Variation in Living Things

Study Notes

Living organisms within a particular species exhibit a remarkable range of variations in traits, despite their shared characteristics. These differences can manifest in several ways, including but not limited to physical attributes such as size and coloration, as well as behaviors that may vary from one individual to another. Moreover, physiological traits, which pertain to the functioning of organisms, can also differ significantly. The origins of these variations are multifaceted; they may stem from genetic diversity, where different alleles contribute to varied phenotypic expressions, or from environmental factors such as climate, food availability, and habitat type that influence survival and reproduction. Additionally, these variations can represent adaptive responses perfected over generations as species encounter different challenges in their environments. A comprehensive understanding of these differences is fundamental for the study of evolutionary biology and the preservation of biodiversity across ecosystems.
Different species can be differentiated by their unique features, such as variations in ear length, which may influence their ability to hear or regulate body temperature, and differing tail types that can serve important functions like balance, communication, or grasping. These characteristics can help in identifying species and understanding their ecological adaptations.
Prehensile tails are found on monkeys specifically from Central and South America.

Individuals within a species are not completely identical, showcasing subtle variations.
Examples of variations include height, finger length, and earlobe attachment.

Continuous Variation: Features vary gradually within a range, like human height or body mass.
Discontinuous Variation: Features have a limited number of distinct states with no gradual transition, like gender or the presence/absence of earlobes.

Features passed from one generation to the next are called characteristics.
The study of these inherited characteristics led to the discovery of genes and the field of genetics.

Gregor Mendel experimented with pea plants to understand how characteristics are inherited.
He controlled pollination by manually transferring pollen and preventing unwanted pollination.
Mendel's experiments suggested that each feature is governed by inherited "factors" (later identified as genes).
He proposed that these factors came in pairs with instructions passed on from parents to offspring.