8/29 Ecology Lecture Notes: Environment, Species Tolerance, and Geographic Ranges

Vocabulary flashcards covering key concepts from the lecture notes about empirical data, abiotic/biotic environments, ecological time, glacial history, and the Shelford’s Law of Tolerance with its zones and factors that shape species distributions.

Empirical data

Data derived from observation or experimentation that is quantifiable, measurable, and observable; used to test hypotheses and accept/reject predictions; supernatural or non-testable concepts have no data to support them.

Abiotic environment

The nonliving physical components of an environment (e.g., temperature, moisture, sunlight, pH, salinity, wind, soil) that shape biotic communities and ecosystem processes.

Biotic environment

The living components of an ecosystem (plants, animals, microorganisms) that interact with abiotic factors.

Dynamic environment

An environment that is changing over time, with conditions shifting across ecological, evolutionary, or geological timescales.

Ecoregion

A geographically defined area with characteristic climate, soils, and vegetation that shapes the local biotic communities.

Driftless Region

An area (northeast Iowa, southeast Minnesota, southeast Wisconsin, northwest Illinois) not covered by the last glaciation, resulting in a unique assemblage of ecosystems.

Glacial cycles (Wisconsin glaciation)

Periods of glacial advances and retreats in North America over roughly the last two million years, shaping plant and animal distributions.

Plant migration in response to glaciation

Plant species moved south during glacial advances and back north as ice receded; movement aided by seed dispersal and animal-mediated dispersal; occurred multiple times.

Shelford's Law of Tolerance

A species’ geographic range is determined by the environmental variable to which it is most sensitive; distribution is bounded by the most limiting condition.

Zones of Tolerance (ZIT)

The range of an environmental variable in which a species can survive; bounded by upper and lower tolerance limits beyond which the species is absent.

Zones of Physiological Stress (ZPS)

The range where a species is present but experiences physiological stress; survival and reproduction are reduced; populations may decline or disappear if stress is severe.

Optimal Range (OR)

The 'sweet spot' where a species has maximum survival, reproduction, and robust population levels.

Critical Factor (CF)

A single environmental factor that limits the geographic range of a species in a given area (e.g., extreme heat or extreme cold).

SP (single-factor-limited species)

Species whose geographic range is limited by a single critical factor.

Dissolved Oxygen (DO)

The amount of oxygen dissolved in water; cold water holds more DO than warm water; essential for aquatic species like trout and salmon and influences habitat suitability.

January average low temperature threshold

A winter low-temp limit (e.g., mean January lows around 32°F/0°C) that can prevent survival or limit distribution of some species.

pH as a limiting factor

The acidity/alkalinity of water that can constrain which aquatic species can survive in a habitat.

Goldilocks analogy

Not too hot, not too cold, just right; used to illustrate how species perform best within a moderate portion of an environmental gradient.

Ta and Nc axes

In tolerance curves, Ta = atmospheric temperature (x-axis) and Nc = census number (population size on the y-axis).

Armadillo range shift

Geographic expansion northward (e.g., in Missouri) over decades due to warming winters; illustrates how climate change can alter species distributions.

Polar bear range and ice dependence

Polar bears are confined to ice-covered polar regions and are highly vulnerable to warming temperatures, which threaten their suitable habitat.