Selection factors are those environmental conditions / factors that affect the individuals and thus their fitness. A distinction is made between abiotic (inanimate) and biotic (living) selection factors.
The selection factors are crucial for the direction of evolution.
Abiotic environmental factors: All selection factors that emanate from the inanimate environment. These can be:
temperature (Example 1: Individuals of one species are usually smaller in warmer areas than their relatives in lower latitudes -> Galapagos penguin inhabits the Galapagos Islands and is about 50cm tall, while the Antarctic emperor penguin comes to about 110cm : Bergmann's rule)
(Example 2: The relative length or size of extremities is greater in animal species in warm areas than in related animals in cold climates -> Comparison of the ear size of wild fox (fennec) and arctic fox See also: Allensche rule
humidity (Example: Exceptional environmental conditions, such as the enormous and prolonged aridity in desert areas, lead to plants with very low water consumption, up to the formation of stem succulents, which can store water)
wind (Example: The wings of the Kerguelenfliege (inhabiting the Kerguelen island groups in the Indian Ocean) have become stubborn in the course of the evolution.Flies with trained pair of wings were often blown out by storms on the open sea.Therefore on windy islands it can be an evolutionary advantage to have degenerated wings.
Nдhrstoffe (Example: Carnivorous plants are able to settle on nitrogen-poor soils as they can balance the missing minerals over their prey animals)
poisons (Example: Selection pressure when antibiotics are given to boost resistant bacterial strains.)