Lesson 1 - Niche

Is there anywhere life cannot be found?

• Only in the most extreme environments where essential biological molecules cannot exist!

• e.g., at the most extreme temperatures or pH

• Life is everywhere!

• Extremophiles are organisms that are able to live in extreme conditions

• Life can be found…

• In temperatures up to 121°C

• In lakes with a pH >11

• In pools with pH < 1

What is Ecology?

• The study of how organisms interact with one another and their physical environment

• The study of the processes influencing the distribution and abundance of organisms

  • Ex. Where is sugar maple found and why?

  • Where is sugar maple not found and why?

• ‘Ecology’ from Ancient Greek

  • oîkos 'house’

  • -logía 'study of

An Ecological Niche

• The range of resources that an organism can use and the physical conditions that it can tolerate

• The range of abiotic and biotic conditions that a species lives in

• i.e., the range of resources and conditions allowing the species to maintain a viable population

Abiotic Factors

• Are the non-living, physical aspects that impact those organisms, such as temperature, mineral nutrients, wind, soils, and water quantity and quality.

• Abiotic conditions help us to identify where organisms can potentially live.

The Fundamental Niche

• The possible range of conditions that a species can tolerate

• Defines the locations where it is physically possible for a particular species to live

• Help us to identify where organisms can potentially live!

• Range of Tolerance → refers to the range of environmental conditions within which an organism can survive, grow, and reproduce

• Defines fundamental niche!

• Ex. In a dry environment, for example, humans die if they are exposed to temperatures above 57°C (130°F)

Biotic Factors

• Are the organisms present—the ones that do the eating and competing and beneficial exchanging

• Ex. Food availability, rates of reproduction, competition, predators, parasites etc

Realized Niche

• Spaces within the fundamental niche where the biotic factors are also sufficient – and thus where the species could survive

• No species occupies its entire fundamental niche → more limited range of conditions

• These biotic interactions can include:

  • Predation or herbivory (literally, "plant eating") that eliminates a species from certain areas;

  • Diseases caused by parasites;

  • Mutualisms involving a strong and beneficial interdependence between two species;

  • Competition for space, nutrients, water, nesting sites, or other resources.

Ecological Niche

Includes both biotic and abiotic factors

Fundamental Niche

• All the possible dimensions in which a species can survive in principle

• Potential range based on tolerances

Realized Niche

• The dimensions in which a species
  survives after the effects of biotic
  interactions

• More conditions = narrower range

Hypothesis and Null Hypothesis

• A proposed explanation for something that researchers have observed

• Are testable because they make predictions

• The “If” Part

• Ex. Sugar maples do not grow well in grassy fields because sugar maples and grass experience intense competition for nitrogen in the soil.

• A null hypothesis states the "not" or "no-effect" contrast to the hypothesis being tested.

• Every hypothesis has a corresponding null hypothesis.

• Ex. Fever-is-adaptive-for-the-host hypothesis → Fever is not adaptive for the host

Predictions

• A statement of an outcome that should occur if a hypothesis is correct

• The “Then” statement

• “If my tomatoes haven't germinated because they need more time, then I should start to see some seedlings emerging if I wait a few more days."

• Ex. Removing the grass from Johnston Green will increase the survival of sugar maples planted there.

Treatment Group vs Control Group

Treatment Group

• A group that experiences experimental conditions that conform to the mechanism proposed in the hypothesis

Control Group

• A group that represents the normal or no-treatment condition

• Serves as a comparison to the treatment group

Outcome Variable

• The variable that is measured in an experimental or observational study. It represents a quantity that is relevant to the hypothesis being tested.

• Ex. Testing the hypothesis that a new medication can improve symptoms in humans with chronic high blood pressure → Blood Pressure measured over time