Life Sciences Two

extant

currently alive on earth

extinct

no longer present on earth

number of extant species

about 8.7 million (plus or minus 1.2 million)

where are the unnamed species

deep oceans, coral reefs, tropics

types of species that remain unknown

bacteria, fungi, plants, invertebrae

number of described/named species

1.2 million

phylogeny

the evolutionary history of a species or group of species

systematics

a discipline focused on classifying organisms and determining their evolutionary relationships

binomial

two part format for scientific names of organisms, goes genus species, developed by linnaeas

taxonomy

the scientific discipline of how organisms are named and classified

phylogenetic tree

a branching diagram showing the evolutionary history of a group of organisms, branching points show common ancestry

sister taxa

groups of organisms that share an immediate common ancestor that’s not shared by any other group (usually closest relatives)

basal taxon

another word for outgroup, a group that diverges early

homology

phenotypic or genetic similarities due to shared ancestry

homology example

number and arrangements of forearms of mammals

analogy

phenotypic similarities due to convergent evolution, not from common ancestry

convergent evolution

when similar environmental pressures and natural selection produce similar adaptations in orgamisms with different lineages

cladistics

using common ancestry to classify organisms

clades

an ancestral species and all it’s descendants are rested within one another

monophyletic

an ancestral species and all it’s descendants

polyphyletic

contains distantly related species but not their most common ancestors

paraphyletic

an ancestral species and some but not all of it’s descendants

shared ancestral character

a characteristic that originated in an ancestor of the taxon therefore is not unique to the taxon

shared ancestral/shared primitive character example

vertebrae in mammals

shared derived character

an evolutionary novelty/characteristic that is unique to a clade (can be loss or gain of a feature)

outgroup

a species or group of species that is closely related to another but not a part of the species being studied (ingroup)

Iarl linnaeus

swedish botanist in 18th century, creationist, claimed that species are unchanging, came up with binomial nomenclature

latin for naming

used because it’s a dead language and is universal for across the world

heirarchy of life

domain kingdom phylum class order family genus species

examples of convergent evolution

sugar gliders and flying squirrels, australian and african golden moles, cacti and euphorbia

systematist

person who organizes phylogenies

node

where two branches come together

valid clade

is monophyletic