ACROSS
1. study of patterns in the geographic distribution of species and communities.
3. degree of adaptation to an environment, as measured by an individual’s relative genetic contribution to future generations.
5. supercontinent that formed about 300 million years ago; broke up 100 million years later.
8. a form of a heritable trait that enhances an individual’s fitness.
9. line of descent.
10. physical evidence of an organism that lived in the ancient past.

DOWN
2. method of estimating the age of a rock or fossil by measuring its radioisotope content.
4. supercontinent that existed before Pangea, more than 500 million years ago.
6. change in a line of descent.
7. characteristic time it takes for half of a quantity of a radioisotope to decay.