GB1 Ch. 25 - Phylogeny

phylogeny

branching evolutionary history of species

systematics

discipline of biology, characterize & classify relationships b/w all organisms on Earth

taxa

any named group of organism at any level

branch

line representing species/taxon through time

root 

most ancestral branch in tree

tip

endpoint of branch

living/extinct species

outgroup

taxon that diverged before the focus taxa

help root tree

node/fork

point within tree where branches split

most recent common ancestor of group

polytomy

node that divides into 3+ descendant branches

sister groups

two descendants that split from the same node and therefore are each other’s closest relatives.

homology

similarity due to common ancestry

homoplasy

when traits evolved independently in two or more different lineages and thus are similar for reasons other than common ancestry

parsimony 

states that most likely explanation is the one that requires fewest steps

convergent evolution

independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and lifestyles

intact fossil

decomposition doesn’t occur

organic remains are preserved intact

compression fossil

sediment accumulate on top of organism & become cemented into rock

cast fossil

buried organism decomposes, empty cavity filled w/ sediment & hardens

permineralized fossil

organism decompose extremely slow

dissolved minerals gradually infiltrate interior of cell, harden into stone

trace fossil

sedimentation & mineralization preserve indirect evidence

ex. footprints

Precambrian

Unicellular organisms were dominant for most of this era, and oxygen was virtually absent

interval between the formation of the Earth, about 4.6 billion years ago, and the appearance of most animal groups about 541 million years ago

Paleozoic era 

interval when most animal lineages first appeared and diversified.

Mesozoic era

end w/ extinction of dinosaurs

gymnosperms were the dominant plants on land and dinosaurs were the dominant vertebrates on land

Cenozoic era

most recent era of geologic time

mammals and birds became the dominant vertebrates on land and angiosperms became the dominant plants on land.

Anthropocene

Proposed name of a new, current epoch in the geologic time scale to reflect the dramatic physical, chemical, and biological changes that humans are causing on Earth

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