1. Patterns of evolution

2. #1. Timing Punctuated Equilibrium Gradualism
Evolution occurs in bursts (thousands of years) followed by millions of years of stasis
Rate of evolution is very slow and constant
(millions of years)
**Note in geologic time “short” and “rapid” can mean hundreds of thousands to millions of years! The fossil record shows both of these theories as possibilities.

3. More on punctuated Equilibrium
Evidence that evolution occurs more rapidly following environmental change

4. #2 Divergent/Adaptive Radiation
Species evolve to look different
Often times many groups evolve from one common ancestor

5. Example Darwin’s Finches on the Galapagos Islands: one species from the mainland evolved into many species

6. Fall of dinosaurs gave rise to adaptive radiation of mammals

7. Interpreting Evolutionary Trees
present
Each line
represents
a species
In an adaptive
radiation, multiple
speciation events
may occur rapidly
enough that
biologists cannot
be certain of their
order
time
Forks
represent
speciation
events
past
(a) Evolutionary tree
(b) Evolutionary tree representing
adaptive radiation
Fig

8. #3 Convergent
Different species evolve to appear similar despite different ancestry = NO RECENT COMMON ANCESTOR
Leads to formation of analogous structures

9. Example – Placental vs. marsupial mammals

10. Example of analogous structures - wings

11. Coevolution:
Process in which two species evolve together in response to change in each other
Examples: Orchid and moth, insects and plant poison, hummingbird & flower structure.

13. Example – milkweed and Monarch Butterflies
Milkweed is toxic
Monarch butterflies feed on milkweed and have evolved to withstand the toxin
They become toxic to predators

14. #4 Aposematic coloration
Prey evolve very bright coloration
Predators have evolved to avoid butterflies with bright coloration

15. #5 mimicry
Harmless species evolve to appear similar to toxic/dangerous species

16. Changes during the embryonic stage can have a huge effect.
#6 Developmental Genes
called hox genes:
Developmental genes
Changes during the embryonic stage can have a huge effect.
This lends itself to patterns in morphology: heads, trunk, legs being an example.
Hox gene video (~5 min)

17. MACROEVOLUTION practice quiz
HW Quiz next class-allele frequency (not the math just the concept behind why they shift), causes of microevolution, phylogenic trees, species, patterns of evolution.