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142 Cards in this Set
- Front
- Back
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Phanerozoic (543)
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Eon with era Cenozoic, Mesozoic ("middle life"), Paleozoic ("old life"), Cambrian ("recent life"). Second of two Eons in history of life. Refers to "abundant life"
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Pre-Cambrian (4,500)
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Eon with Proterozoic, Archaean, Hadean
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Cenozoic (65)
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Era with Quaternary and Tertiary periods
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Mesozoic (251)
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Era with Cretaceous, Jurassic, and Triassic periods. "Age of Reptiles"
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Paleozoic (543)
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Era with Permian, Carboniferous, Devonian, Silurian, Ordovician, Cambrian periods.
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Proterozoic (2500)
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Pre-Cambrian era, "early life". Origin diverse unicellular and multicellular organisms. Planktonic prokaryotes (free swimming in ocean), 1st Eukaryotes, 1st multicellular organisms, 1st land organisms. Increased oxidizing atmosphere (Vendian biota, Ediacaran fauna)
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Archaean (3800-4000)
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Pre-Cambrian Era. Oldest rocks, sedimentary rocks formed. Microbial mats in shallow marine environments - Stromatolites (cyanobacteria mats) and benthic (bottom habitat in oceans) prokaryotes. Reducing atmosphere (methane, ammonia, and other similar gases)
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Hadean (4500)
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Pre-Cambrian era. Earth's formation, initially of molten material. No fossils.Conditions on Earth unsuitable for life, too hot, long periods of bombardment by meteroties, etc.
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Quaternary (1.8)
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Period in Cenozoic era. Recent (5000 years). Bering and Panama land bridges formed, leading to interchange of organisms between continents. Contains Pleistocene epoch
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Pleistocene (1.8)
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Epoch in Quaternary period. Successive advances and retreats of glaciers. Humans expanded out of Africa around globe, neanderthals in Europe before this expansion, may have interbred or been replaced. Cave paintings and other artifacts
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Pliocene, Miocene
Oligocene, Eocene, Paleocene (65) |
Epoch in Tertiary period. Land bridge North and South America. Great expansion grasslands (ungulate radiations). Ends in mass extinction.
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Tertiary
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Period in Cenozoic era. "Age of mammals" but this is misnomer since bivalve moluscs, teleost (bony) fishes, mammals, and birds all underwent equally dramatic adaptive radiation.
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Cretaceous (144)
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Period in Mesozoic Era. Radiation, mammals, birds. Marsupial and placental mammals. Angiosperm and insect diversification. Some birds radiate. Ends in mass extinction.
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Jurassic (206)
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Period in Mesozoic era. Rise of great dinosaurs. First pterosaurs (flying reptiles, not dinosaurs) and birds (ex. Archaeopteryx). Cycads and gingko trees reach peak.
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Triassic (248)
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Archosaurs (including crocodilians and first dinosaurs). Turtles, lizards, ichthyosaurs, plesiosaurs. 1st mammals. Ends in mass extinction.
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Permian (290)
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Period in Paleozoic era. Dimetrodon (mammal-like reptile such as therapsid). 1st plants with water-conducting vessels (xylem). Ends in mass extinction, largest recorded. End of Permian Period and Paleozoic Era
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Carboniferous (35)
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Period in Paleozoic era. Pennsylvanian (325) Epoch: 1st mammal-like reptiles. Dense swampy forests created major coal deposits. Mississippian (354) epoch: Ferns and large lycopods dominant, 1st primitive reptiles, gigantism in insects associated with high oxygen in atmosphere
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Devonian (417)
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Period in Paleozoic era. "Age of Fishes" (placoderms) because of fish adaptive radiation and abundance. 1st amphibians, 1st insects, 1st seeded and wood plants. First land plants arise and spread. Ends in mass extinction
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Silurian (443)
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Period in Paleozoic era. Vascular plants invade land, 1st jawed fish in seas, 1st land invertebrates.Marine invertebrates dominant, some fish also abundant.
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Ordovician (490)
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Period in Paleozoic era. Invertebrates dominant, corals, bryozoans, graptolites radiate, Trilobites peak, 1st land plants, 1st fish. Continuation of animal diversification. Ends in mass extinction, first (Phanerozoic) of six events.
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Cambrian (543)
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Period in Paelozoic era. Explosive radiation fauna with hard skeletons (all major phyla including Burgess Shale Fauna). Includes origin of all major animal phyla, including Chordata.
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Macroevolution
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large evolutionary change (morphology), involves differences in lineages at genus and higher levels of organization
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Lineage
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a group of species that are interrelated because they share one common ancestral species.
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Systematic Biology
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Field of study attempting to understand and explain origin and evolutionary relationships of all biological diversity (organisms)
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Goals of systematic biology
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propose system of classification, construct one phylogeny of all life, develop consistent system of biological nomenclature, inventory of world biota
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Systematics
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Field devoted to classification of organisms
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Distributions of Character States
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Non-random, correlated with geography, importance of gene flow vs. isolation, may be diagnostic of species
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Three Classification Schools or Philosophies
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Evolutionary school, phenetic school, cladistic school
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Phenetic Classification
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Based on organisms overall appearance, not degree of divergence. Overall similarity of character state distribution.
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Adaptive Radiation
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genetic and ecological diversification of a single, ancestral species into multiple derived and at least partially coexisting species, involving new ecological and or geological zones
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Significance of adaptive radiation
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accounts for creative component of evolutionary process, can occur rapidly in time
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Three Fundamental components of adaptive radiations
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ecological opportunities (niches), genetic isolation and differentiatio nof populations, ecological differentiation
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Three ecological situations favorable to adaptive radiation
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1- new general adaptation opens new adaptive zone, 2- new environment opens up adaptive zone after disturbance, 3- species colonizes new environment with a few other competitor species present
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Cambrian explosion
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Rapid generation of new species and new "body plans". Over 10,000 species arose in short time. Origin of essentially all modern groups of animals.
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Body Plans of Cambrian Explosion
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Radially symmetric gnidarians, (2 tissue layers), Bilaterally symmetric flatworms (3 tissue layers), Coelomates (3 body layers including mesoderm and central cavity)
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What's so dramatic about the Cambrian explosion?
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Bulk of new animal classes arose in about 24 million years, geological blink of an eye. Diverse body plans
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What's our source of information about the Cambrian Period?
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Fossils, including preserved soft-parts (non-skeletal). Burgess Shale in Canadian Rockies of British Colombia, fossil field
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Why do we see this burst of animal creativity in Cambrian?
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Predation theory: first predators on invertebrates arose during Cambrian, creating selection for diverse anti-predator adaptations
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Opabinia
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Anomalocaris. Creature with tube-like grasping structure for securing food and 5 dorsal eyes (relative of anomalocaridids?)
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Chelicerates
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related to spiders, horseshoe crabs, scorpions, ticks, mites. Ex. Sanctacaris
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Lobopodians
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discovered in China in 2010. Ex. Diania cactiformis, Hallucigenia
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Pikaia
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stiff notochord-like rod running length of body, for muscle attachment (and fish-like movement); earliest known chordate
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Oxygen limitation hypothesis for Cambrian Period
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Limited oxygen in atmosphere precluding complex multi-cellular animals. Unlikely, since atmosphere became well oxygenated million years earlier in Proterozoic
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New evolutionary mechanism hypothesis for Cambrian Period
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Ex. sexual selection enabled rapid evolutionary change. Little evidence for this.
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Species well armored against biting predator
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Wiwaxia, Hallucigenia, Marella
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Dorsal eyes to detect predators
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Opabinia
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Diverse ways to hide from predators
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Burrowing priapulids and other worms that could retract into holes in ocean floor
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Diverse means of locomotion
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Pikaia, Opabinia, Sidneyia, Santakaris
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Importance of mass extinction in history of life
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Changes caused by unusually large proportion of organisms going extinct in short time. Six events generally recognized. Created dynamic history of living things. Survivors were non-random taxa that subsequently underwent adaptive radiation
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Vendian biota (of the Proterozoic Era)
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Also known as Ediacaran Fauna, from Ediacaran formation Australia, Europe, or US. Include multicellular soft-bodied jellyfish, soft clams, and worms, some large. Almost all went extinct, and probably not ancestral to most modern animals. First evidence of major extinction.
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Paleocene Epoch (65 MYBP)
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Origin of primates, horses
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Eocene Epoch (55.6 MYBP)
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Origin of Whales
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Oligocene Epohc (33.5 MYBP)
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1st apes, 1st extensive grasslands, ended by major extinction
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Miocene (23.8 MYBP)
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Expansion of grasslands across much of North America
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Pliocene (5.2 MYBP)
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Earliest members of genus Homo
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Recent Epoch (5,000 YA)
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Rise of human civilizations
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Relative Dating
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Method of reconstructing paleontological history. Use of sedimentary rocks because fossil bearing rocks. Stratigraphy and correlation by fossils. Rocks of the same age have similar fossil species (Burgess shale fossils found in >30 locations worldwide). Law of superposition- newer layers laid down on top of older
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Stratigraphy
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Rock strata showing relative layers of fossils in order in which deposited
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Absolute Dating
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Radiometric dating of igneous rocks for reconstructing paleontological history. Igneous rocks melted and homogenized at time of formation, which resets clock on process of radioactive decay. Many radioactive isotopes easily detected and rates of disintegration (half life) known -- math
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Criticisms of Absolute Dating method
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difficult to determine precisely how much of the decay product present during rock's formation, rock layers with fossils have to be dated relative to adjoining igneous layers, scientific creationists claim method is flawed (so is chemistry and physics) because decay rates not constant over time
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Major evolutionary advances of living organisms in the history of life on Earth
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Ability to use oxygen, symbiotic relationships (one led to evolution of eukaryotic cell), colonization of land (plants and animals), vascular system in plants (grew), seeds and hard shells
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Problems with Phenetic Classification
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Different ways to be similar (convergence (homoplasy) similarity that does not reflect common ancestor), different ways to be different (birds changed extensively from reptiles despite close relationship)
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Cladistics
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Also known as phylogenetic school. Goal to identify historical relationships branching patterns from a cladogram to determine order of branching, not degree of divergence. Phylogeny may be reconstructed from distributions of homologous character states among taxa. More shared homologies means more recent common ancestry (greater phylogenetic similarity).
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Plesiomorphic
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Ancestral states. Provides no evidence of relationship within the tree
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Apomorphic
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Character states uniquely derived from a shared ancestor. Derived within the tree
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Synapomorphies
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Shared, derived characters . Shared apomorphies
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Homology
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specific form of similarity that results from inheritance of traits from a common ancestor. Ex. arm bones of vertebrates
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Convergence
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similarity evolved in phlogenetically unrelated organisms, due to similar environments. Homoplasy. Ex. bird and bat wings.
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Three methods for selecting best evolutionary tree
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Principle of parsimony, Maximum likelihood method (Bayesian approach), Tree-joining method
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Principle of Parsimony
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Evolutionary change is inherently simple (evolutionary changes are infrequent). Most likely tree is one with fewest changes needed to group all species. Synapomorphy is assumed to be more frequent that homoplasy.
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Monophyletic
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Group that contains all species derived from the most recent common ancestor of the group. All taxa must be monophyletic, according to phylogenetic systematics.
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Paraphyletic
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Group that continas some, but not all, species derived from most recent common ancestor. Not supported in cladistics.
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Polyphyletic
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Group whose members are similar due to homoplasies (convergence), not due to shared ancestry.
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Criticism of Evolutionary Classification
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Subjective selection of characters for study, search for single characters that define group, accepts paraphyletic groups
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Criticism of Phylogenetic classification
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Ignores degree of divergence of descendents
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Steps in DNA-DNA hybridization method
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Extract DNA from blood cells, purify DNA, shear DNA, prepare single-copy DNA (DNA heated so double strands separate), cool and incubate, separate out unique sequence because duplicate DNA find each other (radioactively label unique sequences), prepare hybrids with strands from same or different species, determine hybrid melting temperature, measure radioactivity at each temperature - if hybrid from same species the strands will be similar and share more hydrogen bonds so more heat rquired, distantly related won't bond as much so less heat.
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T50H
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Temperature at which 50% of all strands are melted into single strands. Change in average melting temperature of hybrid DNA (heteroduplex) versus homoduplex of either species. Phylogenetic trees formed from data from melting curves
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Passerine bird example
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Through DNA-DNA hybridization study, it was shown that Australian birds converged through adaptive radiation from Eurasian groups they were previously thought to be part of
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Taxonomic school of DNA-DNA hybridization
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Phenetic because based on overall similarity (of DNA) with no reference to ancestral versus derived traits (ignored which sequences are ancestral). All characters used, not just synapomorphies.
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Astragalus bone
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Top of ankle. Pulley shaped in Artiodactyls (two-toed ungulates) but not Perisodactyls (one-toed ungulates) & other non-artiodactyls. Fossil record suggests that whale ancestors had this pulley-shaped form of bone, and thus was artiodactyl, but this is disputed.
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Two hypotheses for sister group of whales and relatives
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Artiodactyla hypothesis and Hippo hypothesis
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Support for hippo hypothesis
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Molecular data show presence/absence of SINES (short interspersed elements) and LINES (long interspersed elements) which are unambiguous between hippo and whale.
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Difference in fossils vs. modern whales
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Pelvic girdle reduction, loss of hind legs, tail becomes adapted for propulsion, both have vestigial (remnant) pelvic girldle - overall not very similar
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Georgiacetus fossils
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From Georgia, USA. Suggests that hip undulation (to move hind limbs) was important stage towards use of tail flukes by modern whales.
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Molecular clock
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One can date ancient events by degree of molecular differentiation or change if these changes accumulate at a stead enough (clock-like) rate. Theoretical basis on neutral theory of molecular evolution.
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Neutral theory of molecular evolution
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Molecular clock based on this. Relatively constant rate of substitution and fixation of new nucleotides. Due to mutation and genetic drift (and not to natural selection)
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Estimates of clock-like changes in molecular data
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1.8-2.2% mtDNA sequence divergence in sea urchins, mammals, birds. 1 degree Centigrade change in DNA double strand melting temperature per 4.5 million years. Controversial, many authors question how regular these sequence changes are. Regularity greatest over long time periods with large molecular sequences.
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Dinosaur genomics and avian relation
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Reptilian genome size directly proportional to osteocyte (bone cell) size. Birds inherited relatively small genome from dinosaurs.
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Evolution of opsins
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Human color vision tuned to four different wavelengths, each absorbed maximally using different opsin protein. Corresponding genes: Short, medium, and long wavelengths (SWS, MWS, LWS) - cones and Rhodopsin (rods) for low light conditions
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History of color vision in mammals
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Mammals lost color vision when nocturnal in Mesozoic (age of reptiles). Primate color vision re-evolved twice: all old-world monkeys and one New World. Old world monkeys share 236 DNA base pairs in duplicated opsins, longer duplication in howler monkeys (new world).
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How did primate color vision evolve?
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Most mammals have one MWS/LWS opsin gene: maximum absorbance 510-550 nm. Humans have two genes tuned to 530 and 560 nm. Most of the shift accounted for by three animo acids of ancestral opsin gene, which together shift absorption of opsin molecule.
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Why did color vision evolve in primates?
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Many old world primates diurnal, ability to select red-colored foliage from tougher green foliage, evidence that color vision is under stabilizing selection (Macaques)
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Fossil gene
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"Pseudogene". Genes that have lost original function due to unrepaired mutations, because natural selection no longer maintains their function (no longer stabilizing selection). Ex. dolphin with SWS opsin gene
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Coelacanth SWS opsin gene
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Coelacanth and cetaceans convergently lost function of SWS opsin gene. They both share deep-water ecological niche, relaxed stabilizing selection. In natural selection often use it or lose it (ex. island birds flightless)
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How were Galapagos Islands an ecological opportunity?
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Empty niche, analagous situation to other archipelagos, such islands colonized by waif dispersal. Few bird competitors allowed species to expand into broad ecological niche, few other species of any kind
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Empty niche
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Form of ecological opportunity that allows adaptive radiation
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Waif Dispersal
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Species that are pre-adapted to disperse well
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Cocos Finch
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One Darwin's finch not on Galapagos Archipelago. It has expanded its ecological niche dramatically in absence of competitor species. It documents importance of competitors shaping niche (specialization) of target species elsewhere. Generalist.
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Competitive Release
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Dramatic expansion of ecological niche in absense of competitor species. Ex. Cocos Finch, despite clumsy behavior and phenotype, it can thrive due to absence of predators.
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Finches are omnivores
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Eat seeds, flowers, fruits, insects, and even blood. Seeds are a staple resource during the extended dry season.
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What is limiting resource to Galapagos finches?
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Dry season seed abundance limits populations making it a critical resource to understand.
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Galapagos Islands seasonality
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Highly seasonal and unpredictable. Located in the cool Humboldt Current waters off West Coast of South America. Summer rains followed by severe dry season with no rainfall.
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Tribulus (Caltrop)
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One of the plants with fruits (seeds) that are difficult for any but the deep-beaked species (G. magnirostris) and large individuals of G. fortis to use as food. Illustrates adaptive radiation necessary in beak size of Darwin's finches (force of beak increases with size)
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Evolution of beak size via Natural Selection in Darwin's finches
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Differential survival of larger-beaked birds in drought, advantage of larger beak resulted from ability to eat rare, large seeds
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Genetic Isolation
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Second component of adaptive radiation, which leads to speciation. Allopatric model of speciation supported in Darwin's finches. Upon recolonizing ancestral islands, finches differ further via reinforcement.
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Three stages of Lack's model of allopatric speciation
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Original colonization of Galapagos Islands, Allopatric phase, Sympatric Phase. Camarhynchus pauper example.
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Evidence for reproductive isolation of Darwin's finches.
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Hybrids between species occur and typically produce few, if any, viable offspring (selected against). Pre-zygotic isolating mechanisms in fact exist (individuals recognize conspecific individuals). Experimental playbacks of song show recognition ability evolved in sympatry (females discriminate conspecific males from allospecific sympatric males)
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Why 14 (plus or minus) species of Darwin's finch?
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Because of the geologically dynamic changes taking place in the Galapagos Islands, on which populations of Darwin's finch could diversify. Support allopatric speciation
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Character Displacement
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Pattern in which two ecologically similar species differ more in resource-related phenotypic trait in zone of sympatry, where they presumably compete for resources, than where they are allopatric and do not compete.
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Ecological Isolation
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Third and final component of adaptive radiation. Evidence for niche differentiation comes from character displacement and non-random distributions
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Non-random distribution
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Support idea of inter-specific competition. Ex. Geospiza fortis and G. conirostris never coexist sympatrically suggesting they displace each other locally whenever colonization brings them into contact
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Methods to study adaptive radiation
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Hypothetico-deductive model (population limitation, genetic differentiation, ecological differentiation), experimentation using song playbacks and bird models, "natural experiment" demonstrating direct character displacement
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Evolutionary Trend
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any continued change of character within an evolving lineage
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Lineage
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Continuous sequence of species arranged from ancestor to descendant within a clade
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Clade
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All evolutionary descendant species of their common ancestral species. Any clade is monophyletic
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Two theory mechanisms creating evolutionary trends
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Orthogenesis, Finalism (teleology)
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Orthogenesis
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Evolution in overall direction, but without pre-determined goal An inertia of evolutionary change in which evolution maintains direction (and speed?) that linage has shown in the past. Ex. Irish Elk enlargement of antlers to the point of the animal's extinction (used against Natural Selection, erroneous)
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Support for Irish Elk example of Orthogenesis
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Largest deer ever with very oversized antlers up to 12 feet across. Antlers must have been unwieldy and therefore must have progressed evolutionarily to the point they were maladaptive
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Critique of Irish Elk example of Orthogenesis
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No genetic mechanism every proposed that could cause counteradaptation, there are more parsimonious explanations. Huge antlers of this size are exactly what's predicted by allometric relation of antler size to skull or body
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Cause of Irish Elk extinction
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Specialized deer of high productivity grasslands. Very large size for competitiveness. Sexual selection for large size. Human hunting (Overkill Hypothesis) may have contributed. All in all, more explanations making orthogenesis less compelling.
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Finalism (teleology)
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Goal-oriented evolution. Many people with faith argue that God has arranged creation and destined humans as the culmination of creation.Humans have evolved very recently, teleology is not scientifically testable, science can explain human origins much more simply.
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Trends of progress
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Evolutionary trends are mostly illusory. We are still in age of microbes (still dominate the Earth), however the range of organisms in fossil record has increased.
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Passive Trends in Fossil Record
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See increasing range of variability and complexity over time, but no real trend. The trend is passive rather than directed, simply because of the increase in the range. Very different from the ladder of progress, or any real driven trend towards increasing complexity.
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Implication of Gould's assertion
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Which lineage persisted over time was stochastic, by change not by predestination. If life's history was re-run, different groups might have come to dominate in subsequent periods of adaptive radiation. This is very different from showing evolutionary forms leading inevitably towards humans as apex.
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What explains horse evolution trends
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Changes were adaptations, largely because of natural selection, to different environments. Changes seen in legs, teeth, and body size patterns
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Horse evolutionary changes in legs
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Lengthening of bones, Progression from digitigrade to unguligrade posture, strengthening by fusion of toe bones, evolution of hoof (strengthen toe tip). Adaptations lengthen stride and speed
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Unguligrade
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Animals walk up on digits. Elongation of distal parts, especially toes.
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Trends in horse tooth evolution
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Low to high cusps (brachydont to hypsodont), rounded to grinding surfaces (bunodont to selendont). Results from shift browsing to grazing life history, earliest horses were frugivores. Grazing on grasses causes extensive wear on teeth due to high silica content of leaves. Climate shift from warm and humid to cool and arid expanded grassland environment, Miocene of North America
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Mosaic Evolution
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Origin of traits via natural selection at different times and in different species within a lineage. Adaptation of each trait independent and in response to unique environmental conditions that change differentially.
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Body Size Evolution in Horses
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Cope's Rule- tendency for body size to increase linearly, here steadily in evolutionary lineages over time
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Summary of horse example
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Evolution is opportunistic in relation to contemporary environments , rather than goal direct or driven. There is no compelling evidence for any long term, pre-determined trend towards greater complexity in horses (or any other clade). If this were true it would neccesitate arbitrary selection of particular species at particular times to prove trend.
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Parallel Evolution
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Independent, repeated evolution of similar trait (usually adaptation) from same ultimate ancestor. Results from natural selection using same pathway (often same genetic basis). Contradicts mosaic, indepedent evolution, but arises because natural selection operating opportunistically often takes path of least resistance.
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Parallel Evolution in Stickleback
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Sticklebacks repeatedly evolved independent freshwater forms of plates selected against (by dragonfly larvae as predators) from widespread marine species (body plates and spines). Gene sequences of freshwater forms similar for plate number genes (Eda gene). Phylogeny indicates independent use of the same genetic pathway.
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Rate of Evolution
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Evolution progresses in fits and starts, with rapid rates of character change, often associated with speciation, punctuating periods of stasis, or absence of change
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Anagenetic change
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Change in character not associated with speciation. Measured in Darwins (loge (final mensural value) - loge (initial measured value)/ (Tfinal - Tinitial) where T's are times measured i millions of years. Relative rate measurement, because different of logs are logs of a ratio. Gradual evolution. Comparison with cladogenetic rate represents frequency of speciation within clade.
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Bradytely
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One extreme of cladogenetic rate, in which slow (or no) change and no speciation occurs. For example, living fossils like stromatolite bacteria and Ginko tree
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Tachytely
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Other extreme of cladogenetic rate, involving rapid rate of origination of new taxa, for example, rigid origin of Artiodactyla (two-toed ungulate) beginning in Miocene
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Problems with measurement of evolutionary rates
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Change (in Darwins) inversely proportional to measurement interval, thus an artifact of method (highest rates observed in studies of artificial selection, lowest rates Post-Pleistocene), rates differ depending on use of chronological versus generation time, different characters have different rates (biochemical vs. morphological), taxonomic factors (tendency to lump or split taxa such as species) affect cladogenetic rate estimates
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Phyletic gradualism
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Eldridge and Gould. New species arise via gradual transformation over time, transformation is even and slow and involves large populations, often entire species (ex. Ordovician trilobites). Many scientists such as Darwin and Simpson tended to deemphasize sudden large genotypic and phenotypic changes
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Punctuated equilibrium mode
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Eldridge and Gould proposed this explicit coupling of the idea of change punctuating periods of stasis. New species arise rapidly by splitting of lineages (cladogenesis) probably via small populations isolated at periphery of species ancestral range. In the long periods between speciation events stasis (lack or change) is the norm. Most anagenetic change concurrent with speciation
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Mechanisms of rapid evolutionary change at time of speciation
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1) Macromutations (discredited). 2) Rapid phenotypic change due to the breakdown of homeostatic constraints (associated with embryological development) when selection is very strong, which could cause high variability of traits, facilitating further rapid change via natural selection (empirical support is weak). 3) Harsh, changing environments act on small, isolated populations at periphery of species range, causing rapid anagenetic change and reproductive isolation at same time (peripatric speciation). Speciation does not accelerate rate of anagenetic change, but prevents further change once reproductive isolation complete (supported by Gould but not well tested)
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Mechanisms of stasis between times of rapid evolutionary change
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may be developmental constraints once speciation has occurred, but not much evidence because development itself has evolved repeatedly. Stasis may depend on constraints from other species in the community by adaptive gridlock - selection predominantly stabilizing (competition, etc.), large stable environments important because these would have larger populations, other species as selective agents. Idea needs further study
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