BIOL-K 103 Lecture 4: Chap 20-SM16
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Department
BIOL-K - Biology
Course
BIOL-K - Biology BIOL-K 103
Professor
Dr.Yost
Semester
Spring

Description
Chapter 20: Speciation and Macroevolution Objectives 1. Define and describe the biological species concept of speciation and the associated problems (knowledge) 2. Compare and contrast and give examples of prezygotic and postzygotic isolating mechanisms and barriers for reproductive isolation (e.g. temporal, habitat, behavioral, mechanical, and gametic isolation; hybrid isolating mechanisms) (knowledge/comprehension) 3. Define, compare and contrast and give examples of allopatric and sympatric speciation (knowledge/comprehension) 4. Name, define, compare and contrast the three types of hybrid zones (knowledge/comprehension) 5. Name, define, compare and contrast the types of rate and pattern of speciation (knowledge/comprehension) 6. Define, describe and discuss macroevolution in the context of novel features, including preadaptations, allometric growth, and paedomorphosis (knowledge/comprehension) 7. Define, describe and discuss the macroevolutionary significance of adaptive radiation and extinction (knowledge/comprehension) Some key words Adaptive radiation evolution of several species from one or a few ancestral species; occurs in relatively short time frame Allometric growth growth of different body parts at different rates Allopatric speciation formation of two new species following the physical separation of individuals of a single population Gradualism evolution occurs as a result of slow steady changes over time Hybrid inviability egg and sperm of two different species are genetically incapable of producing a viable zygote and embryo Hybrid sterility gametes of interspecies hybrid are not normal and able to produce a zygote Hybrid breakdown the hybrid is unable to reproduce successfully; F1 and and F2 generations may be produced Hybrid zone an area of overlap between closely related species or subspecies in which interbreeding occurs Macroevolution large-scale changes over long time periods resulting in phenotypic changes that warrant placement of the organism into a new taxonomic group at or above the species level Microevolution small-scale changes that occur within a species as a result of changes in the allele or genotype frequencies Paedomorphosis retention of juvenile features in the adult body form Preadaptation a characteristic that functioned in one way originally but later changed in a way that was adaptive to the structure having a different role Prezygotic barrier something that prevents fertilization from occurring (prevents formation of a zygote); prevents hybrid formation Postzygotic barriersomething that occurs after fertilization (formation of a zygote) that prevents a hybrid from living long enough to form a new species Punctuated equilibrium evolution proceeds with period of little or no change and then rapid changes occur over a relatively brief period of time Sympatric speciation formation of two new species within the geographic region of the parent population; no physical barrier is present but reproductive isolating mechanisms are Chapter 20: Speciation and Macroevolution Side 25 Objective 1: Define and describe the biological species concept of speciation and the associated problems (knowledge) What is a species? I. What is a biological species? Reproductive isolation Fertile offspring are produced II. What are some problems? Includes only sexual reproduction Inbreeding Slide 26 Objective 2: Compare and contrast and give examples of prezygotic and postzygotic isolating mechanisms and barriers for reproductive isolation (e.g. temporal, habitat, behavioral, mechanical, and gametic isolation; hybrid isolating mechanisms) (knowledge/comprehension) I. Reproductive isolation in biological species A. What is the dividing point? A zygote formed by the fusion of egg and sperm B. What are the two barrier groupings? 1. Prezygotic reproductive barriers Prior to zygote formation 2. Post zygotic After zygote formation Slide 27 II. Prezygotic barriers A. Temporal (timing) isolation species reproduce at different times of day, season, or year preventing cross fertilization Slide 28 B. Habitat isolation Species are in same geographic area, but live and breed in different habits in that area. IE: Frogs that breed in temporary ponds in woods and living near frogs that breed in permanent pond along edge of woods Slide 29 C. Behavioral isolation Many animal species exchange a distant series of signals before mating(visual, chemical, oral) Slide 30 D. Mechanical isolation Structural differences in reproductive organs prevent mating. Slide 31 E. Gametic isolation Molecular and chemical differences between species gametes prevents formation of a zygote. Eggs and sperm incompatible F. What happens if prezygotic barriers fail? Hybrid is produced Slide 32 III. Postzygotic reproductive barriers(Skipped) A. When do postzygotic barriers occur? B. What do postzygotic barriers do? Slide 33 IV. Barriers to hybrid longevity A. Hybrid inviability Embryo of interspecific hybrid spontaneously aborts B. Hybrid sterility Interspecific hybrid lives cannot reproduce C. Hybrid breakdown Hybrid lives and F1 hybrid mate produces F2 hybrid generation and unable to continue generation because of some defect. Objective 3: Define, compare and contrast and give examples of allopatric and sympatric speciation (knowledge/c
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