Chapter 24

Chapter 24 - Chapter 24 I. II. Concept 24.1 The biological...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 24 I. Concept 24.1 The biological species concept emphasizes reproductive isolation a. Species: Latin for “kind” or “appearance” II. The biological species concept a. Defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring b. Cannot be applied to i. Asexual organisms ii. Fossils iii. Organisms about which little is known regarding their reproduction III. Speciation a. Dependent on i. Reproductive isolation ii. Genetic divergence 1. Once we have enough, over time this can lead to genomes becoming incompatible – they can no longer interbreed IV.Reproductive isolation a. The existence of biological factors that impede members of two species from interbreeding b. Pre-zygotic barriers i. Mating, fertilization c. Post-zygotic barriers i. Mating, fertilization has occurred, but the offspring that results isn’t viable or fertile V. Pre-zygotic barriers a. Impede mating between species or hinder the fertilization of ova if members of different species attempt to mate – figure 24.4 VI.Post-zygotic Barriers
Background image of page 1

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

View Full DocumentRight Arrow Icon
a. Do mate and fertilization does occur, but after it doesn’t normally produce a viable offspring b. Often prevents the hybrid zygote from developing into a viable, fertile adult c. Often much weaker and don’t develop into adult stage where they can mate themselves; die young d. i. Breed and create mules ii. Very strong and long-lived but is incapable of reproduction; this happens because chromosomal differences between the two, during the mitosis the mule is incapable of producing viable cells from the sperm e. Very closely related species or even different breeds within the same species that will produce offspring that are viable and fertile but those hybrids often become weaker in subsequent generations i. Strains of rice VII. Two species of pine are found in the same habitat, but release pollen at different times during the year. This is an example of __ isolation. a. Geographical b. Ecological c. Temporal d. Behavioral VIII. Concept 24.2: Speciation can take place with or without geographic separation a. Speciation can occur in 2 ways: i. Allopatric speciation 1. The original population becomes separated by some kind of geographical barrier ii. Sympatric speciation 1. Population in the same area with 2 subpopulations that become isolated in some way and speciation occurs even though their found in the same area
Background image of page 2
2. Figure 24.5 IX.Allopatric Speciation a. “Other country” b. Gene flow is interrupted or reduced when a population is divide into two or more geographically isolated subpopulations c. Figure in moodle!** i. Original population 1. Single species homogeneous habitat ii. Geographical isolation 1. Geographic barrier isolated population iii. Genetic divergence 1. Genetic drift, mutation natural selection cause genetic divergence iv. Reproductive isolation 1. Barrier removed, populations mix but don’t interbreed
Background image of page 3

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

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/26/2009 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

Page1 / 10

Chapter 24 - Chapter 24 I. II. Concept 24.1 The biological...

This preview shows document pages 1 - 4. Sign up to view the full document.

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