Biology 101- Evidence of Evolution Pick up DARWINS NATURAL SELECTION journal. Begin working on this. EVERYONE NEEDS TO BE IN THEIR SEAT WORKING BY THE TIME THE BELL RINGS!!

Sources of Evidence for Evolution From observations Biochemistry From studies of embryology From the fossil record From studies of anatomy From studies of DNA From Geographic distribution

Fossil Structure Fossil- Remains of organisms Usually found in sedimentary rock Relative age- “date” fossil based on where it is in rock strata Absolute dating: measures decay of radioactive elements into stable forms (Carbon-14 and Uranium-238) Decay rate is steady (half-life)

How is Half-life calculated? How does radioactive dating work? Since decay is steady, you can calculate how old something is by how much of it is left Ex: Carbon 14 converts to Carbon 12 when it decays Decay rate is 5,700 years If you start with 1 gram of Carbon 14, after 5,700 years there would be ½ gram of it left

Archeopteryx Archeopteryx shows evidence of the evolution of birds from reptiles There is evidence of feathers (from birds) There are claws (from reptiles)

Evidence from common structures: Similar skeletal organization Are called Homologous structures- body parts similar in structure but not necessarily in function Suggests common ancestor- but each adapted to different environments

Anatomical studies show.. What are other organisms that have the ability to fly, but have wings very different from those of birds? Structures like the wings of birds and wings of insects are called… Analogous Structures- similar in function, but different structures Do not have a common ancestor, but have evolved with similar adaptations due to similar environments

Do these organisms, a bird, mammals and a fish, show analogous structures or homologous structures? Convergent evolution: results in analogous structures Different bone structures, but similar functions due to similar environments

Do these organisms show analogous or homologous structures? Many different species evolving from a recent common ancestor would be an example of divergent evolution, all showing homologous structures Over 70 lemur species evolved from a species that colonized Madagascar less than 60 million years ago

Why would this bird have wings if it doesn’t fly? Structures are so reduced in size that they are vestiges or traces of homologous organs in other species called VESTIGIAL STRUCTURES

Anatomical Studies show… Why does this salamander have eyes if it never sees the light of day? Human vestigial structures Why does a whale have a pelvis and femur bone if it has no hind limbs? Why does a boa have a remnant hind limb?

Why do these structures occur? These structures may be homologous to ones that had a function in the ANCESTORS of these organisms thus suggesting their evolution from this common ancestor.

Today’s activities The Molecular Connection

Getting Started: Tues 4/22 EVIDENCE PT 2 NOTES START HERE….

Embryology Studies Even though it may not be apparent during the first stage of development, these 5 organisms are very different at later stages of development and at birth Why do they look so similar to each other during early development? Organisms having more similarities during later stages are thought to have a more recent common ancestor

Studies of Biochemistry Humans and chimpanzees have no differences in this amino acid sequence suggesting their close evolutionary relationship They have a more recent common ancestor than any other two species shown Human V-H-T-A-T-A-A-S-D-L-A-T-D-K-R-C-H-E-Y-A Chimp Gorilla V-H-T-A-T-A-A-S-D-L-A-T-D-K-K-C-H-E-Y-A Horse V-Q-S-A-L-A-S-G-E-V-H-A-D-K-R-V-R-D-Y-A

DNA The sequence of the nucleotides making up the DNA would also be similar because DNA determines the sequence of amino acids in the proteins DNA sequences can be used to make “family tree” so that we can see how closely related different species are

What is this diagram showing you What is this diagram showing you? What could be a possible explanation for this?

Penicillin patch Penicillin patches were placed in a bacteria culture. One patch showed growth of bacterial colonies while another one did not. What happened? Bacteria colony grows

Evidence from Geographic distribution Biodiversity First suggested evolution to Darwin Species tend to be more closely related to other species from the same area than to species with the same way of life, but living in different areas Islands tend to have many endemic species that are closely related to species from the nearest mainland

Different Geographic regions, different mammalian “brands” Flying Squirrel from North America Sugar Glider from Australia Different Geographic regions, different mammalian “brands”

Has and Does Evolution Occur? Scientists do not dispute that evolution does occur. Evolution is a fact. How evolution occurs is not completely understood. Charles Darwin explained how evolution occurred through natural selection. Natural selection is a well documented theory uniting all of biology. Modern evolutionary theory uses ideas of genetics, particularly mutations, to help explain how evolution may occur

Today’s Agenda Embryological Evidence Molecular Connection- DNA analysis (front table) Complete any work you have not already finished.