Definitions [1]
Definition: Adaptation
An adaptation is any advantageous structural or functional characteristic developed over time that enables a living organism to survive, reproduce, and constantly adjust to its specific changing environment.
Key Points
Key Points: Population Attributes
- Population is the basic ecological unit for studying genetics, evolution, and ecological change.
- Population density tells the number of individuals per unit area or volume.
- Natality increases population size, while mortality decreases it.
- Sex ratio describes the proportion of males and females in a population.
- The age pyramid helps in identifying whether a population is growing, stable, or declining.
Key Points: Life History Variation
- Organisms evolve life history strategies to maximise reproductive (Darwinian) fitness in their environment.
- Different species adopt different strategies based on selection pressures.
- Some organisms reproduce once in a lifetime (e.g., salmon, bamboo), while others reproduce multiple times (e.g., birds, mammals).
- Species may produce many small offspring (e.g., oysters) or few large offspring (e.g., mammals), depending on survival needs.
- These variations are shaped by biotic and abiotic factors, and studying them is an important area in ecology.
Key Points: Adaptation
- According to Darwin’s natural selection theory, only the most viable and adaptable species successfully survive the struggle for existence.
- The continuous adjustment of a species to its new surroundings serves as the primary factor driving the formation and conservation of species.
- Organisms that are unable to adjust to shifting environmental conditions will gradually diminish in the course of evolution and eventually face extermination.
- These constant structural and functional adjustments directly match living forms to their changing environment, ensuring their survival within specific ecological limits.
