Introduction to Evolution

Natural selection

Natural selection

________ can only increase or decrease heritable traits that vary in a population.

Homology

________: similarity resulting from common ancestry and is the result of divergent evolution.

Homologous structures

________: anatomical resemblances that represent variations on a structural theme present in a common ancestor.

Traits

________ are inherited from parent to child.

Orthologs

________ occur in separate species.

Convergent evolution

________ does not provide information about ancestry.

Selection

________ can act only on existing variations.

Natural selection

________ increases the match between organisms and their environment over time.

Convergent evolution

________: the evolution of similar, or analogous, features in distantly related groups.

natural selection

If an environment changes over time, ________ may result in adaptation to these new conditions and may give rise to new species.

Homology

similarity resulting from common ancestry and is the result of divergent evolution

Homologous structures

anatomical resemblances that represent variations on a structural theme present in a common ancestor

Convergent evolution

the evolution of similar, or analogous, features in distantly related groups

Homologous genes

two genes derived from the same ancestral gene

Natural selection increases the match between

organisms and their environment over time

Why can't natural selection fashion perfect organisms?

Selection can act only on existing variations

Evolution is limited by historical constraints

Adaptations are often compromises

Chance, natural selection, and the environment interact

Two sequences may be similar but not identical due to

the independent accumulation of different random mutations