Lecture 29: Introduction to Ecology
1. The interaction between organisms and their
environments determine the distribution and abundance of organisms
•
Ecologists
make predictions of what should be expected to be observed in the environment
(e.g., number and kinds of species, species distributions, cycling of nutrients
through trophic levels and soils) based on abtiotic
and biotic factors.
•
The
environment of any organism includes the following components:
•
Abiotic
factors: non-living chemical and physical factors such as temperature, light,
water, and nutrients
•
Ecologists
have long recognized distinct global and regional patterns in the distribution
of organisms related to abiotic factors.
•
Biotic
factors: the living components
2. Ecology and
evolutionary biology are closely related sciences
•
Ecologists describ how organisms respond to the environment and how
organisms are distributed.
•
Events
that occur in the framework of ecological time (minutes, months, years)
translate into effects over the longer scale of evolutionary time (decades,
centuries, millennia, and longer).
3. Ecological
research ranges from the adaptations of individual organisms to the dynamics of
the biosphere
4. Ecology
provides a scientific context for evaluating environmental issues
5. Species
dispersal contributes to the distribution of organisms
•
Ecologists
ask a series of questions to determine what limits the geographical
distribution of any species.
6. Behavior and
habitat selection contribute to the distribution of organisms
•
Sometimes
organisms do not occupy all of their potential range, but select particular
habitats.
7. Biotic factors
affect the distribution of organisms
•
Predator
removal experiments can show how predators limit
distribution of prey species.
8. Abiotic factors
affect the distribution of organisms
•
Temperature: some organisms can only tolerate
specific ranges of temperature.
•
Water: some organisms can only tolerate either
fresh or salt water.
•
Sunlight provides energy that drives nearly all
ecosystems.
•
The intensity and quality of light, and
photoperiod can be important to the development and behavior of many organisms.
•
Wind amplifies the effects of temperature by
increasing heat and water loss (wind-chill factor).
• Rocks and soil: the physical structure and mineral composition of soils and rocks limit distribution of plants and the animals that feed upon them.
9. Trophic levels,
food webs and trophic cascades
• What are they, and how do trophic cascades work and why
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Direct vs. indirect effects