Evolution 3 & Evolution 4 Flashcards
Describe stratigraphy
o Assumes rocks above others= younger than those below
o Chronological age relative to older (deeper) or younger (surface)
o May be incorrect (geological processes)
Define anagenesis
(change within a lineage)
define cladogenesis
formation of one or more species (speciation) from another over time
relationship between clad and anagenesis
Cladogenesis= formation of one or more species (speciation) from another over time (branching evolution) > followed by straight line anagenesis
What is the fossil record evidence for
perpetual change common ancestry evolut/ trends intermediate forms evolutionary failure evolutionary stability
does the fossil record provide evidence for fact course or mechanism
fact and course
explain perpetual change
oldest= simple, current= complex shows change
explain evolution failure & stability
o Evolutionary failure: not enough variation to survive change + selective pressures
o Evolutionary stability: little selection pressures= small change of evolutionary time
comparative anatomy and embryology both show what evidence
common ancestry, + phylogenetic constraint
define phylogenetic constraint
evolution constrained by ancestry, can only evolve from what was previously there
explain homologies
Organs modified for different functions
o But all share common, underlying anatomical plan
define vestigial
Organ having become functionless in course of evolution
why are vestigial organs not lost fully, and why is the feature not necessary
- Why haven’t lost completely: difficult to eliminate genes that control creation
- Feature not necessary- is minimised so not to use up energy for its maintenance
what are atavistic features
genetic throwback
what are analogous features evidence of
convergent evolution
define convergent evolution
independent evolution of trait in rather distinctive evolutionary lines
- separate lineages becoming similar because of similar lifestyles
- results in features similar in function, but evolved independently (= analogous features)
similar answers to similar selection pressures describes what
analogous features
what are the three features related to ancestry, function and appearance
homology= ancestry analogy= function homoplasy= appearance
what is artificial selection produce evidence for
mechanism of natural selection rather than just the fact of evolution
define adaptive radiation
Formation of many new species following availability of new environments or development of new adaption
- Radiation of species to fill available niches
what do you need for evolution and won’t occur if there isn’t
- Need:
o System of reproduction
o Inherited variation- genetic differences (mutation)
o Differential reproductive success (aka fitness) - None will occur if there isn’t:
o Changing environment
o Selective pressures
is evolution random
- Evolution is not random (its process can be but not evolution itself)
does natural selection produce perfect organism
o Acting on individuals in environment at that time
o Can only get variation on what was previously there
