Evolution

 Darwin:  HMS Beagle  Galapagos Islands  Artificial Selection -breeding to produce offspring with desired traits-He inferred that if humans could change species (animals or crops) by artificial selection, then over time this process could produce new species.

3  Patterns of Diversity were shown  Unique Adaptations in organisms  Species Not Evenly Distributed  Australia, Kangaroos, but No Rabbits  S. America, Llamas copyright cmassengale

 ALREADY in NOTES…Just going over!  4 Basic Principles:  1. Individuals in a population show difference, or variation  2. Variations can be inherited-meaning passed down from parent to offspring.  3. Organisms have more offspring than can survive on available resources.  4. Variations that increase reproductive success will have a greater chance of being passed on than those that do not increase reproductive success.

5 Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection copyright cmassengale

6 The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) New species evolve New species evolve Darwin’s Theory of Evolution copyright cmassengale

7  1. The Struggle for Existence (compete for food, mates, space, water, etc.)  2. Survival of the Fittest (strongest able to survive and reproduce)  3. Descent with Modification (new species arise from common ancestor replacing less fit species) copyright cmassengale

8  Fitness  Ability of an Individual To Survive & Reproduce  Adaptation  Inherited Characteristic That Increases an Organisms Chance for Survival  Can you name some examples of adaptations for organisms? copyright cmassengale

9 Evolution is the slow, gradual change in a population of organisms over time copyright cmassengale

10 Evidence of Evolution – The Fossil Record copyright cmassengale

11 Similarities in DNA Sequence copyright cmassengale

12 Evolution of pesticide resistance in response to selection copyright cmassengale

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

 The study of the distribution of plants and animals around the world.  Patterns of distribution of living and fossil species tell us how modern organisms evolve from their ancestors.  Two patterns: Closely related but different and distantly related but similar

 Homologous structures-similar structures in species sharing a common ancestor The forelimbs of all mammals consist of the same skeletal parts. The hypothesis that all mammals descended from a common ancestor predicts that their forelimbs would be variations of the structural form in that ancestor.

 Structures that are the reduced forms of functional structures in other organisms.  Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost.  Examples:  Snake Pelvis  Kiwi Wings  Human Appendix

 Can be used for the same purpose and can be superficially similar in construction but are not inherited from a common ancestor.  Examples:  Bald Eagle and the Fly  What is their similarity?

 Similar patterns of embryological development provide evidence that organisms descended from a common ancestor.  The same group of cells develop in the same order and produce homologous tissues in vertebrates.

22 Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development copyright cmassengale

 At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent.  Genetic code is universal for all organisms.  Homologous molecules are found in various organisms and have similar functions.

26 Evolutionary Time Scales Long time scale events that create and destroy species. Macroevolution: Long time scale events that create and destroy species. copyright cmassengale

27 Microevolution: Short time scale events (generation- to-generation) that change the genotypes and phenotypes of populations Evolutionary Time Scales copyright cmassengale

 Any change in the allelic frequencies in a population that results from CHANCE  Founder Effect  Grand Canyon  Bottleneck Effect  Disease, Natural Disaster

If individuals in the group tend to marry within it, there's a greater likelihood that the recessive genes of the founders will come together in the cells that produce offspring. Thus diseases of recessive genes, which require two copies of the gene to cause the disease, will show up more frequently than they would if the population married outside the group.

 A population in genetic equilibrium experiences no gene flow  In reality, few populations are isolated.  Closed system, no new genes entering or leaving  Random movement of individuals, ex: migration, which reduces differences between populations

 Rarely is mating completely random in a population.  Usually, organisms mate with individuals in close proximity.  This promotes inbreeding  Favors homozygous traits

 Recall that a mutation is a random change in genetic material.  Can cause harm or death  However, some mutations provide advantages.