the study of diversity and relationships among organisms.

Compares characteristics of both living and extinct

genera, families, orders, classes, phyla, kingdoms, and taxa.

Grouping organisms based on common traits when their is no common ancestor.

Ex: saying birds and bats are closely related because they can fly.

similarity not due to shared ancestry

• convergent evolution- similar traits evolving in organisms from different lineages.

• small organic molecules (carbon based amino acids and nucleotides)
• join into polymers
• packaging into "protobionts"
• origin of self-replication

Sedimentary strata: relative ages of fossils

-index fossils correlate strata ages across locations

Radiometric dating: absolute ages of fossils

-uses radioactive isotopes, measures decay rate

• synthesized in early atmosphere- stanely miller 1953

• submerged volcanoes and deep see vents

• arrived from space via meteorites

• aggregates of abiotically produced molecules surrounded by membrane

• can form spontaneoulsy

• Formation of earth
• Oldest fossils
• Oldest eukaryotic fossils

• 4.6 billions years ago
• stromatolites: 3.5 BYA, rock like
• 2.1 BYA can see internal stuctures

• Evolution of multicellularity
• animal phyla appear
• plants, animals, fungi colonized land

• 1.5 BYA- oldest fossils, small algae 1.2 BYA
• start of cambrian period- 500 MYA
• 500 MYA, prokaryotes on land earlier.

3.5 BYA in cyanobacteria.

• gradual increase in O2, new energy source doomed anerobic prokaryotes, others exploited new ecosystems.
• Increase started 2.2 bya, thought to be caused by eukaryotic cells with chloroplasts 

eukaryotic cells arose from symbioses btw prokaryotes

-oldest eukaryotic fossil 2.1 bya

-internal structures, mitochondria and plastids were prokaryotes living in larger host cells.

-cytoskeleton allows cell to change shape and engulf other cells 

adaptions to avoid dehydration

fungi help w/ water and mineral absorbtion

plants provided organic nutrients 

manera (prokaryotes), protista (other eukaryotes), plantae (autotrophic eurkaryotes), fungi (heterotrophic euk), animalia (heterotrophic euk)

-recognized the two fundamentally different types of cells 

Bacteria, Archaea, and Eukarya.

Whittaker's groups, were divided into these domains. 

• Autotrophs- have chloroplasts (plant-like algae)
• Heterotrophs- absorb organic molecules (fungus like) or ingest food particals (animal like protozoans)
• Mixotrophs- combination of auto and hetero

both sexual and asexual, stages require at least 2 different host species.

e.g. plasmodium causes malaria, starts in mosquitos completed in humans 

1. multicellular ingestive heterotrophs
2. lack of cell walls
3. nervous and muscle tissue
4. mostly sexual, life cycle mostly diploid
5. have hox genes- regulate expression of other genes

500 MYA (paleozoic era) bigger new body plans, bilateral symmetry, sementation, heads, appendages.

• rise in O2- provide ops for animals w/ high metabolic rates, more movement
• Predator/prey adaptations
• Hox genes- developmental flexibility

• Sponges have none because they are sessil and porus
• Cnidarians, ctenophores have radial don't have sensory organs

1. Sponges have no real tissues
2. Ectoderm and endoderm- cniderians and ctenophores
3. ectoderm, endoderm, and mesoderm which lies in the middle, muscle tissue- bilaterally symetrical groups.

Coelom- fluid filled space btw digestive tract adn outer body wal formed from mesoderm

pseudocoelom- not entirely lined by mesoderm (nematodes)

acoelomates- no coelom (flatworms) 

agreement:

1. animalia clade
2. sponges are basal
3. eumetazoa (true tissues) clade
4. bilateria (bilateral symmetry) clade
5. Deutorostomia