Commercial fisheries target older, larger cod fish, causing cod that reproduce at a younger age and smaller size to be favored by natural selection. Younger, smaller cod have fewer offspring than do older, larger cod. Predict how evolution in response to fishing would affect the ability of a cod population to recover from overfishing. What other reciprocal eco-evolutionary effects might occur? (See Concept 23.3.)

The evolution of a species' adaptive characteristics, which allows them to thrive in harsh environmental situations. Every species has developed from its ancestors, according to evolution. Natural selection leads to the evolution of any species in the population.

Splitting a group of animals or plants into two halves makes it impossible for them to cohabit.For instance, this is an evolutionary change, a river that forms after a flood or people migrating to an area with an impassable mountain range.

Regardless of how beneficial they are, subsequent mutations may only propagate within the group, not throughout the species.

A random sampling of organisms causes the frequency of gene variation (alleles) in a population, known as genetic shifts. Chance determines whether a specific individual can live and reproduce based on the alleles of the parents.

In the case of codfish, the impacts of genetic drift may become more relevant as its population shrinks. Drift, for example, could cause the fixation of detrimental alleles, limiting the cod population's ability to recover from overfishing.