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

§         Direct vs. indirect effects