Mrs. Stewart Honors Biology Central Magnet School Evidence of Evolution Mrs. Stewart Honors Biology Central Magnet School

Standards: Objectives: CLE 3210.5.4 Summarize the supporting evidence for the theory of evolution. Objectives: Differentiate between homologous and analogous structures and give examples of each Define vestigial and give 2 examples of vestigial structures Summarize the evidence of evolution for whales

Shoulder Partners

Descent with Modification Over long periods of time, natural selection produces organisms with different structures, niches or occupy different habitats than their ancestors. Each living species has descended, with changes, from other species over time. Result: species today look/act different from their ancestors

Common Descent Look back: Tigers, panthers and cheetahs all share a common ancestor Look back further: you will find ancestors that these cats share with horses, dogs and bats. Farther back: common ancestors of mammals, birds, alligators and fishes. Logic: looking far enough back we should find the common ancestor for all living things

Common Descent

Tortoise Explain to the Hare the meaning of the evolution theory: Common Descent w/ Modifications

Evidence of Evolution Homologous & Analogous Structures Fossil Records Vestigial Structures Evidence of Evolution Comparative Embryology Molecular Biology

Fossil Records Fossils - preserved remains of ancient organisms Compare fossils from older layers and younger layers and show changes in species over time

Fossil Records Compare fossils found around the world and we can infer when and where different organisms existed. Fossils also provide evidence about the environment in which the organism existed and for which the organism adapted

Transitional Species Fossil records show species which have features that are intermediate between those of hypothesized ancestors and later descendant species

Homologous vs. Analogous Structures Homologous –structures that share the same basic structure but differ greatly in function Analogous –structures that vary greatly in structure but share the same function

Homologous Body Structures

Hare Explain to Tortoise what a Homologous Structure is.

Homologous Body Structures Similar structures with different functions Example: The limbs of reptiles, birds and mammals (arms, wings, legs and flippers) vary greatly in function but are all constructed from the same basic bones.

Analogous Structures Similar functions but different structures

Tortoise Explain to Hare what an Analogous Structure is.

Vestigial Structures organs/body parts that were once used, but by natural or artificial selection, are no longer necessary

Evidence of Evolution Evidence of evolution on your own body

Vestigial Organs Appendix

Vestigial Organs Hip bone in a whale

Vestigial Organs Tailbone in humans

Vestigial Organs Plica Luminaris = Third Eyelid

Hare Explain to Tortoise what a Vestigial Structure is.

Similarities in Embryology The early stages, or embryos, of many animals with backbones are very similar. Does this mean that a human embryo is ever identical to a fish, or a bird embryo? NO But, many embryos look especially similar during early stages of development.

Fish Salamander Tortoise Chicken Pig Man

Comparative Embryology What do these similarities mean? The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.

All animals go through this process Its at the blastocoel step that we differ Blastopore could become mouth or anus, etc. All vertebrates share a common ancestor

Tortoise Explain to Hare how comparative embryology shows evidence of common descent

The number of amino acids that differ from human hemoglobin Molecular Biology Using new technology, we can see how many DNA and RNA sequences organisms share in common The more DNA sequences in common = the more closely related the organisms are on the Tree of Life Amino acid sequences for major proteins used to determine how closely related different species are. The number of amino acids that differ from human hemoglobin

Molecular Biology Amino Acid Similarities Which two plants are the most closely related according to this chart?

Hare Explain to Tortoise how to tell which organisms are most closely related using this chart.

The evolution of the whale Evolution of Whales The evolution of the whale

Assignment: Evidence of evolution dry lab activity packet

Exit Ticket: Question: Summarize the evidence to support that whales evolved from a land mammal.