Adaptations - Modes of Selection Flashcards
What is an adaptation?
A characteristic which increases fitness
=> same adaptation can occur independently from each other for diff. reasons
Examples of adaptations occurring independently
- Unfused skulls occurred in reptiles + birds for easier hatching while it must be for easier live birth in mammals
- Feathers in dino for thermal insulation then later asymmetrical in birds for flight
What is the process of adaptation?
A process whereby organisms become better suited to their environment
The 3 types of Adaptation
Structural - Physiological - Behavioural
What are structural adaptations?
Having adaptations in anatomy to increase fitness
e.g. a penguin’s short stiff tail - can lean back, balance on heels + reduce heat loss from feet
What are physiological adaptations?
Having adaptations in physiology, resulting in changes in responses to the environment to increase fitness
e.g. penguin’s heart rate slows on dives to conserve o2 + spend more time hunting
What are behavioural adaptations?
Changes in behaviour that species do to increase fitness - is learned
e.g. penguins huddle together to conserve heat in winter
Why adaptations are not perfect? - Consequence of Construction
Some adaptations come about without purpose
=> as a result of genetic variation that is neutral (no pro or con)
Why adaptations are not perfect? - Physical Constraint
Some adaptations are physically inefficient or not feasible in a natural environment
e.g. can’t evolve wheels despite efficiency but can’t supply nutrients blood etc. and isn’t useful on irregular terrain
Why adaptations are not perfect? - Historical Constraints
A species may have reached peak fitness for its environment but then it changes
=> can’t reduce fitness to getter across a valley of reduced fitness to then later increase isn’t possible
Why adaptations are not perfect? - Time lag can limit adaptation
A species can be adapted to rely on another species to increase fitness
=> if the other species is extinct, fitness reduces
Why adaptations are not perfect? - Genetic Constraints
Sets evolutionary potential as traits with limited gene variation have little heritability - can only change weekly as a response
- Adaptative combos to traits may not evolve due to genetic correlation between traits caused by pleiotropy (a single gene causes phenotype of diff. traits)
Why adaptations are not perfect? - Trade-off /Compromise
- Organisms must distribute finite resources like time or metabolic energy
- Adaptive evo. is constrained by trade-offs that demands the same resource
- Based on demands rather than genetics + can explain behavioural adaptations
