Biology Chapter on Variation and Adaptation (B4)

Variation

• Variations are observable differences between organisms.
• Variations occur between different species (interspecific variation) and within the same species (intraspecific variation).
• Variation is crucial for survival.

Sexual Reproduction and Variation

• Sexual reproduction is a major contributor to variation within a species.
• Offspring inherit 50% of their DNA from each parent, resulting in new gene combinations and characteristics.
• Variations that enhance survival and reproduction are more likely to be passed on to offspring.
• These advantageous variations can become more common in a population over generations, leading to adaptations.

Phylogeny

• Phylogeny studies the evolutionary history of species or groups of organisms.
• It investigates the origins of variation.

Adaptations

• Adaptations are structural, behavioral, or physiological traits that help organisms survive and reproduce in their environment.
• Structural adaptations relate to an organism's physical appearance.
  • For example, owls have long talons to aid in predation.
• Behavioral adaptations relate to an organism's actions.
  • For example, geese migrate to warmer climates during winter.
• Physiological adaptations relate to internal functions.
  • For example, scorpions produce venom.

Mutations

• Mutations are small changes in the genetic code.
• They occur during DNA replication, which is not always perfect.
• Mutations result in changes in gene expression.

Types of Mutations

• Neutral mutations: No effect on the organism.
• Harmful mutations: Reduce an organism's fitness.
• Beneficial mutations: Enhance an organism's fitness.

Mutations and Selective Advantage

• Some mutations produce beneficial changes in individuals.
• Mutations that increase survival chances are more likely to be passed on.
• Mutations are more common in changing environments.

Natural Selection

• Natural selection describes how traits that increase survival and reproduction become more common in a population over time.
• This process drives evolutionary change.

Natural Selection and Environment

• Whether a trait is selected for or against depends on the organism's environment.
• Environmental changes drive variations within a population.
• Natural selection does not anticipate future environmental changes.
• Random changes can create traits that become beneficial in the future.

Example of Natural Selection: Skin Color

• Skin color is an example of a trait influenced by natural selection.

Explore the concepts of variation, sexual reproduction, phylogeny, and adaptations in this biology quiz. Understand how these elements contribute to the survival and evolutionary history of organisms. Test your knowledge on how variations can lead to adaptations in different species.