Species: group of organisms that breed with one another & produce fertile offspring
Formation of a new species = speciation. Happens:
- Isolation --> geographically
- Genetic variation
- Natural disasters
- Natural selection
individuals - genetically diverse offspring
compete food, water, mates
competative traits, survive, reproduce
frequency of that allele increases in the population
Fossils: preserved remains, impression / traces of animals that lived millions years ago.
some fossils contain mineralised remains of organism // just an impression filled w/ minerals to produce a cast of organism.
1) mud & sand fall to sea bed. layers of sediment build up, heat, pressure covert sediment to sedimentary rock.
2) organisms die. soft tissue decomposes, leaving skeleton,
3) skeleton buried by sediment.
4) over millions of years, more fossils form. upper layers = more recent fossils