Lecure Exam 1 Multiple Choice Flashcards
Basic Facts of Natural Selection (5)
1) Large Reproductive Potential
2) Population Stability Over Time
3) Limited Resources
4) Phenotypic Variation
5) Traits Inherited
Inferences From Natural Selection Facts (3)
1) Struggle for Existence
2) Survival of the Fittest
3) Change Occurs in the Population (Evolution)
Definition of Evoluton
-Change over time
-Change in gene frequencies in a population over time
Major Mechanisms Leading to Evolution (4)
1) Natural Selection
2) Genetic Drift
3) Migration
4) Mutation
Natural Selection
-Process of evolution based on differential survival and reproduction of individuals
-Likely main mechanism for evolution
-Formulated by Darwin
-Based on 5 facts and 3 inferences
Large Reproduction Potential
-Fact of natural selection
-Organisms have large potential to reproduce, creating dozens to thousands of offspring in one lifetime
Population Stability
-Fact of natural selection
-Populations will remain relatively stable over time
Limited Resources
-Fact of natural selection
-Food supply and water or shelter access are all limited in environment
Struggle for Existance
-Inference of natural selection
-Based on 3 facts (large reproductive potential, stable populations, and limited resources)
-In order for populations to remain stable despite large reproductive potential, there is competition for resources leading to stable deaths/survivals over time
Phenotypic Variation
-Individuals will look and act different within same species
Survival of the Fittest
-Struggle for existence means any advantage to resources leads to increased survival
-Due to phenotypic variation, some will be more fit in environment due to advantages
-Best adapted are more fit and will survive to reproduce (leading to inheritable traits)
Traits are Inherited
-Fact of Natural Selection
-Due to more fit individuals reproducing more, those advantageous traits are passed to offspring and less advantageous traits are less seen in a population
-Leads to changes over time
Changes Occur in Population
-Due to more fit traits being inherited and less fit traits not, there will be changes in populations over time
-Change over time = evolution
Genetic Drift
-Mechanism of evolution
-Random chance leads to change in gene frequencies in population
-example: natural disaster randomly wipes out half of population and those genes are no longer passed on
Migration
-Mechanism for evolution
-Movement of individuals in or out of a population, taking genes with them
-Example: 2 grey squirrels move to island of all black, adding their grey genes to population and over time increase in variety of coat colors
Mutation
-Mechanism for evolution
-Least effect on evolution
-Molecular change in a gene can cause new trait in population
Not all Traits are Beneficial/Best (6 examples)
1) Neutral Alleles
2) Genetic Constraint
3) Phylogenetic Constraint
4) Vestigial Structures
5) Side Effects
6) Developmental Constraints
Neutral Alleles
-One allele for a trait is just as good as another so there is no āadvantageā just genetic drift causing one to be more common than another
Genetic Constraint
-A trait may only exist due to a gene causing multiple functions (pleiotropy)
-This trait may not be the best but is selected for due to its other functions
-Similar to side effect traits were one trait is selected for and it happens to have other traits that have no effect on fitness
Phylogenetic Constraints
-A better trait may not be able to evolve due to basics of the animal body
-Example: 6 legs may increase stability in mountain goats but 4 legs is the body plan and in order to develop 6 it would take too many rearrangements
Developmental Constraint
-Due to timing in development some traits may exist despite having no functional use in adult (vestigial)
-Example: nipples develop in some mammals before sex differentiation leading to males having nipples that are not used
Types of Evolution (3)
1) Parallel
2) Divergent
3) Convergent
Convergent Evolution
-Independent development of similar traits in different organisms with NO CLOSE COMMON ANCESTOR
-Usually adaptations to similar environments or similar food sources
-Examples: counter shading or fusiform body shape in ocean animals
Or long tongues for nectar feeding in bats and humming birds
Parallel Evolution
-Independent development of similar traits in 2 different organisms WITH A CLOSE COMMON ANCESTOR
-Leads to homologous structures with similar functions
-Example: 2 rodent families (related) on different continents developed spiny defense hairs (African vs N. American porcupines)
Divergent Evolution
-Homologous structures become different in appearance and/or function over time
-Example: birds have common ancestor with beaks and feet, but species differentiate shape and functions across species
Embryology as Tool for Evolutionary Story
-Ontogeny: sequence of events in develop of individual can give clues to
-Phylogeny: sequence of events in evolution of a group
-Von Baerās Law: embryo development proceeds from general to specific
-Example: look at tooth development in anteater; they begin to develop then stop leading to toothlessness. It indicates that having teeth is primitive to group phylogeny and toothlessness is derived trait
Fossils as Tool for Evolutionary Story
-Useful as they can be accurately dated
-Limited use due to most animals not being fossilized (requires specific conditions) and only hard parts are able to be studied
Outgroup Comparisons for Evolutionary Story
-Technique to suggest which sequence of evolutionary events is more probable by comparing traits/groups with an outgroup that is known to be primitive
-Example: what came first evolutionarily in mammals monotremes, marsupials, or eutherians? Compare traits to reptiles and see monotremes likely came first due to shared trait for egg development over placental
Homologous Traits
-Share common ancestry or developmental pathways
-May or may not look/function similarly in different organisms but are still due to common ancestor
-Examples: inner ear bones of mammal vs. jaw bones of reptile; dog leg vs whale fins
Analogous Traits
-Share common function but NOT common ancestor or development
-Examples: mammal lungs vs fish gills; insect wing vs bird wing; crab leg vs lizard leg
Phylum Chordata Traits (5)
All Chordates have these at some point in development:
1) Notochord
2) Dorsal hollow nerve chord
3) Pharygeal slits
4) Post-anal tail
5) Endostyle
Basic Vertebrate Embryo Dvelopment (6 steps)
1) Fertilization (zygote)
2) Cleavage (cells divide, not grow)
3) Blastula (hollow ball of cells)
-Blastocoel = hollow center
4) Gastrulation:
-Formation of 3 germ layers (ecto-/meso-/endo-derm)
5) Neurulation (forms hollow nerve chord)
6) Simultaneous differentiation of Mesoderm:
a) Epimere (sclero-/derma-/myo-tome)
b) mesomere
c) hypomere (somatic/splanchnic)
Gastrulation (2 steps)
1) Blastula indents forming archenteron (new coelom) and blastopore (opening)
2) Formation of 3 germ layers:
1) Ectoderm: outside tissues
2) Mesoderm: middle (later differentiation)
3) Endoderm: inner (surround gut)
-Formation of primitive gut
Neurulation (3 steps)
1) Dorsal surface (neural plate) folds up to form neural groove
2) Sides fuse to make neural tube (hollow nerve chord formation)
3) Neural crest cells lay between newly formed neural tube and ectoderm
Differentiation of Mesoderm (3 main parts)
-Mesoderm grows dorsal to ventral with 3 areas:
1) Epimere: top part; made of 3 somites:
-Sclerotome
-Dermatome
-Myotome
2) Mesomere: middle part; smallest region
3) Hypomere: bottom part; splits in 2:
-Somatic mesoderm
-Splanchnic mesoderm
-Formation of main body cavity (coelom)
What does epimere mesoderm become?
-Epimere: top part of mesoderm; made of 3 somites:
-Sclerotome: become vertebrae/part of skull/ribs
-Dermatome: become dermis of back area
-Myotome: become most of voluntary muscles
What does mesomere mesoderm become?
Mesomere: middle part; smallest region of mesoderm:
-forms kidney tubules/urogenital ducts
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
-Splanchnic: face inside; become smooth muscle, connect tissue of digest tract, interior blood vessels/heart
What does ectoderm become?
-Neural crest cells
-Nervous system
-Epidermis
What does endoderm become?
-Lining of digestive tract
What is integument?
-Skin of animal
-Made up of 2 main layers:
-Epidermis (outer)
-Dermis (inner)
Epidermis Overview
-Epithelium: multiple layers of cells on a non-living (basement) membrane
-Faces outside world
-No nerves
-Mostly living cells
-Ectoderm origin
-Provides layer of defense
Dermis Overview
-Below basement membrane of epidermis
-Vascularized (provides nutrients/oxygen via diffusion to epidermis)
-Innervated
-Fewer cells and more fibers (ex. collagen)
-Mesodermal origin
-Provides structure to epidermis
Fish Epidermis
-Multi layered
-All live cells
-Many mucous glands:
-Unicellular: goblet cells (most common)
-Multi-cellular
-Mucus has many functions:
-Mechanical protection; antimicrobial; slippery defense; UV protect
Amphibian Epidermis
-More layers (thicker in terrestrial but overall thinner than mammals/reptiles
-Stratified:
-Germinativum: right above membrane; mitosis occurs
-Corneum: outer layer; dead keritinized cells
-Mucous glands common in aquatic
-Poison glands secrete toxins as protection
Reptile Epidermis
-Thickest layers (especially stratum corneum)
-Separation zone: break off area to release outer epidermal generation when shedding
-Pheromone glands for chemical communication
-Derivatives:
-Scales: folds in highly keritinized epidermis for protection
-Claws: keratinized derivatives
Bird Epidermis
-Very thin
-Salt glands: behind eye; marine species
-Uropygial glands: base of tail; secrete oil for conditioning/waterproofing
-Derivatives:
-Claws
-Rampotheca: thin keratinaceous cover over beak
-Feathers: epidermis indents to form follicle and papilla; feathers are made of keritinized dead cells
Mammal Epidermis
-Many layers
-Derivatives:
-Nails/claws/hooves
-Horns: keratin sheath over bony projection
-Scales: rare; beaver tail
-Hair: from follicle pushed into dermis with papilla
-Cuticle: outer, scaly layer
-Cortex: middle, largest layer
-Medulla: inner core
-Glands:
-Sweat/eccrine: evaporative cooling
-Scent: pheromones
-Sebaceous: open into hair follicle; oily secretions
-Mammary: nutrient secretion
Mammal Epidermis
-Many layers
-Derivatives:
-Nails/claws/hooves
-Horns: keratin sheath over bony projection
-Scales: rare; beaver tail
-Hair: from follicle pushed into dermis with papilla
-Cuticle: outer, scaly layer
-Cortex: middle, largest layer
-Medulla: inner core
-Glands:
-Sweat/eccrine: evaporative cooling
-Scent: pheromones
-Sebaceous: open into hair follicle; oily secretions
-Mammary: nutrient secretion
Dermis Structures
-Made of hydroxyapatite: calcium phosphate
-Bone: 65% HA, 35% organic fibers
-Bone can be covered by:
-Dentine (mesodermal): 65-70% HA
-Enamel (ectodermal): 97% HA; hardest substance in body
Fish Scales (4)
1) Cosmoid: ancient; bone coated in dentine/enamel
2) Ganoid: gar; no dentine, just enamel coated bone
3) Elasmoid: modern; no enamel/dentine, just bone
4) Placoid: sharks; no bone/enamel, just dentine
Dermal Derivatives
-Structures made of bone by cells derived from dermis
-Osteoderms: flecks of bone embedded in skin
-Turtle shell (covered in epidermal scales)
-Gastralia: abdominal ribs behind sternum in crocodilians
-Armadillo shell
What is cartilage made of? (4)
-Matrix of cells and fibers:
-Chondroitin sulfate: makes up matrix
-Chondrocytes: living cartilage cells
-Collagen/elastin fibers: dens network in matrix
-Perichondrium: tough membrane of connective tissue that surrounds cartilage system (peri=around)
-Cartilage is avascular; all nutrients diffuse through matrix to chondrocytes from blood vessels in perichondrium
Types of Cartilage (3)
1) Hyaline: most common, thin collagen fibers, often precursor to bone, found in articular surfaces/sharks
2) Fibrocartilage: dense/think collagen fibers, flexible/tough, intervertebral discs
3) Elastic: mostly elastin fibers, flexible but return to shape, found in ear/nose tip
What is in bone made of? (4)
-Hydroxyapatite: matrix of bone; calcium phosphate
-Osteocytes: living bone cells
-Collagen fibers: dense network
-Periosteum: membrane of connective tissue surrounds bone structure
Types of Bone: Microscopic Structure (3)
1) Haversian/Osteon
2) Lamellar
3) Nonlamellar/Woven
Haversian/Osteon Bone (4 parts)
-Osteocytes are in small spaces ālacunaā
-Lacuna are arranged in circular/cylindrical patterns
-Canaliculi connect lacuna
-Osteon/Haversian canal is center of cylinder where canaliculi connect and where capillaries/nerves are
-Nutrients diffuse through canaliculi to osteocytes
Lamellar Bone
-Lacunae hold osteocytes
-Lacunae and fibers arranged in parallel layers
-Adjacent rows are perpendicular to each other; added strength
Nonlamellar Bone
-Seemingly haphazard arrangement of lacunae, osteocytes, and fibers
-Typical of initial growth in life or post-injury
-Weakest type of bone
Compact Bone
-Solid in apperance
-Lamellar or Osteon/Haversian
Spongey Bone
-Open structure like a sponge
-Network of bones pieces (spicules)
Endochondral Ossification
-Cartilage replacement bone
-Initially made of hyaline cartilage; gradually replaced with bone as animal ages
-Diaphysis: ossification from center and moves out
-Epiphysis: ossification from ends moves inward
-Epiphysial cartilage: line between ossification centers; last part to ossify; used to age skeletons
Intramembranous Ossification
-Forms membrane bone; no cartilage precursor
-Bone formed within a membrane
1) Dermal Bone: derived from dermis; forms a lot of the skull
2) Non-dermal:
-Sesamoid: formed within tendons (patella/wrist)
-Baculum/baubellum (Os penis/clitoridis)
Endoskeleton (2 parts)
-All endochondral bones
1) Somatic
-Axial (skull, vertebrae, ribs)
-Appendicular (limbs, pelvis/pectoral girdles)
2) Viseral
-Pharyngeal arches
-Derivatives of arches
Exoskeleton
All dermal bone
Visceral Skeleton: Pharyngeal Arches
-Initially used for filter feeding
-7 arches in vertebrates:
1) Mandibular Arch
2) Hyoid Arch
3-7) Branchial Arches
-5 segments per arch (many modified or fused):
-Pharyngobranchial
-Epibranchial
-Ceratobranchial
-Hypobranchial
-Basibranchial
Mandibular Arch Evolution to Jaws
-First visceral arch evolves into jaws:
-Epibranchials on either side expand and fuse to form upper jaw (palatoquadrate)
-Ceratobranchials expand and fuse to form lower jaw (mandibular cartilage)
Jaw Suspension (3 types)
1) Autostyly: PQ loosely attached by soft tissue to skull
2) Amphistyly: parts of second arch support jaws:
-Hyomandibula: Epibranchials of arch 2 move to support against otic capsule
-Supported both by PQ and HM
3) Holostyly: support only from hyomandibula
Upper Jaw Evolution
1) Rear part of PQ cartilage endochondal ossifies to form quadrate bone, which becomes part of skull
2) Rest of PQ cartilage is functionally replaced by dermal bone (maxilla/premaxilla)
Lower Jaw Evolution
1) Rear part of mandibular cartilage endochondral ossifies to become articular bone (articulates with quadrate in all but mammals)
2) Rest of MC is functionally replaced by dermal bone (dentary, splenial, angular, etc.)
-Number of dermal bones decrease over time to mammals (only have dentary)
Hyomandibula Evolution
-Now that quadrate is part of skull, no need for jaw support from hyomandibula
-It shrinks and moves inwards to become middle ear bone (stapes)
-Hyoid bone formed from 2nd arch and part of posterior arches
-Forms area of support for larynx and tongue muscles
Bones of Articulation Evolution
-All bony vert but mammals:
-Quadrate & Articular
-Mammals:
-Squamosal & Dentary
-Quadrate moves into ear to form incus (IQ)
-Articular moves into ear to form malleus (MA)
-Angular becomes tympanic bone (holds tympanic membrane)
Posterior Arch Evolution
-Arches 3-7 form gill arches in fishes
-Help make up hyoid and laryngeal cartilages in non-fishes
Main Parts of Skull (3)
1) Splanchnocranium
-Parts of skull derived from visceral skeleton
-Smallest portion of skull
2) Chondrocranium
-Oldest/first to form
-From endochondral ossification
-Forms crude box to hold brain (has holes/no lid)
3) Dermatocranium
-Dermal derived bones
-Largest portion of skull
-Provides roof over chondrocranium/covers holes
Secondary Palate
-Roof of mouth
-Mammals evolved sheet of dermal bone to create space between oral cavity and palate for air flow to continue while chewing food
-Air flow from nares through secondary palate to lungs, skipping oral cavity
-Non-mammals airflow from nares, through mouth, to lungs
Temporal Openings (4 types)
-Behind eyes in skull; allows muscles to move outside skull to bulge more and increase bite force
1) Anapsid: no openings (fish, amphib, turtle)
2) Euryapsid: one opening BELOW post-orbital and squamosal bone junction (extinct marine reptiles)
3) Synapsid: one opening ABOVE post-orbital and squamosal bone junction (evolved into mammals)
-Mammals have derived synapsid skull; orbit usually connects to temporal opening
4) Diapsid: two openings both above and below PO and SQ bone junction (snake, lizard, bird)
Types of Vertebrae Centra (4)
1) Amphiocoelous: Concave on both ends, allows for flexibility to L and R (fish/aquatic amphibians)
2) Pro/Opisthocoelous: Concave only on one end (pro=front; opistho=back), works like ball and socket
3) Acoelous: No cavity; little support against gravity (mammals)
4) Heterocoelous: Alternate vertical and horizontal āCā shapes that connect with each other allowing more flexibility in all directions (bird necks)
Vertebrae Differentiation: Fish
1) Trunk: ribs
2) Caudal: hemal arch
Vertebrae Differentiation: Amphibians
1) Cervical: neck; atlas articulate with occipital condyle for increased movement
2) Trunk: ribs
3) Sacral: articulate with pelvic girdle
4) Caudal: tail
-Frogs: Urostyle = fused caudal vertebrae; supports jumping
Vertebrae Differentiation: Reptile
1) Cervical: atlas and axis: articulates with atlas for even more neck movement
2) Trunk: ribs
3) Sacral
4) Caudal
Vertebrae Differentiation: Birds
1) Cervical: heterocoelous
2) Trunk
3) Sacral
-Synsacrum: fused rear trunk, sacral, and some caudal to join with pelvis to support walking
4) Caudal
-Pygostyle: fused terminal caudal to support tail feathers
Vertebrae Differentiation: Mammals
1) Cervical: atlas and axis
2) Thorassic: ribs
2) Lumbar: no ribs; pleurapophysis
3) Sacral: fused to make sacrum
4) Caudal: some (primates) fused into coccyx
Evolution of Vertebrae (3 primitive pieces)
-Vertebrae formed from sclerotomal tissue to surround notochord
-Vertebrae functionally replaced notochord
-Modern vertebrae are fusion of 3 pieces:
1) Neural arch (dorsal)
2) U-shaped intercentrum (ventral)
3) 1 pair of pleurocentra (sides)
Pectoral Girdle
-Behind head, articulates with anterior appendages
-In tetrapods, no direct bone connections to skull or vert column
-In Fish, attached to back of skull
-Both endochondral and dermal
-Early vert are mostly dermal
-Later vert are mostly endochondral (clavicle is only dermal piece left)
-Number of bones deceases over evol time (fusion)
-Birds have furcula: fused clavicles to interclavicle
Pelvic Girdle
-All endochondral bones
-Fish: just puboischiatic bar
-Tetrapods: usually made of 3 bones forming a box around organs and connect to sacral vertebrae
-Ilium
-Ischium
-Pubis
-Posterior appendages articulate
