Old and New Species Flashcards
What does evidence of early life come from?
Fossils
What are fossils?
The remains of organisms from many years ago, which are found in rocks
Fossils can be formed from the hard parts of animals that don’t…
Decay easily
Fossils can be formed from parts of organisms that have not decayed because one or more of the conditions needed for decay are…
Absent
Fossils can be formed when parts of the organism are replaced by…
Other materials as they decay
Fossils can be formed as preserved traces of organisms, ie (3)
Footprints, burrows, rootlet traces
What were many early forms of life? What do this mean in terms of fossils
Soft-bodied, so they left few traces behind
What destroyed some traces of soft-bodied organisms?
Geological activity
What can we learn from fossils?
How much or how little organisms have changed as life developed on Earth
What 6 factors may cause extinction?
New predators, new diseases, new competitors, changes to the environment, the cyclical nature of speciation, a single catastrophic event
What are 2 examples of single catastrophic events?
Massive volcanic eruptions, collisions with asteroids
New species arise as a result of…
Isolation, genetic variation, natural selection, speciation
Isolation?
Two populations of a species become geographically separated
Genetic variation?
Each population has a wide range of alleles that control their characteristics
Natural selection?
In each population, the alleles that control the characteristics which help the organism survive are selected
