WHAT CAUSES EVOLUTION 5 EVOLUTIONARY MECHANISMS 1 2

WHAT CAUSES EVOLUTION?

5 EVOLUTIONARY MECHANISMS 1. 2. 3. 4. 5. MUTATIONS GENE FLOW GENETIC DRIFT NONRANDOM MATING NATURAL SELECTION

FIRST WE MUST REVIEW GENETICS • GENE-PIECE OF DNA THAT CODES FOR A TRAIT • ALLELE- DIFFERENT FORMS OF GENES (B OR b) BB Bb bb Brown Blue GENOTYPE PHENOTYPE

GENE POOL AND ALLELE FREQUENCY • GENE POOL- ALL GENES IN A POPULATION NEW • ALLELE FREQUENCY- PERCENTAGE OF VOCABULARY TERMS ALLELES IN A POPULATION B Bb bb • How many students are in the gene pool? • How many alleles for eye color? BB Bb bb Bb Bb bb bb • What is the allele frequency of B? • What is the allele frequency of b?

MUTATIONS • OCCUR SPONTANEOUSLY • CREATES NEW ALLELES FYI: SOME BACTERIA CAN REPRODUCE AS OFTEN AS EVERY 15 MINUTES!

GENE FLOW • MIGRATION • MOVEMENT OF ALLELES FROM ONE POPULATION TO ANOTHER POLLEN IS CARRIED BY BEES TO OTHER FLOWERS. OVER TIME THE TWO POPULATIONS OF FLOWERS WILL BECOME

GENETIC DRIFT • BAD LUCK CAN REDUCE THE SIZE OF POPULATION • CAUSES RANDOM CHANGES OF ALLELES

WHAT CAUSES GENETIC DRIFT? • POPULATION BOTTLENECK- SUDDEN REDUCTION IN THE NUMBER OF ALLELES IN A POPULATION DUE TO NATURAL CATASTROPHE. and b only b

FOUNDING POPULATIONS MAY PRODUCE BOTTLENECKS FOUNDER EFFECT: A few individuals from a population start a new population with a different allele frequency than the original population. ORGANISM MOVES TO ISOLATED ISLAND MAINLAND POPULATION ALLELE FREQUENCY IS DIFFERENT THAN ORIGINAL POPULATION

NONRANDOM MATING SNOW GEESE ARE MOST LIKELY TO MATE WITH OTHER BIRDS OF THE SAME COLOR. • ORGANISMS RARELY MATE RANDOMLY. • MOST ORGANISMS MATE NEAR THEIR PLACE OF BIRTH AND HAVE PREFERENCE WHEN THEY CHOOSE THEIR MATE.

NATURAL SELECTION • THOSE WITH BEST ADAPTATIONS WILL SURVIVE AND REPRODUCE!

LET’S REVIEW! DIFFERENT VERSIONS OF THE SAME GENE ARE CALLED _________. THESE VERSIONS ARISE AS A RESULT OF CHANGES IN THE SEQUENCE OF ____ THAT FORM THE GENE. AN INDIVIDUAL WITH TWO OF THE SAME COPIES OF THE GENE IS ____________ AND AN INDIVIDUAL WITH TWO DIFFERENT COPIES IS _________. DNA ALLELES HETEROZYGOUS HOMOZYGOUS

LET’S REVIEW! POPULATION BOTTLENECK AND THE FOUNDER EFFECT ARE TWO IMPORTANT CAUSES OF ___________. THIS IS A RANDOM CAUSE OF EVOLUTION IN ______ POPULATIONS AND CAN ________ ALLELES. ELIMINATE GENETIC DRIFT SMALL

An early biological theory stated that a change in a population can occur when organisms with favorable variations for a particular environment survive and pass these variations on to the next generation. This theory is better known as the Theory of — A. NATURAL SELECTION B. GENETIC DRIFT C. MUTATION

During DNA replication, the wrong nucleotide was inserted in the DNA sequence. Which of the following terms describes this situation? A. NATURAL SELECTION B. GENETIC DRIFT C. MUTATION

Title A population of mice is evenly divided into 2 groups, and each group is placed on an isolated island with no existing mouse populations. Which statement best explains the difference in the mouse populations on Island A and Island B at the end of 20 years? a. Conditions on Island B favored the brown mice, while both fur colors were evenly advantaged on Island A. b. Conditions on Island A favored the brown mice, while both fur colors were evenly advantaged on Island B.

A. B. C. D. E. Changes genotype frequency Random changes of alleles Creates new alleles Increases favored alleles Movement of alleles, causes populations to become more similar.