CHAP 29 THEORY OF EVOLUTION CHARLES DARWIN EVIDENCE

CHAP 29 – THEORY OF EVOLUTION • • • CHARLES DARWIN EVIDENCE FOR EVOLUTION MECHANISMS FOR EVOLUTION NATURAL SELECTION SPECIATION Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. http: //evolution. berkeley. edu/evolibrary/home. php

CHARLES DARWIN – 1809 -1882 • ENGLISH • TRAVELED AROUND THE WORLD ON THE BEAGLE – FAMOUS IN THE GALAPAGOS ISLANDS • OBSERVED MANY SPECIES AND FOSSILS • WHY DID SOME SPECIES SURVIVE WHILE OTHERS BECAME EXTINCT? • NATURAL SELECTION Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http: //evolution. berkeley. edu/evolibrary/home. php www. darwinday. org/english. L/life/beagle. html www. darwinday. org/english. L/life/beagle. ht Used by permission of Darwin Day Celebration (at Darwin. Day. org), 2006 I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection. —Charles Darwin from "The Origin of Species" http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

CHAP 29 – THEORY OF EVOLUTION • • • CHARLES DARWIN EVIDENCE FOR EVOLUTION MECHANISMS FOR EVOLUTION NATURAL SELECTION SPECIATION http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Fossil Evidence • The fossil record provides evidence of organisms that existed at different periods of time. • Geologic Time Table outlines the history of life through layers of rock which contain fossils

• Fossils often allow scientists to reconstruct the organism • What is this skeleton?

How about this one?

Evidence • There are certain modern species that resemble, but are not identical to creatures that no longer exist.

Saber tooth Tiger

Modern Day Tiger

Wooley Mammoth

Modern Day African Elephant

EVIDENCE OF EVOLUTION • STRUCTURAL ADAPTATIONS – MIMICRY – CAMOUFLAGE http: //evolution. berkeley. edu/evolibrary/home. php http: //science. howstuffworks. com/animal-camouflage 2. htm Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

EVIDENCE OF EVOLUTION • STRUCTURAL ADAPTATIONS – MIMICRY – CAMOUFLAGE – MILLIONS OF YEARS • PHYSIOLOGICAL ADAPTATIONS – CHANGE IN A METABOLIC PROCESS – WHAT DO YOU HEAR ABOUT IN THE NEWS ABOUT SOME BACTERIA? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http: //evolution. berkeley. edu/evolibrary/home. php WHAT OTHER INDUSTRIES WOULD BE WORRIED ABOUT RESISTANCE? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY – HOMOLOGOUS STRUCTURES http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Homologous structures

OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY – HOMOLOGOUS STRUCTURES – ANALOGOUS STRUCTURES http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY – HOMOLOGOUS STRUCTURES – ANALOGOUS STRUCTURES – VESTIGIAL STRUCTURE – EMBRYOS http: //evolution. berkeley. edu/evolibrary/home. php WHAT IS ANOTHER EXAMPLE OF VESTIGIAL STRUCTURES? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Vestigial Structures

Vestigial Structures

OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY – HOMOLOGOUS STRUCTURES – ANALOGOUS STRUCTURES – VESTIGIAL STRUCTURE – EMBRYOS Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Embryological Similarities

Embryology

OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY – HOMOLOGOUS STRUCTURES – ANALOGOUS STRUCTURES – VESTIGIAL STRUCTURE – EMBRYOS • BIOCHEMISTRY – WHAT 2 THINGS? http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Biochemical similarities • DNA similarities and differences • Organic compounds

CHAP 29 – THEORY OF EVOLUTION • • • CHARLES DARWIN EVIDENCE FOR EVOLUTION MECHANISMS FOR EVOLUTION NATURAL SELECTION SPECIATION http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

MECHANISMS FOR EVOLUTION • DO POPULATIONS OR INDIVIDUALS EVOLVE? • WHAT IS A GENE POOL The total of all the alleles present in a population • HOW CAN THE GENE POOL CHANGE? – MUTATION (can take a long time for ‘s to effect population) – GENETIC DRIFT ( in gene pool of small pop b/c of chance; if those few with diff. genes are lost = genetic pool) – GENE FLOW/MIGRATION (movement in & out of population) • WOULD THESE THINGS EFFECT A LARGE POPULATION OR A SMALL POPULATION MORE? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

ALL IMAGES: http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

CHAP 29 – THEORY OF EVOLUTION • • • CHARLES DARWIN EVIDENCE FOR EVOLUTION MECHANISMS FOR EVOLUTION NATURAL SELECTION SPECIATION http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

WHAT IS NATURAL SELECTION? (p. 612) • Directional-the extreme phenotype becomes the favorable adaptation (long neck giraffes) – alleles for extreme frequency present @ greater freq – Favors only one extreme type • Stabilizing Selection-the average phenotype may be a favorable adaptation and extreme phenotypes are unfavorable (avg. sized mice) – allele frequencies kept relatively constant – Natural selection favors intermediate type • Disruptive/Diversifying Selection-two opposite phenotypes are favorable adaptations, while the average phenotypes are unfavorable (crabs coloration) – Favors both sides of the extremes – [2 subpopulations; if can’t mate become 2 species] http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

CHAP 29 – THEORY OF EVOLUTION • • • CHARLES DARWIN EVIDENCE FOR EVOLUTION MECHANISMS FOR EVOLUTION NATURAL SELECTION SPECIATION http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

WHAT IS SPECIATION? • GEOGRAPHIC ISOLATION • REPRODUCTIVE ISOLATION http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

WHAT IS SPECIATION? • • • GEOGRAPHIC ISOLATION REPRODUCTIVE ISOLATION GRADUALISM – New species arise through gradual changes in their characteristics, and thus evolution occurs very slowly over millions of years (example: whale evolution) • PUNCTUATED EQUILIBRIUM – A species remains the same for a long time and then evolves rapidly during a short time interval Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

WHAT IS SPECIATION? • • • GEOGRAPHIC ISOLATION REPRODUCTIVE ISOLATION GRADUALISM PUNCTUATED EQUILIBRIUM DIVERGENT EVOLUTION – ADAPTIVE RADIATION A species evolves into a number of different species, each occupying a different environment Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTION http: //www. vanderbilt. edu/An. S/english/Clayton/Galapago_finches. gif http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

CONVERGENT EVOLUTION – WHAT IS AN EXAMPLE? http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Hardy-Weinberg Law - Describes a hypothetical population that is not evolving (Hardy-Weinberg equilibrium) - Maintained if… 1. Large population size 2. Individuals must not migrate into or out of the population. 3. Mutations must not occur 4. Reproduction must be completely random 5. No natural selection NOTE: A failure of the Hardy-Weinberg Law is a sign that evolution is occurring.

Why study H-W? • In real populations, the allele and genotype frequencies DO change over time. • One way to assess whether natural selection or other factors are causing evolution is to determine what the genetic makeup of a pop. would be if it were NOT evolving • We can then compare this with what we actually observe within a pop. to determine if a pop. is evolving

Why study H-W? - Microevolution changes in gene freq. within a single population How? - New genetic variation (mutations) Natural selection Random genetic drift Migration Nonrandom mating *essentially, the opposite of H-W equilibrium!

Hardy-Weinberg Law • Sexual reproduction alone does not affect genetic equilibrium – Genetic Equilibrium: • Condition where allele frequencies do not change from one generation to the next. • Allele frequency • “R” or “r” in a gene pool • Genotype frequency • Homozygous: RR & rr • Heterozygous: Rr

Hardy-Weinberg Law – Allele & Genotype Frequencies – Related, but distinct calculations Allele freq. = # of copies of a specific allele in a pop. total # of alleles for that gene in a pop. Genotype freq. = # of indiv. w/a particular genotype in a pop. total # of individuals in a pop.

Mathematics/notation of H-W - For a gene w/2 alleles (R, r) *freq. of R = p *freq. of r = q p 2 = freq. of RR genotype q 2 = freq. of rr genotype 2 pq = freq. of Rr genotype H-W equations: - For allele freq. : p + q = 1 - For genotype freq. p 2 + 2 pq + q 2 = 1

Hardy-Weinberg Law Example 49 Red flowered RR 42 pink flowered Rr 9 white flowered rr 2. Genotype freq. of rr ____9____ 49 + 42 + 9 = 9/100 = 0. 09 1. Allele freq. of r = ___(Rr) + 2(rr)___ 2(RR) + 2(Rr) +2(rr) = ___(42) + 2(9)___ 2(49) + 2(42) +2(9) = 0. 3 freq. of r 1. 0 – 0. 3 = 0. 7 freq. of R

Is the population evolving?