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138 Cards in this Set

  • Front
  • Back
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
different survival of progeny with different characteristics
Selection with dogs - favoured more juvenile features
Founder Effect
New populations established by a few founding individuals
Gene frequencies differ from parent population
Bottleneck effect
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?
Does not change allele frequencies unless offspring have different survival
Do not see HW genotypes
Assortive mating
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
migration of individuals
introduces new alleles to populations
Origin of genetic variation
most are harmful, some are advantageous
Five agents of evolutionary change
Gene flow
Nonrandom mating
Genetic drift
Large population
Random mating
no mutation
no migration
no natural selection
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
Genes for rRNA in all living things
Rudimentary genes for photosynthesis
Common metabolic pathways
*Universal genetic code*
Vestigal Organs
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
all have gill slits, post anal tail, notochord, and dorsal nerve cord
Homeotic genes are all in the same place
Homologous structures
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...
the time of the separation of the groups
(amount of differences depends on the time since departed)
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
Reveals broad patterns of evolution
Recent fossils resemble current species
Shows diversity exploded during Cambrian era
Evidence for Evolution
Fossil record
Comparative anatomy
comparative physiology
molecular biology
modern genetics
Eukaryotic, multicellular, no cell wall
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
ancestor to plants - ancient
invasion of land - ordovician
vascular system - silurian
trees - devonian
radiation of angiosperms - last 150 my
eukaryote, multicellular, cell wall, asexual/sexual, autotrophic
highest above ground mass
Eukaryote, single cell, asexual/sexual, heterotroph/autotroph, ancestral to other eukarya
single cell, prokaryote, asexual, heterotroph/autotroph
methanogens, thermophiles, halophiles
single cell, cell wall, prok., asexual, heterotroph/autotroph
Water Vascular system
water enters through madreporite, radal canals extend
have 5 radial canals
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
Sensory hairs-linked to nerve cells
Tympanum-found with tracheal air sacs
Pheromones - communication signals
Class insecta
3 body segments(head, thorax, abdomen)
3 pairs of legs
modified mouth
Characteristics of arthropods
Circulatory system is open
nervous system
no single respiratory system
excretory system - malpighian tubes
Protosomes vs. deutrosomes
Pro: bilaterally symmetric(tube within a tube)
Deut: bilarteral, mouth second
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
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?
Domains were revealed by rRNA sequences
Common ancestor lived more than 3bya
Eukarya and archaea split 2 bya
Protein infected particle (mad cow disease)
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 systems improve our ability to explain relationships among things
Taxon-unit of classification
domain kingdom phylum class order family genus species
Life elsewhere in the universe?
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
1.5 bya
have internal nucleus, endoplasmic reticulum, mitochondria, sexual reproduction, multicellularity
First photosynthetics were probably anaerobic bacteria -used H2S not H2O
Cyanobacteria split water into hydrogen ions and oxygen
Phylogenetic Tree
Constructed using rRNA sequences and differences between them
use because know it was the first molecule in all ancestors
Earliest cells
Archaea bacteria - lived in extremely hostile conditions, 3 bya
no peptidoglycan, unusual lipids, thermophiles, mathanogens (use sulfur), halophiles
second major bacterial group, 3bya, strong cell walls, cyanobacteria
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
The first genetic material may have been RNA that had a catalytic function and a transfer function
Problem of origin of self replication
First came proteins or nucleic acids?
cells had to differentiate themselves
answer: RNA can self replicate
Miller/Urey (1953)
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
CO2, H2O, CH4, N2, NH3, H2
Small molecules can form and polymerize
Where did life begin?
Deep sea banks - gases coming up
oceans edge
Fundamental properties of life
cellular organization
Characteristics of all living organisms
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
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
Age of mammals, have not diversified ways that others have, not enough time, now going through a mass extinction
dinosoar era, age of reptiles
Marine organisms evolve into those that colonize land
Multicellular life expands in the marine environments
544 mya - present
2.5 bya - 554 mya
evidence of the frist eukaryotes
2.1 bay eukaryotes formed
4.0-2.5 bya
oldest identified rocks found
first fossils appeared around 3.5bya - they were stromalites
hot, fiery furnace
4.6-4.2 bya
most water is in the form of gas
Earth's atmosphere over time
Early atmosphere lacked O2, accumulated O2 after prokaryoes evolved the ability to use H2O
this allowed for increasing evolution
Organisms are normally decomposed or consumed - fossil record is mainly of teeth
divided into eras based on fossil biota
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...
relative ages of the earth's rocks can be determined from their positions
radioisotopes can determine absolute ages
Medel's work
Natural selection -> acts on the phenotype
Population genetics -> explains speciation and evolutionary age
Macroevolution influenced by...
1) infrequent or slowly occuring events
2) massive extinctions
*only hindsight indicates macroevolution*
Microevolution influenced by...
1) natural selection
2) genetic drift
3) mating system
4) population size
5) genetic variation
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
Weismann - chromosomes
Waldemeyer - named chromosomes
Vries - mutation
Impact of genetics
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
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:
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
1) species are not immutable, but change and adapt over time
2)the agent that produces these changes is natural selection
Sent manuscript on theory of natural selection to Darwin
Evolution by natural selection
Beagle: 1831-1836
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
Does not weight characteristics
Uses an outgroup to determine primitive and derived traits
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
Chromosome number, size
Amino acid sequence , DNA
How are traits constructed?
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)
traits that are similar in species but not in their most common ancestor as a result of convergent or parallel evolution
Primitive vs. Derived
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
evaluate evolutionary theory
reconstruct evolutionary history
simplest set of explanations for relationships among organsisms
phylogenetic tree
displays the relationship of organisms over time
larger branches reflect more evolutionary time
all organsims that are selected at present
Why are phylogenetic trees constructed?
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
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
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
easier to determine homology
there is less selection operating on DNA than on the phenotype
Problems with species definition
Group of species that can reproduce with one another
1)not all reproduce sexually
2)can't always carry out
Transformation, transduction, conjugation
transformation - pick up genes from environment
transduction - viruses carry grenes
conjugation - primitive form of sexual rep.
Adaptions that eliminate the ability to interbreed
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:
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
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
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