Ecology: Lecture 1 Introduction

Photo: Stanford University News Service

What is ecology?  “Ecology works at characterizing the patterns seen in nature, studying the complex interactions among organisms and their environments, and understanding the mechanisms involved in biological diversity.”

1. Characterizing the patterns seen in nature  Example: The River Continuum  Many differences are seen between the upstream and downstream stretches of a river  Different types of invertebrates  Different species of fish

2. Studying complex interactions between organisms and their environment  Example: What causes the differences seen between upstream and downstream sites?  Possibilities???

3. Understanding the mechanisms involved in biodiversity  Why do some reaches of a river tend to have greater diversity than others? Why do some rivers have greater diversity than others?  Why do tropical rain forests and coral reefs have relatively high species diversity compared to other ecosystems?

The absolute geographical boundaries of a species are set by abiotic factors  Global scale: Adelie penguins would overheat in the tropics

The absolute geographical boundaries of a species are set by abiotic factors  Local scale: Giant, green anemones are found in pooling water in the intertidal, but not on vertical rock faces

Within limits set by abiotic factors, biological interactions affect the presence & abundance of species  What are some of these biological interactions?

Why are there no polar bears in the Antarctic?

Shelford’s law of tolerance   What do the axes mean? What do different parts of the curve tell us about the species?

Seasonal or geographical shifts in tolerance   What do the three different curves represent? (>1 possibility)   What does the arrow represent?   What types of values belong on the x-axis?

Winter distribution of the Eastern phoebe: Blue line: -4º isotherm, minimum average temp. January Blue patches: Deviation of phoebe distribution from -4º isotherm.

How might natural selection affect a species’ tolerance curve?  Within a single generation?  After several generations?

Global warming and species shifts  Example: malaria Diagram from Bellarmine University website