Abiotic Factors Drive Selection by Their Density-Independent Impact
- Abiotic factors, the non-living components of an ecosystem, shape populations by exerting density-independent selection pressures.
- Unlike biotic factors, which depend on interactions between organisms, abiotic pressures affect individuals regardless of population size or density.
Definition
Abiotic factors
A non-living component of the environment, such as temperature, light, or water availability, that influences the survival and reproduction of organisms.
Definition
Biotic factors
A biotic factor is a living organism that shapes its environment.
Examples of Abiotic Factors in Selection
- Abiotic factors influencing natural selection include:
- Temperature Extremes: Frost or heatwaves can selectively impact survival.
- Salinity: Organisms must tolerate specific salt concentrations in their habitat.
- Droughts and Floods: Water availability is a critical factor for both plants and animals.
- Soil and pH Levels: Soil composition and acidity affect plant survival.
In a marine ecosystem, biotic factors can include: algae, plankton, bacteria, plants, corals, fIsh, sharks, and jellyfish.
Density-Independent Abiotic Factors
- Density-independent factors affect populations regardless of their size or density.
- These factors often include extreme or catastrophic events, such as:
- Temperature Extremes: Heatwaves or freezing temperatures.
- Natural Disasters: Floods, wildfires, or earthquakes.
- Pollution: Chemical spills or air pollution.
- Climate Events: Droughts or hurricanes.
- Abiotic factors are density-independent because their impact remains constant regardless of population size.
- Frost in Plants: In a sudden frost, all plants in a population experience the same conditions.
- Differences in frost tolerance determine which individuals survive.
- Salt Concentrations in Salicornia: Marsh samphire thrives in salt marshes because its cells store excess salt, making it more tolerant to high salinity.
