Transcript Ecology: Lecture 1

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