. Males may use secondary sexual equipment such as antlers to battle competitors.
Chapter 24 26. Distinguish between prezygotic and postzygotic isolating mechanisms.
Prezygotic barriers impede mating between species or hinder the fertilization of ova if members of different species attempt to mate.
If a sperm cell from one species does fertilize an ovum of another species, then postzygotic barriers usually prevent the hybrid zygote from developing into a viable, fertile adult. 27. Discuss several prezygotic and post zygotic isolating mechanisms.
Prezygotic Barriers
Habitat Isolation. Two species that live in different habitats within the same area may encounter each other rarely, if at all, even though they are not technically geographically isolated. For example, two species of garter snakes in the genus Thamnophis occur in the same areas, but one lives mainly in water and the other is primarily terrestrial. Habitat