B2 Biology - Speciation Flashcards
what three ways are fossils formed?
gradual replacement from minerals
casts and impressions
preservations in places no decay happens
what are casts and impressions?
organism buried in soft mineral like clay, clay hardens and organism decays leaving a cast of itself
where can preservation of fossils happen?
glaciers
peat bogs
tar pits
what are some reasons why species become extinct? ( 6 reasons)
environment changes new predators new disease cant compete for food catastrophic event new species develops
what is speciation?
development of new species
when does speciation occur?
when populations of the same species become so different that they no longer breed together to produce fertile offspring
what is isolation?
where populations of species are separated
when does isolation occur?
physical barrier eg. floods, earthquakes
different climates
different characteristcs or change in environment
what is natural selection?
organisms better adapted to their surroundings survive and produce more offspring with the change in adaptations
- weaker die
