Evolution review for test

Explain Darwin's theory of natural selection explain how adaptations arise: Many of Darwin’s ideas came from exploring the Galapagos' islands and observing life there. HERITABLE VARIATION: Exists in populations. OVER PRODUCTION OF OFFSPRING: More offspring than environment can support. COMPETITION: For food, mates, nesting sites, etc. DIFFERENTIAL SURVIVAL: Successful traits= adaptations DIFFERENTIAL REPRODUCTION: Adaptations become more common in population.

How do variations occur? MUTATIONS: random changes to DNA, error in mitosis/meiosis and environmental damage. SEXUAL REPRODUCTION: Mixing of alleles, genetic recombination.

EXAMPLES OF NATURAL AND ARTIFICAL SELECTION: ARTIFICIAL NATURAL MILK QUANTITY PEPPERED MOTH COLE CROPS- FROM MUSTARD DARWIN’S FINCHES DOGS-WOLVES WHITE LIZARDS OF NEW MEXICO INSECTICIDE RESITANCE

Evidences of evolution and an example Artificial/natural selection Fossils– ex) Horse, tetropod fish Homologus organs: Similar structures, different functions and show ancestory ex) Bones in a bat wing or our hands. Genetic code: The DNA sample, blast it, analyze it. Biogeography: Species in a geographic area tend to be more closely linked to each other. **We must also remember the continental drift and Pangaea.

Distinguish between homologs and analogous structures- give an example Homologous: Similar and shows ancestry. Ex– arm of a human, wing of a bat. Analogous: Similar trait, similar environment, doesn’t show ancestry. Ex– Fins in fish compared to fins in dolphins. Another example is the wings in squirrels compared to sugar gliders in Australia. (covalent evolution)

What is endemic species? Give an example Species that are found at a certain location but not found to be anywhere else. Ex) Marine iguanas in the Galapagos’ Islands.

5 things that must be true for hardy weinburg frozen no change situation: No genetic drift: Very large population size. No gene flow: No migration in or out. No mutation: No chemical change to DNA. Random mating: no sexual selection. No natural selection: Equal survival

Know the hardy weinburg equation and problems:

KEEP IN MIND FOR HARDY WEINBURG: Always start with q2 (the frequency of the recessive condition) or q (the frequency of the recessive allele) depending on which is given in the question.

What is microevolution? A small change within the species level.

MICROEVOLUTION CAUSES: Natural selection & Mutations Genetic drift Gene flow (immigration and emigration)

2 TYPES OF GENETIC DRIFT: Chance events FOUNDER: Small group splinters off and starts a new colony ex) A branch with bugs gets blown to a new island. BOTTLENECK: Disaster reduces population to small number and then population re- covers and expands again. Ex) Cheetah

SPECIATION: This is the formation of a new species. It caused by isolation ,hybridization and polyploidy. Once isolation or separation occurs gene pools diverge because they cannot share their new random variations with isolated individuals. Isolation then breaks down into geographic (allopatric) or reproductive (sympatric)- which are still in the same area. The geographic isolation is the most effective when forming a new species.

ISOLATIONS OR BARRIERS WHICH RESULT IN NEW SPECIES: GEOGRAPHIC: They are in different areas. Ex) Squirrel separated by canyon. TEMPORAL: Species that breed during different times of the day. Ex) Spotted skunk. HABITAT: Gardner snakes that live in water/land; as well as the tiger and lion. BEHAVIOURAL: Unique behavioral patterns & rituals isolate species. Ex) Blue footed boobie. MECHANICAL: More biological differences (don’t fit together.) Ex) Snails. GAMETE: Egg and sperm do not join together. Ex) Sea urchin.

POST REPRODUCTIVE BARRIERS: Prevent hybrid offspring from developing into a viable, fertile adult. Reduced hybrid viability. Ex) Salamander Reduced hybrid fertility. Ex) Mule Hybrid breakdown. Ex) Seeds from plants that have fertile themselves but the plants they grow are infertile. **Remember that horse and donkey’s make mules, which are sterile.**

Second way to get a new species: HYBRIDIZATION In rare cases when there is ideal conditions maybe to due habit change, a hybrid does become a real species. Ex) Eastern Coyote came from the small Western Coyote and the wolf. Also, new species can be formed when there is an accident during meiosis and a whole extra set of chromosomes form. It usually happens in plants. Ex) Grey tree frog

MACROEVOLUTION: A drastic change, way above the new species level. Ex) Feather on dinosaurs