Evidence of Evolution [15.2] SPI 5 Apply evidence from the fossil record, comparative anatomy, amino...
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Transcript of Evidence of Evolution [15.2] SPI 5 Apply evidence from the fossil record, comparative anatomy, amino...
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!
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
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
Fis
hS
alam
ande
r
Tur
tle
Chi
cken
Pig
Cow
Rab
bit
Hum
an