How Populations Evolve Slide 2 Questions about Fossils A fossil
is an impression of a life form found in a rock. How did that
impression get there? Slide 3 Famous Fossils Slide 4 Questions
about Biogeography Biogeography is how organisms are distributed
globally. What major discovery opened up the realms of
Biogeography? Slide 5 Questions from Comparative Morphology why
then produce vestigial structures (structures without a use)? Slide
6 Comparative Anatomy Perhaps this is the perfect design? But..
Slide 7 Comparative Embryology Slide 8 Molecular Evidence Slide 9
Missing Links Transitional fossils linking past and present Slide
10 Modern Pieces of Evidence Slide 11 Principles of Evolution
Populations evolve, individuals dont! Why must this be true? A
population is a group of the same species, occupying the same area.
A population exhibits variation among individuals. What is the
cause of these variations? Slide 12 Genetic drift Natural selection
Gene flow Mutation Factors that alter gene frequencies Slide 13 An
evolving population Genetic drift is the random change in allele
frequencies over generations. The magnitude of its effect relates
to population size. Slide 14 An evolving population The bottle neck
effect: an extreme drift Slide 15 An evolving population The
founder effect: a few individuals from a large population leave and
establish a new one elsewhere. Will the allele frequency of the
founders be a good representation of the original population?
Tristan da Cunha Slide 16 An evolving population We know that all
members of a population do NOT survive and reproduce. We also know
that mating is NOT random .the principles behind Natural Selection.
Slide 17 Different types of selection Slide 18 Directional
selection: the peppered moth Slide 19 Different types of selection
Stabilizing selection: favors the most common phenotype. Slide 20
Different types of selection Diversifying selection: favors forms
at the extremes and selects against the intermediate form. Slide 21
Different types of selection Balancing selection: a variation on
the stabilizing theme in which two or more forms of a trait are
maintained in stable proportions. Slide 22 Different types of
selection Sexual selection: any trait that gives a competitive edge
in mating and producing offspring (sexual dimorphism)
