* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Evolution PowerPoint
Survey
Document related concepts
Organisms at high altitude wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Sexual selection wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Evidence of common descent wikipedia , lookup
The Descent of Man, and Selection in Relation to Sex wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Natural selection wikipedia , lookup
Inclusive fitness wikipedia , lookup
Theistic evolution wikipedia , lookup
Population genetics wikipedia , lookup
Saltation (biology) wikipedia , lookup
Transcript
Evolution Evolution Chapters 16 & 17 Darwin’ss Voyage Darwin Voyage Chapter 16 Evolution • Change over time Change over time Charles Darwin Charles Darwin • Developed Developed a scientific theory that explains a scientific theory that explains how modern organisms evolved over long periods of time through descent from periods of time through descent from common ancestors. Darwin’ss Voyage Darwin Voyage • 1831: Darwin sailed around the world in the HMS Beagle making observations and collecting evidence. • Most of his work was done at the Galapagos Islands, located 100 km west of Islands, located 100 km west of South America. • 1859: Darwin publishes Origin of the Species. Darwin’ss Observations Darwin Observations 1.) Different, yet similar, animal species 1.) Different, yet similar, animal species inhabited separated, but similar, habitats around the globe. 2.) Different, yet related, animal species 2.) Different, yet related, animal species occupied different habitats within a local area. 3.) Some fossils of extinct animals were similar to living species. to living species. Ideas that Shaped Darwin Public Perception Public Perception • All All life was only a few thousand years life was only a few thousand years old. • Since Since its creation, not much had its creation, not much had changed. Scientists that Influenced Darwin Scientists that Influenced Darwin • ((1785) James Hutton: Using geological examples, 85) Ja es utto : Us g geo og ca e a p es, concluded that the earth must be much older than a few thousand years. • (1798) Thomas Malthus: Reasoned that if the human population grew unchecked, their wouldn’t be enough space and food for everyone. • (1830) Charles Lyell: Argued for uniformitarianism, which holds that the geological processes we see today which holds that the geological processes we see today must be the same ones that occurred long ago. Jean Baptiste Lamark • (1809) Published a theory on evolution that suggested organisms could change during suggested organisms could change during their lifetimes by selectively using or not using parts of their bodies. These acquired traits parts of their bodies. These acquired traits could then be passed onto their offspring. • What is wrong with this theory??? Natural Selection Natural Selection Words to Know Words to Know fitness: the ability to survive and reproduce fitness: the ability to survive and reproduce adaptation: an inherited characteristic that d i i h i d h i i h increases an organism’s chance of survival • Adaptations increase an organism’s fitness. p g Natural Selection Natural Selection • AKA: AKA: survival of the fittest survival of the fittest • Selected traits increase an organism’s fitness. • No human involvement. (Unlike selective h i l ( lik l i breeding.) For Natural Selection to Occur: For Natural Selection to Occur: 1 The 1. The population must be limited in size, which population must be limited in size which creates competition. (Competition: when two organisms want the (Competition: when two organisms want the same resource at the same time.) 2 Genetic variation (of inherited traits) must 2. G i i i ( fi h i d i ) exist. Sources of Variation 3. This variation must affect the organism’s reproductive success. Recipe for Evolution Descent with modification Descent with modification • Species descend from other species over time. Species descend from other species over time Ex: dogs descended from wolves. Common descent: all things, living and extinct have common ancestors common ancestors Evidence of Evolution Evidence of Evolution Evidence of Evolution Evidence of Evolution 1 Structural adaptations 1. Structural adaptations A. Mimicry: one species resembles another species B Camouflage: species blend in with surroundings B. Camouflage: species blend in with surroundings Evidence of Evolution Evidence of Evolution 2 Behavioral adaptations 2. Behavioral adaptations a. Migration b Courtship b. Courtship c. Defending or claiming territory d C d. Cooperation (Ex: hunting in packs) ti (E h ti i k) e. Kin selection: helping a relative survive because they share the same genes they share the same genes f. Communication (visual, chemical, sound, language) More evidence… More evidence… 3 Fossils 3. Fossils 4. Geographic Distribution of Species (similar, G hi i ib i f S i ( i il but unrelated species live in different parts of the world) h ld) And more evidence… And more evidence… 5. Homologous structures: basic arrangement of 5 Homologous structures: basic arrangement of bones in body structures of different species is similar is similar ex: bird wing and whale flipper Note: Not to be confused with analogous structures Note: Not to be confused with analogous structures (have the same function, but different s uc u es) structures) And more evidence… And more evidence… 6. Vestigial structures: body structures that 6 Vestigial structures: body structures that serve no purpose in the present day organism ex: an ostrich’s wings And more… And more… 7 Similarities in early development 7. Similarities in early development. 8 i h i 8. Biochemistry: comparing the DNA and RNA i h d All Living Things are All Living Things are Related Evolution Misconceptions Evolution of Populations Evolution of Populations Chapter 17 Populations, NOT individuals evolve! Populations, NOT individuals evolve! Gene pool: all of the alleles of a population’s genes Relative frequency = # certain allele x 100% total # alleles total # alleles Ex: attached earlobes ***Let’s calculate this for our class! Genetic equilibrium: when the relative frequency remains the same over several generations • If the relative frequencies in a gene pool change, EVOLUTION has probably occurred! Sexual vs. Asexual Reproduction Sexual vs. Asexual Reproduction • The The two main sources two main sources of genetic variation in sexually reproducing organisms is through mutations and genetic recombination. bi ti • The The main source of main source of genetic variation in asexually reproducing organisms is through mutations only. Natural Selection on Single Gene Traits Natural Selection on Single Gene Traits 12 14 10 12 10 8 Hands Up 8 Hands Up Hands Down 6 Hands Down 6 4 4 2 2 0 0 Before the Predator After the Predator Natural Selection on Polygenic Traits Natural Selection on Polygenic Traits • Because a polygenic trait is controlled by more than one gene, a wide spectrum of phenotypes are observed. p yp ***Let’s calculate this for our class using height. • Three types of natural selection: – Directional – Stabilizing – Disruptive A Average Height H i h 7 6 5 4 Average Height 3 2 1 0 150 160 150 160 165 165 170 170 180 180 cm cm cm cm cm Directional Selection Directional Selection • Natural Natural selection favors selection favors one of the extreme variations of the trait, so the entire graph moves. • Ex: height, beak lengths Stabilizing Selection Stabilizing Selection • Natural Natural selection that selection that favors the average individuals in a population. • Ex: birth weight Disruptive Selection Disruptive Selection • Individuals Individuals with either with either extreme variation are selected for. (The average drops.) • Ex: Light and dark colored limpets Speciation • Occurs when members of the same population can no longer interbreed to produce interbreed to produce fertile offspring. • Can occur from geographic, behavioral or reproductive isolation. Divergent vs. Convergent Evolution Divergent vs. Convergent Evolution Divergent evolution: Divergent evolution: C Convergent evolution: t l ti members of one species members of different become less and less species evolve similar species evolve similar alike, eventually traits because of their resulting in separate environment. species i The Effect of Small Populations The Effect of Small Populations Genetic drift: a change in allele frequencies due Genetic drift: a change in allele frequencies due to something other than natural selection Ex: Ashkenazi Jews the Amish the Holocaust Ex: Ashkenazi Jews, the Amish, the Holocaust Specific types of genetic drift are… Founder effect: a small group starts a new population elsewhere and their particular population elsewhere and their particular genes become prevalent Bottleneck effect: a natural disaster drastically reduces the population d th l ti