1
Q
taxon
A
- a named group of organisms
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
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
4
Q
phylogeny
A
- evolutionary history of any group of organisms
5
Q
phylogenetic tree (2)
A
- graphical representation of HYPOTHESIZED evolutionary relationships among taxa
- can use genetics, traits, behaviours, geography, etc to construct phylogenies
6
Q
monophyletic group
A
- group consists of an ancestor and ALL of its descendants
7
Q
node
A
- each node represents a common ancestor
- not an individual, but a population of organisms
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
9
Q
convergent evolution
A
- produces similar characters that are NOT the result of inheritance from a common ancestor
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
11
Q
ancestral character state
A
- pre-existing character state that is not new to a certain taxon
12
Q
derived character state
A
- character state that has been changed and is new within that taxon
13
Q
synapomorphy
A
- derived character state that is shared by 2+ taxa
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
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)
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
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
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
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
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
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
22
Q
notochord vs nerve cord (2)
A
- notochord provides structural support for body
- nerve cord used for rapid communication of signals within body
23
Q
deuterostomes (3)
A
- echinodermata, hemichordata, chordata
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)
BIOL 204
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