1. Lecture 10. Wednesday, September 17.
1. Biogeography - Why do things occur where they do?

2. Needlefish distribution is strongly influenced by temperature
Needlefish distribution is strongly influenced by temperature. Occur in water above 23.9C. However - not all species occur in all places.

7. Gondwanaland Distribution Example 1 - Cichlids

8. Gondwanaland Distribution Example 2 - Characiformes

9. Gondwanaland Distribution Example 3 - Osteoglossids

10. Lungfishes
Distribution thought to reflect Gondwana connections of southern continents
One the classic examples of supports the Gondwanaland super-continent

11. Lauratian Distribution Example #1 - Percidae

12. Lauratian Distribution Example #2 - Esocidae

13. Cypriniformes, Catostomidae
13 genera
70 species

14. Lauratian Distribution Example #3 - Cypriniformes
53 genera
286 species

16. Gondwanaland Distribution Example 1 - Cichlids

17. Cichlidae - 900 species in African rift lakes = species flocks
L. Victoria
In NA Great Lakes, 230 total speices - all orders/families
Evolve when a new habitat with open niches is invaded
In this case these lakes formed, there were no fish in them, once a single type of fish moved there was explosive speciation

18. Molecular Clock Data Indicate that Cichlids diverged after breakup of Gondwanaland

19. Group Activity #1 -Draw the phylogenetic tree & distinguishing
traits for:
group a - Myxiniformes, Gnathostomata, Chondrichthyes,
Osteichthyes
group b - Petromyzontiformes, Elasmobranchii, Holocephali,
Sarcopterygii, Actinopterygii
group c - Elasmobranchii, Holocephali, Sarcopterygii,
Actinopterygii
group d - Myxiniformes, Petromyzontiformes, Chondrichthyes,
Sarcopterygii

20. Group Activity #3 - Design a dichotomous key that would allow one to distinguish these groups
For example . . .
Step 1 -
lacks vertebrae --> Myxiniformes
if not --> go to step 2
Step 2 -
lacks jaws --> Petromyzontiformes
if not --> go to step 3

21. Review Questions:
1. Distinguish between the “Intrinsic Limitations” hypothesis versus the “Vicariance” hypothesis for the distribution of fish. What assumptions do each make concerning dispersal?
2. List 2 major geological factors that can affect fish distributions. How does glaciation affect fish distribution?
3. List 4 taxa that show a “Gondwanaland” distribution. Which ones have clear-cut fossil support? List 3 taxa that show a “Lauration” distribution.
4. What were the 3 hypotheses for explaining the distribution of cichlids? What evidence is there to support (or reject) each one? How did scientists calibrate a “molecular clock” for cichlids? How did they use it to estimate the origin of cichlids? Do you think it likely that cichlids migrated between Africa & South America? What is neutral DNA?
5. Speculate on the relative roles of vicariance versus dispersal for marine versus freshwater fish. Do you think their relative importance differs between saltwater and freshwater fish? What evidence does your book present on this matter?