Abiotic factors such as temperature, water availability, salinity, light and pH can act as selection pressures in evolving populations in evolving populations.
Coverage 2011–2025 · Updated 16 Jul 2026
Abiotic conditions can act as selection pressures when they affect survival or reproduction differently among heritable phenotypes.
High or low temperature, drought, salinity, pH and other physical conditions may affect individuals regardless of population density, so they are density-independent pressures.
Abiotic condition changes → physiological performance differs → survival or reproduction differs → alleles associated with advantageous traits become more frequent.
During repeated low-temperature events, plants with inherited frost tolerance may survive and set more seed, increasing the frequency of tolerance alleles.
A useful response is evolutionary adaptation only if it is heritable and changes reproductive contribution; temporary acclimatization alone does not alter allele frequency.
This objective is assessed through structured response, commonly using Outline / Explain.
Outline / Explain
Build the answer around this relationship: Abiotic factors are non-living parts of the environment.
Representative question
Explain how natural selection is influenced by changes in the environment.
Core D4.1 examples follow the same causal route: heritable variation exists, a selection pressure acts, individuals differ in fitness, and alleles linked to higher reproduction become more common. Endler’s guppies and sexual selection are evidence versions of the same chain.
Core natural-selection exam answers should never stop at “the best adapted survive.” They need the chain: heritable variation exists, a named pressure acts, some individuals have higher fitness, and their alleles become more common over generations. Use this for abiotic pressure, overproduction, sexual selection, and Endler-style data.
