Question

What are two possible explanations for why a species has a limited distribution (for example saguaro cactus appears in Arizona but not Baja California)?

Answer 1

The possible explanation to the limited distribution of species are as follows:

a) Climate : Each area has their own characteristics in the case of climate. Every organism or species has a microclimate which is specific to them. The environment in which the species live in provides all the favourable conditions for their survival. Other areas may not provide them an adequate microclimate for them to function normally. Hence they are confined to a particular area and limits their distribution.

2) Anthropogenic action : Major factor which cause the limitation in the distribution of species include anthropogenic actions. The human activities increase the environmental pollution, habitat distruction of the species, introduction of alien species, over exploitation of the habitat of the species etc. All these will result in reduction in distribution of the species and can also lead then to the verge of extinction.

In case of the example given, saguaro catcus is seen in Arizona but not in baja california. Saguaro is a catcus found in Sonoran desert located in Arizona. The speciallity of saguaro catcus is that they cannot survive high elevation and cold climate. Baja callifornia has a mediterranian climate and they can a cooler climate than that which can be tolerated by saguaro catcus and the climate is also very different.