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131 Cards in this Set
- Front
- Back
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Origin Time Line
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Sun: 5 bya
Earth and other planets: 4.6 bya Earliest Microfossils: 3.5 bya Atmospheric oxygen: 2 bya First Eukaryotes: 2 bya Multicellular Eukaryotes: 1.2 bya |
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Hypothesis for Origin of Life
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Abiogenesis:
Prior to first prokaryote: abiotic production of small organic molecules from inorganic compounds(proliferation to those that replicate faste, more stable, and more accurately) |
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Stages of Origin
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1) synthesis of monomers from inorganic molecules
2) join together and make polymers (has information content and can transmit information) 3) cellular compartmentalization |
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Earths Atmosphere
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Before: No/little free oxygen, strongly reducing = gaining electrons
After: 21% of oxygen (byproduct of photosynthesis) Oxygen is a corrosive electronstripping molecule |
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Energy Sources on Earth
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solar radiation, lightning, heat, radioactive decay
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Hypothesis for the Formation of Monomers
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Reactions, with an energy source, spontaneously produced small organic molecules from inorganic compounds
Source of abiotic organic monomers was deep in the ocean at hydrothermal vents Molecules arose from outer space and arrived on meteorites |
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Creation of Polymers
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polypetides and polynucleotides can form spontaneously from high concentrated solutions (adsorption of clay particles, evaporation from hot rocks, freezing)
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Protobiont
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proposed prelife, bounded chemical systems with an internal chemical environment that's different from external (separated by membrane), capable of self-replication, and contains macromolecules with enzymatic capacity
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Hypothesis for "RNA came first"
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First genes were short strands of self-replicating RNA enclosed in protobionts may have functioned both as genes and autocatalytic (facilitate own replication) DNA came later from reverse transcriptase
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"RNA World" hypothesis
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abiotically formed short polynucleotide strands existed with many genotypes and phenotypes (phenotypes that replicated faster, more accurately, more stable predominated)
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Earliest Life (Prokaryotes)
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unicellular, heterotrophic, anaerobic (without oxygen), prokaryotes, aquatic
(very similar to cyanobacteria) |
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Heterotroph
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receive nourishment from others and acquire energy from others (Consumers)
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Stromatolites
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large layered structures formed by bacterial mats
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Autotroph
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self nourishing (photosynthesis) use solar energy to convert inorganic to organic matter (Producers)
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"Oxygen Revolution"
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change from oxygen poor to oxygen rich environment (2 bya) causing some anaerobic prokaryotes to become extinct
Evidence: banded iron from precipitated iron oxide, formed as oxygen when dissolved in oceans then released into the atmosphere |
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Evolution of Eukaryotes
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Fossil Evidence: 1.2 bya
Actual First Appearance: 2 bya First Eukaryotes: Protists |
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Advantage of Eukaryotes
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1) greater amount of DNA
2) more complex 3) multicellularity 4) increased genetic variability through recombination |
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Endosymbiosis hypothesis
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origins of certain eukaryote organelles (mitochondira and chloroplasts) are from endosymbiotic prokaryotes
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Endosymbiotic
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small prokaryotes living symbiotically inside larger prokaryotes
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Stages of endosymbiosis
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1) endosymbiotic prokaryotes were engulfed by larger anaerobic cells (photosynthetic bacteria)
2) evolved mutually beneficial symbiotic relationship (chloroplasts) |
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Consequences of endosymbiosis
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"lateral gene transfer" - genes shared horizontally across lineages
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Geological Time Scale
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Eras, periods, epochs
Are delimited by appearance and disappearance of characteristic groups of organisms in the fossil record |
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Ediacaran Fauna
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565-544 mya, Fossil beds in Australia, found fossils with soft bodied, without limbs or heads (worms, jelly fish, sponges)
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Cambrian Explosion
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540 mya, all known animal phyla appeared (phylum chordata - humans)
Burgess Shale, British Columbia 520 mya - evidence of evolved defense against predation (shells) |
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Cause of Cambrian Explosion
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# Ancestral animals were small, soft bodied, and didn't fossilize
# Genetic changes in developmental regulatory genes # Extreme ice age from 750-600 mya |
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Evidence Endosymbiosis
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§Endosymbiotic prokaryotes today
§ Same size as prokaryotes §Circular DNA §Ribosome structure §Protein synthesis §Binary fission |
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Phylum Chordata
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Vertebrates, Cephalochordates, Urochordates
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Chordate Characteristics
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notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail
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Vertebrate Charateristics
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cartilaginous or bony vertebrae, brain and braincase
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Vertebrate Groups
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Hagfish, Lamprey: first vertebrates, lack jaws
Acanthodians, Placoderms: earliest jawed vertebrates Sharks,Rays: cartilaginous skeleton Ray-finned, Coelacanths, Lungfish (lobe-finned fish): bony skeleton, possible tetrapod ancestor Amphibians: first terrestrial tetrapods Mammals: arose from mammal-like reptiles during Mesozoic, hair, lactation Reptiles (turtles, sankes, lizards, crocs): arose from "stem-reptiles" Birds (aves): arose in Jurassic from dinosaurs, feathers, flight |
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Paleozoic Era
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543-250 mya Cambrain, Ordocician, Silurian, Devonian, Craboniferous, Permian
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Origin of Jaws
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Silurian - jaws formed from gill arch supports of jawless fish, evolution of active predation
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Origin of Lungs
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Devonian - evolved in the ancestral bony fish's swim or gas bladder (buoyancy organ)
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Origin of Amphibians
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Devonian - evolved from lobe-finned fish, dependent on water for reproduction
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Origin of Amniotes
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Carboniferous - amniotic egg (water-proof, air-permeable, embryo surrounded by nutrients)
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Amniote lineages (based on skull featuers)
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Synapsids: mammal ancestors
Anapsids: modern turtle ancestors Diapsids:crocs, dinos, ancestors of lizards, snakes, birds |
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Origin of Mammals
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Permian - Therapsids (amniotes gave rise to mammals) GRADUAL process
Changes included.... reduction of lower jaw bones from several to one articulation of lower and upper jaws restructureing of the middle ear from one to three bones |
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Permian Extinction
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Greatest in Earths history
90% of all marine invertebrate species became extinct, 66% amphibians and reptiles became extinct Causes.... Volcanism Decreased atmospheric oxygen Coalition of Continents Asteroid |
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Mesozioc Era "Age of Reptiles"
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250-65 mya Triassic, Jurassic, Cretaceous
Pangea began to split apart |
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Origin of Birds
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Jurassic - Archaeopteryx is one of the earliest birds, dromaeosaur are ancestral group to birds
Feathers evolved before Flight |
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Cretaceous Extinction
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mass extinction of dinosaurs and other terrestrial vertebrates
Cause.... Impact Hypothesis: asteriod struck near Chicxulub, Yucatan, global cooling and darkness Evidence... thin iridium (extraterrestrial element) sediments are found world wide |
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Cenozoic Era "Age of Mammals"
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65 mya to present - Tertiary, Quaternary
Adaptive Radiation of placental mammals |
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Primate Groups
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Prosimians (before apes): lorises, lemurs, galagos, bushbabies, tarsiers
Apes and Monkeys (anthropoids) |
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Monkeys and Apes
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New World Monkeys
Old World Monkeys Apes and Humans (Hominoids) |
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Hominoids
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Lesser Apes: gibbons, siamangs
Great Apes (Hominids): orangutans, gorillas, chimps, bonobos, and humans |
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Primate Traits
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five grasping digits
flattened nails fleshy pads on digits stereoscopic vision intelligence Arboreal Lifestyle causes..... small litter size longer gestation |
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Evidence for Relationships among Primates
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DNA hybridization
protein amino acid sequences chromosome banding chromosome structure DNA nucleotide sequences |
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Molecular Clock
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technique for estimating the are at which two extant species last shared a common ancestor
Involves..... comparing DNA nucleotide sequences determining the number of substitution point mutation differences under the assumption neutral mutation are fixed at a constant rate the amount of time since the two species diverged |
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Changes from Apes to Modern Humand
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Quadrupedal > Bipedal
Increase in braincase size Lower jaw Tooth rows from parallel > parabolic Appearance of chin Eyebrow ridges Reduced sagittal crest |
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Homin Genera
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Ardipithecus
Australopithecus Paranthropus Homo |
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Hominin Evolution
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Tree is "bushy" (numerous branches) as a cause of discovering new fossils
Concurrent species: at least 4 species lived at the same time and place (africa) Early evolution was entirely in Africa (until 1.8 mya) Earliest hominins were bipedal Increasing brain size |
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Earliest Hominin
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Ardipithecus ramidus is one of the oldest known hominins 4.4 mya and 5.5 mya
Australopithecus afarensis is the earliest well known hominin 3-4 mya (Lucy 3.2 mya) Chimps and Humans have a common ancestor about 6-7 mya |
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Robust Species - Paranthropus
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Powerful, coarse, large skull and jaw NOT ancestral to modern humans
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Gracile Species - Australopithecus
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Delicate, slender
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Homo
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First appeared 2.5 mya
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Homo habilis "handy man"
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2.5 - 1.9 mya
Earliest Homo Stone/pebble tools (Oldowan stone) |
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Homo erectus "java man" or "peking man"
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1.8 - .3 mya
First hominin to leave Africa (Eurasia) Stone/bone tools (Acheulean) Rock based shelters Used controlled fire and Big game hunters Homo floresiensis evolved from H.erectus: tiny (1m) |
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Homo heidelbergensis ("archaic" H. sapiens)
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0.6 - 0.2 mya
More sophisticated tool making (Levallois style, flaked points) |
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Homo neanderthalensis
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130,00-30,000 yr
Powerful body, sturdy limb bones, adapted for cold Caves Buried Dead Stone tools (Mousterian) No Art Not ancestral to modern humans (Co-existed with H.sapiens for 10,000 yr) |
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Homo Sapiens
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190,000 Africa
100,000 Africa > Middle East 50,000 Africa > Asia, Australia, and then Europe |
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"Human Revolution"
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Change in behavior and culture
Stone/bone/ivory tools of great techonolgoical skill (Upper Paleolithic) Huntergatherer lifestyle Dwelling and fire pits Art became very important Cause..... refinement of language |
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Origin of Modern Humans
Multi-Regional Hypothesis |
H. erectus population emigrated from Africa, colonized Eurasia, local populations from different regions evolved separately into H. sapiens
"races" are of ancient origin |
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Replacement Hypothesis "Out of Africa"
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H.sapiens evolved in Africa, colonized Eurasia, replace Neanderthals and H.erectus
Best supported hypothesis Evidence...... Mitochondria have their own genome DON'T undergo recombination, passed only maternally mtDNA can be traced back to a single common female ancestor Differences are due to accumulated mutations (fewer differences = more common ancestor) mtDNA can be extracted from fossils |
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Biotic Environment
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others of the same species and different species
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AbioticEnvironment
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physical and chemical
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Population
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individuals of the same species in a particular area
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Communities
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potentially interacting assemblages of different species in a particular area
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Ecosystems
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communities plus their abiotic environment
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Patterns of Dispersion
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clumped (aggregated)
uniformly distributed (evenly spaced) randomly distributed = RARE(location of an individual is independent of the locations of others) |
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Four Factors of Population Growth
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birth, death, immigration, emigration
(measured by the number of individuals per unit time) |
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Population size
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N (change in population size) / t (time) = change in population size in a given time interval
N/t = (births - deaths) N per capita growth rate r = b - d r < 0 population decreases r > 0 population increases r = 0 population is constant |
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Exponential Growth
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occurs when per capita rate remains CONSTANT
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Discrete Growth
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In populations (those with distinct breeding seasons) births and/or deaths occur at discrete intervals
N0 = initial population size Nt = population size at t (time) units later Nt / N0 = populations finite rate of increase x time |
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Continuous Growth "J"
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populations of organism (bacteria and humans) without distinct breeding seasons can grow continuously
if r doesn't change as population size increases it's rate of change increases dN/dt = rN rmax: maximum possible per capita rate (highest reproductive rate and lowest death rate), intrinsic rate of increase |
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Logistical Growth
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regulated population, increasing population size results in resource limitation that negatively affects each individual and dampens per capita rate
Causes..... increased death rate decreased birth rate dN/dt = rN [(K-N)/K] K: carrying capacity |
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Density-dependent factors
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Greater influence on diminishing growth rates as population density increases
Responsible for LOGISTICAL population growth Examples: competition for space, foos, shelter, disease, predation |
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Density-independent factors
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influence independent of population size
Usually responsible for EXPONENTIAL growth then crash to low levels Examples: random weather, flood, storms, fires |
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r-selected species
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potentially HIGH growth rates
have short maturation times short lifespan high mortality rate many offspring usually one reproductive episode in life early age for first reproduction small size offspring no parental care Examples: bugs, plant |
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K-selected species
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LOWER growth rates
better competitive abilities long maturation long lifespan repeated reproductive episodes Examples: humans, elephants, whales |
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Life Table
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summary of age-specidic mortality and survivorship and age-specific birth rates
Cohort: group of individuals followed from birth until all are dead |
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Survivorship Curves
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Type I: low mortality rate in young and middle age classes, high in older classes
Examples: humans, large mammals Type II: relatively uniform mortality rates over all ages Examples: birds, hydra Type III: high mortality rate in young age classes, lower in middle and older Examples: elms, oysters |
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Human Population Growth
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Highly developed nations have zero or negative growth
Development = less-developed country's birth and death decline (initially death declines faster: demographic transition) Industrialization initially is an increase in growth rate |
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Trophic (feeding) levels
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primary consumer: herbivores - eat producers
secondary consumer: carnivores - eat herbivores tertiary consumers: carnivores - eat other carnivores omnivores: feed on both producers and consumers decomposers and detrivores: feed on dead organic matter/wastes from other organisms |
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Habitat
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the place where an organism normally lives
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Niche
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an organism's ecological "role" in its community
sum of biotic + abiotic resources in the environment and interactions with other species |
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Fundamental Niche
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an organisms potential niche, in the absence of competitors
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Realized Niche
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competition from other species with overlapping fundamental niches results in reduction of the niches of one or both to some smaller subset
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Interspecific Competition (-,-)
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involves utilization of the limiting resource by individuals of two or more species
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Interference (direct) competition
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physical exclusion (chasing, fighting, overgrowth, chemical means)
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Exploitation (indirect) competition
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reduction of shared resources by utilization
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Competitive Exclusion Principle
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two species within the same or very similar niches CANNOT co-exist
Outcomes... with broadly overlapping niches = extinction of one niche differentiation: reducing niche overlap (character displacement, resource partioning) |
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Character Displacement
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divergence in some character between two populations as a selective response that reduces competition among individuals
Example: Beak-size, smaller beaks eat smaller seeds, larger beaks eat larger seeds |
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Resource or Niche Partitioning
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adaptive response to past competition, two niches of two formerly competing species have diverged, reducing overlap
Result: resources are partitioned among species Examples: warblers forag on different parts of the tree |
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Symbiosis
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interactions between individuals of two species that live in close association with each other
Commensalism (+,0) Parasitism (+,-) Mutualism (+,+) |
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Commensalism
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One benefits while the other has no effects
Example: barnacles and whales |
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Parasitism "consumptive" (predation, herbivory)
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One benefits while the other does not
parasite (endo- or ecto-) takes nourishment causing damage but doesn't kill it |
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Broad Parasites
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Birds - lay their eggs in the nests of other species
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Keystone species
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(Often predators) have great but often subtle impact on the distribution and abundance of other species in teh community
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Anti-predation adaptations
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crypsis-camouflage
aposematic-warning, bold, colorful, conspicuous patterns mimicry-Batesian: harmless edible species resembles noxious species Mullerian: two or more noxious species resemble each other |
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Coevolution
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one species A evolves in response to the other species B and visa versa
Results.... coadaptations: The Red Queen |
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Mutualism (+,+)
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Both species that interact benefit
Examples: pollination mutualisms flowering plants rely on external agents and attract them with nutrients, odor, and color |
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Amensalism (-,0)
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individual harms another species but doesn't benefit
Example: guano from tree-nestinf colonial birds inhibits plant growth |
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Succession
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following a disturbance in a given area, community composition changes over time in sequence
Causes.... facilitation: species alter their habitat in ways that eventually benefit the assemblage of species inhibition: early colonizing species may delay the establishment of later successional ones, may eventually alter the habitat in ways that make it less suitable for earlier ones |
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Primary Succession
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sequencing of communities in a newly exposed habitat that initially is bare, without life
Example: volcanic island, retreat of a glacier, hurricane island |
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Secondary Succession
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starts with some widespread disturbance to an existing community that leaves the soil intact
Examples: fire, abandoned field |
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Early and Late Successional Stage
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Early Stages - dominated by pioneering of r-selected species
Late Stage Species - have adaptations from successful competition |
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Climax Community Concept
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the endpoint, inwhich the species composition remains relatively stable, under a given set of climatic conditions
repeated disturbances are a regular component of all communities |
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Individualistic Hypothesis
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communities are loose assemblages of species that occur in the same area as a result of independent distribution of the various species along environmental gradients for which they are individually adapted
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Interactive or Organismic Hypothesis
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community is a cooperative cohesive and discrete unit of species that depend upon and interact with each otehr with distinct boundaries
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Carbon fixation from Photosynthesis
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Carbon is incorporated into sugar
Utilization of enrgy for growth, work by organisms = Respiration photosynthesis energy + 6CO2 + 6H20 = C6H12O6 + 6O2 respiration |
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Laws of Thermodynamics
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First Law: the amount of energy in the universe is constant
Second Law: total amount of entropy (disorder) energy in the universe always increases. Energy transformations result in partial conversion to heat (most disordered energy form) All solar energy will ultimately be accounted for as heat loss |
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Gross Primary Productivity
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the total amount of energy converted by autotrophs into photosynthetic products per unit time
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Net Primary Productivity
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is GPP minus respiration. NPP is the energy available to support heterotrophs
Influenced by TEMPERATURE and WATER Tropical areas are most productive |
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Food Chains vs. Food Webs
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Chains: involve the organisms through which energy flows in an ecosystem
Webs: interconnections of food chains in an ecosystem |
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Reason for inefficient energy transfer
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Some productivity of a given level is not eaten by nest lecel
Some ingested is not assimilated (passed to decomposers) Some is used for respiration Lost as heat |
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Energy Pyramids
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"bottom-heavy", roughly a 10% efficiency of energy transfer from one trophic level to the next
Explanations... Inefficiency of energy transfer 90% loss at each level results in too little energy left to support additional ones Numbers of individuals at each level may not be bottom heavy |
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Biochemical Cycles (Materials and Nutrients)
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are passed among levels and to/from environment and are recycled NOT lost
plants > organisms feeding on plants and other organisms > decomposers > abiotic reservoirs (air,soil,oceans, and lakes) |
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Carbon Cycle
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Atmospheric carbon is "fixed" by photoautotrophs by photosynthesis into complex organic molecules (sugar)
Returns to the atmosphere by respiration, burning, weathering limestone Majority of Earths carbon is buried in sediments (fossil fuels) or dissolved in the ocean |
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Nitrogen Cycle
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78% in the atmosphere, is stable and not directly available to organisms
Ammonification Cycles: nitrogen fixing bacteria can convert N2 to ammonia which can convert to nitrates (plants can utilize which then are utilized by consumers) Denitrification (bacteria): nitrates are returned to the atmosphere |
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Water Cycle
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solid, liquid, or gas
oceans <> atmosphere <> land <> organisms Evaporation by plants return liquid water to atmosphere |
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Phosphorous Cycle
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cycles slowly from weathering of rocks to organisms to sediments
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Greenhouse Effect
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carbon dioxide (CO2) permits light energy to strike Earth, then absorbs and reflects some of the re-radiated heat increasing surface temperature
Increase in CO2 = enhanced greenhouse effect Cause... burning fossil fuels Predicted Global Effects.... Melting of polar ice caps causing increase sea level (flooding) Decreased rainfall in the US interior Extinction of plants and animals Ocean acidification |
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Greenhouse Negative Feedback (mitigating warming)
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increased temperatures result in increased photosynthesis rates, which lead to increased carbon fixation - REDUCES carbon
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Biomagnification
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toxic chemicals (DDT, mercury, pesticides, PCBs) are increasingly concentrated in biomass as they pass up the food chains
Carnivores have HIGHEST concentrations Consequences..... Eggshell thining Inhibiting or preventing reproduction Endocrine system disruption |
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Ozone Layer Depletion
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CFCs (refrigerants, propellants, styrofoam) are a source of chlorine atoms which interact with 03 to convert it to O2
Consequences.... skin cancer cataract rates decreased primary productivity |
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Acid percipitation
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sulfuric and nitric acids, produced by burning of fossil fuels, resulting in acid rain and snow
Effects.... terrestrial and aquatic environments Emissions in on area can often cause acid rain in distant areas |
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Coriollis Force
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results in right deflection of wind and currents in northern hemisphere left deflection in southern
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Biomes
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major terrestrial ecosystem types of the world, defined by distinctive vegetation
Determinants of Biomes: Mean Annual Temperature & Mean Annual Percipitation |
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Biomes
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Tropical Wet Forest: most productive region
Subtropical Deserts Temperate Grasslands Temperate Forests Boreal Forests Arctic Tundra |
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Ecotones
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transitions between biomes, generally gradients NOT sharp boundaries
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Aquatic Ecosystems
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NOT called biomes
Oligotrophic lakes: deep, nutrient poor, low productivity Eutrophic lakes: shallow, nutrient rich, high productivity |
