Evolutionary Theory

Genetic variation also arises through processes like mutation, genetic recombination during meiosis, and horizontal gene transfer, not just the simple passing of existing genetics.

Regulatory regions control gene expression. Mutations here can change the rate of transcription (how much protein is made) or disrupt the binding sites entirely, preventing expression.

The Hardy-Weinberg equilibrium assumes a population is not evolving (no mutation, no selection, large population, random mating, no gene flow). Real-world populations rarely meet these criteria.

Evolutionary change is most easily observed in organisms with rapid generation times, such as bacteria or insects, because changes accumulate quickly enough to be measured within a human timeframe.

RNA is generally less stable than DNA and lacks the extensive proofreading mechanisms that DNA replication possesses, leading to higher mutation rates and faster potential evolution.

RNA is more susceptible to mutation because it is single-stranded and lacks the robust error-correction machinery that double-stranded DNA uses during replication.

The primary reason evolution is observed more quickly in mosquitoes than in humans is their short life cycle, which allows for many generations to pass in a short amount of time.

Fossils of transitional or intermediate forms provide strong evidence for evolution by showing links between groups (e.g., whale ancestors, bird-dinosaur transitions). These fossils document evolutionary changes over time.

Fitness is defined by the ability to survive and reproduce. A mutation that decreases fitness will naturally reduce the individual's survival or reproductive success, leading to fewer offspring.

Darwin observed that organisms have the potential to produce more offspring than the environment can support, which leads to competition and is a key driver of natural selection.

Adaptations are specific to the environment in which they evolved. An organism that is highly fit in one environment may not possess the traits necessary to survive or thrive in a different, contrasting environment.

Darwin developed his theory of evolution before the discovery of DNA and the mechanisms of inheritance. Modern molecular biology, specifically DNA sequencing, has provided overwhelming evidence that confirms the shared ancestry Darwin proposed.

Mutations are random changes in the DNA sequence. They are the ultimate source of new genetic variation in a population, providing the raw material upon which natural selection acts.

In evolutionary biology, fitness is defined by an organism's ability to survive and reproduce. Therefore, the most direct measure is the number of offspring that reach reproductive age and pass on their genes.