Chap 24 Outline - Chapter 24 - The Origin of Species...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 24 - The Origin of Species Objectives 1. Define biological species 2. Explain how gene flow between closely related species can be prevented. 3. Distinguish between prezygotic and postzygotic isolating mechanisms. 4. Describe five prezygotic isolating mechanisms and give an example of each. 5. Explain why many hybrids are sterile. 6. Distinguish between allopatric and sympatric speciation. 7. Define adaptive radiation and describe the circumstances under which adaptive radiation may occur. 8. Describe examples of adaptive radiation in the Galápagos and Hawaiian archipelagoes. 9. Explain how reproductive barriers evolve. Describe an example of the evolution of a prezygotic barrier and the evolution of a postzygotic barrier. 10. Define sympatric speciation and explain how polyploidy can cause reproductive isolation. 11. Distinguish between an autopolyploid and an allopolyploid species and describe examples of each. 12. Distinguish between gradualism and punctuated equilibrium. Outline A. What Is a Species? 1. A species is a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but are unable to produce viable fertile offspring with members of other populations. 2. Prezygotic and postzygotic barriers isolate the gene pools of biological species 3. The species is the largest unit of population in which gene flow is possible. i.e. a population is the smallest unit in the hierarchy that can evolve. 4. Geographical isolation can lead to the origin of species (allopatric speciation) 5. A new species can originate in the geographical midst of the parent species (sympatric speciation) – this can be due to genetic change (mutations) in populations. 6. The rate of speciation is a debatable topic. B. The Origin of Evolutionary Novelty 1. Most evolutionary novelties are modified versions of older structures 2. Genes that control development play a major role in evolutionary novelty 3. An evolutionary trend does not mean that evolution is goal oriented Species were described in terms of their phenotype, now genetic makeup is used. Species of the same
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/14/2011 for the course BIOL 2301 taught by Professor Staff during the Spring '11 term at Lone Star College System.

Page1 / 4

Chap 24 Outline - Chapter 24 - The Origin of Species...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online