Lectures 1 & 2: Intro to Evolutionary Anatomy Flashcards
What is meant by functional anatomy?
It is the study of anatomy as it relates to function. A functional explanation of a structure wil focus on what a structure does and how it is used by the organism it is attributed to.
What is evolutionary anatomy?
The study of anatomy as it relates to how organisms are related to each other from a phylogenetic perspective. An evolutionary explanation of a structure will focus on how changes over time, resulting from selective pressure and other evolutionary processes have led to observed similarities and differences among organisms
What is biological evolution?
Descent with modification
What is taxonomy?
A science, concerned with identifying, describing, grouping, and then naming organisms in a systematic fashion
**How we classify organisms based on observed characteristics
What is phylogeny?
Diagram that illustrates a hypothesis about evolutionary relationships within and between groups of organisms.
Phylogenies are constructed using methods of phylogenetic inference to evaluate observable heritable characteristics
What is cladistics?
Essentially unites taxonomy and phylogenetics to create a method of classification of organisms that is based on shared characteristics that are a result of common descent from an ancestral form
What are the 4 processes of evolution?
1) Natural selection
2) Gene flow (migration)
3) Genetic drift
4) Mutation
What are the 6 examples of evidence for evolution provided in class? (Objective says to know 5 of these)
- All life is related
- Organisms form natural groupings
- Species are dynamic
- Vestigial structures
- Biogeography
- Fossil record
What does “All life is related” as evidence for evolution suggest?
Organisms share a universal genetic code and have a common genetic make up
What does “Organisms form natural groupings” as evidence for evolution suggest?
Molecular, anatomical and embryological data support relationships among species
What does “Species are dynamic” as evidence for evolution suggest?
Biological species concept defines a species as an interbreeding population, but there are many cases where it is difficult to define a species this way
What does “vestigial structures” as evidence for evolution suggest?
Organisms often exhibit non-functional or non-adaptive features
What does “Biogeography” as evidence for evolution suggest?
Distinct patterns of species distribution cross the planet tells a story of historical processes that have influenced change over time
What are the 3 conditions for natural selection to occur?
1) Must be variation in a trait, or traits, within a population
2) Variation must be heritable
3) Variation must correlate with fitness (reproductive survival and success)
What is meant by “variation”?
Individual organisms within a population vary from 1 another in observable ways; molecularly, anatomically, behaviorally, etc…
This variation provides the “raw material” of evolution that natural selection works on to produce change over time
What is heritability?
Something that can be passed to offspring via genes.
Variation that has a genetic base is heritable
What is reproductive success?
An individual’s reproductive success is measured by the number of survival offspring that is has
*more serving offspring=higher reproductive success
What is biological adaptation? Example?
The ability of an individual organism or a population of organisms to successfully negotiate the pressures of a given environment in order to survive and reproduce
Giraffes with long necks have greater fitness than giraffes with short necks because they can better reach food
Why is natural selection the best model for explaining adaptiveness?
Natural selection produces a “good fit” between species and environments they inhabit
Natural selection has been observed in wild and simulated under controlled conditions for a very long time aka artificial selection
What are the 4 limits of natural selection?
1) Selection can only act on existing variation
2) Selection will only improve fitness
3) physical and developmental aspects of an organism constrain natural selection
4) Not all change is due to natural selection (genetic drift is example)
What is adaptionism?
The idea that every feature exhibited by an organism is the result of evolution under natural selection
What are the shortcomings of “adaptionism”?
- What about other mechanisms?
- What about characteristics that appear out of sequence or have no apparent adaptive value?
- It can be difficult to test for adaptation, therefore difficult to disprove that is has occurred.
- How do we currently identify relevant traits?
What are homologous structures?
Shared characteristics of organisms that were inherited from a common ancestor
I.e. All tetrapods have 4 limbs
What are analogous structures?
Shared characteristics that arise because of similar selective pressures, thru parallel or convergent evolution
Characteristics that are similar in organisms that have separate evolutionary lineages
I.e. Bird and bat wings
What is parallelism?
Selection has exerted similar pressures on two closely related organisms
What is convergence?
Selection has exerted similar pressures on 2 distantly related organisms
What is a symplesiomorphy?
Shared primitive characteristics
What is a synapomorphy?
Shared derived characteristic that is assumed to be present in the most recent common ancestor
What is a plesiomorphy?
Ancestral state
Explain the functional perspective of the human spinal column
- Protects spinal cord
- Provides structural core for attachment of head, thorax and limbs
- Transmits the weight of the upper body to lower limbs
- Accommodates bipedal/upright postures and locomotion (due to its unique curvature)
What are the similarities between the human and chimpanzee spinal column anatomy?
- Protection of spinal cord
2. Rigid structural core for head and limbs
What are the differences between the human and chimpanzee spinal column anatomy?
- Spinal curvatures that accommodate upright posture
2. Obligate bipedalism versus straighter spinal column that accommodates quadrupedal knuckle-walking
What does the evolutionary perspective show?
Common features that are evidence of common ancestry
Differences indicate key selective pressures that led to adaptations for upright posture and bipedal locomotion in humans
What has lead to the species diversity that we observe?
Process of descent with modification (biological evolution)
Squirrel example of descent with modification
80% = sparsely furred tails
20% = bushier tails
Over time, climate becomes much colder
Bushier tails tend to survive longer and produce more offspring
Later generations
70% = bushier tails
30% sparsely furred tails
Savannah grazers example of descent with modification
50% = longer neck vertebral segments 50% = lack gene
Over time, food becomes scarce and must browse from trees
Longer neck leads to increase in survival and reproduction rates
Later generations
95% = longer neck
What is intersexual selection and example
Favoring traits in one sex that attract the other sex
Bird coloring in males to attract females
Can make males more susceptible to predators
What is intrasexual selection and an example?
Favoring the ability of one sex, typically males, to directly compete with one another for fertilization opportunities
Some male primates have much larger bodies than females and very large canines
Biggest males with largest teeth can drive other males away and gain relatively exclusive access to females
Define microevolution
Occurs when there are changes in gene frequencies in a population from one generation to the next
Define macroevolution
Occurs when there is a descent of different species from a common ancestor over many generations
Among the 15 characteristics that unite members of the order primates are:
Housing of the middle ear in the thick ____________ bone
Emphasis on vision making the orbits ________ and ________
Frontally directed orbits reinforced by a ______________
Petrosal
Convergent and frontated
Post-orbital bar
Among the 15 characteristics that unite members of the order primates are:
___________ vision, allowing for enhanced depth perception
_____________ emphasis on smell
Grasping hands and feet with ________ first digits
Stereoscopic
Decreased
Opposable
Among the 15 characteristics that unite members of the order primates are:
______ sitting posture
___________ bipedalism
___________ brain size
Erect
Facultative
Increased
Among the 15 characteristics that unite members of the order primates are:
__________ life history stages
__________ social behavior and communication
___________ habitat
____________ distribution (location)
Prolonged
Complex
Arboreal
Tropical
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
Relatively and absolutely _______ brain size
____________ developed intellect, awareness, consciousness, etc.
________ facial expressions
Large
Highly
Diverse
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
__________ use of language
___________ life history
__________ bipedalism and its anatomical correlates
Habitual
Extended
Habitual
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
___________ arch of the foot
___________ of hair, ___________ sweating, ______ subcutaneous fat
__________ of the face, __________ of tooth size
Longitudinal
Reduction; increased; more
Shortening; reduction
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
__________ enamel
Food ________ and _________
Extensive _________ culture
Thickened
Sharing; production
Material
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
Use of ___________
Use of __________
Complex _______ behavior and organization
Clothing
Fire
Social
Among the 22 characteristics/trends that unite the genus Homo (humans) are:
______ division of labor as well as extensive division of labor within society
Long-term ______ bonding
Pursuit of _____________ our of context of reproduction
_______ of the habitat
Gender
Pair
Sexual behavior
Reshaping
The 4 complexes of traits that have contributed to the unique adaptive strategy of humans are:
________ bipedalism
________ brain
Ability to sustain high ___________ activities
A life history strategy that depends on complex ________ relationships
Habitual
Enlarged
Metabolic
Social
In the shift from facultative to habitual bipedality, changes occurred in the vertebral column, femoral angle, foot, and pelvis. What were these changes?
The vertebral column gained curvature and successively larger vertebrae from cervical to lumbar
Femoral angle increased to allow humans to place foot directly beneath center of mass
Foot became flattened and more platform-like
Pelvis gained larger lateral shape vs. primates who had longer iliac blade
Who uses oxygen more efficiently, Humans or Primates?
Humans use oxygen 75% more efficiently
What aspect of forearm anatomy allows for stronger movement and dexterity in humans?
Longer flexor muscle of the thumb
In comparing the skulls of hominin vs. other hominids, hominin has:
\_\_\_\_\_\_\_\_\_ brain size Canine \_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_ enamel \_\_\_\_\_\_\_\_\_\_ face \_\_\_\_\_\_\_\_\_ in masticatory mass
Increased Reduction Thickened Shortened Decrease
The general behavioral trends of the genus Homo include:
Ever _________ tool complexity
Incorporation of scavenged and/or hunted _____ food, and later dependence on _________
_______ cultural practice
Increasing
Flesh; cooking
Complex
The size dimorphism in the genus Homo suggests what from gorillas to chimps to humans?
Gorillas: single male + multifemale social units
Chimps: multimale + multifemale units
Humans: serial monogamy (humans)
Describe the primary craniofacial differences between the Australopithecines and Paranthropines in terms of tooth enamel, brain size, dentition trends, and cranial structure
Australopithecines:
Thick enamel, chimp-like brain size, generally large dentition, similar cranial structure among species until sediba who had projecting nose and smaller teeth/chewing muscles
Paranthropines
Massive, thickly enameled molars, slightly larger brain size, molarized premolars with greatly reduced anterior dentition, massive trophic cranial structures leading to increased specialization for food processing
What makes a primate a primate?
Presence of a __________________ in the skull
Orbits are both ____________ and _____________
Hands are ______________, often rotated, and occasionally opposable thumb
Feet are ___________, often with rotated toe (except humans)
All primates have ________
Post-orbital bar
Convergent; frontated
Divergent
Divergent
Nails
In comparing lemurs/lorises vs. monkeys/apes:
Lemurs have split nose with ______ patch; apes have _____ nose
Lemurs have post-orbital bar with _______, but beyond the bar is ______ in apes
Lemurs have a larger and more complex _______ than apes, representing the apes increased dependence on vision
Lemurs have a tooth ______, apes do not
Wet; dry
Opening; closed
Snout
Comb
In comparing New World monkeys to Old World monkeys:
New World have ______ nose with nostrils on the ______, Old World have nostrils toward the ______
OW have lost one _______. NW have a dental formula of 2:1:3:3, OW have 2:1:2:3.
Humans share their dental formula with the _______ monkeys
_______ monkeys have prehensile tails (hang on things)
Flat; sides; front
Premolar
Old world
New world
In what two ways are all monkeys different from apes?
Monkeys may/may not have tails, but NO apes have tails
Apes generally have larger and more complex brains - more gyri and sulci and differentiation of function by hemisphere
