Speciation (fossils) Flashcards
WHAT ARE FOSSILS
A fossil is preserved remains or traces of dead organisms.
Fossils are found in rocks
WHAT ARE FOSSILS FORMED FROM?
- Hard body parts such as bones and shells which do not decay easily
- cast or impressions from footprints or burrows
WHAT DOES STUDYING FOSSILS TELL US?
Scientists can learn how much or how little organisms have changed as life developed on earth
— however many early life forms were soft bodies so they left few traces behind
WHAT IS EXTINCTION
A species becomes extinct when the last individual dies
Animals that have not adapted to their environment well are less likely to survive
FACTORS THAT CAUSE EXTINCTION
- disease
- new predators
- changed to the environment
- a single catastrophic event
WHAT IS GENETIC VARIATION?
Where each population has a wide range of alleles that control their characteristics
WHAT IS NATURAL SELECTION
Where the alleles which help an organism to survive are selected in each population
WHAT IS SPECIATION
Where the populations become so different that successful interbreeding cannot happen anymore
ISOLATION
New species can also arrive as a result of isolation where two populations of species become geographically separated
E.g. Darwin described the separation of finches in this way
