evidence for evolution Flashcards
stratigraphy
fossils in deeper rock are older than those above, and their position within these rock layers gives them chronological age relative to older (deeper) or younger (surface) fossils
why does the fossil record provide evidence for evolution (4)
if species where created independently here would be no order to the fossil record
the fossil record is a dated sequence of morphological change
fossil record also shows
anagenesis
common ancestry
perpetual change
& cladogenesis
fossil evidence of intermediate forms
evidence of evolutionary stability, e.g,, the horseshoe crab
evidence of evolutionary failure
what are evolutionary changes (4) (4)
evolutionary changes are directional changes in features & diversity of organisms
fossil evidence of intermediate forms define it
define it bitch
define cladogenesis (4)
where a lineage splits
define anagenesis (4)
small changes within a lineage
define comparative anatomy (4)
the study of the differences and similarities in the anatomy of different species
species that share a common ancestor will have some features in common because those features were present in the common ancestor.
comparative anatomy homologous trait (4)
pentadactyl limbs, each performs a function - flight, digging, swimming
all are superficially different
but all share a common, underlying anatomical plan
what is phylogenetic constraint (4)
evolution is constrained by ancestry
a species may inherit particular traits of developmental systems that constrain the possible variation that forms the basis for new adaptations
comparative embryology (know what it shows) (4)
closely related species go through similar stages of development
all terrestrial animals of pharygial slits (non-functioning gill slits) as early embryos
many vertebrates embryos
demonstrate primitive tail
this shows homologies - common ancestry
&
phylogenetic constraint
vestigial structures
structures that have no apparent function and appear to just be residual parts from a past ancestor, shows common ancestry, examples include: whale hip bones, human appendix
atavistic features
modification of biological feature where an ancestral genetic trait reappears after having been lost through evolutionary change in previous generations e.g. modern horse has one toe, rarely it can be born with other toes. shows anagenesis and common ancestry
analogous features (4)
similar features evolve independently through similar environmental selection pressures
convergent evolution (4)
seperate lineages that were quite different but become similar become of similar lifestyles. features that are similar in function but evolved independently are called analogous features
wings of bats, butterflies, birds evolved independantly from each other, not from a recent common ancestor, but they have a similar function, flight, so these are analogous
