Chapter 3 Flashcards
What is the norm of reaction?
A graph representing a phenotype expressed by a given genotype as a function of environmental conditions.
Phenotype - y-axis / Environmental conditions - x-axis / Genotype - a single curve/line
What does irreducibly complex mean?
A system composed of many well-matched, interacting parts that does not function if any one part is removed.
It is difficult to imagine such a system evolving step-by-step, as each new part would need to add a slight improvement.
What is a trade-off in biological terms?
Organisms allocate their energy to enhance one trait, which often decreases the fitness of another trait due to constraints such as resource limitations.
Example: In some fish populations, natural selection drove a trade-off where female fish produce large offspring, increasing their survival chances, but can only produce a small number of these offspring due to the energy required for their size.
What is adaptation?
A trait that has evolved as a consequence of selection favoring its current function, increasing an organism’s fitness.
Example: Waxy cuticle of cacti to prevent water loss.
What is exaptation?
A trait that has an adaptive function different from the function that caused it to evolve in the first place.
Example: Bird feathers adapted for thermoregulation, but had exaptations for flight.
What is coevolution?
Where interacting species evolve together due to their interaction, influencing each other’s evolutionary adaptations.
Example: A plant evolves to secrete a toxic chemical as a defense mechanism, and a herbivore evolves resistance to the toxin by altering the tertiary structure of an enzyme.
What is gene duplication?
A new duplicate copy of a gene produced by mutation, providing an evolutionary pathway where an extra copy of a working gene can gain a new function without changing the function of the original gene.
