General Evolutionary Concepts

General Evolutionary Concepts

• Evolution is a change in allele frequency in a population over generations
• Genetic variation is present in all populations and is a prerequisite for evolution
• Natural selection is adaptive evolution that increases a population's fit to its environment. The environment selects for the best/least fit phenotypes.
• Environmental change leads to changes in fitness.
• Other evolutionary mechanisms (not adaptive):
  • Migration/gene flow is the movement of individuals from one population to a new one; random movement can counteract or support natural selection.
  • Mutation is rare, random, and can have positive, negative, or neutral effects; it increases variation in populations.
  • Genetic drift is a change in allele frequency due to random factors and is most significant in small populations. Bottleneck and founder effects are types of genetic drift
  • Bottleneck effect occurs when a disaster reduces population size, leaving few random individuals.
  • Founder effect occurs when a random assortment of a few individuals found a new population.

Allele and Genotype Frequencies

• Allele frequency = number of copies of an allele / total number of alleles in the population.
• Genotype frequencies are calculated based on the number of individuals with each genotype.

Species Interactions

• Competition (-/-) : Involves two competing species both losing some resources.
• Predation (+/-): One species benefits, and the other is harmed, for example, an Arctic fox and lemming.
• Parasitism (+/-): One species benefits by absorbing nutrients, while the other loses nutrients, for example, tapeworms and humans.
• Mutualism (+/+): Both species benefit, for example, bees and flowers.
• Commensalism (+/0): One species benefits; the other is unaffected, for example, egrets and cattle.

Fundamental and Realized Niches

• Fundamental niche: the total area/habitat that a species could potentially occupy in the absence of others.
• Realized niche: the actual/current area/habitat that a species occupies when others are present.
• Competition and other factors can cause a species' realized niche to be smaller than its fundamental niche.

Mechanisms of Evolution

• Natural selection/adaptive evolution
• Descent with modification and homologous features (examples)
• Convergent evolution and analogous features (examples)
• Mutation (non-adaptive)
• Genetic drift (non-adaptive)
• Bottleneck & Founder Effect
• Migration/Gene Flow

Taxonomy

• Taxonomy/classification is the science of describing, naming, and classifying species.

Specific Notes

• Homozygous (GG); Heterozygous (Gg); Homozygous (gg) determine genotype frequencies for the guppy species.
• Evidence of speciation comes from the inability of the two populations (A and B) to interbreed, resulting in a confirmation using the biological species concept.

Other Concepts

• Speciation (allopatric, sympatric)
• Fossils (transitional - Tiktaalik)
• Mass extinctions and adaptive radiations
• Human evolution
• Prokaryotes vs. Eukaryotes
• Evolution of eukaryotic organelles
• Transitions to life on land
  • Vertebrate animals (features)
  • Land plants (features)

Test your knowledge on the fundamental principles of evolution, including natural selection, genetic variation, and evolutionary mechanisms. This quiz covers key concepts such as migration, mutation, and genetic drift. Understand how these factors contribute to the evolutionary process and the dynamics of populations over time.