Evolution TIME

13-1 Evolution and Life’s Diversity Evolution is a theory, like many other scientific theories Scientists have accumulated significant evidence that modern organisms were produced by change over time.

Evolution: the process by which a species changes over time resulting from environmental pressure.

Who was Darwin? Lived Well educated in biology and natural history Traveled the world by sea The plant and animal life he saw on many of the remote islands he visited, peaked his curiosity.

Darwin: “Why is it that way?” –famous for the theory of Natural Selection: Survival and reproduction by individual organisms based on their respective fitness in changing environments. “Survival of the Fittest”

Diversity of Life Diversity – a variety of living things Estimates for # of species on Earth range from 3 to 20 million. More than 99.9% of the species that have inhabited Earth are now extinct.

What is Fitness? Fitness- An organism’s ability to survive and reproduce in a given environment based on its physical traits and behaviors. An organism with favorable traits and behaviors is more likely to survive, and pass those traits on to subsequent generations

Principle of Common Descent Darwin’s theory that species have shared or common ancestors. Just as each individual organisms comes from previous organisms, each species has developed from previous species.

Adaptation Adaptation: any inherited characteristic that allows an individual to better survive and reproduce in a given environment –Tiger’s camouflage stripes –Polar bear’s thick fur and fat –Eagle’s talons and beak

Evidence in Living Organisms Similarities in Early Development –Embryology Similarities in Body Structure –Homologous Structures Similarities in Biochemistry

Early Development Embryology- study of organisms at early stages of development Vertebrates (for example) show significant similarities during early development

Which one is human?

Homologous Structures - structures that develop from the same body parts Ex: Human arm, dolphin fin, bat wing, bird wing…. Body Structures

Analogous Structures - Structures that are not homologous, but serve similar purposes: Ex: trachea tubes vs lungs Ex: bird wings vs dragonfly wings

Vestigial Structures - organs or structures that serve no purpose –wisdom teeth, appendix, snake legs –whale pelvis

Biochemistry DNA/RNA structure identical throughout all organisms ATP found in all living systems Complex proteins (cytochrome c) Closely related organisms have almost identical biochemistry

6.5 Evolution How Change Occurs

14-1 Evolutionary Theory A collection of carefully reasoned and tested hypotheses about how evolutionary change occurs.

Early Explanations of Evolutionary Change Lamarck ( ) –Natural urge to better themselves –Use and disuse –Passing on acquired traits

Shaping Darwin’s Thinking: Charles Lyell- Understood that Earth was very old.

Shaping Darwin’s Thinking Malthus- Babies are being born faster than people are dying. Population must be limited Darwin realized that plant and animal populations must be controlled against growth.

14-2 Evolution by Natural Selection Natural Selection- Survival and reproduction by individual organisms based on their respective fitness in changing environments.

14-2 Evolution by Natural Selection Four Main Parts 1. Overpopulation- more individuals born than can survive

2. Variation- Each individual is genetically different. 3. Competition- Individuals compete for resources: Food, water, space, mates “Survival of the fittest”

Natural selection- Individual with best traits (adaptations) to the environment will survive and reproduce.

Kettlewell and the Peppered Moths

14-3 Genetics and Evolution Evolution happens through changes in genes The environment dictates which adaptations (phenotypes) are favorable.

An individual’s phenotype is controlled by it’s genes (genotype) The total amount of genes found in a population is the GENE POOL

Changes in the Gene Pool can cause the population to evolve Changes in the gene pool are caused in many ways

Causes of Change 1. Mutations in the genes (DNA) of individuals allowing new adaptations 2. Geographic Isolation- population is split by some physical barrier: river, mountain, ocean

3. Reproductive Isolation: individuals unable to breed together: behavior or physical characteristics 4. Temporal Isolation: changes in mating cycles

The formation of a new species from a preexisting population is SPECIATION.

Some species evolve to new environments with new adaptations- divergent evolution

The environment also causes different creatures to become similar looking- Convergent Evolution

4-5 Evolutionary Theory Evolves Genetic Drift is because of evolution by random chance No Natural Selection Happens by accident

2 types of Genetic Drift 1. Bottleneck Effect- Competition is killed and is a random act 2. Founders Effect- No competition in new environment – the evolution of a new Island.

Rates of evolution 1. Gradualism- Slow steady evolution of species

2. Punctuated Equilibrium- long periods of no evolution, then brief periods of change

End Here

13-2 The Age of the Earth Earth’s age is estimated at 4.6 billion years. James Hutton in proposed that features of the earth were influenced by volcanoes, erosion, etc.. These things all act very slowly

In 1830, Charles Lyell agreed that the earth had been shaped over a long period of time…but also stressed the importance of explaining theory in terms of scientific method.

Geologic Time Scale Relative Dating- the age of some rocks “relative” to others based on their position. NEWER: RECENTLY DEPOSITED OLDER: DEPOSITED EARLIER

Absolute Dating: using scientific techniques to find the approximate actual age of artifacts. Radioactive Dating: using the known rate of decay to calculate the age of artifacts. ( 14 C)

13-3 The Fossil Record Fossils- preserved remains of ancient organisms Formation of fossils- when animals are buried in some medium that prevents decay –mud, sand, silt, tar pits –Sedimentary Rock

Specific conditions are required for fossils to form –mountains vs. rivers and streams –many organisms never fossilize Not all fossils have been found Problems with the Fossil Record:

The quality of fossils varies greatly As a result, the fossil record is not as complete as paleontologists would like

Cabrian: 500 million

Triassic: 250 million

Jurassic: 200 million

Trilobite

The Fossil Record Collectively, the millions of fossils that have been collected make up The Fossil Record Many pieces are missing Scientists have been able to construct detailed paths of change through time for many species

Evidence indicates that Earth’s climate has changed significantly over time Evidence also shows that species of plants and animals changed to fit those environments, or perished.