Tell me the difference between and all that you know about… Evolution Natural Selection Speciation

Mechanisms for change among Populations. Natural Selection, Speciation, and Evolution

Evolution: Collection of adaptations over time. Macroevolution: Large scale change in populations resulting in new species, genera, families, etc.

Microevolution: small scale genetic changes in organisms through chance mutations resulting in slight changes in a population. This has been observed for centuries.

Darwin and Natural Selection Darwin’s Plight Natural Selection: Process of sorting individuals based on their ability to survive and reproduce within their ecosystem Mechanism for speciation and evolutionary change in populations. Acts as a filter. NS is not EVOLUTION.

Various “Selection Pressures” can determine the type of Selection. a.k.a. Disruptive Selection

Again, tell me the difference between… Evolution Microevolution vs. Macroevolution…examples?? Natural Selection Speciation

Factors that influence and/or drive Natural Selection. Genetic Variation: Mutations: New alleles created. Sexual Reproduction: Recombines existing genes to create variation. Reproduction in Excess: Greater number = greater chance of survival and reproduction. Selecting Agents: Environmental factors that select for certain characteristics. Examples?? Differential Reproductive Rates. Differential mate selection = Sexual Selection

Populations Evolve, not individuals. Population: All members of a species that live in an area. Biological Species: Group of organisms that can interbreed and produce fertile offspring. Is survival enough to ensure the continuation of a species?

Speciation is determined by: Environmental factors that affect the populations of organisms. Sexual Selection: Sexual reproduction among certain individuals of a gene pool. Those that mate/reproduce contribute to the next generation. Genetic diversity within the gene pool. The more genetic diversity, the better ability to adapt to changes. Factors that affect Gen Diversity: Mutations: Change in a sequence of DNA. Genetic drift: alteration of allelic frequency by chance events. Greatly affects small pop. Migration: movement of organisms into and out of a population Sexual Reproduction: Crossing over (recombination) and independent assortment (random inheritance of alleles).

Speciation: The evolution of new species Causes of speciation… Geographic isolation: a physical barrier separates a population. Continental drift, rivers, lakes, mountains, etc. Results in inability to interbreed and each population collect mutations and variations independent of each other.

Reproductive Isolation: Once interbreeding organisms can no longer mate and produce fertile offspring. Can be behavioral or due to geographic isolation.

Polyploidy: Instant Speciation Any species with multiple sets of chromosomes. Occurs mostly in plants.

How do you think variation amongst the finches helps them survive? Variation is a good thing…explain why a lack of genetic variation could be harmful to a population. Divergent Evolution.  How do you think variation amongst the finches helps them survive?

Application… The Gila monster is the only venomous lizard in North America. Their distinct coloration makes them easy to identify. What survival advantage does this coloration provide for the Gila Monster? Identify a plausible “Selecting Agent” or “Selection Pressure” that might have influenced the development of this coloration in the Gila monster population. Another adaptation of the Gila monster is their large tail. It is used to store excess fat. How would this trait contribute to their survival? Identify a plausible selecting agent or pressure that would account for the acquisition of this trait.

Homework: Identify 3 adaptations that each organism shown below has that helps them survive in their habitats. Propose /identify some plausible selecting agents or pressures that could have contributed to the development of these adaptations.