Biotic factors - data
Living elements of an ecosystem, such as plants and animals. factors are living. They include:
- availability of food
- the presence of new An animal that hunts, kills and eats other animals for food. and Microorganism that causes disease.
Both the abundance and distribution of living organisms in an The living organisms in a particular area, together with the non-living components of the environment. are affected by biotic factors.
The effect of biotic factors on organisms
Red squirrels are native to Great Britain. They weigh around 300 grams, and about half the mass of the larger grey squirrel. The red squirrel A type of organism that is the basic unit of classification. Individuals of different species are not able to interbreed successfully. was introduced around a hundred years ago from America by wealthy land owners who wanted a fashionable addition to their forests.
The larger grey squirrel has provided competition for the native red squirrel, which has resulted in a lack of food for the species. Organisations like the Red Squirrel Support Trust have sampled the numbers of both squirrel types over time. Their results are shown below.
Question
What conclusions can you draw from this data?
In 1945 grey squirrels were only found in central Southern England and in small numbers on the East coast of Northern England. By 2000 they had spread throughout England and Wales. The red squirrel is now only found in parts of Scotland and Ireland. The pattern does not appear to have changed much between 2000 and 2015.
Question
What limitations might there be in drawing these conclusions and how could these be improved?
This information is only from one source. It could be compared with others to ensure its reliability.