Science Notes Revision: Evolution

Biodiversity

• Biodiversity refers to the variety and variability of life forms on Earth, encompassing different genes, species, and ecosystems.
• Species diversity measures the number of distinct species present in an ecosystem.
• Genetic diversity indicates the range of genetic variations within a species.

Evolution

• Evolution involves gradual changes in the characteristics of species over extensive periods and across multiple generations.
• All living organisms share a common ancestor, suggesting a universal origin of life.

Causes of Genetic Variation

• Genetic variation arises from mutations in genes that can be inherited across generations, creating new gene options and phenotypes.
• Environmental variation includes non-genetic traits developed in response to environmental factors, which can influence selection.

Mutations

• Mutations are spontaneous alterations in an organism's genetic material, introducing new genetic variations.
• Changes in DNA sequence can impact protein production, potentially leading to significant changes in an organism's traits.

Gene Pool and Allele Frequency

• The gene pool of a population comprises all the genetic copies present within that group.
• Allele frequency determines how prevalent a specific allele is within a population, impacting genetic diversity.

Bottleneck Effect

• A reduction in genetic diversity resulting from a severe decrease in population size, which can lead to a less varied gene pool and increase extinction risk.

Founder Effect

• Occurs when a small group from a larger population establishes a new population, leading to reduced genetic variation and potential differences in allele frequency compared to the original population.

Importance of Genetic Variation

• Genetic variation plays a crucial role in determining individual phenotypes, with some variations providing better adaptations to the environment.
• Organisms with advantageous traits have a higher survival and reproductive success, aiding overall species persistence.

Natural Selection and Speciation

• According to Darwin, natural selection serves as the primary mechanism driving evolutionary change.
• Natural selection favors traits that improve an organism's chance of survival and reproduction, ultimately leading to speciation over time.

This quiz covers key concepts in evolution and biodiversity, including species diversity and genetic diversity. Discover how species change over time and the implications of the theory of evolution. Perfect for students revising their science notes.