Evolution Darwin ( ) English naturalist, wrote “On the Origin of Species by Means of Natural Selection” English naturalist, wrote “On the Origin of Species by Means of Natural Selection” explain why evolution and how, natural selection explain why evolution and how, natural selection

The voyage

Previous 1. Malthus (1798), Essay on the Principle of Population human populations increases geometrically but the food resources grows arithmetically human populations increases geometrically but the food resources grows arithmetically

2. Lamarck: evolution occurred by the inheritance of acquired characteristics, body and behavior evolution occurred by the inheritance of acquired characteristics, body and behavior giraffes evolved long necks because ancestral giraffes tended to stretch their necks and this neck extension was passed on to subsequent generations giraffes evolved long necks because ancestral giraffes tended to stretch their necks and this neck extension was passed on to subsequent generations

Darwin Darwin variation is not created by experience but already exists when selection acts on it variation is not created by experience but already exists when selection acts on it populations of ancestral giraffes contained variation in neck length individuals who were able to feed higher up on the trees had more food and so were able to survive and reproduce better than their shorter-necked relatives populations of ancestral giraffes contained variation in neck length individuals who were able to feed higher up on the trees had more food and so were able to survive and reproduce better than their shorter-necked relatives

Darwin’s evidence to explain how species evolve rather than remain fixed Darwin’s evidence to explain how species evolve rather than remain fixed 1. fossils resemble living organisms 2. Organisms change gradually when move into new habitats, islands have diverse animals and plants related to the mainland sources Comparative Embryology Molecular Biology

230 M 150 M 65 M (Extinction) Fossils

Modifications seen in newer species Older species replaced Elephant Evolution

Four Galápagos finches and what they eat: 1. all the finches shared a common ancestor 2. their beak sizes had evolved to suit their food 3. genetic differences account for the physical differences in the beaks Proof of Evolution - Biogeography

Proof of Evolution – Comparative Embryology Comparing structures during embryo development Ex: vertebrates and gills

Proof of Evolution – Molecular Biology All cells have same/similar molecules Suggest organisms share similar ancestor

1. adaptive radiation: species changes to occupy different habitats: adapt Concepts

2. Macroevolution: grand scale evolutionary changes that result in the creation of new species 3. Microevolution: evolutionary change within a species (population) that make that species different from its immediate ancestor

4. Homologous structures: derive from the same body part present in an ancestor derive from the same body part present in an ancestor same bones used for different functions in related species same bones used for different functions in related species 5. Analagous structures similar-looking structures in unrelated lineages similar-looking structures in unrelated lineages parallel evolution or convergent evolution parallel evolution or convergent evolution

Forelimbs of Animals – Homologous Structures Same bones and similar structures Different functions

Examples of Analogous Structures Organisms not related! Insect Bird

Agents of Evolution 1. Mutation: change in DNA sequence 2. Migration: movement of individuals between populations, effects based on two factors: proportion of migrants in the populationproportion of migrants in the population difference in allele between migrants-original populationdifference in allele between migrants-original population 3. genetic drift: genetic changes in populations isolated from one another 4. Selection: some individuals leave behind more progeny than others artificial selection, a breeder selects for the desired characteristicsartificial selection, a breeder selects for the desired characteristics natural selection, conditions in nature determine natural selection, conditions in nature determine

Natural selection “survival of the fittest” Natural selection “survival of the fittest” frequency of favorable characteristics increasing in a population frequency of favorable characteristics increasing in a population favorable characteristics are specific to an environment (not the biggest or the strongest) favorable characteristics are specific to an environment (not the biggest or the strongest) organisms whose characteristics are best suited to their particular environment survive more often and leave more offspring organisms whose characteristics are best suited to their particular environment survive more often and leave more offspring

artificial selection artificial selection Evolution of domesticated animals through selective breeding Evolution of domesticated animals through selective breeding the resulting differences between breeds of domesticated species are more extreme than what exists in nature the resulting differences between breeds of domesticated species are more extreme than what exists in nature

2 Who Are We? Humans are apes Humans are apes Family: Hominidae Family: Hominidae Opposable thumbsOpposable thumbs 1% DNA difference to chimps1% DNA difference to chimps

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 3 Hominid Evolution First hominids appeared 5–7 mya First hominids appeared 5–7 mya Characteristics of hominids Characteristics of hominids Large brainsLarge brains BipedalBipedal ToolmakingToolmaking walked uprightwalked upright

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 6 Oldest Homo fossils are from 2.4 mya Oldest Homo fossils are from 2.4 mya

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© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 9 H. sapiens showed primitive technology H. sapiens showed primitive technology Toolmaking Toolmaking Building shelters Building shelters Control of fire Control of fire

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13 H. sapiens gave rise to Neandertals and modern humans H. sapiens gave rise to Neandertals and modern humans

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 11 Origin and Spread of Humans Out-of-Africa hypothesis Out-of-Africa hypothesis Multi- regional hypothesis Multi- regional hypothesis

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 14 Evolutionary Future of Humans Brain size Brain size Agriculture Agriculture Genetic drift Genetic drift Natural selection Natural selection Infectious disease Infectious disease Anything else? Anything else?

Lecture Practice questions 1. Changes in organisms over a long period of time, including the rise of novel organisms and extinction, is known as A) natural selection.B) microevolution. c) macroevolution.D) punctuated equilibrium. 2. One of the major sources of evidence for evolution is in the comparative anatomy of organisms. Features that have a similar look but different origin are called: A) homologous B) analogous c) vestigial structures.D) equivalent 3. Chance events that cause a population to lose some individuals (die), and hence a loss of alleles to the population, results in: A) mutation.B) migration.C) selection.D) genetic drift.