The Fundamental Niche: Abiotic Constraints on Organisms

Flashcards covering the fundamental niche, abiotic constraints, thermal and water regulation, and vector-borne diseases in the Anthropocene based on EEMB 120 Class 2 lecture notes.

Physiology

The branch of biology concerned with understanding the function of tissues, organs, and organ systems.

Physiological Ecology

The study of how organisms are physiologically adapted to their environment.

Niche

Environmental conditions under which we expect to find an organism, or the job/role a species has in an environment.

Fundamental Niche

The full range of environmental conditions (abiotic factors) under which an organism can survive, shaped by its tolerance of factors like heat and desiccation.

Realized Niche

The theoretical niche that is further constrained by biotic interactions, such as competition and mutualisms.

Trait

A heritable feature of an organism that can be measured on the level of the individual, such as body size, desiccation tolerance, or larval production.

Optimal Foraging Theory

The theory that natural selection favors individuals able to maximize energy intake per unit of time or effort to acquire resources effectively.

Principle of Allocation

The concept that organisms have a finite amount of energy to allocate to physiological adaptations, meaning evolving to tolerate one set of conditions reduces the capacity to adapt to others (trait tradeoffs).

Thermal Performance Curve

Also known as a Thermal Reaction Norm, it shows how an organism's performance varies with temperature, bounded by $T_{min}$ and $T_{max}$, with a peak at $T_{opt}$.

Endotherms

Organisms that expend metabolic energy to regulate their body temperature, typically maintaining more constant internal temperatures.

Ectotherms

Organisms that do not expend metabolic energy for temperature regulation and instead rely on external sources or behaviors (like using microhabitats) to maintain preferred body temperatures.

Homeotherms

Organisms that tend to maintain a constant body temperature regardless of environmental conditions.

Poikilotherms

Organisms whose body temperature is dictated by the temperature of their environment.

Thermal Neutral Zone (TNZ)

The range of environmental temperatures over which the metabolic rate of a homeothermic animal does not change.

Aestivation

A state of dormancy, usually in response to drought and heat, where an organism may dig underground to avoid extreme conditions.

Torpor

A state of slowed-down metabolism, usually in response to cold and food deficiency, to reduce energy expenditure.

Hibernation

A state of prolonged torpor.

Migration

The seasonal movement of organisms from one region to another and back again.

Osmosis

The movement of water through a cell membrane toward a more concentrated solution due to the presence of solutes.

Water Budget Equation

$$\text{Internal Water} = \text{Water Uptake} - \text{Water Loss}$$

Anthropocene

The proposed geological epoch for the present era, characterized by significant human impacts on Earth’s geology and ecosystems.

Vector-Borne Disease

Disease-causing agents (like plasmodia) transmitted by animals other than humans (the vectors, such as mosquitoes or ticks).

$$R_0$$

The number of new cases resulting from one single case, used to measure how infectious a disease is.

Three Scales of Temperature

The three scales of temperature are global, seasonal, and microhabitat.

Ways Organisms Deal with Temperature

Organisms may deal with temperature by actively regulating, adapting, or avoiding temperature extremes.

Temperature's Impact on Metabolism

Temperature affects the metabolic rates of enzymes; higher temperatures can enhance enzymatic activity up to a point, beyond which enzyme denaturation can occur.

Challenges for Marine Fish with Osmotic Stress

Marine fish face the challenge of losing water due to the higher salinity of seawater.

Solutions for Marine Fish with Osmotic Stress

Marine fish consume seawater and excrete excess salts through specialized cells in their gills.

Challenges for Freshwater Fish with Osmotic Stress

Freshwater fish must contend with the challenge of gaining excess water from their hypoosmotic environment.

Solutions for Freshwater Fish with Osmotic Stress

Freshwater fish excrete large volumes of dilute urine and actively absorb salts through their gills.

Disease-Causing Agents

Disease-causing agents include bacteria, viruses, parasites, and fungi that can lead to infections or diseases.

Disease-Causing Vectors

Vectors are organisms, typically arthropods like mosquitoes and ticks, that transmit pathogens from one host to another.

Impact of Warmth on Disease Vectors (Mosquitoes)

Warmer temperatures particularly influence the development rate of mosquito larvae, increase their biting rate, and extend their active seasons, leading to higher populations and increased transmission of vector-borne diseases.