Why are some pathogens species-specific, and how can others cross species barriers?
Why are some pathogens species-specific, and how can others cross species barriers?

Why are some pathogens species-specific, and how can others cross species barriers?
How do unique molecules on the surface of cells help in distinguishing between self and non-self in organisms?
How can patterns of chromosome number in certain genera suggest speciation due to polyploidy?
How do geographically isolated populations show differences in allele frequencies, and why are these differences significant?
How does polyploidy contribute to speciation in the genus Allium?
How can directional, stabilizing, and disruptive selection be identified in populations?
What are the conditions under which speciation can occur abruptly?
How does gradual divergence of isolated populations lead to speciation?
What are the types of reproductive isolation, and how do they prevent populations from interbreeding?
How does evolution depend on changes in allele frequencies within populations over time?