Natural selection is the process by which organisms with traits that better suit their environment tend to survive and pass on those traits, while organisms with less advantageous traits tend not to survive or reproduce. Charles Darwin observed that organisms vary, some are better adapted to their environment, and these better-adapted organisms are more likely to survive and reproduce, passing on their favorable traits. Over generations, this leads to changes in the characteristics of populations and evolution of species as the proportion of individuals with beneficial traits increases.
This document provides information about genetic variation and evolution. It discusses how genetic variation arises from mutations and gene shuffling during sexual reproduction. It also describes how natural selection and genetic drift can change allele frequencies in a population over generations, resulting in evolution. Key factors that can lead to the formation of new species like geographic isolation and reproductive isolation are also summarized. Studies on Darwin's finches provide evidence of natural selection shaping beak traits in response to environmental pressures like food availability.
The document discusses several key topics related to biodiversity and evolution: - It estimates that there are 10 million species on Earth, demonstrating high biodiversity. - It defines evolution as genetic changes in a population over generations, and describes microevolution within populations and macroevolution leading to new species. - The main mechanisms driving microevolution are natural selection, where individuals with advantageous traits are more likely to survive and reproduce, and genetic drift. - Speciation occurs when one species evolves into two or more reproductively isolated species, increasing biodiversity, and can happen in isolation (allopatric) or without isolation (sympatric).
This document discusses how natural selection and genetic drift can cause evolution by changing allele frequencies in populations over time. It explains that natural selection may cause some alleles to become more common if they increase an individual's chances of survival and reproduction. Genetic drift is the random change in allele frequencies that can occur in small populations by chance. The document also describes the conditions required by the Hardy-Weinberg principle for a population to maintain genetic equilibrium and not evolve.