Question

By what mechanisms can adaptation be constrained?

Answer 1

Adaptation is a feature which enhances the fitness of an organism in a population. An Adaptation evolves through natural selection and has evolved due to the selective advantage for the current function.

There are several constraints on adaptation:

1. Ecological conditions & life History strategies by

having tradeoffs between reproduction, survival, and lifespan, thus adaptation cannot maximize everything. e.g. The favoured phenotype depends on if you have high/low predation

2. Developmental constraints are constraints due to developmental dynamics which select biologically realizable phenotypes. e.g.Irish elk in which development of height limited to development of antler size.

3. Phylogenetic constraints by current features are modifications of ancestral features, which limits selection in improving fitness to the environment. e.g. Three-digit limb which modifies the basic design for grasping, walking, flying, swimming, digging.

4. Genetic Constraints by variation (lack of genetic variation constrains selection), pleiotropy & linkage (creates the situation where traits aren't always independent). e.g. Irish Elks are constrained because body size & antler size correlated.

4. Engineering Constraints: Organisms have to obey physical and chemical laws. e.g. Life without water is not possible.