BZ110 exam 1

Evolution

A change in the heritable characteristics of biological pops over multiple generations

mutation

source of new alleles in a pop; changes in DNA

natural selection

advantageous phenotypes are more likely to reproduce and survive

genetic drift

random change in frequency of gene variants in a pop over time; allele frequency due to random chance

bottleneck effect

catastrophic event that results in a large portion of the gene pool dying; the surviving pop is no longer representative of the original pop (genetic drift)

founder effect

few individuals become isolated from a larger pop to make a new pop (genetic drift)

gene flow

flow of alleles in and out of a pop resulting from migration

microevolution

evolution within a pop over time (the process that explains patterns)

macroevolution

processes that rise to new species & higher taxonomic groups with widely divergent characteristics (large scale changes observed above a species level)… patterns of evolution (descent with modification)

speciation

the process of a pop diverging into 2 descendant species; helps link microevolution to macroevolution

allopatric isolation

pop divergence due to pops being geographically relocated (dispersal & vicariance)

dispersal

parts of the pop move independently

vicariance

some geographic event that separates the pop

sympatric speciation

pops diverge but live in the same geographic area (prezygotic & postzygotic barriers)

evidence for evolution

fossils, anatomy & embryology; biogeography; molecular bio

anatomy & embryology

presence of structures due to a common evolutionary origin (homologous & analogous structures

homologous structures

similar underlying structure due to common evolutionary origins (aka homology)

analogous structures

similar characteristics that arose independently (aka homoplasy)

age of the earth

4.54 billion years old

order

eon → era → period → epoch

hadean era

(1) hell on earth (earth forms); lots of asteroids

archean eon

(2) anoxic and oxygenic photosynthesis; oceans form & origin of life

proterozoic eon

(3) great oxidation event; eukaryotes evolve

ediacaran period

during proterozoic eon; jellyfish evolve

phanerozoic eon

current eon; paleozoic & mesozoic & cenozoic eras

paleozoic era

cambrian → ordovician → silurian → denovian → carboniferous → permian periods

cambrian period

“cambrian explosion” - explosion of complex life & more nutrients in the water due to land erosion and flooding; complex ecosystem… nearly all major phyla evolve

ordovician period

first non-vascular plants & vertebrates; arthropods on land. ends with ordo-silur mass extinction

silurian period

first vascular plants on land; jawed fish arise; huge coral reefs

devonian period

first fish with teeth; first amphibians & vertebrates on land; wood & early seed plants evolve

carboniferous period

large forests & giant insects; peak of oxygen in atmosphere

permian period

seed plants & conifers diversity; pangea supercontinent & ended with largest mass extinction in earth’s history

mesozoic era

triassic → jurassic → cretaceous periods

triassic period

first turtles & dinos

jurassic period

pangea breaks up; feathered and flying dinos & more bugs; dinos are dominant vertebrates

cretaceous period

flowering plants evolve; lots of T-rex’s; ends wiht K-T extinction

cenozoic era

paleogene → neigene → quarternary periods

paleogene period

graasses evolve & grassland ecosystems start to form; birds & hoofed animals evolve

neogene period

continents near modern distribution; mammals & marine mammals start evolving; first hominins

quaternary period

genus Homo evolves; current period

monophyletic group

a group of 2+ species where you are including the common ancestor of that species & all of the descendants of that common ancestor

shared-derived characteristics

shared characteristics that evolved more recently (analogous characteristics; homoplasy)

shared-ancestral characteristics

shared characteristics but arose from a common ancestor (homologous characteristics; homology)