Lecture Exam 1 Essay Questions Flashcards
Homology vs. analogy; give examples
-Homology:
-Traits share close common ancestry or developmental pathways
-May or may not look/function similarly
-EXAMPLE
-Human arm and whale front flipper bones (humerus/carpals)
-Inner ear bones of mammal (Incus/Malleus) & jaw bones of reptile (Quadrate/Articular)
Analogy:
-Share common function but NOT close common ancestry or developmental pathways
-EXAMPLE
-Gills of fish & lungs of tetrapods (both for respiration but not related)
-Butterfly wing and bird wing
Convergent vs. parallel vs. divergent evolution; give examples
1) Convergent
-Independent development of similar traits in different organisms with NO close common ancestors
-Leads to analogous traits
-Similar adaptations due to living in same environment/food sources
-EXAMPLE:
-Shark, penguin, and dolphin countershading and body shape
-Nectar collector tongues in some bats and butterflies
2) Parallel
-Independent development of similar traits in 2 dif organisms WITH close common ancestor
-Leads to homology with similar functions
-EXAMPLE:
-African & N. Amer porcupines developed defense quills
-Tasmanian wolf & European wolf developed similar body/hunting
3) Divergent
-Homologous traits become different in appearance/function over time
-EXAMPLE:
-Bird beaks and feet (specialized to different foods/environments) like duck feet & eagle feet or pelican beak & flamingo beak
Describe the embryological development/major divisions of the mesoderm in a generalized vertebrate.
1) Gastrulation of blastula leads to primary germ layers:
-Ectoderm
-Mesoderm
-Endoderm
2) Neurulation occurs on ectoderm plate
-Dorsal hollow nerve chord is formed
3) Simultaneously, differentiation of mesoderm:
-Mesoderm grows down from nerve chord between endo and ecto as it differentiates
-Epimere: top part splits into 3 somites:
-Sclerotome
-Dermatome
-Myotome
-Mesomere: middle area; smallest region
-Hypomere: lower part; splits in 2 parts with cavity
-Somatic
-Splanchnic
-Coelom (main body cavity)
Summarize the history of the first visceral arch from lower vertebrates to the mammals
(Not jaw suspension)
-First arch is Mandibular arch (becomes jaws)
1) Sharks:
-Epibranchials on either side grow and fuse into palatoquadrate (upper jaw)
-Ceratobranchials expanded and fused to form mandibular cartilage (lower jaw)
2) Bony fish, Amphib, Rept, Birds:
-Rear part of PQ endochondral ossifies to become quadrate (upper jaw articulation)
-Rest of PQ replaced by dermal bone to become pre/maxilla
-Rear part of MC endochondral ossifies to become articular bone (articulate with quadrate)
-Rest of MC replaced by dermal bone to become dentary, splenial, angular (lower jaw)
3) Mammals
-Quadrate moves into ear to become Incus (IQ)
-Articular moves into ear to form malleus (MA)
-Articulation bones are Squamosal and Dentary
-Number of dermal bones in lower jaw decreases (only dentary remains)
Describe the method of ossification, position, and relative contribution of the chondrocranium and dermatocranium to the skull of a terrestrial vertebrate.
1) Splanchnocranium
-Smallest portion
-Visceral skeleton derivatives (jaws)
2) Chondrocranium
-Oldest phylogenetically and earliest to form in embryo
-Endochondral ossification
-Forms inner crude box around brain (holes and no lid)
3) Dermatocranium
-Largest portion of skull
-Dermal derived
-Provides dermal roof over chondrocranium/covers holes
What are temporal openings and what is the proposed reason for their development?
-Jaw muscles are located between dermal roof and chondrocranium in temporal area (behind eyes)
-This limits jaw bite force as there’s not room for muscles to bulge
-Openings evolved in dermal roof, putting muscles outside of skull, allowing room to bulge and inc bite force
What is natural selection and how does it differ from evolution?
-Natural selection is likely main mechanism for Evolution
-Based on differential survival and reproduction of individuals in a population:
-Large reprod potent, pop stable, and limit resource leads to struggle for existance
-Pheno vary leads to survival of the fittest
-Inherit traits leads to changes in population
-Evolution: change in gene frequencies in a population over time
Which groups possess each type of temporal opening?
1) Anapsid
-Fish, amphibians, turtles
-No openings
2) Euryapsid
-Extinct marine reptiles
-One opening BELOW post-orbital and squamosal bone junction
-BEST = Below is Euryapsid; Synapsid is Top
3) Synapsid
-Reptiles that evolved into mammals
-One opening ABOVE post-orbital and squamosal bone junction
-Mammals are derived synapsid (PO bar or fused orbit and temporal opening hole)
4) Diapsid
-Snakes, lizards, birds
-Two openings both above and below PO and SQ junctions
What are the major divisions of mesoderm in the embryo and what do they become in adults?
Mesoderm:
1) Epimere: 3 somites
-Sclerotome = vertebrae, ribs, part of skull
-sclero = hard
-Dermatome = dermis in back area
-derma = skin
-Myotome = most of voluntary muscles
-myo = muscle
2) Mesomere: smallest portion
-forms kidney tubules & urogenital ducts
-mess = piss
3) Hypomere: 2 parts and main body cavity
-Somatic: limb bones, rest of dermis, outer blood vessels/connective tissue
-soma = body
-Splanchnic: smooth muscle, interior blood vessels/heart, connective tissue of digest tract
-splanch = entrails
Summarize Darwin’s Arguments for Existence of Natural Selection
-5 Facts of Natural Selection:
1) Large reproductive potential
2) Population stability over time
3) Limited resources
4) Phenotypic variation
5) Traits inherited
-3 Inferences:
1) Struggle for Existance: first 3 facts; in order for populations to remain stable despite reproductive potential, the limited resources leads to a struggle to survive
2) Survival of the Fittest: due to pheno vary, some traits are more advantageous to get food/breed so are more fit to survive
3) Change Occurs in Population: due to inherited traits, fit individuals offspring will carry those advantageous traits and change population ratios over time
What does epimere mesoderm become?
Epimere: TOP part of mesoderm; made of 3 somites:
-Sclerotome: become vertebrae/part of skull/ribs
-sclero- = hard (bone)
-Dermatome: become dermis of back area
-derma- = skin
-Myotome: become most of voluntary muscles
-myo- = muscle
What does mesomere mesoderm become?
Mesomere: middle part; smallest region of mesoderm:
-forms kidney tubules/urogenital ducts
-“mess means piss” = urogenital/kidney
What does hypomere mesoderm become?
Hypomere: bottom part; splits in 2 and forms body cavity (coelom)
-Somatic: face outside; become limb bone/rest of dermis, outer blood vessels/connective tissue
-soma- = body
-“somOUT” = outer blood vessels
-Splanchnic: face inside; become smooth muscle, connect tissue of digest tract, interior blood vessels/heart
-splanch- = entrails (organs)
-NI = INner blood vessels
