1. Homologous and Analogous Structures

2. Homologous structures
Structures that are similar but has different functions
Shows common ancestry

3. Convergent Evolution Acquiring the same biological trait independently
Example: Flight
Humming bird and moth - last common ancestor did not have wings
They acquired these traits separately
Only very few designs for a wing would allow for hovering

4. Porpoises

5. Sharks

6. Analogous Structures Similar functions but differ in structure
Ex: wings of a hummingbird and humming moth – both can hover to feed

8. Vestigial Structures
Features that were useful to an ancestor, but they are not useful to the modern organism that has th.
tailbone in humans
Appendix
Some snakes have tiny pelvic bones and limb bones

9. Vestigial Structures

10. Comparative Embryology
Closely related organisms often have similar stages in their embryonic development
All vertebrate embryos are similar
Vertebrates share a common ancestor
lemur
pig
human

11. Vertebrate Embryos

12. Similarities in Macromolecules:
The more similar homologous proteins are in different species, the more closely related the species are thought to be.
Ex: the amino acid sequence in human hemoglobin and gorilla hemoglobin differ by ONE amino acid
While the Hb of humans and frogs differ by 67 amino acids!!

13. Coevolution
Change of two or more species in close association with each other
Predators and their prey sometimes co-evolve
Pollinators
Bees can’t see red, but can see in blue, yellow, and UV
Bee landing pad!

15. Divergent Evolution
Two or more related populations or species become more and more dissimilar.
Divergence is nearly always a response to differing habitats and can result in new species

16. Adaption Radiation
Many related species evolve from a single ancestral species ex: Galapagos finches

17. Canis familiaris
artificial selection: all domestic dogs are the same species “Canis familiaris”