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Evidence for Evolution (for SPHS)

Terms in this set (13)

homologous structure
an anatomical structure found in different species that shows evidence of being inherited from a common ancestor
embryology
this is the study of developmental similarities that indicate common ancestry, such as the leg nubs Darwin found when studying developing snakes or teeth in developing whales
biogeography
the study of species' and ecosystems' distributions across continents and over geologic time; helps scientists understand how continents were arranged on earth in the past.
molecular homology
similarities in DNA or protein sequences that indicate descent from a common ancestor
law of superposition
states that rock layers are laid down sequentially, from oldest to youngest; allows scientists to date fossils and determine ancestry
punctuated equilibirium
a model of evolution where long periods of no evolutionary change (stasis) are followed by short periods of rapid evolutionary change and the formation of new species; probably caused by a sudden, drastic environmental change.
gradualism
a model of evolution where species slowly change over long periods of time, showing many intermediate steps; probably results from slow environmental change.
vestigial structure
a structure no longer used in the same way as it was in a species' ancestor.
fossil evidence
What type of evidence indicates that the circled species in layer 1 could have been the ancestor of the boxed species in layers 2-5?
vestigial structure
Cats and dogs have a dewclaw--a raised fifth toe not used for walking. Most other mammals, as well as reptiles and amphibians, have five toes. What is the name for this kind of structure?
biogeography
A species of salamander in India is more similar to salamanders in Africa than in surrounding Asian countries. What explains this similarity?
embryology
all developing vertebrates have skin in between their toe bones. In reptiles, birds and mammals, this webbing is reabsorbed before birth or hatching. What explains this similarity during development between land animals and fish?
DNA evidence
Scientists studying possums, bears, and beavers find fewer differences within an important developmental gene between bears and beavers, than when they compare either to possums. What type of evidence shows that bears have a more recent common ancestor with beavers?
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