Review of evolution Evolution: organisms change over time. Natural selection: nature selects what traits increase/decrease fitness. Fit traits get passed down. This drives evolution.

Review of evolution

WWBAT use 4 types of evidence as proof of evolution…. Our objective WWBAT use 4 types of evidence as proof of evolution…. ….last class we did DNA and fossils……

Embryology Which one is the cow? cat cow horse human

Embryology Embryos are eukaryotic organisms in their earliest stages of development.

Embryology

Embryology All embryos look almost identical in the early stages of development—that’s not a coincidence! The similarities in this stage represents a common ancestor that all the organisms evolved from.

The fact that all animal embryos are so similar shows that ALL animals evolved from the SAME common ancestor

Embryology Embryos will be most similar in early stages/different in latest stages.

Structures-Anatomy Comparing the anatomical (body) structure of organisms shows the process of evolution.

Structures There are 3 structures that prove evolution… Homologous structures Analogous structures Vestigial structures

Structures Homologous structures: 2 organisms have the SAME structure (but not necessarily the same function) because they have a recent common ancestor. Proof: shows they evolved from a common ancestor.

Humans, cats, whales, and bats all inherited their forearm from the same common ancestor

Homologous structures prove evolution by showing how one structure can evolve to meet a variety of functions.

Structures Analogous structures: 2 organisms have different structures but the SAME function because they evolved separately. Proof: in same the environment, natural selection will select for similar traits in less related organisms

No recent common ancestor!!! Insects, bird, and bat wings evolved completely separately. Unrelated organisms will evolve similar adaptations in response to similar environmental pressures! No recent common ancestor!!!

Structures Vestigial structures: structures that are no longer used for anything. Proof: unless it decreases fitness, the trait will hang around.

Letter “c” = hind legs of a baleen whale skeleton Vestigial = no longer used!!!

Blind salamanders have eye sockets!?!? They live in caves. Siiick.

VESTIGIAL Guided Practice (GP) Is this structure… (A) Homologous, (B) Vestigial, (C) Analogous? Snakes don’t have legs, but they do have hip and leg bones. After revealing the correct answer, ask random students to explain how the structure supports evolution VESTIGIAL

HOMOLOGOUS Guided Practice (GP) Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? Cat embryos and human embryos both have tails. After revealing the correct answer, ask random students to explain how the structure supports evolution HOMOLOGOUS

VESTIGIAL Guided Practice (GP) Is this structure… (A) Homologous, (B) Vestigial, (C) Analogous? The human appendix – a small organ next to the intestines – doesn’t seem to do anything at all. After revealing the correct answer, ask random students to explain how the structure supports evolution VESTIGIAL

ANALOGOUS Guided Practice (GP) Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? Dolphins and sharks both have fins, but they evolved completely differently. After revealing the correct answer, ask random students to explain how the structure supports evolution ANALOGOUS

HOMOLOGOUS Guided Practice (GP) Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? Alligators and bats have the same bone structure in their forelimbs (front legs for alligators, wings for bats). After revealing the correct answer, ask random students to explain how the structure supports evolution HOMOLOGOUS

ANALOGOUS Guided Practice (GP) Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? Birds and insects both have wings, but they developed in completely different ways. After revealing the correct answer, ask random students to explain how the structure supports evolution ANALOGOUS

VESTIGIAL Guided Practice (GP) Is this structure… (A) Homologous, (B) Vestigial, (C) Analogous? Humans have wisdom teeth (third molars), even though they are not needed to chew up food. After revealing the correct answer, ask random students to explain how the structure supports evolution VESTIGIAL

EXIT TICKET. 1. Explain how the study of embryos provides proof of evolution. 2. Insects and birds both have eyes but they are not the same anatomical structure. What type of structures are these? homologous structures analogous structures fossilized structures biochemical structures 3. Whales and mice have similar skeletal structure in their limbs. What type of structures are these?

Exit Procedure Exit tickets in the EXIT TICKET BOX ONLY. Put your binder away BUT NOT YOUR HOMEWORK FOLDER Notes IN THEIR PLASTIC SHEETS back on the front table