BIOL112 - Ecology (Set 1)

Lecture 19 - Drivers of Distributions

What is the study of ecology?

Ecology is the study of the relationships between organisms and their environment.

What affects the distribution and abundance of organisms?

Abiotic factors, biotic interactions, behaviour, dispersal, and biogeography.

What is an optimum range?

A certain level for a factor where organisms grow or survive best.

What is a range of tolerance?

The entire range for a factor in which organisms are capable of surviving.

What are the limits for the range of tolerance?

The high and low ends of the range of tolerence.

What are zones of stress?

Areas between the optimum range and high or low limit of tolerence.

Is latitude or longitude more important for considering variation?

Latitude.

What are the key abiotic conditions for aquatic environments?

Temperature, light, depth, salinity, oxygen, soil type, and pH.

What are the key abiotic conditions for terrestrial environments?

Temperature, light, temperature, elevation, and soil type.

How does salinity differ between marine and freshwater aquatic environments?

Salinity is lower for freshwater environments (e.g. lakes, rivers, wetlands), and higher for marine environments (oceans, seas).

What are freshwater systems with flowing water called?

Lotic (e.g. rivers, streams).

What are freshwater systems with still water called?

Lentic (e.g. lakes).

Where in aquatic systems is light greater?

Near the surface and equator.

Where in aquatic systems is temperature higher?

Near the surface and equator.

Where in aquatic systems is there higher oxygen availability?

Near the surface (this is also influenced by the abundance of plants and animals).

How does species richness vary across the globe?

Species richness tends to increase towards the equator (less richness towards higher latitudes).

When is the population density of a species greatest?

When all conditions are optimal.

What does the range of tolerence affect?

An organism’s growth, health, survival, and reproduction.

How does stress increase along the range of tolerance?

Towards the upper and lower limits of tolerance.