natural selection 
noun [mass noun] Biology
The process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as be the main process that brings about evolution. Compare with survival of the fittest (see survival).Studying the Galapagos islands helped to inspire Charles Darwin's theory of natural selection....
- By a process of natural selection the better adapted individuals and species survived while the others died out.
- The theory of evolution by natural selection is the unifying theory of biology.
- xoloitzcuintli
- XOR
- XOR gate
- XPF
- x-radiation
- X-radiograph
- X-radiography
- X-rated
- X-ray
- X-ray astronomer
- X-ray astronomy
- X-ray binary
- X-ray burst
- X-ray burster
- X-ray crystallographer
- X-ray crystallography
- X-ray dermatitis
- X-ray diffraction
- X-ray diffractometer
- X-ray fish
- X-ray fluorescence
- X-ray microscope
- X-ray nova
- X-ray pulsar
- X-ray spectrum