Adaptive Radiation and Evolution on Islands

Why are islands laboratories of evolution? How do islands contribute to adaptive radiation?

Allopatric Speciation and Sympatric Speciation

Contrast allopatric speciation with sympatric speciation. Why is sympatric speciation more likely to occur in plants than animals?

Evolution and Genetics Relating to Roses

We know that all modern roses were developed from the wild five-petal variety. Not only do modern roses have many more petals, but they have a much larger number of chromosomes. Explain how this probably came about.

Effect of hybridization

For each of the following examples, indicate what type of hybridization barrier is in effect. A. Eastern and western meadowlarks have overlapping ranges, but their songs are different. B. Mules are sterile. C. One species of pine trees in California sheds its pollen in February; another species of pine growing in the same parts of California sheds its pollen in April. D. In Asia, Asiatic lions live in open grasslands, while the Bengal tiger lives in nearby forested areas. E. Pollen from one species of tobacco plant cannot form a pollen tube to reach the egg of a different species of tobacco even if the pollen lands on the stigma (the receptive, female flower part). F. In th... click for more

Tempo and Mode of Evolution

Much of the current debate among scientists today is over the tempo and mode of evolution. Describe and contrast gradualism with punctuated equilibrium.