The Process of Microevolution Selection: Directional, Stabilizing, and Disruptive Selection Microevolution vs. Macroevolution Microevolution: change in allele frequency Macroevolution: formation of new species

Microevolution The environment selects the best traits in the form of alleles that are advantageous for the given conditions i.e. the ability to digest a new food, or a new skin pigment may allow an organism to blend in with its environment Genotype = genetic make-up, what alleles an organism has Phenotype = appearance, what it looks like

Examples of Microevolution Case 1: Galapagos Finch Case 2: English Pepper Moth Case 3: Mystery Predator Case 4: Human Blood Types The common denominator in each of these cases is the change in the alleles of a given gene or set of genes If there is a change in the frequency of the allele(s), then there will be a change in the genotype and phenotype of the population

Before industrial revolution After industrial revolution English Peppered Moth

M and M’s in the wild

The “M and M” Predator Showing effects of different M & M colors surviving over time

Your turn! Be the chocolate predator… Empty M and M bag on table. Place colors on matching dots. Place colors that don’t match (green) wherever you have space. Now, EAT your M and M prey that don’t match (easiest to find)

M and M Population- Before Predation

M and M Population- After Predation

Microevolution effects on populations over time Life history patterns = how species reproduce How successful each of the variations in species will be at reproducing Which M and M’s color will likely have a frequency change?

Summary The environment is the selecting force that determines the best fit of traits. Positive and negative selecting pressures cause a shift in the % of a trait in a population of a given species The changes result in genetic shuffling Eventually these gene shifts may be great enough to cause species to change

Human Example Four Human Blood types- O is original A and B are two blood type changes resulting from dietary shifts and immune responses AB is newest, due to mixed A and B populations