The document summarizes key concepts about the origin of species from Charles Darwin's theory of evolution by natural selection. It discusses Darwin's observations in the Galapagos Islands that led to his ideas, defines microevolution and macroevolution, and describes the biological species concept of reproductive isolation. It also covers the mechanisms of allopatric and sympatric speciation, examples of adaptive radiation, and models of punctuated equilibrium versus gradual evolution.
36. LE 24-8
Failure of cell division
in a cell of a growing
diploid plant after
chromosome duplication
gives rise to a tetraploid
branch or other tissue.
Gametes produced
by flowers on this
tetraploid branch
are diploid.
Offspring with
tetraploid karyo-
types may be
viable and fertile—
a new biological
species.
2n = 6
4n = 12 4n
2n