unit 3/4/5 evolution

uniformitarianism

earths landscapes hav ebeen shaped by gradual process that are still observable today

radiometric dating

technique that allows feologists to estimate the precise ages of specimens determining the relative proportion of radioactive isotopes present in a sample

can be used to estimate fossils

radioactive dating

discovered the structure of atoms leading to a reliable and precise method for estimating the age of rocks

radiocarbon dating

a scientific method that determines the age of ancient organic materials by measuring their remaining levels of carbon-14

can be used to estimate the age of recent organic material

life

assembly of molecules that can capture energy from the environment and replicate itself

biomarkers

evidence of life in the fossil record

zicron’s

extremely durable microscopic crystals that can survive for billions of years, preserving chemical signatures from Earths earliest days

stromatolites

layered structures formed by the mineralization of bacterial communities, particularly Cyanobacteria

prokaryotes (bacteria and archaea)

single celled organisms that lack membrane bound organelles and a nucleus

Eukaryotes

evolved from a symbiotic association between Archean and a bacterium, leading to membrane bound organelles

Great Oxygenation event

there were only trace amounts of oxygen in atmosphere of early earth

oxygen was toxic to most existing life on Earth, causing a mass extinction of anaerobic bacterial species

aerobic respiration

requires oxygen to make ATP, provides cells with energy

Ediacaran fauna

diverse species with unusual body plans that bear little resemblance to animals alive today

synapsids

first mammals evolved from a lineage of vertebrates

diapsids

having two temporal openings in the skull instead of just one

hominids

the human lineage diverged from other great apes

angiosperms

flowering plants

vertebrates

animal that has a backbone or spinal column

phylogeny/ phylogenetic trees / or evolutionary trees

a visual representation of an evolutionary history

branches

Lineages evolving over time

nodes

points in the phylogeny where lineages split

internal node

represents the most recent common ancestor MRCA of all lineages descended from that branching point

root / root node

represents the most recent common ancestor of all taxa included in the phylogeny

tip/ terminal node

represents a species, population, gene, or taxonomic group being compared in the phylogeny

systemics

uses those phylogenies to classify life

clades

evolutionary lineages and fundamental unit of classification

monophyletic clade

a clade that includes common ancestor and all of the descendents of that common ancestor

polyphyletic clade

describes a group of organisms that does not share an immediate common ancestor

paraphyletic clade

describes a group of organisms that shares a common ancestor but does not include all of the descendants of that common ancestor but does NOT include all of the descendants of that common ancestor

character

heritable trait that can be compared across taxa

character states

different forms of that trait

out group

taxa that is closely related to the group being studied but not part of the group

Synapomorphies

shared, derived character states that are inherited from the common ancestor of a group (used to identify clades)

parsimony

principle that the best phylogenetic tree is the one that requires the fewest evolutionary changes to explain the observed distribution of character states among taxa

consensus tree

represents both the resolved and unresolved portions of the phylogeny

polytomy

evolutionary relationship (order of branching) is uncertain

homoplasy (opposite of homology)

describes similariesies in character states that is NOT due to shared ancestry

convergent evolution

independent evolution of similar traits, often due to similar selections pressures

evolutionary reversal

when a derived trait is lost and the ancestral trait reappers

divergence

related species become increasing different over time

chordates

we belong to a lineage of animals _____ that first appears in the fossil record 515 million years ago as aquatic vertebrates

tetrapods

vertebrates with 4 limbs or descended from vertebrates with 4 limbs (ex snakes)

lobe finned fish (coelacanths)

fins contain a robust skeletal structure with distinct bone elements

wide range of morphologicals and molecular evidence points to these as being closest living relatives of tetrapods

-coelacanths are among the closest living relatives of tetrapods (are NOT ancestors of tetrapods because of divergence)

Eusthenopteron

early clues from the devonian era

Tiktaalik

a key transitional fossil

-lived approximately 375 million years ago

(mobile neck, functional wrists, tetrapod limb structure, ribs supporting internal organs)

Exaptation

trait that is initially evolves for one function and is later co-opted for another function

coelacanth

rare ancient deep sea fish, once thought to have gone extinct but

theropod

mostly carnivorous dinos

Archaeopteryx

extinct bird like dinosaur

Acanthostega

extinct fish like water animal