Adaptation and Evolution - SS3 Biology Past Questions and Answers - page 2

Natural selection and adaptation to the environment

Mutation and genetic drift

Homologous structures in different species suggesting a common ancestor

Adaptation in nature refers to the process by which organisms undergo structural, behavioural, or physiological changes to better suit their environment. Examples include camouflage in animals, drought-resistant traits in plants, and thermoregulation mechanisms. Adaptation enhances an organism's chances of survival and reproduction, leading to the passing on of advantageous traits to future generations, ultimately contributing to the process of evolution.

Competition in nature refers to the rivalry among organisms for limited resources such as food, territory, and mates. This competition drives natural selection, favouring individuals with advantageous traits and leading to the survival of the fittest. Examples include the competition between predator and prey, interspecific competition among different species sharing the same ecological niche, and intraspecific competition within a single species. These competitive interactions play a significant role in determining species distribution, abundance, and overall biodiversity in ecosystems.

The theory of evolution is supported by various lines of evidence. Palaeontology provides evidence of transitional fossils, showcasing the gradual changes in species over time. Comparative anatomy reveals homologous structures, indicating common ancestry among different species. Molecular biology studies show similarities in DNA and proteins, confirming genetic relatedness between organisms. Biogeography highlights the distribution of species across different regions, supporting the idea of evolution through geographic isolation. Collectively, these lines of evidence provide compelling support for the concept of evolution.

The modern theory of evolution is based on several key principles. Genetic variation, arising from mutations and genetic recombination, introduces diversity within populations. Natural selection acts upon this variation, favouring individuals with traits that offer a survival advantage in their specific environment. Over time, this process leads to the gradual adaptation and change of species, as less fit individuals are less likely to survive and reproduce. Speciation occurs when populations become reproductively isolated, leading to the formation of new species. Unlike earlier concepts of evolution, the modern theory incorporates the role of genetics and emphasizes the gradual and cumulative nature of evolutionary change. Genetic mutations serve as the raw material for new traits, providing the genetic basis for evolutionary innovations and adaptations.