evidence for evolution powerpoint
TRANSCRIPT
Evolution: Evidence
SC.912.L.15.1 Explain how the scientific theory of evolution is supported by the
fossil record, comparative anatomy, comparative embryology, biogeography,
molecular biology, and observed evolutionary change
Types of Evidence we will be covering
• Fossil Records– Transitional fossils
• Comparative Anatomy– Homologous Structures– Analogous Structures
• Vestigial Structures • Biogeography
Fossil Records • Fossils support the idea
of evolutionary progression.
• By looking at fossils Paleontologists/zoologists can: – Identify extinct animal
species – Follow the path of
evolution through different stages of development
Evolution of the Whale
Key Points of the Fossil Record
• Provides evidence of evolution from one species to another– Shows ancestral
intermediates
• Only hard tissue is preserves
• Fossil Formation
Transitional Fossils
• FLASH CARD ALERT: • TRANSITIONAL FOSSIL: fossils
that show transitions in evolution.
• Transitional fossils are RARE findings – Small proportion of
organisms become fossils
– Many fossils represent dead evolutionary branches
Support: Comparative Anatomy • Homologous Structures:
Similar features found in different species that are derived (come from) a common ancestor – Ex. Tetrapod limbs, fur,
lungs • Bone formation:
developmental and evolutionary similarities
• Evidence of intermediates
Analogous Structures
• FLASH CARD ALERT: • Analogous Structures: a trait or an organ that
appears similar in two unrelated organisms• Happens because of convergent evolution: – FLASHCARD ALERT: CONVERGENT EVOLUTION: Species
evolve in similar environments and have similar environmental stressors/survival factors
Analogous Structures
Vestigial Structures
• Vestigial Structures: characteristics found in existing species that have no known function
• Provide evidence of common ancestry• As species evolve their structures change– Two things will happen • Species will adapt the organ/structure to a new use
– penguin
• The organ or structure will no longer have a use – Whale pelvis/snake feet.
Useless for Flying but excellent for swimming
Vestigial Structures
• Stubs on pythons, boas, and other snakes– Ancestral legs
• No known function
• Useless Vestigialstructures are BETTER sourcesof evidence forevolution
Amphiuma
Flightless Wings
Plica semilunaris
CFU:
• What is the major difference between analogous and homologous structures?
• What structure is the best evidence of evolution: analogous, homologous or vestigial
• What kind of tissue/part of an animal is preserved in fossils?
• What type of fossils are paleontologists most interested in?– Why are they hard to find?
Comparative Embryology
• Incredible similarities in embryos of different species provides evidence of common ancestor – Patterns of embryo
development are also important.
Biogeography
• Zoologists seek to understand how very closely related species ended up in completely different parts of the world
Support for Pangaea
Key Point of Biogeography
• Seeks to answer the question: how/why different but similar species exist in similar yet separate parts of the world
• Can be explained by geological changes, migrations, convergent evolution
• Support ideas of common ancestor and Pangaea
EVOLUTION CFU
• What are the five steps of evolution?• How does the environment affect the process of
evolution?• Adaptations help the organism: • The three types of structures that support evolution
are: • Paleontologists are excited to find what kind of
fossil and why?