History of Life on Earth Projected on a 24-hour Day Life Appears a.m MIDNIGHT NOON 6 p.m. First atmospheric oxygen First eukaryotes First multicellular organisms First plants First humans (11:59:58) Billions of years ago First vertebrates

Biology – The Continuity of Life Objective 1 Objective 1 –Describe Darwin’s Theory of Natural Selection and the thinkers he used to formulate his ideas.

Evolution “A Species’ Genetic change over time” “A Species’ Genetic change over time” Process by which modern organisms descended from ancient organisms Process by which modern organisms descended from ancient organisms 10 million species alive today 10 million species alive today OVER 99.9% of all species that have ever existed ARE EXTINCT! OVER 99.9% of all species that have ever existed ARE EXTINCT!

Why do things survive? Fitness Fitness –Collection of traits and behaviors that help an organism survive and reproduce Adaptation Adaptation –Any change that allows an organism to survive and reproduce …IN A SPECIFIC ENVIRONMENT!!!!

Charles Darwin Late 1830s Late 1830s Sailed for England on the HMS Beagle as the ship’s “naturalist” Sailed for England on the HMS Beagle as the ship’s “naturalist” Collected, examined, and studied animals on his journey (especially from the Galapagoes Islands, Equador) Collected, examined, and studied animals on his journey (especially from the Galapagoes Islands, Equador)

Natural Selection Process by which the most fit organisms in an environment survive and reproduce Process by which the most fit organisms in an environment survive and reproduce –In a SPECIFIC ENVIRONMENT! –Survivors MUST REPRODUCE!

Natural Selection 1. Organisms in a population must have Variation… 2. …Those variations must be genetic 3. Overpopulation…leads to… 4. …Competition for resources (food, water, space, reproductive rights…)

“Survival of the Fittest” The Winners The Winners –Survive to reproduce…the best TRAITS are passed onto the next generation The Losers The Losers –Do Not Reproduce (they don’t necessarily die)…the worst TRAITS are not passed on REMEMBER, its not about surviving to live…it’s all about surviving to REPRODUCE!

Natural Selection Peppered Moth Example Peppered Moth Example Before 1850’s Before 1850’s –Peppered Moths were mostly white –Lived on trees with white bark (from lichens) –Black moths stood out and got eaten –The white moths were “selected for” and survived to reproduce –Black moths were “selected against” and were eaten

Peppered Moth - Before

Natural Selection Peppered Moth Example Peppered Moth Example After 1850’s – After 1850’s – Pollution from Industrial Revolution Pollution from Industrial Revolution –Tree bark gets darker from pollution –White moths stand out and get eaten –Black moths are now “selected for” and survive to reproduce

Peppered Moth - After

Biology – The Continuity of Life Objective 3 Objective 3 –List the pieces of evidence for evolution

1. Fossils Direct observations of changes over time Direct observations of changes over time Problems?? Easily Damaged Not everything fossilizes Can’t find them all – “Missing Link”

Archaeopteryx - the evolutionary link between reptiles and birds

2. Biochemistry ALL Life uses… ALL Life uses… –DNA –RNA –Glucose – for energy –ATP – as an energy storage molecule –Lipids for cell membranes –The Same 20 Amino Acids to make protein Shows all living things had a common ancestor with all of these traits.

3. Homologous Structures Body parts that share similar functions or structures in different species Body parts that share similar functions or structures in different species Shows “Common Ancestry” Shows “Common Ancestry” Ex: Bone patterns in humans, cats, chickens, whales, bats… Ex: Bone patterns in humans, cats, chickens, whales, bats…

Homologous Structures

4. Embryo Similarities Many animals show a similar pattern of development as an embryo (after conception, way before birth) Many animals show a similar pattern of development as an embryo (after conception, way before birth) Shows “Common Ancestry” Shows “Common Ancestry” The following slide has a rabbit, cow, chicken, human, fish, pig, salamander…can you tell which is which??? The following slide has a rabbit, cow, chicken, human, fish, pig, salamander…can you tell which is which???

Embryo Similarities – which is the human, turtle, fish, pig…?

5. Vestigial Organs Body parts that have lost all function. Body parts that have lost all function. “Vestiges” (reminders) of past functions “Vestiges” (reminders) of past functions We evolved to a point where a malfunction in one of these organs did not harm the individual. The “bad” organ got passed down… We evolved to a point where a malfunction in one of these organs did not harm the individual. The “bad” organ got passed down… Examples… Examples…

Vestigial Organs Darwin’s Ear Bump Appendix Tail Bone

Biology – The Continuity of Life Objective 4 Objective 4 –Describe how a new species is created

Speciation Creation of a new species by evolution. Creation of a new species by evolution. Evolution = any change in the gene pool of a population Evolution = any change in the gene pool of a population Species Species –A group of organisms that can successfully reproduce (there are limits to this definition though…)

How speciation can occur 1. Geographic and/or Reproductive Isolation – take one species and place them in separate, non-reproducing groups. Then wait… 2. Genetic divergence…evolution allows adaptations to accumulate. 3. IF the groups cannot reproduce anymore, THEN they are a new species

Evolution can also occur by …(besides NatSelection.) 1. Genetic Drift – random changes in a small population 2. Founder effect – a small group is the ancestors of many similar organisms 3. Migration – immigration and emigration

Biology – The Continuity of Life Objective 5 Objective 5 –Describe how evolution can occur

Modes of evolution Equilibrium Equilibrium –No change. No evolution. “Equal” Gradualism Gradualism –Gradual changes over time. Small changes Punctuated equilibrium Punctuated equilibrium –Long periods of no change…then bursts of lots of changes.

Modes of evolution Co-evolution Co-evolution –Two or more species causing changes in each other –Predator/prey relationships Mass Extinction Mass Extinction –Many species go extinct, all at the same time

Biology – The Continuity of Life Objective 6 Objective 6 –Explain how life appeared on Earth

The Origin of Life Earth before life… Earth before life… –NO Oxygen in atmosphere, in atmosphere, –warmer, – iron-red oceans, –many thunderstorms, –organic molecules

Proteinoid microspheres Proteinoid microspheres –Some lipid bubbles trapped other organic compounds (protein, nucleic acids) Appearance of… Appearance of… –Cells…when chemical reactions began inside the bubbles

The Origin of Life Rise of Oxygen Rise of Oxygen –Mutations allowed some cells to use sunlight to create carbohydrates. –These cells put Oxygen in the air Eukaryotes Appear Eukaryotes Appear –Endosymbiant Hypothesis –Some larger cells took up smaller cells that could do photosynthesis/cell respiration –Chloroplasts and mitochondria were once free living organisms

The Origin of Life Multicellular organisms Multicellular organisms –Once organisms could make enough energy, cells could become specialized and bodies became larger Sexual Reproduction Sexual Reproduction –With more specialization, some cells were able to be used for reproduction. –Sex allows for more diversity and better adaptations to the environment