Evidence For Natural Selection Flashcards
5 Different Pieces of Evidence
Artificial Selection, Fossil Record, Comparative Anatomy, Comparative Embryology, and Molecular Biology
Artificial Selection
Selective breeding of organisms for desired traits.
Difference from natural selection
Humans are the pressure instead of the environment.
how long have we been modifying organisms
Thousands of years
Example of artificial selection
Cash crops, chicken, cattle (eurochs), dogs (wolves), bacteria
Fossil record
Chronology is appropriate, complexity comes later. Existence of transitional forms.
Example of Fossil Record
Prokaryote before eukaryote before multicellular. Vertebrate decent. Fish to amphibians to reptiles to birds to mammals. Archeopteryx, tikktalik, hominid species.
Comparative Anatomy (3 structures)
Homologous structures – physical structures built the same sharing common ancestry but used for different purposes. Analogous structures – Structures used for the same purpose but built differently. Independent evolution due to same selective pressures. Vestigial structures – evolutionary remnant that haven’t been completely selected away.
Comparative Anatomy Example (Homologous)
Cat forelimb, human hand, whale flipper, bat wing.
Example (Analogous)
Whale flipper and shark pectoral fin.
Example (Vestigial)
Snake limbs, pelvic bones, mole eyes.
Comparative Embryology
Closely related species pass through similar developmental stages.
Comparative Embryology Example
Vertebrates pass through a gill slit stage with a tail (humans included)
Molecular Biology
Similar organisms have similar DNA sequences and produce similar proteins. (Genes and gene expression, reflects common ancestry)
Molecular Biology Example
All plants make rubisco enzyme, humans and chimps share 98% of genome.
