Geology 105 - Paleontology
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Paleoecology

Reading: Chapter 8

We're going to use the chapter inside out - starting at Environmental Limiting Factors (p. 124-129). The go back and read the beginning of the chapter (P. 119-124). Skip the section on Paleobiogeochemistry - you'll read a better description of stable isotopes in paleontology later. Read the section on Ecological Ideas from p. 135-140, skip the section on Evolutionary Paleoecology on p. 141-145. Do read the section on Escalation (p. 145).

Background

Terms:

Key Concepts and Questions:

1. What physical aspects of the environment limit where and how organisms live?

For each limiting factor, describe how that factor varies in the ocean, and how the factor affects the biology of organisms:

Factor	How does it vary?	How does it affect organisms?
Temperature
Oxygen
Salinity
Depth/Light
Substrate

In class we will apply this framework to these reef environments:

Environment	How do limiting factors vary?	Adaptations we expect to see
Fore-reef - seaward side of reef, below wave base, gets landslides from upper reef
Reef Core - where water shoals over the top of the reef, strong wave action, biologically very crowded
Back reef - lagoonal area behind reef, shallow water, may have fresh water input

2. What biological aspects of the environment limit where and how organisms live?

A. Competition - organisms that use the same resources eventually subdivide the resource or use it in different ways. Competition is only a factor when the resource is limited.

Direct competition - both organisms use the same resource

Interference competition - the use of one resource by an organism interferes with another organism's ability to use a different resource. E.g., human-built dams may release enough water for salmon to spawn, but it may be the wrong temperature.

 

B. Predation

Looking for direct evidence:

A. Shell breakage/Bone damage

 

 

 

 

B. Mouthparts

 

 

 

 

Indirect evidence

A. Defenses

 

 

 

 

Using predation as evidence of warmbloodedness - how does the predator-prey ratio vary between endothermic and ectothermic organisms?

 

 

 

 

Predation as driving force of natural selection - how did the evolution of shell-crushers change the fauna of the ocean floor from the Paleozoic to the Mesozoic?

 

 

 

 

 

Assessment

1. Background

You should be able to:

• define all the terms listed and use them propoerly in context
• explain the limits of paleoecological conclusions given the limits of the fossil evidence

2. Physical environment

You should be able to:

• describe how each of the five limiting fatcors vary within the oceans, and how they each affect the biology of organisms.
• describe how each limiting factor varies within reef environments, and what adaptations organisms have to deal with these environmental conditions
• given sufficient information about a new environment, predict how the limiting factors will vary in that environment and suggest potential adaptations you expect organisms in that environment to have.

3. Biological environment

You should be able to:

• cite examples of how direct and interference competition affects evolution of marine organisms
• cite examples of direct and indirect evidence for predation in fossilized marine communities
• explain the statistical relationship between predation and homeothermy
• explain how predation and competition have influenced the patterns of evolution of marine copmmunities over time