Evidence for Evolution Flashcards
5 pieces of evidence for evolution
fossils, geographical distribution (biogeography), comparative anatomy, embryological development, biochemical/molecular
How do fossils show evidence for evolution?
Fossil evidence shows how some organisms changed slowly over time
ex) Older rocks contain fossils of simpler organisms
How are fossils organized?
by the age of the fossil
(oldest –> youngest)
Examples of relationships that fossils can show
dinosaurs and birds
whales and four-legged mammals
Fossil record
chronological collection of life’s remains in rock layers recorded during the passage of time
What are fossils?
the preserved remains of ancient organisms
How do geographical distribution (biogeography) show evidence for evolution?
they show the existence of an a common ancestor
Biogeography
the study of where organisms live now and where they and their ancestors lived in the past
Two biogeographical patterns of evolution
divergence (closely related species differentiate from different environments)
convergence (distantly related species become similar from similar environments)
What happens to an organism when a bunch are spread out over a bunch of islands?
they differentiate because of differing environments
Examples of differentiation based on the environment (biogeography)
finches on the Galapagos Islands having different beaks and fur color
How does comparative anatomy show evidence of evolution?
Suggests that these organisms developed from a common ancestor
Homologous body structures
similar structures found in more than one species that share a common ancestor
Vestigial structures
organ/structure that serves no useful function in an organism
What do vestigial structures suggest?
organs had a function at one time but as the organism changed over time, it was no longer needed.
Examples of vestigial structures
appendix and coccyx in humans; leg bones in whales
Examples of homologous structures
forelimbs of mammals
ex) humans, cats, whales, and bats have very similar skeletal parts in the forelimbs
Why are homologous structures different?
different functions
ex) humans have metacarpals for dexterity, bats have very long metacarpals to have more tissue -> bigger wingspan
How does embryological development show evidence of evolution?
provides visual evidence that organisms descend from a common ancestor, even if their adult forms are different
Embryos of closely related organisms have…
similar early stages of development
ex) All vertebrates (animals with backbone) have an embryonic stage in which pouches appear on the sides of the throat
The development of embryos adds evidence to evolution. How?
homologous bones and organs developing from the same clumps of embryonic cells in vertebraes
Embryo
an unborn or unhatched offspring in the process of development
Similarities of embryos of different species
eye placement, vertebrae, head formation, etc.
How does biochemical/molecular analysis show evidence of evolution?
“confirmation” of evolution
(can only be applied to existing organisms)
