Biology, 6th Edition

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Greg Steinberg AP Biology Chapter 24 The Origin of Species A. What is a Species? a. Reproductive Isolation i. The Biological Species Concept is a population that’s members are able to interbreed. ii. It is the largest set of populations which a genetic exchange is possible. b. Prezygotic Barriers i. Prevent the fertilization or mating of two organisms. c. Habitat Isolation i. Maybe live in the same area but are unlikely to encounter each other and mate. d. Behavioral Isolation i. Behavior among animals that attract them to mates that is unique to that species. e. Temporal Isolation i. Breeding times are offset, when one species is ready, the other is not. ii. Can be daily to seasonal. f. Mechanical Isolation i. Anatomically incompatible species may not be able to mate. It’s kind of sad, like Romeo and Juliet. g. Gametic Isolation i. The gametes may not be able to form a zygote, or the females reproductive system may be too harsh for the male sperm. ii. Gamete recognition can be based on surface proteins of the sperm that serve the female’s system to recognize them. h. Reduced Hybrid Viability i. Genetic Incompatibility may abort the offspring at an embryonic stage. i. Reduced Hybrid Fertility i. If as offspring is formed, it may be sterile, or if it is, it may not have another species to breed with anyway. j. Hybrid Breakdown i. The F2 generation may be sterile or dead. k. Limitations i. There is no way to determine the interbreeding characteristics of extinct species. l. Alternate Concepts of Species
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i. Ecological Species Concept defines a species in it’s adaptations for what it needs for survival. ii.
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bio24 - Greg Steinberg AP Biology Chapter 24 The Origin of...

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