1. Fri. 2/21 Collect: Ch. 18 guided reading
Today: Quiz Ch 18, Notes Ch 17.
Homework: Ch 17 Guided Reading
Next class: Quiz Ch 17
Test corrections must be done by Wed. 2/26.
Late work will only be accepted up to the day we take the test over that chapter.

2. Pg. 132
Guided Reading-Ch 17
Pg. 133
EK paragraph Ch 17
1C1 or 1C2

4. In: Pg 134
Watch the Bozeman video “Speciation and Extinction” and write 5 facts.

5. Extinctions
Extinctions are always occurring at a low rate (background rate)
Occasionally, mass extinction events will happen when many more species will go extinct than normally
Example:
Permian (250 million years ago):
90% of marine animals; Pangaea merge
***Human Impact on Ecosystems & Species Extinction Rates***

6. Mass extinction
Cretaceous (65 million years ago): death of dinosaurs, 50% of marine species; low angle comet (maybe?)

9. Pg 135 Chapter 17Speciation and Macroevolution

10. Macroevolution: the origin of new taxonomic groups
Speciation: the origin of new species.
As opposed to microevolution…alelle frequency changes in a population—no new species.

11. Yellow Pine Chipmunk
Tamius amoenus
Least Chipmunk
Tamius minimus

12. Newfoundland dog
Canis familiaris
Chinese Crested
Canis familiaris

13. What is a species?
Biological species concept (Mayr): a population or group of populations whose members have the potential to interbreed and produce viable, fertile offspring (genetic exchange is possible and it is genetically isolated from other populations)
Limitations
Asexual organisms
Fossils
Don’t know all organisms that can breed with one another.

14. Alternative ways of classifying species
Morphological- body shape and structures
Problems: different members of the same species can look different and members of different species can look the same.
Evolutionary- use fossil record to decide speciation
Problems: still based on morphology and incomplete fossil record

15. Phylogenetic- based on evolutionary relationships, a species is a breeding population that have a common ancestor and share a common trait.
Problems: may
be gene flow between species,
very small genetic differences
may divide species.

16. Reproductive Isolation (isolation of gene pools)
1. Prezygotic barriers: impede mating between species or hinder the fertilization of the ova
Habitat (snakes; water/terrestrial)
Behavioral (fireflies; mate signaling)
Temporal (salmon; seasonal mating)
Mechanical (flowers; pollination anatomy)
Gametic (frogs; egg coat receptors)

17. 2. Postzygotic barriers: fertilization occurs, but the hybrid zygote does not develop into a viable, fertile adult
Reduced hybrid viability (frogs; zygotes fail to develop or reach sexual maturity)
Reduced hybrid fertility (mule; horse x donkey; cannot backbreed)
Hybrid breakdown (cotton; 2nd generation hybrids are sterile)

18. Modes of speciation (based on how gene flow is interrupted)
Allopatric: populations segregated by a geographical barrier; can result in adaptive radiation (island species)
Sympatric: reproductively isolated subpopulation in the midst of its parent population (change in genome or habitat separation).
Polyploidy-when 2 parents with different # of chromosomes mate but produce infertile offspring-common in plants.

19. Figure 24.10
Researchers from the University of Leiden placed males and females of Pundamilia pundamilia and P. nyererei together in two aquarium tanks, one with natural light and one with a monochromatic orange lamp. Under normal light, the two species are noticeably different in coloration; under monochromatic orange light, the two species appear identical in color. The researchers then observed the mating choices of the fish in each tank.
EXPERIMENT
P. nyererei
Normal light
Monochromatic
orange light
P. pundamilia
Under normal light, females of each species mated only with males of their own species. But under orange light, females of each species mated indiscriminately with males of both species. The resulting hybrids were viable and fertile.
RESULTS
The researchers concluded that mate choice by females based on coloration is the main reproductive barrier that normally keeps the gene pools of these two species separate. Since the species can still interbreed when this prezygotic behavioral barrier is breached in the laboratory, the genetic divergence between the species is likely to be small. This suggests that speciation in nature has occurred relatively recently.
CONCLUSION

20. Adaptive Radiation
Evolution of many diverse species from a common ancestor.
New environments/new “branches”
Cambrian Explosion  600 mya, origin of most animal phyla

22. Convergent Evolution
Similar traits evolve in 2 unrelated species due to similar environments.
Cichlids in African Rift Lakes.

23. Coevolution Species evolve together because of some relationship
Predator/Prey or Parasite/Host:
“Evolutionary arms race”
Symbiotic relationships
Flowers (Plants ) and pollinators (insects, bats, birds)

24. Tempo of speciation
Gradualism-changes are slow and steady over time(Darwin).
Punctuated equilibrium-changes occur in bursts
Helps to explain gaps in the fossil record.

27. Out Read “Ghost Stories from the Ice Age” and answer the questions.
What was the fate of the large herbivores?
What are the 2 ways plants were reliant on the large herbivores?
Of which type of evolution is this an example?
Discuss how each of the following was dispersed in the past and is dispersed today:
Devil’s claw
Osage orange
Gourd-bearing vines