Exam 1 Flashcards
The Basics
Evolution
Change through time
This is the “overall” definition; more specific definitions vary
Capital evolution
Biological evolution
Change thru time of genetic structure, population, and phenotypes
NOT “people came from monkeys”
Biodiversity
Variety of living forms and their habits
Life is abundant; INTELLIGENT life is rare
Anatomy and Physiology
Structure and Function
Behavior
How animals do thing
Ecology
Interactions of animals w/ each other and their physical environments
Molecular biology
How molecules within cells interact
Cell biology
How cells function
Physiology
How tissues/organs of an individual organism function and interact
INTRAspecific Level
How individuals within a species interact
Population biology
INTERspecific level
How different kinds of organisms interact
Community biology
Scientific theory
- Provides powerful explanation for variety of related phenomena
- Purpose is to guide scientific inquiry by providing specific predictions
- Supported by overwhelming evidence from numerous studies (NO logic based evidence can refute it)
Hypothesis
A theory WITHOUT any scientific proof
Evolution is a ________
Theory
Evolution (capitalized)
Biological evolution
Charles Robert Darwin
-Born in wealthy family (father religious and medical; Darwin didn’t make it as either)
-Met naturalists that got him interested in nature
-Developed theory of natural selection
~Started research first
-Published “On the Origin of Species” after hearing another scientist was researching natural selection as well
Alfred Russel Wallace
-Also researched theory of natural selection (the “other” scientist)
Theory of Natural Selection
- Darwin and Wallace researched INDEPENDENTLY
- Covered in Darwin’s “On the Origin of Species”
Influences on Darwin
- Lamark: 1st sci. explanation of evolution (“Inheritance of acquired characters”); made case that fossils are remains of extinct animals
- Lyell: Uniformitarianism (same physical laws and geological processes operate now as during Earth’s history)
- Voyage of HMS Beagle
Voyage of HMS Beagle
Travelled to:
-S. America
-Galapagos Islands
-Europe
-British Isles
-Africa
-Australia
Activities:
-Observed and collected fauna and flora
-Found fossils
-Found seashells in mnts @ 4000m
-Suggested Earth is
dynamicGalapagos Islands
Hugely influential on Darwin’s development of theory of evolution
Full of unique organisms; organisms most similar to those found in S. America
600 miles W of coast of S. America
Darwin spent 5 weeks here
Perpetual Change and Geological Time
The rule to evolution
Earth is NOT static:
-It is always changing both
abiotically and biotically
NOT entropy; we have the sun, huge energy inputRadiometric dating
Based on physics, chemistry, and math; very reliable
Challenge: getting samples
Earth is _______________ years old
4.6 billion
Evidence of Perpetual Change
-Banded Iron Formation in Australia
-Rocks up to 3 bil years old
-Big Island, Hawaii
-Oldest part of island
400,000 years old (7,500
years YOUNGER than the
old rocks)
-Kawaii is the oldest of all
Hawaii’s islands (Oldest
islands are in NW)
-New island coming up SE of
Big Island
Fossil Record
Oldest micro fossils: 3.5 billion years
Oldest macro fossils: 650 million years
Most animal phyla present 540 million years ago
MINIMUM AGES
Burgess Shale
505 mil years old (Cambrian)
- Many phyla present long extinct
- Some extant phyla represented
- Cnidaria
- Sponges
- Arthropods
- Flatworms - “Natural experiment” of evolution
Cambrian Explosion
- New lineages evolving very rapidly
- Many life forms didn’t persist and died out
- Another chunk survived and are present in some form today
Extinct
No living members
Extant
Living branch on tree of life
Taxon/Taxa
Life is a taxon (i.e. humans, birds, etc.)
Oldest vertebrates are >__________ years old
500 million
Human agriculture is ~________ years old
10,000
Human agriculture is about _____________________ as old as the oldest of vertebrates
- 00002% (two one-hundred thousandths of one percent)
0. 00002% of a mile = 1/3 of a millimeter
____% of all metazoan species that have ever lived on Earth are extinct
~99.9
Of these estimated _____ of animal species have been discovered as fossils
<0.1%
Fossil record is a ______ sample of what has existed:
a) large
b) moderate
c) minimal
c) minimal
Fossil records are biased toward ____________:
a) soft-bodied animals (i.e. worms)
b) hard animals (i.e. mollusks)
b) hard animals (i.e. mollusks)
Common Descent
Suggests a single origin of life:
-All forms of life ultimately
descended from a common
ancestor via branching of
lineages
Overwhelming evidence:
-Organismal form
-Cell structure
-Developmental patterns
-DNA
An individual is connected by a genetic line to everything on earthPhylogeny
-Structure of life’s history is like a tree
-A tree-like diagram of relationships among taxa
Should actually be “Phylogenetic hypothesis,” since some phylogenies are theoretical and still changing
Nodes
Branch points
- Represent ancestors and speciation events
- Inferred ancestors
- Branched points at the nodes represent the speciation events
Branches represent __________
Lineages
Could be broad or specific
What determines phylogenetic relationships?
a) DNA (Molecular Data)
b) Morphological data (skeletal structure)
c) Both of these
d) Neither of these
c) Both of these
DNA is NOT a definitive way of distinguishing relationships, so sometimes morphological data is favored over molecular data
Cladogram
- A phylogeny based on cladistic methods
- Cladistics are NOT exactly the same as phylogenies; all methods are VARIATIONS of original cladistics method
Branch tips represent ____
Species
Lowest level non-reticulating lineage
Hybrids are __________
a) Completely normal and abundant
b) The exception, not the norm
c) Both of the above
d) Nonexistant
e) None of the above
b) The exception, not the norm
Synapomorphy
Relationships constructed based on shared derived characters
Clade
A group defined by synapomorphies
I.e.: Squamata (lizards, snakes, amphisbaenians)
Some ancestor and all of its descendents
Synapomorphies defining amniotes
-Extraembryonic membranes of amnion, chorion, and allantois; lungs ventilated by negative pressure via the ribs
Shared ancestral characters _____ define clades
Do NOT
I.e. diapsid skulls do NOT distinguish squamates from other diapsid amniotes
Polarity
-Directionality of ancestral/derived condition among groups
-Outgroup comparison
-Direction of evolution (gain or loss of any trait)
I.e.: Presence of teeth ancestral for amniotes and therefore lack of teeth derived for birds
Monophyletic group
Ancestor and ALL descendants
I.e.: Every ancestor is included
Chordates are a clade
Paraphyletic group
Ancestor and some descendants
I.e.: Showing only SOME of a tree’s branches (makes about as much sense as saying a specific tree branch is not part of that tree)
Polyphyletic group
Common ancestor NOT included
I.e.: Putting all flying creatures together
Must acknowledge that they aren’t related to not seem like a complete fool (used mainly just for comparison purposes)
Family
Anything that ends in -idae
TRUE OR FALSE: Orangutans, gorillas, and chimpanzees form a monophyletic group.
FALSE. Humans are not included, so not all descendants are shown (paraphyletic).
Now, Pongidae is eliminated and orangutans, gorillas, and chimps are all considered Hominidae with humans.
Homology
-“Same organ in different organisms under every variety of form and function” (Sir Richard Owen)
-Homo = same: Studying the Same Things, the similarities
Example: Forelimbs share homologous elements because they evolved from same original forelimb (fin)
Homologous structures
Can be macroscopic or at molecular level (proteins, DNA)
Analogy
Structures with similar function but that do NOT reflect common ancestry
NOT similar ancestry; similar function ONLY
I.e.: Bird wing vs. Butterfly wing
Same function (powered
flight), NOT related
genetically or historically
What is a species?
Biological Species Concept
Proposed by Mayr in 1940
An interbreeding natural population (or group of populations) that is reproductively isolated from other such groups
- Population-centered view
- Interbreeding gene flow
- A population or group of populations w/ gene flow keeping them cohesive but NO gene flow with other species
- Something stops different species from breeding with another
What is a species?
Evolutionary Species Concept
Proposed by Simpson in 1961 and Wiley in 1981
A single lineage of ancestral-descendant populations that maintains its identity from other such lineages and that has its own evolutionary tendencies and historical fate
- You get a speciation event and it does NOT go back to another species (NO reticulation)
- Phylogenetic viewpoint
Speciation
Formation of new species
How does speciation occur?
1) Evolution of reproductive barriers
2) Allopatric Speciation
Evolution of Reproductive Barriers
Physical: -I.e. incompatible sexual organs Physiological: -I.e. Egg can't fuse w/ sperm Ecological: -I.e. different locations/niches Behavioral: -I.e. mating call differs & attracts only same-species members Geographic barriers: -I.e. Mtn range, isolated island Endemism/Endemic: -Found only in a very specific location
Allopatric speciation
Population separated into two separate groups by geographic barrier - then reproductive barriers can evolve
Most pervasive speciation mechanism
Gradualism
Major differences in traits among species evolve by accumulation of many small incremental changes over time
Indicates Gradual change
Argues AGAINST sudden appearance of new species and rapid morphological changes
-Now accepted that new
species CAN appear
suddenly and rapid morph.
changes CAN evolve
Punctuated Equilibrium
Sudden appearances and changes of species
Evolution uses:
a) Gradualism
b) Punctuated equilibrium
c) Both gradualism and punctuated equilibrium
d) Neither
c) Both gradualism and punctuated equilibrium
Ontogeny
Development of organism throughout life
From zygote to death
Role of Ontogeny
Evolutionary changes in development can result in major differences in an adult organism
Heterochrony
Evolutionary change in timing of development
Etymology: Different timing
Example: Axolotl keeps gills thru/out life (normal salamanders undergo metamorphosis to live on land; axolotls remain in water and thus in “tadpole” stage)
Natural Selection
Organisms have great reproductive potential and many more are produced than can survive (Malthus)
Populations fluctuate in size but do not show continuous exponential increase w/o limitations
Not all offspring survive: limited resources (Malthus)
Proposed by Darwin and Wallace (independently)
Supported by ABUNDANT evidence
Describes how populations accrue ‘favorable’ characteristics over evolutionary time
Evidence from artificial selection (i.e. dog breeds)
Supported by observations and inferences
Inference: Struggle for existence among individuals in a population that increases w. greater numbers of individuals
Variation is heritable
Inference: Differential survival and reproduction generate new adaptations and species
These are examples of _________:
Natural Selection
Dog breeds are an example of _________
Artificial selection
Certain traits are selected for and specifically bred for
Survival of the fittest was proposed by________
NOT Darwin; the media
Evolutionary Patterns
1) Adaptive Radiation
2) Convergence
3) Reduction and Loss
4) Reversal
5) Specialization
Adaptive Radiation
Evolution of many diverse species from a common ancestor (via multiple allopatric speciation in rapid succession)
Typically associated w/ invasion of areas w/ unoccupied niches
Convergence
Independent evolution of a similar characteristic in 2 or more taxa
Morphology, physiology, ecology, behavior, etc.
The presence of the similarity is NOT due to common ancestry
Convergence or Not?
Turtles and mice both have forelimbs
NO
The presence of forelimbs in turtles and mice explained by common ancestry
Convergence or Not?
Birds and bats both have wings.
YES
Common ancestor did NOT have wings, and birds and bats are NOT closely related, so they evolved wings independently of one another
Evolutionary Reduction
Some character is reduced in size or prominence
Evolutionary Loss
Some character is lost
Evolutionary Reversal
Return to a condition seen in an earlier ancestor
Character that has reverted is called “secondarily derived”
Secondarily Derived
A character that undergoes evolutionary reversal
Specialization
Evolutionary modification(s) for a specific biological role
Adaptation
Current role must be the SAME as what it originally evolved for; a TYPE of specialization
T or F:
All adaptations are specializations, but not all specializations are adaptations
TRUE
What IS Evolution
Like a tree
Parts of an organism can be ancestral or derived; not necessarily the entire organism
Organism is the sum of its parts
Unifying theme of biology
What is Evolution NOT
A ladder
Progress
Chordates: Shared Ancestral Characters
1) Bilateral symmetry
2) Anteroposterior Body Axis
3) Arrangement of body cavities (coloem)
4) Segmented metamerism
5) Cephalization (having a head with sensory structures)
Synapomorphies of Deuterostomes
1) Blastopore forms anus
2) Mouth formed from secondary opening
3) Radial cleavage
4) Coelom formed by fusion of enterocoelus pouches
Chordata Synapomorphies
1) Notocord
2) Single, dorsal, tubular nerve cord
3) Pharyngeal pouches/slits
4) Endostyle
5) Postanal tail
Chordata: Notocord
Flexible rod-like structure
Ventral to the nerve cord
Role in Locomotion:
-Skeletal axis for muscle attachment to facilitate undulatory movements
Chordata: Single, Dorsal, Tubular Nerve Cord
- First part of the endoskeleton to appear in embryo
- Persists in protochordates (some) and jawless vertebrates
- Replaced by cartilaginous or bony vertebrae in jawed vertebrates
- Initially hollow (tube) but mostly fills in during development in most taxa (this is a synapomorphy)
- Produced by infolding of dorsal ectodermal cells
- In Vertebrates: Anterior end becomes brain, cord passes through protective neural arches (cartilage or bone)
Chordata: Pharyngeal Grooves/Pouches/Slits
Formation:
1) Inpocketing of ectoderm (this forms pharyngeal grooves)
2) Outpocketing of adjacent endodermal lining of pharynx (this forms the pharyngeal pouches)
In Aquatic Chordates, inpockets and outpockets fuse to form pharyngeal slits
In Amniotes, pouches produce middle ear cavity, Eustachian tube, and other structures
Pharynx with pharyngeal slits originally evolved as a filter-feeding apparatus (water drawn in through mouth by ciliary action and passes our through slits with food trapped in mucus)
In Aquatic Vertebrates, the pharynx is a respiratory organ (internal gills)
-Pharynx muscularized and contractions drive water flow over highly vascularized pharyngeal arches
Chordata: Endostyle
Protochordates and lamprey larvae:
-Mucous-secreting organ for trapping food parts. in pharynx
Vertebrates (including ADULT lamprey):
-Thyroid gland derived from endostyle (homologous to endostyle)
-Lamprey is basal vertebrate
—Larval stage: Protochordate-like
—Adult stage: Vertebrate-like
Evidence from homology: Endostyle and thyroid gland both secrete rare iodinated proteins
Chordata: Postanal Tail
Role in Locomotion:
-Propulsion in water
Associated somatic musculature
Great diversity of form and function in extant taxa
Protochordates
Urochordata
Cephalochordata
NOT a monophyletic group
It doesn’t include vertebrates, so it doesn’t include all of the descendants: this is an example of a paraphyletic group
Protochordates: Urochordata
AKA Tunicata (Tunicates) (preferred term)
Notocord (restricted to tail) in larvae disappears during metamorphosis into adult
>3000 species in 3 classes
Found near shore to open ocean habitats
Ascidians (sea squirts) are the best known (>2000 species)
- -Larvae short-lived, non-feeding
- -All 5 chordate synapomorphies
- —Adults retain only pharyngeal slits and endostyle
- -Adults:
- –Sessile
- –Filter feed w/ incurrent and excurrent siphons and mucus-secreting endostyle
- –Hermaphroditic (both gonads; no genders)
Protochordates: Basics of Cephalochordata
Small (3-8cm)
Elongate
Laterally Compressed
~30 species
Found in coastal waters w/ sandy bottoms
RESEMBLES hypothesized ancestral chordate (NOT necessarily the common ancestor itself)
Possesses all 5 chordate synapomorphies in clear and simple form as adult
Filter Feeders
Example: Amphioxus
Compressed
Laterally flattened
Sides are pushed in so that the width of the organism is much more slender than its depth
AKA Laterally Compressed
Depressed
Dorso-ventrally flattened (like a sting-ray)
Humans are depressed (stomach is ventral, back is dorsal)
Cephalochordata: Circulatory System
Closed system
NO heart: Blood pumped by contractions of aorta
Colorless blood (no hemoglobin or erythrocytes)
Blood transports nutrients (derived from filter-feeding) but also plays NO role in gas exchange (oxygen attained through diffusion)
Physiological explanation: Why is amphioxus small and compressed?
Depend COMPLETELY on simple diffusion of oxygen from water into their bodies
Lateral compression allows a molecule of oxygen to travel a shorter distance when diffused into body
Thus, amphioxus CONSTRAINED to small size to allow for effective diffusion
What Matters in Diffusion
Surface Area
Thickness (THIN is better)
Gradient (how much stuff do you have in one place compared to the other place you want it to go)
Cephalochordata: Nervous System
Dorsal nerve cord retains tubular structure
Unpaired nerve receptors on sides of body
Brain-like vesicle at anterior end of the nerve cord
—NOT a true brain (true brain is vertebrate synapomorphy)
Cephalochordata: Reproduction
Sexes separate
Gametes released out of atriopore
EXTERNAL fertilization (fertilization occurs in the environment, NOT internally)
Shares characteristics with vertebrate body plan:
- Hepatic cecum (secretes enzymes to digest food)
- Segmented trunk musculature
- Basic plan of circulatory system
Earliest Known Chordate:
Pikaia
- -Seen in Burgess Shale >500mil yrs ago
- -Notocord, myotomes, anteroposterior axis
- -About 2.5-4cm
- -Known from 114 specimens
- -Much like extant chordates
- -Thought to be one of the original chordates
- -Small like modern-day amphioxus
Sister Taxa:
Lineages sharing more recent common ancestor with each other than either does with any other lineage
Original hypothesis of relationship of chordate tree
Cephalochordata and Vertebrata are sister taxa
Current hypothesis of relationship of chordate tree
Urochordata and Vertebrate are sister taxa
More accepted version
