The Imperfection of Life Flashcards
How is natural selection related to adaptations?
Natural selection results in adaptations.
What is an adaptation?
A phenotype that is selected for in a population. A heritable trait that increases the fitness of the individual with the at trait.
What is a contrivance?
An adaptation that has been evolutionarily modified during the course of its inheritance from the ancestral condition.
What is an exaptation?
A trait that was adaptive under a prior set of conditions and later provides the initial stage of for evolution of a new adaptation (contrivance) under a set of new conditions (descendants).
What is a vestigial trait?
A trait that is possessed by every member of a species but is no longer used in the present environment. (was most likely an adaptation for the ancestor)
What is atavism?
A trait that is no longer used or has no use in the present environment, but is possessed by a small number of individuals in the population.
What is homoplasy?
When organisms have traits in common but do not have a common ancestor that provided them those traits.
What is convergent evolution?
The independent natural selection of similar traits by unrelated individuals. It is the most common form of homoplasy.
How can adaptations be compromises if they are supposed to increase an organism’s fitness?
Adaptations aren’t perfect. There are conflicting demands in every environment and thus conflicting adaptations. A certain adaptation could provide an organism success in one situation while proving to be detrimental in another situation.
How are adaptations affected by environmental change?
When natural selection occurs in a population, it is the current set of environmental conditions that is selecting for or against certain traits. But when the environment changes, those adaptations lag behind. And if the environment is continuously changing, the adaptations will always lag behind, meaning that the organisms may never look the best-suited for the current conditions.
How are adaptations limited?
Natural selection is not a process that creates new traits: it acts on pre-existing variation in a population. The adaptive changes in the morphology of a species is dependent on pre-existing structures.
How are contrivances and exaptations related?
Both contrivances and exaptations are adaptations. You cannot have one without the other, because adaptations are developed from structures that already exist.
A contrivance at once time may serve as an exaptation to a new adaptation (contrivance) at another time.
How do adaptations fit into the biological hierarchy?
How does natural selection result in adaptations?
Exptation gives rise to a contrivance. That contrivance can become an exaptation that gives rise to another contrivance. Is this process called evolution? Could you say that evolution is the process by which new adaptations are developed upon older adaptations over time? (Because technically, new adaptations would be genetically inherited from the parents to the offspring?)
