Evidence of Evolution [15.2] SPI 5 Apply evidence from the fossil record, comparative anatomy, amino acid sequences, and DNA structure that support modern classification systems.

What are some of the way fossils are formed? Transitional Species: description & examples Vestigial Structures: description & examples Comparative genomics Comparative embryology

Fossils Compression/impression – Organism is squished or imprinted into a 2D layer Permineralized fossils. – Minerals leech in from the ground and replace soft tissue Casts and molds – Ground hardens around organism, leaving the shape of it behind Preserved organic material – Ice, peat bogs, amber

Homologous Structures – Characteristics that are similar because they share an evolutionary origin are homologous Analogous Structures – Characteristics that look similar but have independent evolutionary origins are analogous

Transitional Species If evolution happens to an extent that new species evolve from ancestral species, shouldn’t we find fossils of “in-between” species in the fossil record? Yes!

Winged Lizards 11 fossils from Southern Germany, dated to ~150mya Archeopteryx

Microraptor gui China, 120mya – 4 winged dinosaur

Early tetrapods Eusthenopteron- one of the earliest “lobe finned” fishes that display structures of both fish and amphibian Late Devonian ~385mya

Acanthostega & Ichthyostega Upper Devonian ~365mya Younger species of “fishapods” with progressively more developed pectoral and pelvic girdles, legs, and feet

Tiktaalik roseae Early Devonian ~375mya Fish: gills, scales Fishapod: half-fish, half- tetrapod limb bones and joints, including a functional wrist joint and radiating, fish- like fins instead of toes; half-fish, half-tetrapod ear region Tetrapod: tetrapod rib bones tetrapod mobile neck tetrapod lungs

Other examples? Mammal-like Reptiles Horses Many others…

Vestigial structures – structures that once had a function but that there is no longer a use for. Whales have a pelvis but no legs Snakes have legs Humans have a tail

Comparative Embryology – study of embryonic development Closely related species have very similar patterns of development Fish Salamander TurtleChicken Pig Cow Rabbit Human

Genetics/Biochemistry Many genes share very similar sequences between species The more closely related two species are, the more similar the sequence All species share common sequences in genes that regulate the most basic aspects of life… from bacteria to humans!