Unit 5 Day 2: Evidence of Evolution

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​Looking at fossils allows us to see roughly how old an organism is, because newer fossils will be at the top, and older fossils will be at the bottom

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With carbon dating, we can actually determine EXACTLY how old a fossil is​

Evidence Type 1:

The Fossil Record​

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While technically a fish, TikTaalik ​has many bones similar to four legged land animals

TikTaalik's fossils indicate that it existed around 375 million years ago

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This is TikTaalik, the "missing link" between aquatic and land animals​

Biogeography refers to the distribution of various species and ecosystems geographically and throughout geological time and space.​

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Specifically, species vary geographically based on latitude, habitat, segregation (e.g., islands), and elevation.

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Evidence Type 2: Biogeography​

A Homologous Structure is a physical feature that is shared by organisms with a common ancestor ​

Homologous structures do not necessarily serve the same purpose in all organisms which have them​

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Evidence Type 3: Homologous Structures​

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Homologous Structures​

Some animals have structures with similar FUNCTIONS, but ​different development and anatomy

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These are known as analogous structures​

​(ex. Butterfly vs Bird Wings)

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This is called CONVERGENT EVOLUTION​

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On the other hand...​

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​Some Homologous structures have no function at all in some organisms, but still remain as part of their development. These are known an Vestigial ​Organs

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​Whales still have pelvic bones, despite having no use for them

By comparing different stages of embryotic development ​between organisms, we can see how closely related they are

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Evidence Type 4: Comparative Embryology​

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​Now that we have the technology to sequence DNA, we can compare the genetic code of different species to each other

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(This image shows the percent of our DNA that is the same as each animal)​

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Evidence Type 5: Molecular Record

Any Questions?​