Phylogenies and Origin of Life

How do phylogenies help in evolutionary biology

They show how closely/not closely certain species are related to each other

Phylogenies vs. cladograms

The more boxy graph vs. the diagonal line

Tips of phylogeny

organisms

Branches

connect species to ancestors

Nodes

divergence from one species into two (or more)

Root

hypothetical common ancestor of all organism on tree

Outgroup

A less related organism that is used as a reference point

Steps of building a phylogeny

Choose an outgroup, choose your traits and organisms, put traits/organisms on the tree and assess

Analogous vs homologous traits

Arose from similar selective environments vs. descended from a common ancestor. Homologous better for phylogeny because it shows related.

Monophyletic group

Includes a common ancestor and all of its descendants

Paraphyletic group

Includes a common ancestor and some, but not all, of its descendants

Polyphyletic group

Doesn’t include common ancestor

Synapomorphies

Shared derived characters that are new and arose from a common ancestor. Define monophyletic groups

Principle of Parsimony

The tree w/ the fewest evolutionary changes is (usually) preferred. Not always right as sometimes multiple losses and gains of traits does occur

What makes an organism “alive”

Reproduce, heredity, homeostasis, metabolism, cellular, respond to environment, growth

What was necessary for the very earliest life

A membrane to separate inside from outside, ability to pass down genetic info (evidence suggest single stranded RNA was first), and ability to use proteins to make energy to do biological work

Unicellular vs. Multicellular

One cell is the organism vs. organisms are made up of more than one cell. Unicellular came first.

Organic compounds

Prove earliest origins of life through complex organic compounds are made by living things that already existed on Earth

Microfossils

Can be evidence of carbon or other organic compounds deposits, things that look like cells, and evidence of movement (trace fossils)

Geologic evidence

evidence (of rocks) of huge changes in the Earth’s atmosphere due to life

Prokaryotic cells

Usually smaller and have simple structure and cell walls, no nucleus to hold DNA, have ribosomes, don’t have organelles, produce through mitosis

Which of the three domains of life are prokaryotic

Out of bacteria, archaea, and eukaryotes: bacteria and archaea

ATP

adenosine triphosphate. The energy currency for cells in all living organisms

Anoxygenic photosynthesis vs. Oxygenic photosynthesis

Uses CO2, light energy, and electron donor to make carbohydrate and water vs. replaces electron donor w/ water and also makes glucose

Aerobic respiration vs. anerobic respiration

Uses O2 and makes 38 ATP per glucose molecule vs. doesn’t use O2 and makes 2 ATP.

Is aerobic or anerobic more efficient

Aerobic is more efficient but needs O2

What are the effects of oxygen concentrations rising in the atmosphere ~2.5 billion years ago

Very bad for bacteria that couldn’t survive in the presence of oxygen but allowed for evolution of the first aerobic bacteria and later, Eukaryotes

Continental drift

Affected the evolution of life through movement of the continents which made new habitats and barriers through: plates diverse which cause deep rift valleys and continental collisions which form high mountain chains

Climate and sea level change

Severe drops of sea level caused mass extinction of marine life

Volcanic eruptions

Ash and SO2 injected into atmosphere which block sunlight and result in cooling. Massive volcanic eruption caused by a collision of continents to form Pangea caused the greatest mass extinction in history.

Meteorites

Caused the extinction of dinosaurs. Tsunamis, debris plumes that blocked the sun, and massive fire.

Changes in atmospheric oxygen

Caused many bacteria to die but helped with the evolution of aerobic bacteria

Permian Extinction (251mya)

96% of all marine species went extinct bc of massive volcanic eruptions in Siberia around formation of Pangea and released CO2 which raised climate which resulted in: ocean acidification, increase in phosphorous run-off, oxygen depletion by decomposing bacteria

Cretaceous extinction (65mya)

Likely caused by a meteorite which made tsunamis, debris plumes that blocked sun, and massive fire. Took out ½ all marine species, many terrestrial plants and animals, and all dinosaurs (except birds)