Intro and Phylogeny

1. What factors are thought to have contributed to the Cambrian explosion? Provide details on how they may have contributed to diversification and if they are mutually exclusive.

Major evolutionary changes

• Environmental changes

o Increased oxygen

 Multicellularity

 Metabolism (muscles)

• Ecological interactions and co-evolution

o Predator/prey relationships

• Developmental modularity and evolvability

o Homeotic genes

 Direct formation of body plans

• More mutations = greater possibility for changes

Increased oxygen, likely driven by the sudden increase in the gas to near-modern levels in the ocean would have triggered the Cambrian explosion

The ecological interactions are not mutually exclusive with the increased oxygen

2. Know the historic and current methods used to group organisms, i.e. describe early taxonomy methods vs current methods, and how this relates to sources of taxonomic information

Aristotle: shared characteristics, plants and animals

Greeks and Romans: Classified based of the genera

Linnean system: An early method included the use of “ranks”: species, genus, family, order, class, etc.

Abandoned to classify organisms rank-free based off evolutionary history

Modern Taxonomic methods group organisms based on molecular, genetic, and phylogenetic information determine evolutionary relationships and relatedness.

3. Be able to define and differentiate the following terminology:

• Taxonomy: The science of ordering species into formal groups based on morphological, genetic, physiological, behavioral, ecological distribution, and molecular differences

• Nomenclature: Application of scientific names to species and groups

o Binomial nomenclature

o International Code of Zoological Nomenclature

• Systematics: the study of species and the phylogenetic relationships among them

• Phylogenetics: the study of evolutionary relationships

• Clade: Group of species that share a common ancestor

• Monophyletic: the most recent ancestor and ALL its descendants

• Paraphyletic: the most recent ancestor and some of its descendants

• Polyphyletic: group with some similarities but does not include the most recent common ancestor

• Synapomorphies: ancestral/derived characteristics

• Shared derived characteristics: A characteristic that evolved in the lineage that sets the clade apart from other individuals

• Sister groups: The closest/most related relative

• Molecular clock: Estimate of time since divergence

o Aka how long ago did they share an ancestor?

• Convergent evolution: when organisms that are not closely related evolve similar features or behaviors (due to facing similar problems)

• Divergent evolution: Evolution where related species evolve characteristics that make them different to each other

• Homologous characteristics: Characters in different organisms that are similar because they were inherited from a common ancestor

• Analogous characteristics: Characteristics that have separate evolutionary origins (similar due to natural selection)

• Maximum parsimony: the tree that has the fewest evolutionary events is the most likely

• Basal taxon: a group of organisms that diverged early in the history of a group

4. What are the sources of Phylogenetic Information?

Comparative morphology, embryology, cytology, and biochemistry.

5. What are the Linnaeus taxonomic levels?

Did King Phillip Came Over For Good Soup

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

A hierarchical naming system

6. Be able to draw and provide synapomorphies on a rudimentary tree showing the domains of life and their relationships to each other.

7. Draw/label a prokaryotic vs a eukaryotic cell – label differences and know what domains are represented.

Both have DNA, protein synthesis, and use ATP

Prokaryotes:

- Genetic material: nucleoid

- Bacteria and Archaea

Eukaryotes:

- DNA in nuclear membrane

- Membrane-bound organelles 

8. Describe the endosymbiotic theory, give specific examples

One cell engulfed but did not digest the other, and usurped its cells

For example, a eukaryotic cell with mitochondria engulfed cyanobacteria

Which supports why mitochondria with purple bacteria are more related to protists than the cell in which they are contained

They are similar to a tiny bacteria living inside a living eukaryotic cell

All eukaryotes have them

Example, a eukaryotic cell engulfing cyanobacterium that developed into chloroplasts and purple bacteria that developed into mirochondria

9. Differentiate between primary and secondary endosymbiosis

Primary Endosymbiosis: A process in which a eukaryotic cell engulfs a prokaryotic cell that can undergo photosynthesis (cyanobacteria)

Secondary Endosymbiosis: A process in which a eukaryotic cell engulfs another eukaryotic cell that has already engulfed a prokaryotic cell previously (double membrane and organelles)

10. What are the following folks known for (relevant to this class 😊):

Anton van Leeuwenhoek: Father of Microbiology, “animacules” in pond water

Charles Darwin: evolutionary biology

Ernst Haeckel: champion of the theory of evolution

Lynn Margulis: Endosymbiotic Theory

Carl Woese: defined Archae

Questions to think about…

Phylogenetics: grouping organisms based on a common ancestor – what are the 4 primary methods scientists use to provide insights into the relatedness of organisms?

1. Comparative morphology

2. Comparative cytology

3. Comparative embryology

4. Comparative biochemistry

Brainstorm specific examples of each method.

One of these methods has only recently come into widespread use and in fact is now responsible for major reorganizations (i.e. the Kingdoms have fallen). Why is this?

The kingdoms have fallen because grouping was not based on evolutionary relationships