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Bellringer -March 12, 2014

Bellringer -March 12, 2014. Imagine a population of 200 birds, some red and some yellow. The red allele, R, is dominant over the yellow allele, r . There are 72 RR birds, 96 Rr birds, and 32 rr birds in the population. What are the genotypic frequencies in the population ?

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Bellringer -March 12, 2014

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  1. Bellringer-March 12, 2014 • Imagine a population of 200 birds, some red and some yellow. The red allele, R, is dominant over the yellow allele, r. There are 72 RR birds, 96 Rr birds, and 32 rr birds in the population. • What are the genotypic frequencies in the population? • What are the allelic frequencies in the population? • Using the frequencies you calculated in b, what would Hardy-Weinberg predict the genotypic frequencies should be? What about allelic frequencies? Is this population in Hardy Weinberg equilibrium?

  2. ANSWER KEY • RR = 72/200 = 0.36; Rr=96/200 = 0.48 ; rr= 32/200 = 0.16 • R=72 + 72 + 96 = 240/400 = 0.6; • r = 32 + 32 + 96 = 160/400 = 0.4 • P=R= Red q= r= yellow • 32/200= 0.16 = yellow = rr= q2 • √0.16=√q2 • q = 0.4 then p = 0.6 • RR = p2 = (0.6)2 = 0.36 = 36.00% • Rr = 2pq = 2(0.6)(0.4) = 0.48= 48.00% • rr = q2 = (0.4)2 = 0.16 =16.00%

  3. Evolution and Speciation (Macroevolution part 1) Ms. Kim H. Biology

  4. What is microevolution? • Evolution on a small scale • Change in allele frequencies from one generation to the next • A process that leads to a change in a species • Natural selection • Genetic Drift • Gene Flow • Mutation • Sexual Selection • Microevolution explains how populations evolve

  5. What is Macroevolution? • Origin of different species • SPECIATION • Extinction of species • Evolution of major features

  6. Types of Adaptations • Protective Coloring • Camouflage and Mimicry • Physiological Adaptations • Reproductive/Hormonal Changes • Color changes • Behavioral Adaptations • Courtship dances/ songs • “Fighting” tactics • Also arise in response to environmental pressures • Temperature, Antibiotic/pesticide resistance

  7. Mechanism for change in a population of organisms • Animals who have greater fitness survive in environment and live to reproduce • Random changes in DNA (mutations) can lead to greater or less fitness • Produced by Sexual Reproduction • Allow for DIVERSITY in a Population • Adaptations allow an organism to survive better in their environment

  8. RECALL: 3 Types of Natural Selection • Directional • Extreme form favored by natural selection • Stabilizing • Middle form most successful • Disruptive • Two extreme forms successful in separate environments

  9. Types of Evolution • Analogous Structures 1. Convergent evolution • organisms that are NOT closely related independently evolve similar traits as a result of having to adapt to similar environments. • 2 species acquiring same characteristics from 2 different ancestral species Ex: Dolphins & fishes Ex: Wings of bees & bats

  10. 2. Divergent evolution • 2 species gradually become different • Often occurs when closely related species diversify to new habitats • Formation of 2 descendent species from an ancestral species Ex: Darwin’s finches Type: Adaptive radiation • Homologous structures

  11. Adaptive RadiationExample of divergent evolution • Appearance of numerous species over a short period of time • Adapted species from a common ancestor when they are introduced to new environmental opportunities • Typically occurs when a few organisms make their way to new, usually distant areas OR mass extinctions occur, which open up new niches

  12. Hawaiian archipelago  Example of adaptive radiation N Dubautia laxa 1.3 million years KAUAI 5.1 million years MOLOKAI MAUI OAHU 3.7 million years Argyroxiphium sandwicense LANAI HAWAII 0.4 million years Dubautia waialealae Dubautia scabra Dubautia linearis

  13. What type of evolution? • Divergent • Convergent • Coevolution

  14. What type of evolution? A. Divergent B. Convergent C. Coevolution

  15. 3. Coevolution • 2 organisms evolve (change) in response to each other • Insects and the flowers (ex: orchids) they pollinate

  16. 4. Parallel Evolution • 2 species evolve independently of each other, maintaining similar traits • Usually occurs between unrelated species (but similar ancestors) that do NOT occupy the same or similar habitats • Ex: Eutherians (placental) and Marsupial mammals

  17. What type of evolution? A. Divergent B. Convergent C. Parallel Evolution

  18. What is Speciation? • Origin of new species How would we identify if a species is “new”?

  19. Two Basic Patterns of Evolutionary Change • Anagenesis (phyletic evolution) • transforms one species into another • Cladogenesis (branching evolution) • the splitting of a gene pool, giving rise to one or more new species

  20. LE 24-2 Anagenesis Cladogenesis

  21. How fast does evolution occur? • Gradualism • Species change slowly (gradually) over time • Punctuated Equilibrium • Species can make rapid “leaps” in evolution

  22. Time Gradualism model Punctuated equilibrium model

  23. What is a Species? • Species is a Latin word meaning “kind” or “appearance” • A population of organisms that produces viable fertile offspring in nature. • They can NOT interbreed with other populations

  24. Example 1 • CASE 1 • A mule is the offspring of a female horse and a male donkey. In contrast, the hinney is the offspring of a male horse and female donkey. The mule is easier to breed and larger in size than the hinney. For these reasons, the mule became an important domesticated animal. Horses have 64 chromosomes, donkeys have 62. The mule has 63 and cannot evenly divide, that is why the animal is sterile.

  25. Example 2 • CASE 2 • A liger is a cross between a female tiger and a male lion. In contrast, the tigon is a cross between a male tiger and a female lion. These two species do not breed in nature because their habitats are so different. Lions live in open grasslands while tigers live in forests. In captivity, it is possible to produce ligers and tigons. Male ligors are sterile, but female ligers are fertile and may reproduce with either tigers or lions.

  26. Example 3 • CASE 3 • E.coli is a bacterium normally found in the intestines. It is harmless and may actually be beneficial to the human digestive system. There is a pathogenic strain of E.coli that produces a toxin that can kill its human host. The two strains look very similar under a microscope. Comparison of their genomes reveals that the pathogenic strain lacks 528 genes found in the normal strain and has 1,387 genes not found in the normal strain.

  27. What are other species concepts? • 5 Types: • Morphological • Group of individuals sharing similar characteristics • Recognition • Behavior/chemical recognition between individuals • Genetic • Range of variation in DNA- similar in individuals • Cladistic • Species defined as a branch in a cladogram • Biological • Group of individuals capable of interbreeding

  28. Similarity between different species  different behaviors and songs Diversity within a species  defined by capacity to interbreed.

  29. Speciation • Speciation = the origin of new species • Must explain how new species originate and how populations evolve • Microevolution (genotype evolution) • adaptations that evolve within a population’s gene pool • Macroevolution(phenotype evolution) • refers to evolutionary change at the population level • Major biological changes evident in the fossil record

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