Chapter 24

The Origin of Species

1- The fossil record chronicles two patterns of speciation (origin of new species). How would you characterize these two patterns? Which one would increase species diversity? Why?

Fig. 24.1

SPECIES C

SPECIES A SPECIES B

SPECIES D

Fig. 24.2

2- There are four species in the previous slide. Why is it difficult to define the concept of species based on physical traits? How would you characterize the concept of species? What’s the justification for your answer?

3- The concept of biological species depends on reproductive isolation; that is, barriers that prevent interbreeding and hence genetic mixing. What do you think are those barriers? How would you classify them?

To ponder for Thursday Jan 20th

Natural hybridization is common and hybrids are not uniformly unfit, they are genotypic classes that are less, equally or more fit than their parental taxa.Some scientists think that hybridization could generate biological diversity. How?

Hybridization is common when populations invade new environments. Why?

Hybrid