COMPLETE EXAM 2 REVIEW Flashcards
Analogous
i.e. convergent
-similarities that are independently evolved are called analogous
NOT used in cladograms
Example: similarity of vertebrate and invertebrate eyes… both have independently arrived at essentially the same solution to the problem of converting EM radiation to neural impulses
“Tree Thinking”
Darwin thought of life as a tree- described living species at the tips, branches are groups of closely related species, branch points are speciation events
- united by shared ancestry
- completely revolutionized comparative and evolutionary biology
- linked embryology, genetics, medicine, etc.
Analysis of Fossils
pros: direct
cons: fragmentary, can be hard to interpret
phylogenetic analysis
- compare similarities of organisms (molecular)
- construct cladograms
phylogeny is constructed by…
speciation
origin of new characteristics
Systematics
classification to reflect the phylogeny of organisms
cladogram
a branching diagram depicting an estimate of the phylogeny
clade
a grouping that includes a COMMON ANCESTOR and all of the descendants (living & extinct) of that ancestor
monophyletic
shared derived trait (syapomorphy)
single origin- an ancestral species and all of the descendant species grouped together
implies close relationship
monophyletic groups = clade
polyphyletic
convergent similarity
- independent origins
- does not imply close relationship
i. e bats and birds
Paraphyletic
primitive similarity
- single origin
- does not imply close relationship
- e.g. lizards and crocs lack feathers, but so did the ancestor of birds
- paraphyletic groups
- most recent common ancestor but not all of its descendents
Goal of Phylogenetic analysis (Cladistic Methods)
-monophyletic groups
accurately describe relationships
Willi Hennig’s (1950,1966) Two principles for reconstructing phylogeny
parsimony
outgrip analysis
parsimony
the cladogram requiring the fewest evolutionary changes is (usually) preferred (AKA Occam’s Razor)
-uses the simplest explanation for the distribution of characters
taxon
group of similar and related individuals
speciation
the origin of new species, is at the focal pint of evolutionary theory
microevolution
consists of changes in allele frequency in a population over time
macroevolution
refers to broad patterns of evolutionary change above the species level
BSC Concept of species
all members have the potential to interbreed under natural conditions and produce viable, fertile offspring
“some” hybridization o.k. as long as it doesn’t occur naturally enough to overwhelm the boundary
Limitations of BSC Concept
-not always clear who has the “potential” to interbreed
-does not apply to asexual organisms
-can’t be applied to fossils
boundaries are arbitrary- i.e. dog x wolf
how much hybridization is too much?
morphological species
concept is a practical substitute for BSC- looks at structural features
phylogenetic species
smallest group on a tree
ecological species
viewed in terms of niche (function or place of an organism in a given ecosystem)
pre zygotic barrier
separates species by: preventing formation of a zygote or fertilized egg 1. habitat isolation 2. temporal isolation 3. behavioral isolation 4. mechanical isolation 5. gametic isolation
post zygotic barrier
separates species by: preventing development of viable or fertile offspring 1. reduced hybrid viability 2. hybrid infertility 3. hybrid breakdown
habitat isolation
may occupy the same range and be potentially able to hybridize, but prefer different habitats so never (or rarely) mate.
i.e. maggot fly races
temporal isolation
may potentially interbreed, but are “ready” at different times
many plants, animals breed at different times
i.e. apple maggots and hawthorn maggots
frogs
behavioral isolation
species may encounter each other, but do not mate because of differences in courtship or other behaviors.
i.e. birds, fire fly bling patterns, bird songs
mechanical isolation
e.g. lock and key
-found in many insects and flowers
(different anatomy)
gametic isolation
gametes do not recognize each other due to different receptors
reduced hybrid viability
hybrid offspring do not develop
do not survive as well
i.e. sticklebacks: benthic V. Limnetics
hybrid infertility
i.e. mules, tigons etc.
They are sterile
hybrid break down
1st generation hybrids are fertile, but when they mate, the 2nd generation hybrids are sterile or weak
-common in plants?
Allopatirc speciation
physical barrier divides population (vicariance)
i.e. a rise of a mountain range, formation of a river or valley, or changes in sea level
examples:
migration to an island or a new habitat
adaptive radiation
evolution of many diversely adapted species from a common ancestor (speciation on islands)
populations become different due to…
founder effect at outset (especially if one or both of the new populations are small) through genetic drift
natural selection under different conditions. May result in physical or behavioral differences that inhibit breeding even if contact is restored
Recontact of populations:
may reinforce differences acquired in isolation
hybrids gradually cease to form
-may overwhelm differences acquired in isolation
reinforcement
hybrid offspring have lower survival, so selection favors assortative mating
fusion
large areas of hybridization and highly fit hybrids may fuse the two species back into one
sympatric speciation
no physical barrier separating diverging populations
i. e. hawthorn maggots shows fidelity to hawthorn trees
1. Autopolypoidy
2. Allopoloploidy
autopolploidy
same species mate
duplication of chromosomes number occurs due to meiosis failure
reproductively isolates offspring from parent population
common in plants
facilitated by ability to self-fertilize
Allopoloploidy
hybridization and errors in meiosis lead to polyploid offspring with chromosomes from 2 different species that are FERTILE
i.e. marsh grass= wheat
Allopolyploidy in plants
key forces in plant speciation = new species
occupy novel ecological “intermediate niches” from parents
- hybrid vigor
“Evolution is a Tinkerer”
evolution takes a character and gives it an unexpected function
i.e. turns a leg into a wing
Macroevolutionary patterns
Broad-Scale patterns of change, diversification and extinction in the fossil record
- crossing the big boundaries- origin and consequences of new body plans
Anagenesis
patterns of change over time
Cladogenesis
patterns of diversification
Gradualism
-classic darwin
generally slow, constant change
distinction among fossil species fairly arbitrary
appeal to sketchiness of fossil record to explain gaps
does not claim that all change will be gradual, only that this is a predominant pattern
Punctuated equilibrium
emphasizes periods of stasis interspersed with periods of “rapid” change (geologically speaking)
works well with cladistics
emphasizes that most change occurs at speciation
stasis
long periods of subtle evolutionary change
“living fossils”
lineages that have changed so little for such a long time
i.e coelacanths
What causes Stasis
not always clear
-prob includes
stabilizing selection keeping the species from changing
variable directional selection that keeps the species fluctuating around a mean
genetic/ developmental constraints
- retention of primitive features in the absence of appropriate variation or directional selection
mosaic evolution
the evolutionary change of different adaptive components of the phenotype of an organism at different times or at different rates in an evolutionary sequence
“rapid” change
origin of a new species and characteristics over a time period that is short relative to the period of stasis
does NOT say that speciation/ changes are instantaneous - merely that they happen too quickly to be generally captured in the fossil record
spending on resolution of fossil record, may still be a million years!
What causes rapid diversification
- environmental change
2. ecological opportunity
environmental change
“sudden” appearance of every animal phyla within about 50 millions of years
why?
increased O2 levels supporting larger body size
predation
ecological opportunity
extrinsic
- extrinsic factors
provide opportunities to occupy previously unavailable niches - adaptive radiation
examples:
darwin’s finches
radiation of mammals after dinosaur extinction… also factor in the explosion of bilateral
ecological opportunity (intrinsic)
key innovations: characteristics that open up new opportunities
i.e. flowers, wants, etc.
novel characteristics
(tinkering)
6 origins of evolutionary novelty
- exaptation
- duplication
- Serial Homology
- Heterochrony
- Lateral Gene Transfer
- Homeotic genes and pattern formation
exaptation
evolution is a tinkerer!
flowers are modified leaves
insect wings may have arisen as heat collecting devices
duplication
evolution of genes with novel functions:
duplicated genes can evolve different (novel) functions
i.e. globin genes, Pseudogenes
Serial Homology
i. e. arthropod libs
- repetitive segments in the same organism
- duplicated limbs/ segments can specialize
heterochrony
changes in developmental timing can radically alter the adult appearance of an organism
example pedomorphosis
Paedomorphosis
a sexually mature adult retains features that were juvenile structures in its evolutionary ancestors
example: starfish
Lateral Gene transfer
horizontal movement of individual genes, organelles or fragments of genomes from one lineage to another
(often in bacteria)
homeotic genes
small sets of genes function as developmental master switches
homeotic genes and pattern formation
simple developmental/ genetic changes can have major effects
Factors influencing the shape of the tree of life:
key innovations and their consequences (wings and flowers)
major transformations
major radiations
Does the fossil record show gradualism and punctuated equilibrium?
yes
Origin of Life Problems
- we can’t observe, even indirectly the earliest steps
- even simplest forms of life are very complex
Which, if either, came first
DNA- info storage
OR
Proteins- do work, require info from DNA to be assembled
Four BIG steps to life
- formation of small organic compounds
- formation of complex polymers
- formation of liposomes to protect complex polymers (and more)
- formation of a system of self-replication
Formation of small, organic compounds
i.e. amino acids, nucleotides, sugars, etc. How? Oparin-Haldane Theory Miller (1953) tested how: atmosphere, spark
Oparin Haldane Theory
early atmosphere had little oxygen
early atmosphere was reducing (Lots of CH4, NH3, H2)
this favored reactions forming organic molecules
Panspermia Hypothesis
organic material (or actual life itself) from elsewhere
Formation of polymers
possible without cellular catalysts? yes.
need to concentrate monomers
need to catalyze reaction inorganically
not a huge obstacle
formation of liposomes
“aggregates of abiotically produced molecules”
can spontaneously form
artificial vesicles can be created from phospholipids
Protocells
can carry out cell like processes
store energy across membrane
take-up and release “metabolites”
Formation of a system of self-replication
information, and a means of replicating it
may have preceded association with protocols
Protein or DNA first?
Niether! it could have been an RNA (enzyme- ribozyme) that could poorly cut nucleic acids
Why RNA?
genetic info. stored in DNA.
RNA is created from DNA to put info. into action
RNA can direct creation of proteins (mRNA; tRNA; rRNA)
DNA can’t do this
RNA is versatile
3 Problems with RNA
- In the absence of cells, products of ribozyme activity would be shared
- Self-Replication of large RNA’s has not been demonstrated
- initial formation of RNA
History of Life
earth forms- 4.6 billion years ago environment very different -volcanoes -meteor impacts -low amount of oxygen Life appears "quickly" -prokaryotes -How do they metabolize
Prokaryotes
dominant life forms on earth -10x the biomass of all eukaryotes 10^14 prokaryotic cells in your gut; 10^13 cells make up your body EXTREME metabolic diversity the basis for all eukaryotic metabolism
Changes in Earth’s physical environment
-atmospheric oxygen concentration has also changed over time
- The early atmosphere probably had little or no oxygen, until some bacteria evolved photosynthesis (about 2.5 bya)
-the O2 dissolved in water and reacted with iron to form iron oxide, which accumulated in alternating layers of red and dark rock, known as banded iron formations.
earliest evidence of photosynthesis
-O2 also began to accumulate in the atmosphere
-cyanobacteria formed stromatolites which are abundant in the fossil record and are still formed today
o2 released by cyanobacteria allowed evolution of oxidation reactions as the source for ATP synthesis
prokaryotes are haploid or diploid?
haploid
prokaryotes
no nuclear envelope no membrane bound organelles circular DNA, with relatively few genes no mitosis; instead do binary fission began 3.8 billion years ago bacteria & Archea
prokaryotes are mono, poly, or para phyletic?
paraphyletic
prokaryotic chromosome
small size (relative to Euk.) extreme diversity simpler structure haploid no sex. no centromere, chromatin, etc.
prokaryotic plasmids
few genes independent replication & transcription variable importance for cell growth antibiotic resistance genes facilitate lateral gene transfer
transduction
genes via virus infection
conjugation
plasmids from live bacteria
transformation
genes from environment such as dead batters/ archaea
mechanisms of lateral gene transfer
transduction
conjugation
transformation
Why is evolution so rapid in prokaryotes
lateral gene transfer
short generation time
high mutation rates
BUT no independent assortment
Requirements of Metabolism
1. energy- phototrophs use light chemotrophs use chemical compounds 2. carbon- autotrophs use CO2 heterotrophs use organic compounds they consume
photoautotrophs
use energy from light and carbon dioxide to create energy
e.g. plants and some prokaryotes like cyanobacteria
chemoautotrophs
energy from inorganic and carbon from carbon dioxide
e.g. some prokaryotes like archea
photoheterotrophs
energy from light, carbon from organic sources i.e. some prokaryotes
chemoheterotrophs
energy and carbon from organic sources
e.g. some prokaryotes & us
Origin of Cyanobacteria
increased oxygen levels (eventually)
oxygen is very reactive- breaks bonds
bad news for anaerobic organisms
but allowed the evolution of aerobic respiration
methanogens
important decomposers
use H2 to reduce CO2 to methane
archaea
halophile
thrives in water 10x as salty as the ocean
archaea
thermophiles
up to 105 degrees C
archaea
acidophiles
archaea
in pH below 1.0 (battery acid)
lytic virus
destroy host cell
virulent
lysogenic
silent in host genome
can become active
Eukaryotes include:
protists- mostly unicellular with 5 major groups
plants animals fungi
Endosymbiosis theory
lynn Margolis
a cyan bacteria ancestor engulfed a eukaryote
secondary endosymbiosis
a heterotrophic ports engulfed an alga containing chloroplasts
Eukaryote Features
biomarkers (traits) modernn eukaryotes have: - membrane bound nucleus membrane bound organelles chromosomes cytoskeleton
closest relatives of modern plants
green algae
Life in water was easy because
bathed in nutrients supported against gravity extensive transport not necessary gametes, offspring can be transmitted by water no problem of desiccation
why leave the water?
direct sun light nutrients and minerals on land abundant CO2 absence of herbivores new niches
sporophytes
produces spores
2n -> 1n
meiosis
gametophytes
produces gametes
mitosis
1n ->1n
Nonvascular plants
mosses, horn worts
can be abundant in moist habitats
spores and gametes similar in size
non vascular plants
two major break throughs
- cuticle
- protected embryo
Ferns
first vascular plant
angiosperms and gymnosperms produce seeds
true
in seed plants the sporophyte is nutritionally dependent upon the gametophyte
false; the other way around
the sperm of gymnosperms require water for fertilization
false; wind
seed plants are homosporous
false; heterosporous
the evolution of seeds greatly aided the colonization of drier area
true
fertilization occurs simultaneously with pollination
false; pollination occurs first
the main function of older wood, produced by secondary growth is water transport
false; structure
confers are the most abundant gymnosperms
true
fungi
more closely related to animals than to plants
chitin
store glycogen
multicellular heterotrophic eukaryotes
What are animals
metazoans multicellular nervous and muscle tissue collagen heterotrophic embryonic development HOX genes with specific DNA monophyletic
animals origin
originate from protists
multicellularity independent of plants, fungi
Early animals
porifera no true tissues 2 cell types choanocytes ameobocytes no symmetry hermaphrodites asexual regeneration
sponges
adults sessile skeletal fibers in middle layer-> spicules filter feeders full of holes create current with choanocytes flagella
Cnidarians
jelly fish radial symmetry two phases in the life cycle -polyp -medusa Reproduce sexual asexual budding -nematocysts stinging organelles nerve net
Eumetazoa
diploblastic two tissue layers -ecto end- e.g. Cnidarians jellyfish, coral
Bilateria
bilateral symmetry cephalization development of head sense organs in front direction in movement origin: triploblasty mesoderm- forms muscles and supports organs
Ceolemates
animals with body cavity that develops within the mesoderm
more control over movement of fluids
better support of organs and better digestions
protosomes
pore becomes mouth
deuterstomes
pore becomes ass hole
lophotrochozoans
mollusks, annelids, flat worms (acoelomates)
annelids
segmented worms
can operate segments independently
coelom
redundancy
segmentation
evolved multiple times in annelids
antropods
chordates
4 classes of mollusks
- chitons
- bivalves
- gastropods
- cephalopods
ecdysozoans
cuticle and molting
arthropods
jointed appendages
regional segmentation
exoskeleton (chitin)
open circulatory system
Four Phylas of Dueterostomes
- echinodermata
- heminchordata
- xeno
- chordata
4 chordate characteristics
- notochord- structural support
*most distinctive derived trait - dorsal hollow
nerve cord - pharyngeal slits- feeding, then breathing
- Muscular tail- propulsion
vertebrates
jointed skeleton extreme cephalization great sense orans closed circulatory system internal organs suspended in coelom
4 derived mammal traits
hair
lactation
three-bone middle ear
sweat glands
Gnathostomes
have jaws
tetrapods
jointed limbs
Hamprey & Lampreys
cartilage
no jaw
no limbs
no amniotic egg
chondrichthyes
sharks cartilage jaws begin paired fins no amniotic egg
Esteichthyes
ray finned fishes bones begin present jaw paired fins no amniotic egg
amphibia
frogs bony jaw present for limbs begin no amniotic egg
reptiles
lizards, turtles, snakes, birds bony jaw present four limbs AMNIOTIC EGG
Derived Traits of hominids
large brain; short jaws
forward looking eyes
complex social care
fully opposable thumb
hominids closest relatives
chimps and bonobos
1-5% of DNA can be traced back to…
neanderthals
Lucy
Ausralopithecus afarensis
fully bipedal
Differences in courtship behavior are an example of post zygotic barriers to mating
FALSE
prezygotic
A small isolated population is more likely to change into a new species than a large population
True
The most metabolically diverse are prokaryotes
true
reptiles represent a polyphyletic phylogeny
FALSE paraphyletic
A phylogeny is constructed using analogous characters
False; homologous
flat worms have a true body cavity or coelom
no coelom/ acoelomate
the prezygotic barrier where gametes are unable to recognize each other due to different molecular receptors is called mechanical isolation
false; gametic isolation
allopolyploidy is a form of sympatric speciation that involves errors in meiosis and hybridization between two different species of organisms
true
sponges are the first animals with true tissues
false; no tissues- Cnidarians or jelly fish are the first with true tissues
birds and mammals independently evolved a high metabolism
true
one of the 4 characteristics of all chordates is extreme chepalization
FALSE notochord tail slits/ gills dorsal nerve cord
when a horse and a donkey mate, they produce mules that are sterile. This is an example of post zygotic isolation
true
homeotic genes contribute to evolutionary novelty by altering an organism’s body plan
true
viruses are subject to natural selection processes
true
after the demise of dinosaurs, the process by which mammals diversified into new species as they filled newly opened ecological niches is called adaptive radiation
true
a recent view of early prokaryotes states they obtained their energy from inorganic sources and their carbon from CO2. Thus, they are called photoautotrophs.
False; chemoautotrophs
Changes in timing or rate of developmental events such as sexual maturation are generally known as serial homologies.
heterochrony
protists alive today are the closest relatives to both animals and plants
true
The concept of species has changed over time. What is the essential aspect of the BSC.
a. individuals of a species occupy identical ecological roles
b. all members of the same genus are able to mate successfully
c. individuals within a genus share behaviors and appearance
d. individuals of a species are able to mate and produce fertile offspring in the wild
D.
Which of the following is the most successful (abundant) of the animal phyla?
a. annelids
b. arthropods
c. vertebrates
d. prokaryotes
b.
If a new animal species appears suddenly in the fossil record that is completely different from other animal species which of the following macroevolution patters would be supported?
a. gradualism
b. punctuated equilibrium
c. adaptive radiation
d. anagenesis
b.
peripheral and isolated populations are more likely to undergo speciation than large or connected populations, because a small population
a. contains a greater amount of genetic diversity
b. is more susceptible to gene flow
c. is more affected by genetic drift
d. is more subject to errors during meiosis
c.
the predominant generation in the life cycle of angiosperms is the?
a. seed
b. sporphyte
c. gametophyte
d. sperm
b.
what defines a chordate
a. ability to live on land
b. development of an anus from the blastopore
c. presence of a well-developed circulatory system
d. presence of four specific morphological traits
d. gills/ slits dorsal nerve cord nochtocord tail
One of the techniques developed by Willi Hennig for reconstructing the phylogenic histories of organisms.
a. cladograms
b. punctuated equilibrium
c. parsimony
d. anagenesis
c.
which of the statements below about the Fungi is correct?
a. all fungi are heterotrophs, but are able to switch to photosynthesis when stressed or the food supply is depleted
b. all fungi are asprophytic
c. all fungi receive their nutrients through absorption
d. most fungi are parasitic in their feeding methods
e. all of the above
c.
Which animals are protostomes sponge earthworm roundworm arthropod liver fluke sea urchin
earthworm
roundworm
arthropod
liver fluke
All chordates share the following characteristics notochord muscular tail pharyngeal slits 3-bone middle ear dorsal nerve cord
notochord
muscular tail
pharyngeal slits
dorsal nerve cord
Organisms with an amniotic egg lamprey snakes platypus zebra frogs penguins
platypus
zebra
penguins
the following land plants have vascular tissue mosses ferns gymnosperms angiosperms
ferns
gymnosperms
angiosperms
one of the final steps in the formation of life is development of a system of self-replication. Explain the significance along with the problems of RNA molecules in the “RNA world.” is there an alternative to RNA? explain.
- RNA is an auto-catalyst & it self replicates
- those forms that self-replicated through own enzyme- ribozyme were selected for in evolution
RNA can store genetic information
RNA can catalyze reactions
RNA forms that were better at at surviving and reproducing would have been a selective advantage
Problems:
without cells, products of enzyme would be shared
no one has seen large RNA self-rep
hard to imagine initial RNA molecule
maybe a pre-RNA world
proteins can form and polymerize abiotically and catalyze their own rep
explain the significance of oxygen to the development of life on earth- sometimes called oxygen rev
early life consisted first of organisms who were anaerobic- glycolysis with out oxygen was first form of metabolism
when photoautotrophs hit the scene O in the atmosphere increased due to increase in photosynthesis
this allowed for the evolution of aerobic organisms who used the oxygen
much more energy was produced = mor growth and activity
more energy and greater size= variety of life forms- cambrian explosion
what is endosymbiosis ? give some examples of this kind of relationship today. prove the evidence that supports the theory of endosymbiosis
explains the origin of eukaryotes as one species being engulfed by another chloroplasts and mitochondria were once free-living aerobic prokaryotes examples: similar membranes modes of replication simple genomes transcription susceptible to similar antibiotics evidence today: solar sea slugs protists inside animals
compare and contrast the adaptations of plants and animals to life on land.
plants have adapted cuticle to conserve water vascular tissue allows larger size overcome gravity and able to move to land seed protected embryo animals have adapted tissues cephalization limbs & appendages coelom allowed for amniotic egg
driving force of evolution
Symbiosis
define and give an example of exaptation
a trait that evolves to serve one particular function, but then it may come to serve another in a different environment.
example: bird wings- heat collectors with feathers and now used for flight
