Biology Final Cards
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- Darwin's finches
- measurements of beak shape and size, only birds with large bills survive, correlation between parent and offspring beak shape
- Quantitative traits
- Traits that are determined by many genes
- Disruptive selection
- Favors individuals at both extremes - can result in new traits/species
- Directional selection
- Changes the mean value of a trait - shift is usually in one direction
- Stabalizing selection
- Reduces variation bue does not change the mean
- Artificial selection
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different survival of progeny with different characteristics
Selection with dogs - favoured more juvenile features - Founder Effect
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New populations established by a few founding individuals
Gene frequencies differ from parent population - Bottleneck effect
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Occur when few individuals survive a random event
Original pop--> chance environmental eventm --> small surviving population -->new pop with different allele frequencies --> results in reduced genetic variation - Random Genetic Drift
- causes random, large alterations in allele frequencies
- Effects of non-random mating?
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Does not change allele frequencies unless offspring have different survival
Do not see HW genotypes - Assortive mating
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When capable of self mating want to avoid it
In mprimulus plant have two different morphologies - different position of female and male body parts
Self fertilization is prevented by a)bee movement and b)pin polin does not germinate with pin stigmass.. - Non random mating
- when do not mate randomly with respect to the phenotype/genotype (sexual selection in birds)
- Gene flow
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migration of individuals
introduces new alleles to populations
HOMOGINIZES POPULATIONS - Mutation
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Origin of genetic variation
most are harmful, some are advantageous - Five agents of evolutionary change
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Mutation
Gene flow
Nonrandom mating
Genetic drift
Selection - Hardy-Weinberg
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Large population
Random mating
no mutation
no migration
no natural selection - Evolution
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May result in slower, smaller, less complex
Life simply uses what it has to adapt to where it is
Human involvement influences further evolution - Rates of Evolution
- Rapid rates of evolution occur when changes to the physical and biological environment create conditions that favour new traits
- Conservation of Genetic Sequences
- More closely related organisms show greater similarity in gene sequences
- Molecular Biology
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Genes for rRNA in all living things
Rudimentary genes for photosynthesis
Common metabolic pathways
*Universal genetic code* - Vestigal Organs
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serve no current function but still see evidence of them
Indicate evolutionary past
Cave dwelling fish still have eyes, breasts in males, legsin whales - Homologous Characteristics in early development
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all have gill slits, post anal tail, notochord, and dorsal nerve cord
Homeotic genes are all in the same place - Homologous structures
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Homologous - same ancestor
Analogous - same structure and function
those with recent common ancestor will have more homologous structures - Degree of morphologial distance depends on...
- strength of selection (depending on climate and demands for different traits)
- Degree of Genetic difference depends on...
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the time of the separation of the groups
(amount of differences depends on the time since departed) - Biogeography
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The longer that continents have been separated the greater their differences in their fossils nad living organsisms (marsupials in australia)
See similar species clustered in the same area
Ex: Drosophila in Hawaii (the further the distance between the two islands hte less the species will diverse) - Fossil Record
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Reveals broad patterns of evolution
Recent fossils resemble current species
Shows diversity exploded during Cambrian era -
Evidence for Evolution
(6) -
Fossil record
Biogeography
Comparative anatomy
comparative physiology
molecular biology
modern genetics - Anamalia
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Eukaryotic, multicellular, no cell wall
Asexual/sexual
heterotroph - Fungi
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eukaryote, multicellular, cell wall, asexual/sexual
heterotroph (produce hyphae into what they are feeding on - when another gets close can reproduce)
more closely related to animals than plants - Life History of Plants
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ancestor to plants - ancient
invasion of land - ordovician
vascular system - silurian
trees - devonian
radiation of angiosperms - last 150 my - Plantae
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eukaryote, multicellular, cell wall, asexual/sexual, autotrophic
highest above ground mass - Protista
- Eukaryote, single cell, asexual/sexual, heterotroph/autotroph, ancestral to other eukarya
- Archaebacteria
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single cell, prokaryote, asexual, heterotroph/autotroph
methanogens, thermophiles, halophiles - Eubacteria
- second major bacterial group, 3bya, strong cell walls, cyanobacteria
- Water Vascular system
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water enters through madreporite, radal canals extend
have 5 radial canals - Echinoderms
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6,000 living, have water vasuclar system
Secondary radial symmetry - bilateral symmetry during development but become more symmetric as adults - Class Arachnida
- Have a pair of cheliceral, pedipalps and 8 legs, carnivores
- Sense receptors for insecta
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Sensory hairs-linked to nerve cells
Tympanum-found with tracheal air sacs
Pheromones - communication signals - Class insecta
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3 body segments(head, thorax, abdomen)
3 pairs of legs
modified mouth - Characteristics of arthropods
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Circulatory system is open
nervous system
no single respiratory system
excretory system - malpighian tubes - Protosomes vs. deutrosomes
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Pro: bilaterally symmetric(tube within a tube)
Deut: bilarteral, mouth second - Coelomates
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a new body design (cavity between digestive tract and body wall)
increase in body size
development of complex tissues
greater range of movement - Benefits of sex
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species can overcome environmental changes
eliminate deleterious traits
evolve more quickly - Theory of endosymbiosis
- Ancestral eukaryotic cell -->aerobic bacteria enters --> endosymbiosis --> bacterium becomes mitochondria --> photosynthetic bacterium enters --> endosymbiosis to become chloroplast
- Why Three domains?
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Domains were revealed by rRNA sequences
Common ancestor lived more than 3bya
Eukarya and archaea split 2 bya - Prions
- Protein infected particle (mad cow disease)
- Viruses
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Arguably living
DNA in a protein coat
Smaller than cells
cannot reproduce, feed or grow - Hierarchical Classification
- Linnaean classification systems: species are grouped into higher level units
- Classification
- classification systems improve our ability to explain relationships among things
- Taxonomy
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Taxon-unit of classification
domain kingdom phylum class order family genus species - Life elsewhere in the universe?
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meteorites contain many biochemical compounds
many other stars are known to have planets - New life still evolving?
- No longer being assembled because simple biological molecules that form are oxidized or consumed by existing life
- Prokaryote to eukaryote
- Loss of cell wall ->folding increases SA(as folding increases some membranes could have gone inside)->internal membrane surrounds DNA -> cytoskeleton formed -> precursor of nucleus ->flagellum formed ->digestive vesicles -> mitochondria formed (engulfed eubacteria) -> chloroplasts
- First eukaryotic cell
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1.5 bya
have internal nucleus, endoplasmic reticulum, mitochondria, sexual reproduction, multicellularity - Photosynthesis
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First photosynthetics were probably anaerobic bacteria -used H2S not H2O
Cyanobacteria split water into hydrogen ions and oxygen - Phylogenetic Tree
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Constructed using rRNA sequences and differences between them
use because know it was the first molecule in all ancestors - Earliest cells
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Archaea bacteria - lived in extremely hostile conditions, 3 bya
no peptidoglycan, unusual lipids, thermophiles, mathanogens (use sulfur), halophiles - Origin of metabolism
- Earliest cells were anaerobic heterotrophs, used dissolved organic materials
- DNA evolved...?
- earliest probably evolved after RNA based life became surrounded by membranes
- Bubble hypothesis
- volcanoes erupt under sea-> gases produce molecules-> bubbles rise to surface and pop -> react to form more complex molecules -> go back into ocean
- Protobionts
- The first genetic material may have been RNA that had a catalytic function and a transfer function
- Problem of origin of self replication
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First came proteins or nucleic acids?
cells had to differentiate themselves
answer: RNA can self replicate - Miller/Urey (1953)
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Knew there was water and heat and a mixture of gases - no O2
used electricity to stimulate lightening to break bonds -> formed amino acids - Necessary conditions for life
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CO2, H2O, CH4, N2, NH3, H2
Small molecules can form and polymerize - Where did life begin?
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Deep sea banks - gases coming up
oceans edge - Fundamental properties of life
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cellular organization
sensitivity
growth
development
reproduction
regulation
homeostasis - Characteristics of all living organisms
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cellular
same 20 amino acids
RNA and DNA for same things
all cells have ribosomes
carbohydrates from same sugars
all reactions catalyzed by proteins - Movement of earth
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continents have moved due to plate movement in water
think the ice age began due to land movements
Gondwanaland -australia, africa, asia, south america, antartica - Cenozoic
- Age of mammals, have not diversified ways that others have, not enough time, now going through a mass extinction
- Mesozoic
- dinosoar era, age of reptiles
- Permian
- Marine organisms evolve into those that colonize land
- Paleozoic
- Multicellular life expands in the marine environments
- Phanerozoic
- 544 mya - present
- Proterozoic
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2.5 bya - 554 mya
evidence of the frist eukaryotes
2.1 bay eukaryotes formed - Archaean
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4.0-2.5 bya
oldest identified rocks found
first fossils appeared around 3.5bya - they were stromalites - Priscoan/Hadean
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hot, fiery furnace
4.6-4.2 bya
most water is in the form of gas - Earth's atmosphere over time
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Early atmosphere lacked O2, accumulated O2 after prokaryoes evolved the ability to use H2O
this allowed for increasing evolution - Fossils
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Organisms are normally decomposed or consumed - fossil record is mainly of teeth
divided into eras based on fossil biota - Stratigraphy
- places fossils in relative sequences to each other
- Index Fossils
- fossils which are indicative of the time horizon (layer of rock)
- Half Life
- half life of an isotope is the time it takes 1/2 the number of molecules to decay into the end product
- Know the earth is ancient because...
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relative ages of the earth's rocks can be determined from their positions
radioisotopes can determine absolute ages - Medel's work
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Natural selection -> acts on the phenotype
Population genetics -> explains speciation and evolutionary age - Macroevolution influenced by...
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1) infrequent or slowly occuring events
2) massive extinctions
*only hindsight indicates macroevolution* - Microevolution influenced by...
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1) natural selection
2) genetic drift
3) mating system
4) population size
5) genetic variation -
Evolution
(defenition/aphorism) -
change in the genetic composition of a population over time
nothing in biology makes sense except in the light of evolution -
Synthetic theory
"three ideas" -
1) variation exisits and has genetic basis
2) natural selection is powerful in shaping the course of evolution
3) population genetics helps explain speciation and evolutionary change - Other contributers to the evolutionary theory
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Weismann - chromosomes
Waldemeyer - named chromosomes
Vries - mutation - Impact of genetics
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Mendel's work helped explain inheritance
Recognized role of germ cells
published work in 1866 - What directs the course of evolution ?
- Natural selection
- Raw materials for natural selection
- the variations within a population
- Speciation
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Species arise through the cumulative addition of differences within a population
Become extinct because they fail to adapt to changing environmental conditions or due to natural catastrophies - Darwin based his theory on:
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1)populations are a constant size
2)high mortality rate among offspring
3)all populations show variations
4)variations are inherited
5)offspring with the best traits will survive - Two components of the theory of evolution
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1) species are not immutable, but change and adapt over time
2)the agent that produces these changes is natural selection - Wallace
- Sent manuscript on theory of natural selection to Darwin
- Darwin
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Evolution by natural selection
Beagle: 1831-1836 - Lamark
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common decent with modification
spontaneous origins of life
environment stimulates change in characteristics
inheritance of acquired characteristics
changes needed in many generations so earth must be very old - Teleological thinking
- idea that species changed to improve themselves - tried to reach a goal of perfection
- Cladistics/Parsimony Method
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Does not weight characteristics
Uses an outgroup to determine primitive and derived traits - Clade
- entire portion descended from a common ancestor
- Distance Based Method
- measure in terms of the main number of differences between organisms
- Know traits are homologous
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Morphology
Chromosome number, size
Amino acid sequence , DNA - How are traits constructed?
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Use only homologous traits
Distinguish between ancestral and derived traits
Difficult because divergent evolution makes homologous traits look dissimilar and convergent evolution makes traits look similar - Divergent evolution
- the appearance of different morphologies in those species that share a common ancestor
- Convergent evolution
- the evolution of similar features independently (body of fish and whales)
- Homoplastic
- traits that are similar in species but not in their most common ancestor as a result of convergent or parallel evolution
- Primitive vs. Derived
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Primitive - shared traits as a result of a common ancestor
Derived - traits found in taxons that were not found in the common ancestor - Phylogeny goals
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evaluate evolutionary theory
reconstruct evolutionary history
simplest set of explanations for relationships among organsisms - Cladogram
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phylogenetic tree
displays the relationship of organisms over time
larger branches reflect more evolutionary time - Taxon
- all organsims that are selected at present
- Why are phylogenetic trees constructed?
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display evolutionary patterns
provide framework for conservation and classification - How are phylogenetic trees reconstructed?
- Must distinguish between ancestral and derived traits, and only use homologous traits
- Parsimony method
- Uses an OUTGROUP to determine which traits are derived and which are primitive
- Steps in making a tree
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Select a group
Choose homologous characteristics to compare
Distinguish derived traits from ancestral
Group taxa by number of shared derived traits
Construct cladogram - Paraphyletic, monophyletic, polyphyletic
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Para = shares some but not all descendents
Poly = contains members with more than one recent ancestor
mono = includes all descedents of a sinlge ancestor - Benefit of DNA data for phylogenetic tree
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easier to determine homology
there is less selection operating on DNA than on the phenotype - Problems with species definition
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Group of species that can reproduce with one another
1)not all reproduce sexually
2)can't always carry out - Transformation, transduction, conjugation
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transformation - pick up genes from environment
transduction - viruses carry grenes
conjugation - primitive form of sexual rep. - Adaptions that eliminate the ability to interbreed
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ecological
behavioural
mechanical
gametic
genetic - Allopatric speciation
- when a single population is divided into two different populations by a physical barrier, isolation reduces gene flow, populations diverge
- Founder events lead to...
- alopatric speciation
- Sympatric speciation
- A multiplication of chromosome numbers
- Parapatric Speciation
- Environmental differences prevent gene flow in adjacent environments
- Prezygotic barriers to gene exchange:
- habitat isolation, temporal isolation, behavioural isolation, mechanical isolation, gametic isolation
- Post zygotic barriers to gene exchange:
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Hybrid inviability
hybrid infertility - Habitat isolation
- potential mates do not meet due to different resource use
- Temporal isolation
- age of reproductive maturation differ
- Behavioural isolation
- courtship displays, preferences for mates differ
- Mechanical isolation
- reproductive structures prevent gamete transfer
- Gametic incompatability
- Gametes rejected prior to fertilization
- Hybrid inviability
- abnormalities that reduce survival
- Hybrid infertility
- produce offspring but offspring can't reporduce
- Adaptive Radiation
- when have rapid speciation, low extinction rates
- Adaptation
- a genetically determined characteristic that improves an organisms ability to survive and reproduce
- Puncuated equilibrium
- Rapid speciation followed by a long period of little change
- Hawaiin Honeycreepers
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Species from mainland go to closest island-because of pressures become species B - species B goes next island and becomes C due to selection pressures - some C species go back to first island
*HAVE FOUNDER EVENTS, SYMPATRIC SPECIATION AND ALLOPATRIC SPECIATION