Chapter 22 - Systematics + Phylogeny

systematics

the reconstruction and study of evolutionary relationships

phylogeny

the evolutionary history of an organism, including which species are closely related and in what order related species evolves, often represented in the form of an evolutionary tree.

derived character trait

a characteristic used in taxonomic analysis representing a departure from the primitive form.

More understandable ——> a newer feature that evolved from the ancestral trait in a specific, more recent lineage.

ancestral/ancestral trait (primitive)

an older feature inherited from a common ancestor

cladistics

a taxonomic technique used for creating hierarchies of organisms that represent actual phylogenetic relationships. distinguishes similarity among species that are inherited from the most recent common ancestor of an entire group.

character states

one of 2+ distinguishable forms of a character, such as the presence of absence of teeth in amniote vertebrates.

Easier - The specific variation or condition of that feature (e.g., blue vs. brown eyes, red vs. white petals, or A, C, G, T in a DNA sequence).

Shared derived character

a character state that is shared by species that is derived.

polarize

to determine whether character states are ancestral or derived.

outgroup

a group used to polarize characters that is distantly related to groups under study.

aka - a reference group of organisms that is closely related to, but distinct from, the specific group of organisms you are studying

clade

a taxonomic group composed of an ancestor and its descendants

synapomorphy

a derived character that is shared by clade members

Plesiomorphy

term for an ancestral character state

symplesiomorphy

a plesiomorphy that is shared by 2+ different lineages

homoplasy

a shared character stat that hasn’t been inherited from a common ancestor exhibiting that state, instead from convergent evolution or evolutionary reversal.

evolutionary reversal

a trait or character state changes from a derived (recently evolved) state back to a state that resembles the ancestral condition.

convergent evolution

unrelated species independently develop similar traits due to similar environmental pressures

principle of parsimony

principle stating that scientists should favor the hypothesis that requires the fewest assumptions.

molecular clock

a way of dating evolutionary events using the observation that some proteins evolve at a constant rate, which proves a clock that can be correlated with the fossil record

monophyletic

a group that includes the most recent common ancestor of the group and all its descendants. a clade counts as one.

paraphyletic

a group that includes the most recent common ancestor of the group, but not all of its descendants

polyphetic

a group that doesn’t include the most recent common ancestor of all members in the group

binomial name

the scientific name of a species that consists of two parts, the genus name and specific species name.

taxonomy

the science of classifying living things.

• first word - genus (CAP)

• second word - specific epithet (non cap)

Linnaean hierarchy

• domain

• kingdom

• phylum

• subphylum

• class

• order

• family

• genus

• species

domain

archaea, bacteria, eukarya

archaea

highly diverse group of unicellular prokaryotes

1. methanogens - obligate, anaerobic archaeabacteria that produce methane

2. extremophiles - an archaean organism that lives in extreme environments

3. non extreme archaea - non extremophiles

endosymbiosis

theory that proposes that eukaryotic cells evolved from a symbiosis between different species of prokaryotes

aka - a close relationship where one smaller organism lives inside a larger host organism

bacteria

microscopic, single celled prokaryotes

eukarya

includes all organisms that contain complex cells holding a true membrane bound nucleus

node

a branching point on a phylogenetic tree (or cladogram) that signifies a common ancestor where lineage is diverged

most recent common ancestor

the youngest individual organism, species,