Aim: Introduction to Evolution Enter Date Aim: Introduction to Evolution Warm-up: HW:
What is Evolution? Evolution changes in living organisms over time explains how modern organisms have descended from ancient organisms Evolution! Evolution! Evolution! Why do we accept this as a Scientific Principle?
What do we know? Biodiversity of Life on Earth There are many different creatures on Earth How do we know this? OBSERVATION Biodiversity of Life on Earth
What do we know? cells DNA Unity of Life on Earth All creatures have common characteristics How do we know this? OBSERVATION cells DNA Unity of Life on Earth
What do we know? Life is very old! The Earth is very old How do we know this? TESTING & OBSERVATION Radioactive Dating of the Rocks Life is very old!
What do we know? Creatures have changed over time How do we know this? OBSERVATION Fossil Record
Primitive Earth Primitive earth was VERY different. 1. The atmosphere did not contain oxygen 2. There was an abundance of energy from lightning, heat, and UV rays 3. The temperature was super hot. Not many things could live here. (Only heterotrophs)
Extremophiles Scientists believe the first organisms on earth were heterotrophs. They were mostly microscopic organisms like bacteria and viruses. They were able to live in extremely harsh conditions. Heterotrophs used anaerobic respiration and ate small organic molecules from the ocean.
Heterotroph Hypothesis This theory explains how living things may have developed on the primitive earth. According to this hypothesis, the first organisms were able to synthesize oxygen from carbon dioxide and sunlight. ALSO known as PHOTOSYNTHESIS!
BUT THEN!!! One organism developed the ability to do photosynthesis! All of the organic molecules in the ocean combined to form autotrophs. Autotrophs used carbon dioxide and released oxygen into the air.
Aerobic Respiration These autotrophs gave the air oxygen Now a new life form could evolve by breathing oxygen. These are called aerobic.
What has the fossil record shown us? Many creatures that lived in the past don’t exist today Origin of new species
What has the fossil record shown us? The creatures alive today haven’t always been around Different species lived in the past
What has the fossil record shown us? Many creatures in the past looked like living ones we see today “Family Tree” Relatives with similar, but not the same traits
Quick review, so far…. Evolution Many different species alive today All life shares common characteristics The Earth is very old Life is very old Life has changed over time The changes have been little changes over long periods of time Evolution But how does this work?
Evolution explains Unity & Diversity Only evolution explains both unity of life similarities between all living things diversity of life wide variety of different creatures on Earth DNA