Phylogeny Flashcards

1
Q

taxon

A
  • a named group of organisms
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2
Q

homologous structures (2)

A
  • features that share a common ancestry: structures arise from the same structure in their MCRA
  • structures that are homologous may also be similar in function and appearance, but this is not true for all homologous structures
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3
Q

how can embryonic origins support comparative morphology studies (2)

A
  • can provide evidence for whether or not structures are homologous
  • is a certain feature has the same precise embryonic origin, it is most likely homologous; due to broadness of differentiation in embryos, we cannot confirm that the are homologous
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4
Q

phylogeny

A
  • evolutionary history of any group of organisms
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5
Q

phylogenetic tree (2)

A
  • graphical representation of HYPOTHESIZED evolutionary relationships among taxa
  • can use genetics, traits, behaviours, geography, etc to construct phylogenies
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6
Q

monophyletic group

A
  • group consists of an ancestor and ALL of its descendants
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7
Q

node

A
  • each node represents a common ancestor

- not an individual, but a population of organisms

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8
Q

common ancestor and homologous characters

A
  • more recently two groups shared a common ancestor, the more homologous characters we would expect them to share
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9
Q

convergent evolution

A
  • produces similar characters that are NOT the result of inheritance from a common ancestor
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10
Q

evolutionary divergence (2)

A
  • can produce characters that no longer appear similar, even though they are homologous
  • can lead to secondary loss of characters
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11
Q

ancestral character state

A
  • pre-existing character state that is not new to a certain taxon
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12
Q

derived character state

A
  • character state that has been changed and is new within that taxon
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13
Q

synapomorphy

A
  • derived character state that is shared by 2+ taxa
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14
Q

how can deuterostome and protostome taxa be identified (2)

A

based on early embryonic development:

  • protostomes (“first mouth”): blastopore at anterior end of embryo and gives rise to region of the mouth
  • deuterostomes (“second mouth”): blastopore at posterior end of embryo and gives rise to region of the anus
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15
Q

what are the shared characters of all chordates (5)

A

all appear in at least one developmental stage, although it may not be retained into adulthood:

  • dorsal hollow nerve chord
  • notochord
  • pharyngeal slits
  • post-anal tail
  • endostyle (homologous to thyroid gland in vertebrates)
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16
Q

dorsal hollow nerve chord (5)

  • synapomorphy for….
  • definition
  • origins
  • composition
  • function
A
  • synapomorphy for chordates
  • hollow, fluid-filled structure dorsal to the digestive tract
  • arises from neural tube/neural plate ectoderm
  • composed of neurons and glial cells and forms central nervous system (the brain and spinal cord in vertebrates)
  • transmit signals to rest of body
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17
Q

notochord (5)

  • synapomorphy for….
  • definition and structure
  • function
  • origins
  • presence in vertebrates
A
  • synapomorphy for all chordates
  • slender rod with core of cells and fluid surrounded by tough fibrous sheath
  • provides structural support: can bend from side to side, but cannot be axially compressed (length remains the same)
  • arises from mesoderm
  • functionally replaced by vertebral column during development in many vertebrates
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18
Q

pharyngeal slits (3)

  • synapomorphy of…
  • position
  • formation
A
  • most likely a synapomorphy of deuterostomes
  • pharynx is anterior chamber of digestive tract (posterior to the mouth)
  • during development, walls of pharynx penetrated by series of openings, but are closed before embryo is born/hatched in many terrestrial vertebrae
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19
Q

endostyle (5)

  • synapomorphy for…
  • position
  • definition
  • function
  • homologous to…
A
  • synapomorphy for chordates
  • arises from ventral side of pharynx during development
  • groove filled with glandular tissue
  • produces mucus and processes iodine
  • homologous to thyroid gland in chordates
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20
Q

post-anal tail (3)

  • synapomorphy for…
  • definition
  • function
A
  • synapomorphy for chordates
  • posterior elongation of the body extending beyond the anus; notochord extends into structure
  • functions to produce lateral undulation for movement
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21
Q

myomeres (2)

  • definition
  • function
A
  • segmented blocks of skeletal muscle separate by layers of connective tissue; arranged in series from anterior to posterior
  • pull notochord from side to side to create movement
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22
Q

notochord vs nerve cord (2)

A
  • notochord provides structural support for body

- nerve cord used for rapid communication of signals within body

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23
Q

deuterostomes (3)

A
  • echinodermata, hemichordata, chordata
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24
Q

chordata (3)

A
  • cephalochordata, urochordata, vertebrata
25
echinodermata (2)
- sea stars, sea cucumbers, sea urchins, sand dollars, etc | - adults have pentaradial symmetry
26
hemichordata
- includes acorn worms and pterobranchs
27
cephalochordata
- amphioxus or sea lancelot | - have all 5 chordate characteristics
28
urochordata
- eg. sea squirts | - undergo metamorphosis; lose some chordate characteristics as adults
29
vertebral column
- series of separate bones or cartilage blocks located along the longitudinal axis of the body
30
cranium
- composed of cartilage/bone
31
muscular pharyngeal pump
- for feeding, likely replaced ciliary pump of chordata common ancestor
32
what characters differentiated ancestral vertebrates from ancestral urochordates (3)
- vertebral column - cranium - muscular pharyngeal pump
33
agnatha (2)
- vertebrates without jaws | - include myxinoidea (hagfish) and lampreys (petromyzontida)
34
myxinodea (5) - characteristics (3) - phylogeny (2)
- agnatha and vertebrata - hagfish only found in marine environments - often scavengers. feeding on dead fish, dying fish, or invertebrates; can also be predatory - release huge volumes of slime if attacked - lack vertebrae; likely secondarily lost
35
petromyzontida (4) - phylogeny (1) - characteristics (3)
- agnatha and vertebrata - lamprey have a larval stage using muscular pharyngeal pump for suspension feeding - have endostyle; during metamorphosis into adult, it transitions to thyroid gland - some adults are parasitic and attach to prey using their round mouths to feed on blood and fluids; others do not feed at all as adults
36
what characters differentiated ancestral gnathostomata from ancestral agnatha (3)
- bone - jaws - pectoral and pelvic fins/girdles
37
jaw (2)
- biting device derived from splanchnocranium of the skull - allowed for great increase in gnathostome diversity due to wider variety of food sources than available for filter-feeding ancestors
38
pectoral and pelvic fins
- gave ancestral gnathostomes stability and precise control of steering while swimming, allowing for increased maneuverability
39
gnathostomes (2)
give rise to: - chondrichthyes - teleostomi
40
chondrichthyes (4)
- elasmobranchii and holocephali - cartilaginous fish: secondary loss of bone - control their buoyancy by producing oils (using their liver) and by swimming - negatively buoyant, so they will sink if they stop swimming
41
teleostomi
- actinopterygii, sarcopterygii, tetrapods
42
what characters differentiated ancestral teleostomi from ancestral gnathostomes (3)
gas bladder
43
gas bladder
- acts as a swim bladder that provides natural buoyancy | - act as lungs for gas exchange in other teleostomi
44
actinopterygii
- teleosts exist within actinopterygii and contain large number of extant species
45
tetrapoda
- amphibia, sauropsida, mammalia
46
what characters differentiated ancestral tetrapoda from ancestral lobe-finned fishes
- legs and digits
47
legs and digits (2)
- paired muscular appendages and well-defined joints | - evolved from fleshy fins
48
amphibia (3)
- salamanders, newts, frogs and toads, and caecilians - most have thin, scaleless skin covered in mucous to allow for cutaneous respiration - most have aquatic larval stage, then undergo metamorphosis into a semi-terrestrial or terrestrial adult stage
49
anamniotes (2)
- fish and amphibians | - do not produce amnion, chorion or allantois; many still produce yolk sacs
50
amniotes (4)
- embryos that produce amnion, chorion, allantois, and yolk sac - two main lineages: sauropsida and mammalia - in oviparous (egg-laying amniotes), the embryo is packaged within a tough shell - waterproof membranes allowed for laying of eggs on land (transition to terrestrial environment) and prevent desiccation
51
sauropsida
- testudinata, lepidosauria, archosauria
52
archosauria
- crocodilia | - aves
53
testudinata (4)
- turtles - have bony shell made up of dorsal carapace and a ventral plastron - secondary loss of teeth - beak composed of keratin
54
lepidosauria (2)
- snakes, lizards | - hemipenes are synapomorphy; pair or intromittent organs
55
crocodilia
- crocodiles, alligators, caiman
56
aves (2)
- birds | - can be distinguished by presence of feathers and endothermy
57
mammals (2)
- monotremata, metatheria, eutheria | - synapomorphies: endothermy, hair, mammary glands
58
monotremata (2)
- platypus, beaver | - lay eggs, oviparous
59
metatherians and eutherians
- give birth to free-living young (viviparous)