Evidence of Evolution

Grade 10 BiologySpring 2011

Describe how the fossil record supports evolution

Summarize how biological molecules such as proteins and DNA are used as evidence of evolution

Infer how comparing the anatomy and development of living species provides evidence of evolution

Fossils show a pattern of development from early ancestors to modern descendents

Offer direct evidence that evolution has taken place

Provide an actual record of Earth’s life forms

Change over time (evolution) can be seen in the fossil record

Fossil intermediates linking great groups of organisms have been found Between fish and amphibians Between reptiles and birds Between reptiles and mammals

Based on a large body of supporting evidence, three major points: Earth is about 4.5 billion years old Organisms have inhabited Earth for most of its

history All organisms living today share common

ancestry with earlier, simpler life forms

The fossil record, the record of evolution of life, if not complete

Many species have lived in environments where fossils do not form

Most fossils form when organisms and traces of organisms are rapidly buried in fine sediments deposited by water, wind, or volcanic eruptions Organisms also decay at different rates

The fossil record will never be complete, but it still presents strong evidence to support evolution

Paleontologist: scientists who study fossils Discover fossils and analyze sediments around

it Radiometric dating of rocks and minerals, can

arrange the fossils in order from oldest to youngest

Shows orderly pattern of evolution

Comparisons of anatomy of different types of organisms often reveal basic similarities in body structures even though the structure’s function may be different

Vestigial structures: bones that are present in an organism but have been reduced in size and either have no use or have a less important function than they do in the other related organism Ex. Hind limbs of whales

Homologous Structures: are structures that share a common ancestry As different groups of vertebrates evolved,

bodies evolved differently Similarities in bone structure can still be seen Similar structure in two organisms can be

found in the common ancestor

Development of embryos shows evolutionary history In some point of

development all vertebrate embryos have a tail, buds that become limbs, and pharyngeal pouches

If species have changed over time, then the genes that determine species’ characteristics should also have changed by mutation and selection

Changes would have become part of their genetic instructions

Changes in a gene’s nucleotide sequence should build up over time

Prediction was first tested by analyzing amino acid sequence of similar proteins found in several species

Of evolution occurred, then species descended from a recent common ancestor should have fewer amino acid differences between their proteins than do species that share a common ancestor in more distant path i.e. humans and chimps should have fewer

differences in their proteins than humans and frogs

Species that are thought to have shared a common ancestor more recently (humans and gorillas) have few amino acid sequence differences

Species that are though to have shared a common ancestor more distant past (humans and mice) have many amino acid sequence differences

Hemoglobin Comparison

Species A.A differences from human hemoglobin

protein

Gorilla 1

Mouse 8

Rhesus monkey 27

Chicken 45

Frog 67

Lamprey 125

This pattern, doesn’t hold true for all proteins, some proteins may evolve more rapidly than others

Evolutionary histories are generally not inferred from any single protein’s amino acid sequences

More accurate evolutionary histories are based on large numbers of gene sequences

These evolutionary histories based on DNA sequences tend to be very similar to evolutionary histories inferred by biologist based comparative anatomy and evidence from fossil record

Game: http://biodude.wikispaces.com/file/view/E

volution+Review+Game.pdf