Evolution and Darwin

* Evolution Is defined as the processes that have transformed life on earth from it’s earliest forms to the vast diversity that characterizes it today. A change in the genes!!!!!!!!

SCI.9-12.B-5 - [Standard] - The student will demonstrate an understanding of biological evolution and the diversity of life.

*Old Theories of Evolution Jean Baptiste Lamarck (early 1800’s) proposed: “The inheritance of acquired characteristics” You would pass on to your children a skill you learned. If you played the piano, your children would be born playing the piano. “Use – Disuse” He proposed that by using or not using its body parts, an individual tends to develop certain characteristics, which it passes on to its offspring.

“The Inheritance of Acquired Characteristics” Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

*Lamarck’s Theory of Evolution Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them Blacksmiths & Their Sons (muscular arms) Giraffe’s Necks Longer from stretching) copyright cmassengale 6 6

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https://www.youtube.com/watch?v=GhHOjC4oxh8

Charles Darwin Influenced by Charles Lyell who published “Principles of Geology”. This publication led Darwin to realize that natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

*Charles Darwin Darwin set sail on the H.M.S. Beagle (1831-1836) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals. On the Galapagos Islands, Darwin observed species that lived no where else in the world. These observations led Darwin to write a book.

copyright cmassengale HMS Beagle’s Voyage copyright cmassengale 11 11

copyright cmassengale The Galapagos Islands Small Group of Islands 1000 km West of South America Very Different Climates Animals On Islands Unique Tortoises Iguanas Finches copyright cmassengale 12 12

copyright cmassengale The Galapagos Islands Volcanic islands off the coast of South America Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises copyright cmassengale 13 13

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copyright cmassengale The Galapagos Islands Finches on the islands resembled a mainland finch More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had different types of beaks adapted to their type of food gathering copyright cmassengale 17 17

copyright cmassengale 18 18

*Charles Darwin Wrote in 1859: “On the Origin of Species by Means of Natural Selection” Two main points: 1. Species were not created in their present form, but evolved from ancestral species. 2. Proposed a mechanism for evolution: NATURAL SELECTION

*Natural Selection Individuals with favorable traits are more likely to leave more offspring better suited for their environment. Example: English peppered moth (Biston betularia) - light and dark phases

*Darwin’s 5 points Population has variations. Some variations are favorable. More offspring are produced than survive Those that survive have favorable traits. A population will change over time.

SCI.9-12.B-5.1 - [Indicator] - Summarize the process of natural selection.

What is natural selection? https://www.youtube.com/watch?v=0SCjhI86grU

*Artificial Selection The selective breeding of domesticated plants and animals by man. Question: What’s the ancestor of the domesticated dog? Answer: WOLF

*Evidence of Evolution 1. Biogeography: Geographical distribution of species. EX. Most marsupials live in Australia. 2. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock tells us the order that they appeared on earth (strongest evidence).

Eastern Long Necked Turtle

*Evidence of Evolution 3. Taxonomy: Classification of life forms. 4. Anatomy: Structures that are similar because of common ancestry (comparative anatomy) Vestigial structures (remnant or leftover) structures that now have no function (human appendix)

Homologous Structures

SCI.9-12.B-5.5 - [Indicator] - Exemplify scientific evidence in the fields of anatomy, embryology, biochemistry, and paleontology that underlies the theory of biological evolution.

What is the evidence for evolution? https://www.youtube.com/watch?v=lIEoO5KdPvg

*Evidence of Evolution 5. Comparative embryology: During the early development of organisms very similar structures appear in different organisms. Ex. At one point, humans have gill slits and webbed fingers. 6. Molecular biology: DNA and proteins (amino acids) cow insulin was once used to treat humans with diabetics

Similarities In Embryonic Development Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development

copyright cmassengale Human Fetus – 5 weeks copyright cmassengale

copyright cmassengale Chicken Turtle Rat copyright cmassengale

Similarities in DNA Sequence

* Population A localized group of individuals belonging to the same species. Species A group of populations whose individuals have the potential to interbreed and produce viable, fertile offspring.

Evolution of pesticide resistance in response to selection copyright cmassengale

copyright cmassengale Evolution of drug-resistance in HIV Evidence for Evolution – Evolution Observed copyright cmassengale

*Gene Pool The total collection of genes in a population at any one time.

*Microevolution A change in a population’s gene pool over a secession of generations. Evolutionary changes in species over relatively brief periods of geological time.

*Five Causes of Microevolution 1. Genetic drift: Change in the gene pool of a small population due to chance. Two examples: a. Bottleneck effect b. Founder effect

*a. Bottleneck Effect Genetic drift (reduction of alleles in a population) resulting from a disaster that drastically reduces population size. Examples: 1. Earthquakes 2. Volcanoes

*b. Founder Effect Genetic drift resulting from the colonization of a new location by a small number of individuals. Results in random change of the gene pool. Example: 1. Islands (first Darwin finch)

Genetic Drift Animation http://highered.mheducation.com/sites/9834092339/student_view0/chapter22/simulation_of_genetic_drift.html

SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life. SCI.9-12.B-5.4 - [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

*Five Mechanisms of Microevolution 2. Gene Flow: The gain or loss of alleles from a population by the movement of individuals or gametes. Immigration or emigration.

*Five Causes of Microevolution 3. Mutation: Change in an organism’s DNA that creates a new allele. 4. Non-random mating: The selection of mates other than by chance. 5. Natural selection: Survival of the fittest

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter20/animation_-_mechanisms_of_evolution.html

SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life. SCI.9-12.B-5.4 - [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

Modes of Action Natural selection has three modes of action: 1. Stabilizing selection 2. Directional selection 3. Diversifying selection Number of Individuals Size of individuals Small Large

1. Stabilizing Selection Acts upon extremes and favors the intermediate. Number of Individuals Size of individuals Small Large

Continuing our oyster example, very light-colored or very dark-colored oysters might be more frequently preyed upon by shore birds, simply because they are more obvious on the oyster bar; as a result, the intermediate hues become more common.

2. Directional Selection Favors variants of one extreme. Number of Individuals Size of individuals Small Large

If thicker-shelled oysters are more resistant to breakage than thinner-shelled oysters, crabs will be less able to prey upon them, and thicker-shelled oysters will be more likely to survive to reproduce

3. Diversifying or Disruptive Selection Favors variants of opposite extremes. Number of Individuals Size of individuals Small Large

This might happen in shallow water among rocks This might happen in shallow water among rocks. Light-colored oysters are more camouflaged. (less easy for a predator to see) because they match the rock color. Dark-colored oysters blend into the shadows cast by the rocks. In this case, intermediate-colored oysters would be most heavily preyed upon by the crabs, and very light and very dark oysters would survive to reproduce.

Selection against small guppies results in an increase in average size Evidence for Evolution – Evolution Observed Selection against small guppies results in an increase in average size

SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life. SCI.9-12.B-5.4 - [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

*Speciation The evolution of new species. There is a new species when an organism cannot breed back to the parent species and produce fertile offspring.

*Reproductive Barriers Any mechanism that stops two species from producing fertile and/or viable hybrid offspring. Two barriers: 1. Pre-zygotic barriers 2. Post-zygotic barriers

*1. Pre-zygotic Barriers a. Temporal or seasonal isolation: Breeding occurs at different times for different species. One species of a fish reproduces in the spring while another reproduces in late summer.

b. Habitat isolation: Species breed in different habitats. c. Behavioral isolation: Little or no sexual attraction between species. Birds and courtship

*1. Pre-zygotic Barriers d. Mechanical isolation: Structural differences prevent gamete exchange. e. Gametic isolation: Gametes die before uniting with gametes of other species, or gametes fail to unite. Chromosome numbers don’t match up.

SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life. SCI.9-12.B-5.4 - [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

*2. Post-zygotic Barriers a. Hybrid inviability: Hybrid zygotes fail to develop or fail to reach sexual maturity. b. Hybrid sterility: Hybrid fails to produce functional gametes. Example: mule c. Hybrid breakdown: Offspring of hybrids are weak or infertile.

Crash Course Video on Speciation https://www.youtube.com/watch?v=2oKlKmrbLoU

*Interpretations of Speciation Two theories: 1. Gradualist Model (Neo-Darwinian): Slow changes in species overtime. 2. Punctuated Equilibrium: Evolution occurs in spurts of relatively rapid change.

Figure 24.13 Gradualism model. Species descended from a common ancestor gradually diverge more and more in their morphology as they acquire unique adaptations. Time (a) Punctuated equilibrium model. A new species changes most as it buds from a parent species and then changes little for the rest of its existence. (b)

*Convergent Evolution Species from different evolutionary branches may come to resemble one another if they live in very similar environments. Example: 1. Ostrich (Africa) and Emu (Australia). 2. Sidewinder (Mojave Desert) and Horned Viper (Middle East Desert)

*Divergent Evolution When a group of organisms starts living together but become separated into different habitats. They can evolve into different species

Darwin's finches are a clear and famous example of divergent evolution, in which an ancestral species radiates into a number of descendant species with both similar and different traits.

SCI.9-12.B-5 The student will demonstrate an understanding of biological evolution and the diversity of life. SCI.9-12.B-5.4 - [Indicator] - Explain how genetic variability and environmental factors lead to biological evolution.

*Coevolution Evolutionary change where two or more species change to depend on each other Example: 1. Acacia ants and acacia trees 2. Humming birds and plants with flowers with long tubes