Unit 2: Evolution Flashcards
Fossil records
Most important evidence
-preserved remains of traces of organisms or its activities
-fossils are formed when an organisms body is trapped under rock and becomes compressed into layers
Erasmus Darwin
All organisms come from a single life source
Lyell
Uniformitarianism -> Earth undergoes slow and steady change
Buffon
Buffon - species could change over time and create new species
Lamarck
Lamarck - Theory of acquired traits (if the environment changes the next generation would acquire a favourable trait)
Vestigial structure
Vestigial - a structure that was useful but now has lost its function (whale’s femur/pelvis, wisdom teeth and appendix)
Analogous structure
Analogous - species without a common ancestor but they have evolved similar features (insect wing and bird wing)
Homologous
Homologous -species with a common ancestor but they traits are now used for different functions (Horse and dogs legs)
Natural selection proposes…
-all species have inherited traits
-the variation in traits are selected by the species struggle for survival
- individuals will produce more offspring than will survive
Stabilizing selection
Stabilizing Selection - most common of the traits are favoured by the environment
Directional selection
Directional selection - one of the most extreme/rare traits are favoured by the environment
Disruptive selection
Disruptive selection - the 2 most extreme/rare traits are selected for while the most common dies off
Sexual selection
Sexual selectrion - allows for greater reproductive success
Behavioural Differences - doing a behaviour to attract a mate
Sexual Dimorphism - striking differences between males and females
Convergent Evolution
Convergent evolution - 2 species without a recently common ancestor evolve in a similar fashion because they exposed to the same environment (analogy)
Divergent evolution
Divergent evolution - when species with a recent common ancestor change to become different species (homology)
