Final answer:
The number of pest species is typically proportional to habitat area; as the habitat area increases, so does the number of species, based on the species-area relationship. However, specific interactions, such as competition and resource overlap, can influence these general trends. Conservation preserves are created to be large enough to maintain biodiversity and prevent species extinction.
Step-by-step explanation:
The number of pest species in relation to island or habitat area generally follows the species-area relationship, which can be summed up by saying that as the area of habitat increases, so does the number of species. This is described by ecological studies, including island biogeography, which draw correlations between habitat size and biodiversity. However, in some specific cases, a pest species might increase in population when there is an overlap in the needs for resources, and there isn't sufficient competition to curb their numbers. For example, if Species A increases in population due to overlapping needs for food and nesting space, and Species B remains the same, this could indicate a lack of competition or predation allowing Species A to flourish.
Conservation efforts often focus on creating preserves that are large enough to maintain biodiversity. The size of the preserve depends on the particular needs of the species it aims to protect, with larger preserves supporting a broader range of species and providing more optimal habitat and niche diversity. Scientists use various metrics, such as the total number of species and the density of the population (population size divided by the area) to assess biodiversity.
It is also important to note that a decrease in habitat area generally leads to a decrease in the number of species present due to the species-area relationship. For instance, a forest area reduction from 100 km² to 10 km², or a 90 percent decrease, can result in a reduction of species by about 50 percent. This demonstrates the significant impact of habitat size on biodiversity and why habitat conservation is of paramount importance.