Explain how each of the following makes it difficult to clearly define a species: variation within a species, geographically isolated populations, asexual species, fossil organisms.

Distinguish between microevolution and macroevolution.

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans.Human populations today are not considered separate species under the biological species, morphospecies, and phylogenetic concepts. Explain what kind of evidence supports this statement.

Which of the following factors would not contribute to allopatric speciation?a. A population becomes geographically isolated from the parent population.b. The separated population is small, and genetic drift occurs.c. The isolated population is exposed to different selection pressures than the parent population.d. Gene flow between the two populations continues to occur.

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans.Before the application of DNA sequencing to fossils, which species concept was most useful for distinguishing human fossils? What is one disadvantage of this approach?

A revolution in the study of human evolution is under way thanks to the invention of techniques that enable DNA sequencing of not only modern humans, but also ancient humans.Modern humans (Homo sapiens) and archaic humans called Neanderthals (H. neanderthalensis) shared a common ancestor in Africa but diverged in different geographic areas. When modern humans migrated out of Africa and dispersed around the world starting about 100,000 years ago, they overlapped with Neanderthals in Europe. This scenario is best described asa. species living in sympatry following allopatric speciationb. species living in sympatry following sympatric speciationc. species living in allopatry following allopatric speciationd. species living in allopatry following sympatric speciation

Explain why allopatric speciation would be less likely on an island close to a mainland than on a more isolated island.

Svante Pääbo and colleagues were the first to sequence the Neanderthal genome from fossils and compare the sequences to modern humans. According to the data shown here, did the two species interbreed when they overlapped in Europe? Explain.

What does the term punctuated equilibria describe?