Evolution Evolution Change over time Occurs to a

Evolution

Evolution • Change over time • Occurs to a species, NOT INDIVIDUALS!! • Natural selection or Survival of the fittest

How Evolution Works 1. Overpopulation – More individuals born than can survive

How Evolution Works 2. Competition – For limited resources – Some will survive, some will not

How Evolution Works 3. Variation – Differences among individuals – A result of genetic mutations in DNA

How Evolution Works 4. Adaptation – Some variation gives some individuals a slight survival advantage – These are favorable traits…

Types of Adaptations A. Structural • Physical structure that helps organisms survive

Types of Adaptations B. Chemical • Chemicals that helps organism survive

Types of Adaptations C. Behavioral = Behaviors that help organisms survive

Types of Adaptations • Camouflage

Types of Adaptations • Warning Coloration

Types of Adaptations • Mimicry

How Evolution Works 5. Natural Selection – Those with best traits survive, reproduce and pass favorable traits on to their offspring – The mechanism of evolution

How Evolution Works 6. Speciation • Isolation – causes changes; if one part of a population is separated or isolated from another, speciation is more likely

Evidence for Evolutionary Theory 1. 2. 3. 4. Homologous Structures Vestigial Structures Embryology Fossil Record

Homologous Structures same kinds of cells that grow in similar patterns in different organisms Ancient lobe-finned fish Turtle *Analogous Structures – Structures that are similar in function, but are not inherited from a common ancestor. Alligator Bird Mammal These limbs of these four modern vertebrates are homologous structures

Vestigial Structures – Organs that no longer serve a purpose or function This suggests that ancestors of modern whales probably had legs and lived on land.

Vestigial Organs

Embryology Common Ancestry In their early stages of development, chickens, turtles, and rats look similar, providing evidence that they shared a common ancestry.

Embryology

Fossil Record – Remains of ancient life – Record of history of life – Shows change over time – Transitional fossils

Transitional Fossils

Transitional Fossils

Transitional Fossils

TIME Magazine; August 23, 1999, pp. 54 -55.

Evidence Beaver Geographic Distribution of Living Species Beaver Muskrat NORTH AMERICA Muskrat Beaver and Muskrat Coypu Capybara SOUTH AMERICA Coypu and Capybara

Common Ancestry • Similar structures • Similar structural location • Similar embryos All provide evidence of a common ancestor!!!!

The theories that led to evolution. . . • Bonnet – Periodic catastrophes affected the entire planet, and that after each catastrophe, life began anew. • Lamarck – Organisms constantly strive to improve themselves. – The most-used body structures develop, whereas unused structures waste away. – Once a structure is modified by use or disuse, the modification is inherited by the organism’s offspring (inheritance of acquired characteristics). • Darwin – There is variation within populations. – Some variations are favorable. – Not all young produced in each generation can survive. – Individuals that survive and reproduce are those with favorable variations.

Punctuated Equilibrium Populations remain genetically stable for long periods of time, interrupted by brief periods of rapid genetic change.

Types of Evolution • Divergent Evolution – When isolated populations of a species evolve independently. • Convergent Evolution – Different species with different ancestors develop similar characteristics. • Coevolution – Over millions of years, species that interact closely often adapt to one another.

Types of Selection Stabilizing Selection - A shift that favors the intermediate variants. Directional Selection - A shift in frequency to an extreme phenotype. Disruptive Selection - A selection that does not favor the most common variation within a population.

Frequencies • Genetic Equilibrium – Constant state of allele frequency. • Genetic Drift – Random change in allele frequencies in a population due to chance events.

It’s not that far of a stretch… • Humans have forced evolution (or change in a species over time) … • Artificial Selection – nature provides variation and humans select variations that they think are useful