Biotic Factors That Affect Population

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How are populations affected past conditions in an ecosystem?

The affluence of organisms in an ecosystem is dependent upon biotic (living) and abiotic (non-living) factors. Affluence and distribution are estimated using techniques such equally transects and quadrats.

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Biotic factors affecting the abundance and distribution of organisms

The abundance and distribution of organisms are also affected past biotic factors, which are factors that are living.

Availability of food

All animals require food to live. The availability of food is a major factor in how many animals live in an ecosystem . Areas like rainforests with rich food supplies have more than species of life than other areas similar deserts and the polar regions where there is less nutrient.

New predators

The arrival of new predators in an ecosystem can take a devastating effect. In balanced ecosystems, predators and prey accept evolved together. Predators can catch plenty prey to survive, simply not too many to mean they kill all their prey.

The arrival of a new predator can upset this balance. An example of this is the introduction of the red fox to Australia , which has caused concern over their effect on native birds and pocket-sized mammals. Introducing new predators can cause a rapid decline in the numbers of prey, which then reduces the food supply for existing predators.

New pathogens

A constitute affected past ash dieback disease

When organisms inhabit new ecosystems they oftentimes bring new pathogens . As an example, when Europeans first colonised North America, they introduced new pathogens like the influenza virus. Many Native Americans had not developed immunity to new diseases such every bit this, so many were killed past them.

In that location are many examples of new pathogens existence introduced to the UK. Ash dieback is a affliction caused by a fungus which has killed many ash trees since it was kickoff found in the UK in 2012.

Pathogens accept likewise been introduced on purpose. Myxomatosis is a disease that affects rabbits. It is caused past a virus and infected rabbits develop skin tumours and may get bullheaded. In the 1950s information technology was purposefully released into the wild in the UK to reduce the population of rabbits. It did exactly this and some people estimate that more than than 99 per cent of rabbits in the UK died. Nevertheless, our rabbits developed immunity to it and the population has now returned to previous levels.

Out-competition

The introduction of a new species into an ecosystem can result in it out-competing another native species. Several hundred years ago grayness squirrels were brought over from North America by wealthy people and let free in their grounds. Our smaller native red squirrel couldn't compete with the newer, larger gray squirrel. Because grey squirrels are larger they can shop more fatty and survive harsher winters. So the numbers of carmine squirrels and the places they live has reduced dramatically.

Other examples of out-contest of native species by newly introduced species include the Canada goose in Europe and the cane toad in Australia, Himalayan balsam in Cambodia and harlequin ladybirds in United kingdom are also current concerns.

The effect of biotic factors on organisms

Cerise squirrels are native to Britain. They weigh around 300 grams, about half the mass of the larger grey squirrel. The grey squirrel species was introduced around a hundred years agone from America past 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 nutrient 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.

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 tin can you depict from this information? [4 marks]
: In 1945 grey squirrels were only plant in primal Southern England and in small numbers on the East coast of Northern England [1 mark] . By 2000 they had spread throughout England and Wales [1 mark] . The red squirrel is at present merely found in parts of Cumbria, Island of Wight, Scotland and Republic of ireland [1 mark] . The design does non announced to have changed much between 2000 and 2010 [1 mark] .

Question: What limitations might in that location exist in drawing these conclusions and how could these be improved? [2 marks]
: This information is only from one source [ane mark] . It could be compared with others to ensure its reliability [i marker] .