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Evidence For Evolution
Common Descent (See earlier notes/slideshow)
Anatomy - Homologous/Analogous/Vestigial Structures
Fossil Evidence
Embryological Evidence
Biochemical Evidence
Anatomy
structural features with common evolutionary origin
similar in arrangement, function, or both
suggest a common ancestor
Homologous Structures
AnatomyHomologous Structures
AnatomyHomologous Structures
Darwin’s Finches
Anatomy
structural features without common evolutionary origin
similar only in function
common ancestor does not have that structural feature
Analagous StructuresAnatomy
Analagous Structures
The supports for insect wings are not homologous with bones of bat/bird wings.
Bones are homologous
Insect and bird wings evolved separately when difference ancestors adapted differently to similar ways of life
Anatomy
Living in the open ocean as a fish eater requires a streamlined body and the ability to move very quickly when needed. These pressures caused first sharks, then ichthyosaurs and finally dolphins, to all adopt a very similar body shape and method of movement.
In all these animals the tail is the major motor, other flippers and fins are used merely for steering and the body has taken on a shape that has the least resistance to water.
They come from three animal groups that have been separate for hundreds of millions of years yet there they are, all looking so much alike.
Ichthyosaurs, Dolphins, and Sharks
Analagous StructuresVestigial Structures
body structure with no function in a present-day organism, but was probably useful to an ancestor
a structure becomes vestigial when the species no longer needs the feature
Vestigial StructuresThe Wings
of Flightless BirdsHind Leg Bones
in Whales
Vestigial StructuresErector Pilli
and Body HairThe Human Tailbone
(Coccyx)
Vestigial StructuresThe Blind Fish,
Astyanax mexicanusWisdom Teeth In
Humans
Vestigial StructuresThe Human
AppendixMale Breast Tissue
and Nipples
Fossils
provide record of early life
similarities suggest ancestral relationships between difference species
Fossils used to trace the
evolution of the modern camel.
Ancestors were as small as rabbits.
Embryologyembryo - earliest stage of growth and development in plants and animals
gill slits and tail in each embryo, not present in any of these as adults, except fish
similarities in embryos suggest evolution from distant, common ancestors
Biochemistrystructure of molecules of life reflect descent from common ancestors
similar vital molecules in all species “molecular fossils”
nucleic acids came first (RNA), still in all organisms,and then DNA-based inheritance developed
comparison of DNA and RNA identifies how closely related species are
triplet code to make proteins used in bacteria to man