Lecture 2: Environmental Influences

Environmental factors affect

- individual organisms, populations, communities and ecoscapes.

What processes do environmental factors affect?

Productivity, decomposition, and nutrient cycling.

Environmental factors can be _____ or _________.

Abiotic or biotic.

True or false: Environmental factors affect survival, tolerance, resistance, and the existence of organisms in an environment.

True.

Abiotic factors are and include.

Nonliving factors that have implications for survival.

•Temperature

•Moisture

•Radiation

•Wind and currents

•Nutrients

•Toxic substances

Biotic environmental factors can be _______ or _________

Conspecific - of animals belonging to the same species

Interspecific - across species

Biotic factors have a ________ or _________ impact.

direct or indirect

Principle of limiting factors

Certain ecological processes are controlled by whichever environmental factor is present in least supply relative to demand for it.

What controls growth

the limiting factor (factor with the lowest availability relative to need)

Example of the limiting factor

Eutrophication in Lake Erie.

- productivity of lakes or other bodies of water increased as nutrients added. - this increase leads to noxious algae blooms.

- not enough interaction between water molecules and the environment

- not as much oxygen

- organisms die.

Eutrophication

productivity of lakes or other bodies of water increases as nutrients are added.

What is one of the most sophisticated and complex system on earth?

Tropical rainforests.

- Have an abundance of resources and a high productivity.

- Lots of resource availability.

Some organisms are able to thrive in extreme environments, such as

Thermophilic bacteria and organisms in high altitudes.

Limitation of growth is called

stress

Stressors are

environmental influences that limit the performance of organisms.

True or false: Most ecosystems do not have limiting factors.

False. Limiting factors are present in majority of ecosystems in the world.

Tolerance is defined as

How long an organism can survive limiting factors.

Trying to survive the limiting factor is called

Stress

What is the stress exposure response model?

•describes how biological and ecological changes will occur when the capacity of the system to endure stressors is exceeded.

What is phenotypic plasticity?

the ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions

True or false: Phenotypic plasticity allows the acclimatization of a genotype to stress.

True.

What does long term exposure to stress over generations lead to?

Genetic adaptation

The organism's performance and fitness under stress is influenced by

The degree of adaptation

Stressors limit

growth

Disturbances affect

already grown organisms

Disturbances

interruptive experiences that will shape your experience.

We build our ability for adaptation due to

disturbance

True or False: Disturbances are permanent.

False. Disturbances are temporary.

Explain the difference between stressors and disturbances

Stressors - environmental influences that limit the performance of organisms - related to attributes such as productivity and fitness. inherent, attributes that are characteristics of species.

Disturbances - externalities that come into system and interrupt it. Rapid change. Followed by period of ecological recovery known as succession

True or false: Organisms tolerate stressors to different extents.

True

Anthropogenic stressors

Stressors modified or caused by human activty.

Changed climate or hydrology, increased levels of toxic substances, diminishing of vital stocks are all examples of

anthropogenic stressors.

Pollution

increased concentrations of natural substances such as metals which have ecological effects. effects lessen with increasing distance from the source.

Biomagnification

Humans produce toxic substances that do not occur naturally like DDT and they can accumulate in food chains producing unexpected effects.

What are the primary factors affecting structure and function of ecosystems?

Biotic and abiotic factors

Principle of limiting factors shapes growth of organisms (Leibig law) but when they persist,

stress manifests.

Stressors are either

Anthropogenic or environmentally induced.

Resilience

speed and degree to which an organism, population, community, or landscape can recover to its original condition following a disturbance or after some other stressor becomes lessened in intensity.

What do mineral nutrients often limit

ecosystem productivity,

imports of limiting nutrients in an ecosystem can lead to

eutrophication

phosphorous limits lake productivity, the addition of it leads to

eutrophication

When something is trying to survive it mimics strange behaviour which can constitute

evolutionary change

when exposure exceeds a limit of tolerance a change will occur called a

response

Disturbances can create opportunities for

species that require open space for establishment and growth.

Lasting damage around the world is connected to

anthropogenic stressors

Examples of anthropogenic stressors

pollution, climate or hydrology change, biomagnification

Example of direct biotic effect

predation

example of indirect biotic factor

Competiton for limited resources

- trees reducing amount of light for smaller plants.