All Review Cards Flashcards
Darwin’s Mechanisms for Natural Selection
- ) Populations are variable
- ) variants that are successful leave more viable offspring
- ) Change will appear over time
Darwin’s Important Claims
- ) all living things share a common ancestor
2. ) species on Earth evolve from a natural process
Evidence for Evolution (4)
- ) Fossil Record
- ) Classification and biography
- ) Morphology and development
- ) DNA (Genetics)
Main questions debated by early scholars concerning fossils
- ) Are they organic material?
- ) How did they get there?
- ) Did they form in the rock or did the rock form around them?
6 Verifiable Predictions of Evolutionary Theory
- ) Because there are fossil remains of ancient life, we should be able for find some evidence for evolutionary change
- ) We should be able to find some cases of speciation in the fossil record with one line of descent diving in to two or more.
- ) We should be able to find examples of species that link together major groups suspected to have common ancestry.
- ) We should expect that species show genetic variation for many traits.
- ) We should find imperfect adaptations
- ) We should see natural selection occur in nature
Glossopetrae
“Tongue Stones” ; Steno dissected a shark and found that these stones were actually shark teeth (proving that fossils were once living and therefore organic in origin)
Principle of Original Horizontality
strata originally deposited horizontally or nearly so; departures indicate that strata have moved after their formation
Faunal Succession
based on the observation that sedimentary rock strata contains fossilized flora/fauna
- these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances
Leonardo da Vinci (objections to Diluvialism)
- ) some shells were too fragile to have traveled great distances
- ) some fossils in strata appeared to be in living positions and resembled living communities
- ) multiple layers of fossil-rich strata separated by unfossiliferous strata (multiple depositional events)
William “Strata” Smith
- coined the term ‘faunal succession’
- made the first geological map of England when he was commissioned to build the canals
Biostratigraphy
the use of fossils and how fossils resemble change between sedimentary layers to date rocks
Robert Hooke
- argued for the organic origin of fossils
- suggested that fossils were the remain of extinct organisms and that species have a ‘limited lifespan’
- said that fossils could be used to correlate strata (biostratigraphy!)
Principle of Original Lateral Continuity
strata originally deposited continuously; if interrupted by gaps in the same strata it indicates rocks have been removed after they’ve formed
3 Properties of an “Index Fossil”
- ) easily identifiable
- ) Geographically and Environmentally widespread
- ) Short stratigraphic range (only exist for a brief amount of time)
3 Types of Unconformities
- ) Angular
- ) Disconformity
- ) Nonconformity
Alcide d’Orbigny
- believed that new species were being created in the wake of each catastrophe (each extinction event)
Georges Cuvier’s Significance of Unconformities
catastrophes are what explains unconformities and extinctions
- life moves toward its perfect state with each catastrophe
Modern Doctrine of Actualism
modern geology is a combination of gradualism and catastrophism
- only assumption that is made today is that the principles of nature have been uniform through time
Charles Lyell
- wrote “Principles of Modern Geology”
- believed that the present is the key to the past and that there is unconformity in nature
- advocated for GRADUALISM not CATASTROPHISM
Disconformity
flatline sediments resting on other flatline rocks and visible erosion
Cross-Cutting Relations
- molten rock can intrude into older, pre-existing rocks
- molten rocks can enclose older pre-existing rock
- relative timing (age) can be determined by this relation
Uniformitarianism
using present processes to understand the past in recorded rocks
Unconformities
a surface erosion and/or non-deposition separating two rock bodies
- represents missing time
Rock Cycle
Earth’s change is a cyclical cycle
- the formation of new rocks balanced by the destruction of old
Catastrophism
events in the past occurred suddenly and by different mechanisms than those occurring today
- these catastrophes are separated by long periods of stability
Georges Cuvier
- used comparative anatomy to prove extinction
- advocated for catastrophism
Nonconfomity
sedimentary deposited on top of one another
Sedimentary Rocks
- made of sediment and created by the erosion of preexisting rocks
- fossils usually found here
Darwin’s 5 Observations while sailing on the HMS Beagle
- ) Fossils are species that are now extinct
- ) the difference between species and the variation of species is sometimes unclear
- ) Geographic variation and species replacement
- ) different variations on different islands
- ) South American affinities of Galapagos Island populations
Alfred Russel Wallace
- spent months traveling the Amazon gathering species (But burned when ship went up in flames)
- discovered the Malay Archipelago is a mixing of Asiatic and Australian fauna and flora
Stabilizing Selection
selection against the extremes in a population
i. e. timing of spawning, mating calls in frogs, flowering
- can decrease varaibility
Who wrote the first papers on Natural Selection?
Darwin and Wallace
- Darwin gets the most credit even though they came to the same conclusion
No Selection / Drift
no differential reproduction, all forms are equally successful
Fecundity
the ability to produce and abundance of offspring
Origin of Species
Darwin’s Book
- provided the central tenants for the theory of evolution by natural selection
Genotype
the blueprint for building and maintaining and organism
Phenotype
the outward manifestation of a genotype
- identifiable physical characteristics
Ecophenotype
morphological changes caused by varying environmental-nutritional conditions rather than genetic differences
Directional Selection
the selection where a single phenotype is favored (allele frequency shifts in one direction over time)
- i.e. the color of desert mice
Thomas Malthus’s “Principle of Population”
predicts that a population size increases at a geometric rate but there must be some sort of check to prevent insane amounts
- Chess Board multiplying example
Three Requirements for Natural Selection
- ) Variation: cannot be a exact replica of their parents
- ) Inheritance: must inherit characteristics from both parents
- ) Differential Reproduction: the most successful offspring will produce the most offspring in the future
**4.) Overpopulation (not necessarily one of the main requirements but it is an important factor)
Allele
a variant form of any given gene
Disruptive/Diversifying Selection
the selection for the extremes within a population
- the color of fur in Himalayan rabbits
Types of Natural Selection
- ) Stabilizing
- ) Diversifying/Disruptive
- ) Directional
- ) No Selection / Drift
What is an individual’s ‘fitness’?
the ability of an individual to reproduce and contribute to the next generation
Dominant Allele
expressed even when heterozygous
Mitosis
normal cell division
- in the parent cell, each chromosome is copied and 2 daughter cells are produced
Which tenants of Mendelian Genetics are often broken?
- one gene codes for one trait
- Some dominant and some recessive alleles
Meoisis
reproductive cell division;
- in the parent cell, each chromosome is copied and 4 egg or sperm are produced (unpaired chromosomes)
Biological Species Concept
a group of inter-breeding natural populations that are reproductively isolated from other such groups
Chromatids
- the two threadlike strands which a chromosome divides longitudinally during a cell division
- humans have 46
Three Reasons Darwin Focused on Artificial Selection
- ) Natural selection process is too slow
- ) Artificial selection results in dramatic changes
- ) Artificial selection demonstrates inheritance
Principle of Independent Assortment
each allele pair behaves independently of other allele pairs
Chromosomes
- carries the genetic information
- found in the nucleus
- made up of chromatids
Heterozygous
the alleles are different
Locus
a fixed point on a chromosome
- i.e. position of a gene or a marker
Darwin’s Dillema
- ) What is the source of this variability?
2. ) How does variability work?
Principle of Segregation
each parent contributes one randomly chosen allele to each offspring
Five Tenants of Mendelian Genetics
- ) Phenotypic traits are determined by unites of heredity (genes)
- ) One gene codes for one trait
- ) Some alleles are dominant and others are recessive
- ) Each parent contributes one randomly chose allele to each offspring
- ) Each pair of alleles (genes) behaves independently of other allele pairs
Recessive Allele
only expressed when homozygous
Blending Hypothesis
predicts that each hereditary factor is permanently diluted in a hybrid
** PROVEN TO BE INCORRECT BY MENDEL THROUGH DISCRETE UNITS**
What does it mean that DNA Replication is ‘Semi-Conservative’?
DNA replication creates DNA molecules that are half old and half new (preserving part of each original strand)
Episistasis
when one gene masks the phenotypic effect of another gene
Nucleotide Bases and Their Pairings
ATCG
A <=> T
C<=> G
What are some commonly observed ‘Non-Mendelian’ characteristics of Genes or Traits?
- ) Incomplete Dominance between alleles (red flower + white flower = pink flower)
- ) Co-Dominance of alleles (A and B blood types are fully expressed in AB)
- ) More than 2 alleles for one gene in a population
- ) one gene may have multiple effects (i.e. albinism = associated with cross eyed and larger body type)
- ) One trait may result from input of multiple genes (milk production is controlled by several genes)
- ) Genes may influence each other (coat color in labs is controlled by two genes)
What determines the function of a protein?
the sequence of amino acids determines how the chain unfolds, how the chain unfolds determines the structure, the structure determines the function
What are ‘immortal genes’?
short portions of the sequence of a protein found in all domains of life
What is translation?
the process of translating the sequence of an mRNA molecule to a sequence of amino acids during a protein synthesis
Roles of Different Enzymes (Helicase, Primase, DNA Polymerase, Ligase)
Helicase: unzips the paired DNA strands forming a replication fork
Primase: binds leading strand and synthesizes an RNA primer completely to the DNA template (marks the starting point for DNA synthesis)
DNA Polymerase: synthesizes DNA in the 5’ to 3’ direction
Ligase: DNA ‘glue’ that links Okazaki fragments together
Okazaki Fragments
- used on the lagging strand so that the polymerase can add to the nucleotides in the 5’ to 3’ end
- this process ends up with a bunch of little fragments that are not all connected
- all eventually put together by DNA ligrase
- Primase will come in to switch out the RNA with new DNA
Central Dogma
the idea that DNA replication begins by being transcribed to mRNA and then is translated to proteins (DNA => RNA => Proteins)
DNA Transcription
the process by which DNA code is turned in to messenger RNA
T is switched out for U
RNA Polymerase
similar to DNA polymerase; it is used to make mRNA strand by reading DNA strand
Messenger RNA (mRNA)
the type of RNA that carries the message of DNA to be transcribed and turned in to a specific protein
mRNA Codons
RNA units that are triplet nucleotide base
What are Homeobox (Hox) Genes?
Homeobox genes are a large family of genes that direct the formation of body parts during early embryonic development
- encode proteins that regulate gene expression in multicellular organisms
Vestigial Structures
degenerate or underdeveloped;
reduced in size and function by natural selection because they are no longer required
Atavastic Features
an evolutionary “throwback”, only occurs occasionally within a species
Pseudogenes
‘dead’ genes that no longer function
Prokaryotes
bacteria and archae;
- small cell size
- DNA is in a circular loop
- organelles are absent
NO NUCLEUS
Eukaryotes
protists, plants, animals
- large cell size
- DNA is in chromosomes in nucleus
- organelles are located in mitochondria and chloroplasts
NUCLEUS
Homologous Structure
structurally similar adapted to serve different functions, reflects shared inheritance and common ancestry
Analogous Structure
structurally dissimilar features adapted to serve the same function
- does NOT reflect common ancestry
Convergent Evolution
the process whereby organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches
Three Domains of Life
- ) Bacteria
- ) Archaea
- ) Eukarya
Sexual Dimorphism
differences in morphology between male and female members of a species
- can include physical traits as well as behavioral
What is sexual selection?
differential success in reproduction
- ) Mate Choices (power to charm females)
- ) Intra-Sexual Selection (power to conquer other males in battle)
How does sexual selection perpetuate sexual dimorphism?
- females choose the males with distinctive traits
- offspring inherit exaggerated trait (males) or the preference for that trait (females)
- selection reinforces both trait and preference
Factors involved in evolution of typical sex roles
- ) relative investment in reproduction (usually greater in females and makes them more choosey)
- ) Reproductive potential (usually greater for males so they’re more aggressive and competitive)
Correlation between levels of aggression and disparity in number of mates
the greater the disparity among males in terms of number of mates results in a greater level of aggression
Batesian Mimicry
when a palatable (tasty) species mimics a toxic species to deceive predators
- palatable mimics only occur in areas where the unpalatable species occur
Why is tinkering a good analogy for natural selection rather than engineering?
natural selection has no plan, whichever works best will produce more offspring
- modifies what already exists, doesn’t create from scratch
Exaptation
the process by which pre-existing traits and structures adapted to serve one function are all co-opted to serve a new function
- i.e. wings on a dragonfly
Pre-Zygotic Isolation
union of egg and sperm never occurs because gametes never encounter one another
Post-Zygotic Isolation
egg and sperm encounter one another but the zygote is either not viable or gives rise to individuals that cannot reproduce or have very low fitness
Pre-Zygotic Mechanisms for Reproductive Isolation
- ) Geographic Isolation (existences of geographic barrier)
- ) Gametic Isolation (occurs when incompatibility in gametes (egg and sperm) do not permit fertilization)
- ) Mechanical Isolation (male parts don’t fit female parts)
- ) Temporal Isolation (inter-species differences in timing of reproduction)
- ) Behavioral Isolation (can occur when mating displays and courtship rituals become intertwined with reproductive act)
- ) Ecological Preferences and mating Isolation (occurs when environmental preferences reduce the frequency of interbreeding)
Post-Zygotic Mechanisms for Reproductive Isolation
- ) Zygote Morality (occurs when a successfully fertilized egg begins development but fails to complete)
- ) Hybrid Inviability (gametes fuse, development progresses but offspring cannot survive to adulthood)
- ) Hybrid Sterility (gametes fuse, development progresses and offspring survive to adulthood but cannot reproduce)
- ) Low Hybrid Fitness (gametes fuse, development progresses and offspring survive to adulthood with the ability to reproduce but their offspring will have very low fitness in the wild)
3 Geographic Models of Speciation
- ) Allopatry (occurs when populations become completely, physically separated from one another by geographic barriers)
- ) Parapatry (separated not by geographical areas but an extreme change in habitat)
- ) Sympatry (occurs when there is no spatial separation but reproductive isolation still occurs)
Ring Species
two populations that do not interbreed are living in the same region but they are connected by a geographic ring of population that do interbreed
Pairwise Evolution
involving just two particular species
Coevolution
two or more unrelated species adapting to each other
Diffuse Coevolution
involving multiple species
Symbiosis
interaction between two different organisms living in close physical association
- ) Commensalism (host is not affected)
- ) Mutualism (host benefits)
- ) Parasitism (host is not harmed)
Miller and Urey Experiments
- demonstrated the basic blocks of life (20 amino acids) can be synthesized from inorganic molecules
- amino acids are common place in our solar system
Stromatolites
oldest fossils on Earth (not actual organisms but were mats of cyanobacteria)
Architarchs
- oldest Eukaryotes (found in the proterozoic)
- primitive forms of marine algae
What is the Ediacara Fauna?
assemblage of soft bodied marine animals found in neoproterozoic aged rocks
“Cambrian Explosion”
all major phyla with hard parts suddenly appear (explosion of life; specifically marine)
- trilobites
Possible Mechanisms for Cambrian Explosion
- intense chemical weathering of rocks supersaturated the oceans with ions which marine organisms use to grow shells
- change in the seawater chemistry to do continental denudation
- active predators may have made organisms form protective shells
- maybe a rise in oxygen levels
Ordovician Land Plants
- seedless (used spores), non-vascular mosses
- no system for transporting nutrients and water
Silurian Land Plants
- seedless plants with a primitive vascular system
Devonian Land Plants
Lycopods!
- seedless, vascular plants, cool swamps
First Gymnosperms: naked seed plants meaning the seed is not covered by the ovary (allowed the move from wet conditions)
How did the evolution of large plants with roots affect global carbon cycle and climate?
roots pump CO2 into soils and thereby enhance chemical breakdown of silicate minerals which pulls CO2 atmosphere levels DOWN
First Land Animals
- silurian
BUGS
- trigonotarbids
