Explain how abiotic factors can determine the boundaries of a species' fundamental niche, using temperature as an example.

The fundamental niche is the full range of abiotic and biotic conditions under which a species could theoretically survive and reproduce.

Temperature is an abiotic factor that limits a species’ niche. Each species has a thermal tolerance range – a lower and an upper limit – within which its enzymes work efficiently, allowing normal metabolism, growth and reproduction.

Temperatures below the lower lethal limit or above the upper lethal limit cause enzyme denaturation or metabolic failure, so the species cannot survive or reproduce outside this range. These limits therefore set the temperature boundaries of the fundamental niche.

The niche can be visualised as a multidimensional hypervolume; temperature is one axis, and other abiotic factors such as pH, salinity and light intensity add further axes that together define the full fundamental niche.