Species Selection Pressure
(Redirected from Selection Pressure)
Jump to navigation
Jump to search
A Species Selection Pressure is an evolutionary force that alters the behavior, physiology, or genetics of organisms, leading to changes in the population over time.
- Context:
- It can (typically) result from environmental factors such as availability of resources, climate changes, and predator-prey relationships.
- It can (often) cause populations to evolve by selecting for advantageous traits, while unfavorable traits may diminish over time.
- ...
- It can range from being a Strong Selection Pressures (such as those exerted by severe environmental changes) to being a Weaker Selection Pressure (e.g. from gradual, long-term factors like sexual selection).
- It can range from being a Abiotic Selection Pressures (like climate, water availability, and soil composition) to being Biotic Selection Pressures (like competition, predation, or parasitism).
- It can range from being a Density-dependent Selection Pressures (where the intensity of selection changes with population size) to Density-Independent Selection Pressures (where factors like weather or natural disasters apply selection pressures regardless of population size).
- ...
- It can affect organisms of all sizes, from bacteria and viruses (e.g., antibiotic resistance) to plants and animals, shaping their evolutionary trajectories.
- It can drive adaptive traits, such as camouflage, resistance to toxins, or faster reproductive cycles, increasing survival rates in changing environments.
- It can lead to the formation of new species by contributing to Reproductive Isolation and Speciation events.
- It can be observed in controlled settings like laboratory experiments on Artificial Selection as well as in natural environments, such as predator-prey dynamics in ecosystems.
- It can act on traits such as size, coloration, behavior, metabolic rates, or reproductive success, depending on what confers survival advantages in a given environment.
- It can be both positive (favoring the survival of a trait) or negative (reducing the frequency of a trait in the population).
- ...
- Example(s):
- a Peppered Moth Selection Pressure (for Peppered Moths in Industrial England), where pollution caused dark-colored moths to be favored due to better camouflage, occurring during the late 19th and early 20th century.
- a Giraffe Neck Selection Pressure (for Giraffes in African Savannas), where taller giraffes with longer necks were favored due to their ability to access higher leaves, resulting from food scarcity in recent millennia.
- a Antibiotic Resistance Selection Pressure (for Bacteria), where exposure to antibiotics leads to the survival of resistant strains, observed in medical environments in recent decades.
- a Polar Bear Selection Pressure (for Polar Bears in Arctic Regions), where selection favored bears with thicker fur and greater fat reserves due to cold environments over thousands of years.
- a Cheetah Speed Selection Pressure (for Cheetahs in African Plains), where selection favored individuals with higher sprinting speed for successful hunting, resulting over thousands of years.
- a Homo Sapiens-Related Selection Pressures, such as:
- a Human Lactose Tolerance Selection Pressure (for Homo sapiens in Northern Europe), where populations developed lactose tolerance as a beneficial adaptation due to dairy farming around 7,500 years ago.
- a Human Malaria Resistance Selection Pressure (for Homo sapiens in Sub-Saharan Africa), where populations evolved traits like sickle cell trait to survive malaria, within the last 10,000 years.
- a Human Skin Pigmentation Selection Pressure (for Homo sapiens), where lighter skin was selected in higher latitudes to facilitate vitamin D synthesis, occurring over tens of thousands of years.
- a Darwin’s Finches Beak Selection Pressure (for Galapagos Finches), where changes in available food sources led to selection of different beak sizes and shapes, observed over the last 2-3 million years.
- a Pesticide Resistance Selection Pressure (for Insects in Agricultural Fields), where resistance to pesticides evolved due to repeated exposure, within the last 50 years.
- a Desert Plant Water Conservation Selection Pressure (for Desert Plants), where traits like reduced leaf surface area and water storage capabilities were selected over millions of years.
- a Polar Fox Camouflage Selection Pressure (for Arctic Foxes in Polar Regions), where white fur provided camouflage in snow-covered environments, evolving over tens of thousands of years.
- ...
- Counter-Example(s):
- Genetic Drift, which involves random changes in gene frequencies that are not driven by selection pressures.
- Neutral Evolution, where genetic changes have no effect on the fitness of the organism and thus are not influenced by selection pressures.
- Gene Flow, which may reduce the effects of selection pressures by introducing new alleles into a population.
- See: Natural Selection, Sexual Selection, Adaptive Traits, Speciation, Artificial Selection, Evolutionary Biology.