1. Evidence for Evolution
Section 7.4

2. The Evidence for Evolution
Learning Goal: To learn explore the evidence for evolution that led to Darwin’s theory on the evolution of species.
Success Criteria:
I know I am succeeding when I can…
explain how biogeography, patterns in embryonic development, homologous organs, and vestigial features provide evidence for evolution
explain how competition for resources is necessary for evolution to occur

3. Biogeography
Biogeography: the observed geographic patterns of distribution of species (living and fossils)

4. Biogeography Cont’d…
unusual assortment of species found on remote islands
isolated islands have many species that were found nowhere else, and species bear a resemblance to those on the nearest continental land mass

5. Biogeography Cont’d…
Darwin proposed that remote oceanic islands became populated by species that arrived by water or air and then many of these species evolved into new species over time

6. Biogeography Cont’d…
to date, Darwin’s hypotheses have been supported by the observations of life on all remote islands (ex. Hawaiian islands)

7. Homologous and Analogous Features
the structures of numerous anatomical features provide strong evidence that they have evolved from an original, homologous structure
homologous feature: a structure with a common evolutionary origin that may serve different functions in modern species (for example, bat wing and human arm)

8. Homologous and Analogous Features Cont’d…
all mammals have an almost identical number and arrangement of bones (ex. bats and humans)

9. Homologous and Analogous Features Cont’d…
the early embryos of all vertebrates share many homologous features, including tails and gill slits

10. Homologous and Analogous Features Cont’d…
analogous feature: a structure that performs the same function as another but is not similar in origin or anatomical structure (for example, bird and insect wings)
Practice

11. Vestigial Features and Anatomical Oddities
vestigial features: features that no longer serve the function they do in similar species
believed that the feature lost its usefulness as the species evolved
for example, number of mammals, including pigs, horses, and dogs, possess vestigial toes that serve no useful purpose

12. Competition within Populations
species produce more offspring than can survive to reproduce
results in competition for resources between members of the same species
Darwin wondered if the environment might be favouring certain individuals in this struggle for survival

13. The Evidence for Evolution
Learning Goal: To learn explore the evidence for evolution that led to Darwin’s theory on the evolution of species.
Success Criteria:
I know I am succeeding when I can…
explain how biogeography, patterns in embryonic development, homologous organs, and vestigial features provide evidence for evolution
explain how competition for resources is necessary for evolution to occur

14. Homework
7.4 questions #1, 2 & 4-8