1. Chapter 22 The Origin of Species
AP Biology

2. 22.1 The Nature of Species
Sympatric – species occurring in the same area but are phenotypically different Example – birds at a bird feeder Different species will utilize different parts of a habitat

3. 22.2 The Biological Species Concept
Group of organisms that are reproductively isolated from each other – different species cannot mate with other species and produce viable offspring – reproductively isolated

4. 1. Geographic Isolation – species occur in different areas separated by a barrier – river, mountain range 2. Ecological Isolation – species are in the same area, but do not live in the same habitat and do not interact with each other 3. Behavioral Isolation – species differ in mating rituals 4. Temporal Isolation – reproduction of species occurs at different times

5. 5. Mechanical Isolation – structural differences between species prevent mating 6. Prevention of Gamete Fusion – fertilization is “blocked” 7. Hybrid Inviability or Infertility – embryos do not develop properly or adults are infertile

6. 22.3 The Evolution of Reproductive Isolation
Cladogenesis – one species evolving into two Over time groups need to become reproductively isolated

7. 22.4 The Role of Genetic Drift and Natural Selection in Speciation
Genetic Drift – Conditions favor one phenotype (and therefore genotype) within a population because it may be better suited Adaptation leads to speciation

8. 22.5 The Geography of Speciation
Allopatric populations (separated geographically) will evolve differently because they do not interbreed Sympatric Speciation – occurs due to Polyploidy Individuals with more than two sets of chromosomes – common in plants

9. 2 types of polyploidy 1. Autopolyploidy – all chromosomes come from a single species 2. Allopolyploidy – due to hybridization – more common In either case most offspring are infertile b/c of meiosis but can reproduce asexually

10. 22.6 Species Clusters: Evidence of Rapid Evolution
Adaptive Radiation – closely related species found in different parts of an environment --Galapagos Islands Key Innovation – new trait that appears and allows a species to use part of the environment that it was not able to use before

11. Groups Hawaiian Drosophila Darwin’s Finches Lake Victoria Cichlid Fish
New Zealand Alpine Buttercups