Post on 23-Jun-2015
Darwin Presents His Case 15.3
Artificial Selection• Selection by humans for breeding of useful
traits from the natural variations among different organisms.
Struggle for Existence • Competition among members of a species for
food, living space, and other necessities of life.
Fitness • Ability of an organism to survive and
reproduce in its environment.
Adaptation
• Inherited characteristics that increases an organism’s chance of survival.
Survival of the Fittest
• Process by which individuals that are better suited to their environment survive and reproduce most successfully.
Natural Selection
• Process by which individuals that are better suited to their environment survive and reproduce most successfully.
Descent with Modification • Principle that each living species has
descended, with changes, from other species over time.
Common Descent
• Principle that all living things were derived from common ancestors.
Homologous Structures • Structure that have different mature forms in
different organisms but develop from the same embryonic tissues.
Vestigial Organ
• Organ that serves no useful function in an organism.
Key Concept
• How is natural variation used in artificial selection?–In artificial selection, nature provided
the variation, and humans selected those variations that they found useful.
Key Concept
• How is natural selection related to a species’ fitness?–Natural selection results in changes in
the inherited characteristics of a population. These changes increase a species’ fitness in its environment.