Adaptation is any structural, functional, or behavioural characteristic of an organism that enables it to survive and reproduce successfully in a particular environment.
Definitions [2]
Define the carrying capacity.
Habitats are species-specific and have resources up to a limit that can support a maximum number of individuals to grow and reproduce; this limit of habitat to subsist a species is called carrying capacity.
Definition: Adaptation
Key Points
Key Points: Population Attributes
- Population - Group of same species in a given area, sharing resources & reproducing. E.g., cormorants in a wetland, lotus in a pond.
- Birth & Death Rate - Measured per capita. Birth rate = 8/20 = 0.4 offspring/lotus/year; Death rate = 4/40 = 0.1 individuals/fruit fly/week.
- Sex Ratio - Proportion of males to females. E.g., 60% females & 40% males.
- Population Density (N) - Number of individuals per unit area. Can be as low as <10 (Siberian cranes) or millions (Chlamydomonas). Sometimes measured as biomass or % cover.
- Indirect Estimation - Used when a direct count is difficult. E.g., fish per trap = lake density; tiger census uses pug marks & fecal pellets.
- Population Ecology - Connects ecology to genetics & evolution. Natural selection operates at the population level.
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
- Adaptation is any morphological, physiological, or behavioural feature that helps an organism survive and reproduce in its habitat.
- Desert plant adaptations → Thick cuticle, sunken stomata, and reduced leaves (spines in Opuntia) help to reduce water loss.
- CAM pathway → Special photosynthesis in desert plants where stomata remain closed during the day to minimise transpiration.
- Behavioural adaptation → Desert lizards regulate body temperature by basking in sun or moving to shade/burrowing.
- Cold region adaptations (Allen’s Rule) → Animals have shorter ears and limbs to reduce heat loss; aquatic mammals have a thick fat layer (blubber) for insulation.
