1. Evidence for Evolution
Topic 5.1

2. Evolution
Occurs when heritable characteristics of a species change over time
*Characteristics acquired over a lifetime (such as blisters) are not heritable
Occurs through natural selection

3. Evidence: Selective Breeding
Humans have been breeding plants and animals purposefully for thousands of years through artificial selection
The breeds of these animals greatly vary from their wild counterparts
Shows that selection can cause evolution

5. Evidence: Fossil Record
The sequence of the fossil record matches evolutionary theory.
Older, simpler fossils are found in the bottom strata of rock layers
Newer, more complex fossils are found in the upper strata of rock layers

6. Evidence: Fossil Record
Sequence of the fossil record matches theory:
Plant fossils appear on land before animal (herbivores) fossils do
Some sequences of fossils are known
Link together common ancestors
Predicts close living relatives accurately

7. Evidence: Homologous Structures
Homologous structures are structures in different species that may look different, perform different functions but have a common structure and common origin.
Ex: forelimbs in humans, cats, whales and bats

8. Pentadactly limb: Forelimb

9. Homologous structures are not to be confused with analogous structures
Analogous structures have similar functions and may have similar shapes, but do not have a common origin.
They have evolved independently of each other

10. Evidence: Patterns of Variation
If populations gradually diverge over time, we should be able to see examples of populations in different stages of divergence
Variation within a species that is recognizable, but not enough to be considered a different species.

11. Peppered moth populations in pre and post industrial England
Peppered moths (Biston betularia) have natural variation in their wing colors
Melanic: dark colored wings (morpha: typica)
Non-melanic: light colored wings (morpha: carbonaria)
Peppered moth populations in pre and post industrial England

12. Explain the trends seen in the graph above

13. Evidence: Speciation
Populations of a species can gradually diverge into separate species by evolution
Speciation occurs when a population becomes separated into two or more groups and are cut off from breeding with each other.
Over time each group will evolve in different ways, creating distinct characteristics.
If the two different populations can no longer successfully breed with each other, they have speciated into two distinct species.

14. *Speciation occurs often on islands where species are geographically isolated.
These populations are endemic: only found in a distinct geographic areas.

15. Evidence: Speciation
Geographical distribution of species matches the idea of gradual speciation
*Different species of mockingbirds are distributed in the galapagos islands suggesting the main island was populated first and outlying islands populated from the main island species then speciated.