Question #f7bab

1 Answer
Nov 8, 2017

There are many reasons that often work together.


Habitat loss - Many habitats are being destroyed due to human development and agriculture, this removes the habitats of species.

Example: the palm oil industry relies on deforestation and this is threatening the orangutan.

Climate change - Many species can only tolerate certain temperatures and a change (up or down) can threaten them.

Example: in some turtle species eggs developing above a certain temperature will be males and eggs developing below a certain temperature will be females. Therefore, if the average global temperature increases there will be an increase in female turtles, resulting in a biased sex ratio, a decrease in offspring and subsequently fewer turtles.

Over hunting/harvesting - If an animal is hunted too much or a plant if harvested too much the population numbers can become dangerously low.

Example : humans have been overfishing cod and their numbers are declining rapidly.

Competition with other species - This often occurs when a new species is introduced to a new area and it outcompetes native species.

Example : In the 19th century the prickly pear was introduced to Tenerife for agriculture. The prickly pear is a cactus that is very well adapted to dry areas, the species spread rapidly through the island, meaning it is taking up resources needed by the native plants. This can result in a reduced population of the native species.

Disease - Disease can kill large numbers of species.

Example : red squirrels are native to the UK, but the grey squirrel was introduced by humans. The grey squirrel carries a disease that does not affect them, however it devastated red squirrel populations.

Pollution - Can result in the death of species.

Example : Oil spills have been known to kill many birds.

Low genetic diversity - This is a particular problem when species numbers are low. Genetic drift is more damaging in low population as a species with a low population is more likely to lose genes through chance.

There is rarely a single reason for a species being endangered,
often the reasons above combine.