Exam 1 Flashcards
(176 cards)
1
Q
vertebrate
A
A vertebrate is a deuterostome, specifically, a chordate, with a cranium, a vertebral column, an endoskeleton, and neural crest cells.
2
Q
five derived features of vertebrates
A
- vertebral column
- cranium
- endoskeleton
- neural crest cells
- cephalization
3
Q
vertebral column
A
bony or cartilaginous endoskeleton around the spinal cord
4
Q
cranium
A
bony or cartilaginous brain protective case
5
Q
endoskeleton
A
an internal skeleton
6
Q
neural crest cells
A
an early embryonic feature in development which has an inductive effect on later development giving rise to the jaw, cranium, nerves and part of teeth
7
Q
cephalization
A
has a head with sensory
8
Q
List the five diagnostic characteristics of a chordate.
A
- notochord
- dorsal hollow nerve cord
- pharyngeal slits
- endostyle
- postanal tail
9
Q
notochord of vertebrates
A
replaced by a vertebral column
10
Q
urochordata notochord
A
larval notochord tail only
11
Q
cephalochordata notochord
A
notochord entire body for whole life
12
Q
notochord
A
stiff but flexible rod
13
Q
sea squirt notochord
A
lacks notochord as an adult
14
Q
dorsal hollow nerve chord
A
integrates and coordinates longitudinal muscle fiber in trunk/trail; replaced by spinal cord in humans and filled with cerebrospinal fluid
15
Q
pharyngeal slits
A
slits in pharynx, pouch is similar embryologically; water passes through
16
Q
endosyle
A
longitudinal groove in floor of pharynx, glandular, ciliated; secretes mucus to collect food
17
Q
postanal tail
A
extension of body past anus; useful for locomotion
18
Q
sea squirt postanal tail
A
lacking in adult
19
Q
vertebrate examples from lab
A
lamprey and shark
20
Q
protochordate
A
invertebrate with some or all of the 5 diagnostic characteristics of a chordate
21
Q
Explain why there are five diagnostic characteristics and why the characteristics were chosen from embryogenesis.
A
- each of these traits can be traced back to just chordates which share the same common ancestor whom did not possess these traits
- the traits were chosen from embryogenesis because organisms can deviate from their embryo and larval stages but their developing structures remain the same; as they grow older some organisms lose derived features
22
Q
Describe the characteristics that unite craniates and make them distinct from the invertebrate chordates.
A
- craniates have a bony or cartilaginous brain-protecting case
- most have a vertebral column
23
Q
oldest craniates
A
agnathans, specifically myxini (hagfishes) then petromyzontidae (lamprey)
24
Q
Consider the phrase: “ontogeny recapitulates phylogeny”. What does this mean in terms of studying the embryology of organisms to uncover evolutionary relationships?
A
Haeckel: development of an organism (ontogeny) expresses all of the intermediate forms of its ancestor throughout evolution (phylogeny).
- Believed that development early on was well-conserved and that organisms changed after their similar first stage developments
- studying organism’s development gives insights on its ancestral history (if they share developmental stages or not)
25
Explain the significance of a study of the protochordates to understanding vertebrate evolutionary history.
protochordates are essential to studying vertebrate evolutionary history because all verts have the 5 chordate characteristics so earliest vertebrates were close to an early protochordate
26
Describe how one might use knowledge about homologies during embryogenesis among invertebrate and vertebrate chordates to support the theory of evolution.
- at some point in development they all have a flexible rod (notochord) supporting them that runs the length of their bodies
- fish evolution shows invertebrates --> vertebrates
- sea squirts form stiff rod like vertebrates do
27
Describe the invertebrate chordate subphyla. Recognize names of each.
- hemichordata: half notochord; acorn worm
- urochordata: tail notochord; tunicates
- cephalochordata: tail --> head chord; amphioxus
28
urochordata (tunicates)
Small invertebrates with gill slits, notochord, postanal tail, dorsal hollow nerve cord, and endostyle.
29
cephalochordata
small laterally flattened, filter feeders with wheel organ, oral cirri for chemoreception, mucus sheets --> pharynx in verts
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non-vertebrate chordates
- sea squirt and sea lancelets
- share some or all of the 5 diagnostic characteristics of chordates and are thought to be closely related to vertebrates
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old use of pharyngeal slits
filter feeding
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chordate
deuterostome, coelomates, bilateral symmetry, complete gut, 3 germ layers, and 5 derived features of chordates
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hemichordata are (chordate, protochordate, vertebrate)
protochordate
34
vertebrate? Ammocoetes
yes
35
lamprey
yes
36
Why study protochordates?
To gain insight into what the first vertebrates may have been like in anatomy and physiology.
37
tunicates also called ___
sea squirts
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amphioxus also called ___
branchiostoma or sea lancelet
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sea lancelet closely related to ___
vertebrates
40
are chordates vertebrates or invertebrates?
they can be either
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human pharyngeal slits
Have it embryonically but we don’t have it as an adult
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human endostyle
thyroid gland
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Homoplasy
Similarity in characters in different species that is due to convergent or parallel evolution, not common descent.
44
Homologous structures
- those derived from the same structure in a common ancestor. Homologous structures generally have similar genetic and developmental underpinnings
- provides evidence of common descent.
45
convergent evolution
the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches
46
parallel evolution
the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades
47
Vestigial structures
retaining a structure that no longer serves a purpose
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secondarily aquatic
recent ancestor was a land organism
49
earliest vertebrates to evolve
agnathans
50
The only living agnathans are:
the lamprey and the hagfish
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organism name for lamprey
Petromyzontida
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Cephalochordates most closely related to:
vertebrates
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Hagfish (Slime Eel): Phylum, Subphylum, and Class
Phylum Chordata
Subphylum Vertebrata
Class Myxini
54
Hagfish characteristics
lack bone, jawless circular mouth used to rasp flesh, no
paired appendages, scavengers, slime glands beneath skin, persistent notochord in adult, entirely marine, large number of ancestral features
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Lamprey: Phylum, Subphylum, and Class
Phylum Chordata
Subphylum Vertebrata
Class Petromyzontida
56
All living agnathans lack ____ and possess a single _____ .
bone; median nostril
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Cephalaspidomorphi
lack jaws; lack paired appendages (?); retain notochord as adult; lack a well-developed vertebral column in lamprey; single, median, dorsal nasal opening; marine and freshwater; lamprey has secondary loss of bone
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Phylogenetic position for Myllokunmingia and Haikouichthys
after cephalochordates but before hagfish and lampreys
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Phylogeny
the evolutionary history of a species or group of species -- not based off of similarities, but on history
60
Craniates that may be important transitional fossils
Myllokunmingia, Haikouichthyes, Haikouella
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node
represents point on phylogenetic tree when population became genetically isolated into more than one species
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Monophyletic group
includes the most recent common ancestor of a group of organisms, and all of its descendents
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polyphyletic taxon
composed of unrelated organisms descended from more than one ancestor; does not include the common ancestor of all members of the taxon
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sister taxa / sister groups
Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.
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craniate theory
lamprey and hagfishes are not sister taxa
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cyclostome theory
lamprey and hagfishes are sister taxa
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ostracoderm
paraphyletic group of armored jawless fish; not a phylogenetic term, just the name of the grouping
68
conodonts
early vertrebrates; extinct chordates representing eels, mineralized dermal skeleton evidence; Anaspids --> internal skeleton; Theolodonti --> scales, precursor for paired appendages
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why ostracoderms are thought to be more closely related to gnathostomes than
cyclostomes (hagfish or lamprey)
Because they share several synapomorphies
- dermal and cellular bone
- gill pouches
- heterocercal tail
- inner ear and brain anatomy
70
Describe three ancestral and three derived traits found in ostracoderms when they are compared to protochordate
ancestral traits: jawless (filter feeders), head, soft body
| derived: bony armor, ?, ?
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why are ostracoderms important to evolutionary history of vertebrates
allow us to identify which features were early/defining of vertebrates and begin to show reduction in size and body armor
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Innovations during fish evolution
1. dermal and endochondral bone and their derivatives (vertebral centra, bony endoskeletons, braincases, teeth),
2. jaws
3. brains
4. appendages, and
5. the internal organ systems that characterize all vertebrate groups today
73
Fishes dominated during ____
| and _____ Eras
Paleozoic; Mesozoic
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First clearly recognizable fish
Sacabambaspis
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Sacabambaspis
- 1st clearly recognizable fish
- an arandaspid pteraspidomorph
- shallow seas, probably around estuaries
- dermal bone on outside, jawless, evidence of endoskeleton
76
The earliest jawless fishes were
1. soft-bodied Myllokunmingia discovered in early Cambrian (530 MY) deposits of China
2. the true bone bearing craniate Sacabambaspis from Bolivia (470 MY).
77
major groups of ostracoderms that preceded gnathostomes
Pteraspidomorphs (Sacabambaspis, Pteraspis, Drepanaspis) Anaspids, Thelodonts, Osteostracans
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plesiopmorphy
An evolutionary trait that is homologous within a particular group of organisms but is not unique to members of that group and therefore cannot be used as a diagnostic or defining character for the group
79
synapomorphy
a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants.
80
outgroups
a group of organisms that serve as a reference group when determining the evolutionary relationship among three or more monophyletic groups of organisms; not witin the studied group but closely related
81
Describe three ancestral and three derived traits found in cyclostomes when they are compared to other craniates.
derived: round mouth, horny teeth, ?
ancestral: craniates, agnathans, ?
82
cephal-
head
83
phyl-
race
84
gnath-
jaw
85
-stome
mouth
86
-derm
skin or covering
87
osteo-
bone
88
ostraco-
shell
89
morph-
shape
90
homo-
same
91
cono-
cone
92
proto-
first, earliest form of
93
-dont
tooth
94
mono-
one, alone
95
plesio-
near, similar
96
a-
on, to, toward
97
tetra-
four
98
-pod
foot
99
syn-
with, together
100
ptery-
winged
101
myx-
slime, mucus
102
pheno-
showing
103
hypo-
below
104
cleavage
total cell number dramatically increases; cells are changing size but the overall total size is not changing; Early cleavage results in the production of doubling of the cells; Cleavage converts unicellular zygote into a multicellular embryo.
105
gastrulation
the process of cell differentiation that follows blastula formation and results in the 3 germ layers; cell differentiation
106
agnathan
superclass of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. The group excludes all vertebrates with jaws, known as gnathostomes.
107
amniote
an animal whose embryo develops in an amnion and chorion and has an allantois; a mammal, bird, or reptile
108
anamniote
any of the vertebrates of the group Anamnia (Anamniota), comprising the cyclostomes, fishes, and amphibians, characterized by the absence of an amnion during the embryonic stage
109
gnathostomes
having a mouth with jaws, including all vertebrates except the agnathans
110
tetrapods
a four-footed animal, especially a member of a group that includes all vertebrates higher than fishes
111
craniate
chordates that have a braincase (also called a cranium or a skull), mandible (jawbone) and other facial bones.
112
ectoderm
the outer germ layer in the embryo of a multicellular organism
113
derived traits
derived is when a trait shows up that was NOT present in a common ancestor.
114
endoderm
the innermost cell layer of the embryo in its gastrula stage.
115
phenotype
the appearance of an organism resulting from the interaction of the genotype and the environment.
116
chorion and funciton
the outermost of the extraembryonic membranes of land vertebrates, contributing to the formation of the placenta in the placental mammals; completely surrounds the embryo; layer just underneath the shell of an egg
function: gas exchange
117
mesoderm
the middle cell layer of the embryo in its gastrula stage.
118
amnion and function
the innermost of the embryonic or fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended; function: shock absorbe, prevents drying out
119
Describe the basic developmental process of vertebrates from zygote to organogenesis.
```
zygote
cleavage, cells divide, no increase in size
2-4-8-16-32 cell (morula)
blastula
gastrulation
organogenesis and neurulation
```
120
Recognize different types of vertebrate eggs and examples for each
Microlecithal eggs - holoblastic, small , forms isolecithal egg (placental mammals)
Macrolecithal eggs -meroblastic, telolecithal egg (birds, reptiles, monotremes, sharks, teleosts, marine lampreys
Mesolecithal eggs - holoblastic, telolecithal (amphibians, lungfish, ganoid fish (sturgeon), lampreys (freshwater)
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Pteraspis
a heterostracan that is a sister group to the Arandaspids; hypocercal tail
122
earliest well-known ostracoderms
Pteraspidomorphs
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zygote to gastrula
Zygote --> 8 cell stage --> morula --> blastula --> gastrula
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Cleavage is affected by
the amount and distribution of yolk
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Differences in egg type (i.e. yolk amount and distribution) influences selection and sequence
of expression of nuclear genes
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patterns of cleavage
Holoblastic - entire zygote divides (mammals, amphibians)
| Meroblastic - incomplete division; cleavage furrow doesn’t extend into yolk (birds)
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the three germ layers
endoderm, ectoderm, mesoderm.
128
macrolecital gastrulation
blastopore is not visible due to large amount of yolk; Primitive streak is homologous to blastopore
129
Developmental studies help us
| understand: (4)
Evolutionary history
Constraints on evolutionary history
Major evolutionary change
Complexity
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Evo-Devo
Species evolve by changes in their embryological processes.
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most diverse form of fish today
ray fin fishes
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heterostraci
- extinct
- sister group of arandaspids
- pteraspids
133
fish tail types
homocercal (normal, goldfish, salmon), heterocercal (top is longer, shark), hypocercal (bottom is longer, early fish)
134
Thelodonti
- extinct
- hollow scales, nipple teetch
- phlebolip is example
- scales used for stratification studies
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all vertebrates come from ____
eggs
136
"blastula"
hollow ball
137
"archenteron"
ancient gut
138
blastocoel
open space inside blastula
139
blastopore in humans becomes ___
anus
140
Gastrulation in microlecithal egg
Cells at vegetal pole change; then blastula invaginates.; Eventually blastocoel lost; archenteron forms.
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gastrulation in mesolecithal
Animal pole cells migrate down embryo surface; move into interior. Cells change shape, sink inward at dorsal lip of blastopore. Archenteron forms, blastocoel shrinks; Blastopore becomes ring shaped; cells that fill it are called the yolk plug.
142
primitive groove of bird egg
chick's blastopore
143
epiblast
formed from animal pole cells that make up upper layer of embryo; form thickened region called the primitive streak; the outermost layer of an embryo before it differentiates into ectoderm and mesoderm
144
Hensen’s node
cells that will become the notochord
145
Organogenesis
process of organ formation.
146
endoderm becomes:
epithelium of respiratory tract, pharynx, liver, pancreas
147
ectoderm becomes:
hair, nails, brain, spinal cord, neural crest
148
mesoderm becomes:
notochord, lining of thoracic and abdominal cavities, blood, skeletal muscle, bone, kidney
149
Neurulation
formation in the early embryo of the neural tube
150
when does neurulation occur?
shortly after gastrulation
151
Induction
process by which the presence of one tissue influences the development of others. Certain tissues, especially in very young embryos, apparently have the potential to direct the differentiation of adjacent cells
152
Cells to become neural ectoderm are located
in the dorsal surface of the embryo overlying the
| notochord.
153
neurulation steps
neural plate --> neural fold --> neural groove --> neural tube and neural crest cells
154
isolecithal egg
evenly distributed yolk
155
telolecithal egg
unequal distribution
156
evolution and examples
descent with modification
examples: natural selection favoring shorter legs in cetaceans for easier swimming; mysticetes acquiring disabling genes for their teeth building genes
157
homology and examples
similarities in phenotype or genotype that are the result of common descent; seals flipper, human arm, and bat wing; comparable embryology between animals
158
Why do comparative vertebrate anatomists
consider development of the neural crest cells a
key event in the evolution of vertebrates?
a lot of the characteristics that make vertebrates vertebrates come from neural crest cells
159
classes of animals with amniotic egg
mammals, bird, reptiles
160
the first organs to develop in the
| early vertebrate embryo:
the notochord, brain, and spinal cord
161
chorionic villi
villi that sprout from the chorion to provide maximum contact area with maternal blood
162
allantois
stores nitrogenous waste in birds and reptiles; non-functional in mammals except for having blood vessels that contribute to placental formation
163
yolk sac
source of nutrient for the developing embryo; in mammals a center for early red blood cell formation
164
Extraembryonic membranes (4)
chorion, amnion, allantois, and yolk sac.
165
Evolution of extraembryonic membranes
| led to variety of reproductive strategies:
internal fertilization, elimination of larval stage, viviparity (retention and growth of the fertilized egg within the maternal body until the young can live on its own), and ovoviviparity (embryos develop inside eggs that are retained within the mother's body until they are ready to hatch)
166
extraembryonic membrane advantage
allowed for life on land
167
ontogeny
pertains to the developmental history of an organism within its own lifetime
168
the Biogenetic law
largely discredited biological hypothesis that in developing from embryo to adult (ontogeny), animals go through stages resembling or representing successive stages in the evolution of their remote ancestors (phylogeny)
169
the biogenetic law also called"
theory of recapitulation
170
Late tailbud stage common features:
somites, neural tube, optic anlagen (pre optic lobe or optic structure), notochord, and pharyngeal pouches.
171
two principles that make evolution possible
1. variation in traits
2. inheritance: traits passing from parents to offspring
leads to: organisms evolve over time and organisms evolve toward greater adaptiveness
172
Explain the relationship between artiodactyls and whales
artiodactyla = closest living thing to whale (hippo)
- both have lungs, hip bones, milk young, similar teeth, thickened involucrum, ankle bone and DNA match
artiodactyla: hooved animals
173
Analogous structures
pertain to the various structures in different species having the same appearance, structure or function but have evolved separately, thus do not share common ancestor.
174
Explain how a phylogeny can serve as a hypothesis.
A phylogeny is a hypothesis because it takes all evidence we have into consideration to make the best prediction to what the truth is. We do this in phylogeny by taking molecular, embryological, and bone evidences to describe how different organisms are linked
175
Explain how variation in a phenotype can range around a mean.
variations are possible; bell curve median variation is most common around a mean while the extremes are less likely to demonstrate the mean
176
Explain why most phenotypes cannot be directly linked to genotypes.
environmental factors have extensive affects on phenotypes making the contribution of genes hard to measure
