bio 94 diversity of life (quiz 2)

phylogeny

branching evolutionary history of species or other groups or organisms

phylogenetic tree

a branching diagram that depicts the evolutionary relationships among species or other taxa

branches

part of the phylogenetic tree that represents populations through time

nodes

the point where two branches diverge, representing the point in time when an ancestral group split into two or more descendant groups

character

any heritable, genetic, morphological, physiological, developmental, or behavioral characteristic of an organism to be studied; aka trait

trait

any heritable, genetic, morphological, physiological, developmental, or behavioral characteristic of an organism to be studied; aka character

outgroup

any taxon that is not part of the taxonomic group being studies; researchers often select one or more outgroups that are closely related to the ingroup to help root phylogenetic trees and to determine the direction of character changes

ancestral trait

trait found in the ancestors of a particular group

derived trait

• derived trait = trait that is a modified form of an ancestral trait, found in a descendant

  • originate via mutation, selection, genetic drift

synapomorphy

trait found in two or more taxa that is present in their most recent common ancestor, but missing in more distant ancestors

monophyletic

passes one snip test

paraphyletic

descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.

parsimony

method that implies as few evolutionary steps as possible

coherence

trees built using different synapomorphies should agree

precambrian

ended 542 MYA

the interval between the formation of the earth (4.6 billion years), and the appearance of most animal groups about 541 mya; unicellular organisms were dominant for most of this era, and oxygen was virtually absent for the first 2 billion years

life was exclusively unicellular

cambrian

start 542 MYA; the first geological period of the Paleozoic Era, marks a pivotal time in Earth's history, spanning from roughly 538.8 to 485.4 million years ago, and is known for a period of rapid diversification of life forms

edicaran radiation

the relatively sudden evolutionary radiation of complex, soft-bodied multicellular organisms, including forerunners of modern animal phyla

cambrian explosion

the rapid diversification of animal body types and lineages that occurred durin a 50-million-year period about 541 mya at the start of the proterozoic eon

eukaryote

includes animals, plants, fungi, protists, and amoeba

era

broad, long-term timeframe marked by significant events or changes

period

specific, shorter timeframe within an era, often characterized by particular developments

paleozoic

the interval of geologic time from 541 to 252 mya during which fungi, land plants, and most animal lineages first appeared and diversifies

—began with the Cambrian explosion and ended with the extinction of almost all multicellular life-forms at the end of the permian period

mesozoic

after Permian extinction ; 252 to 66 mya, gymnosperms were the dominant plants on land and dinosaurs were the dominant vertebrates on land; ended with extinction of the dinosaurs

cenozoic

after K/T ; most recent era of geologic time, beginning 66 mya, during which mammals and birds became the dominant vertebrates on land and angiosperms became the dominant plants on land

adaptive radiation

-rapid evolutionary diversification within a lineage, producing numeric species with a wide range of adaptive forms

—following mass extinctions, surviving species are initially released from competition = expand range and diverge (and evolve new niches)

—eventually species become more specialized

mass extinction

a geologically sudden extinction event that is geographically and taxonomically widespread and kills relatively unselectively

-15% of families or 60% of species lost

-natural selection rapidly increases in order to create new speceis

-there are very long spans of time in which no new species evolve

-the surviving biota radiates to form new species

end Devonian extinction

cooling of climate = lower sea levels

-359 mya

end permian extinction

extreme global warming, low O2 in atmosphere/oceans, acidic ocean

-mother of mass extinctions

-252 mya

end cretaceous (K/T)

66 mya

-impact hypothesis = collision between earth and asteroid

massive tsunami and world-wide fires, acid rain, ash and dust that blocked out the sun

—dinos wiped out…mammals filled their niches

background extinction

an extinction that reflects the outcome of competition among species for niche space

niche differentiation

aka resource partitioning; evolutionary change in resource use

resource partitioning

aka niche differentiation; evolutionary change in resource use

character displacement

evolutionary change in species traits, allowing species to exploit different resources

biota

the animal and plant life of a particular region, habitat, or geological period

continental shelf

a gently sloping, submerged extension of a continent that stretches from the shoreline to a drop-off point called the shelf break, where the seafloor descents into the deep ocean floor

neritic zone

the shallow, sunlit part of the ocean above the continental shelf

competitive exclusion principle

two species cannot occupy the same niche simultaneously, because one will out-compete the other