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Vertebrate Evolutionary Biology Flashcards

(55 cards)

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1
Q

Apomorphy

A

Derived character

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2
Q

Homology

A

Characters from common ancestor or within an organism under common genetic regulation

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3
Q

Homoplasy

A

Independent evolution of character in two or more taxa

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4
Q

Monophyly

A

Common ancestor and all descendants

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5
Q

Paraphyly

A

Ancestor and some of its descendants

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6
Q

Plesiomorphy

A

“Primitive” character

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7
Q

Synapomorphy

A

Shared derived character

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8
Q

Phylogeny

A

Evolutionary relationships among species

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9
Q

Crown group

A

Clade starting with most recent common ancestor of 2+ extant species (can include extinct)

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10
Q

Stem group

A

Fossil sister tax on to a crown group e.g. Mammal like reptiles aren’t in crown mammalian

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11
Q

Oldest synapsids

A

Archaeothyris

Clepsydrops

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12
Q

Deuterostomia

A

Initial blastula unfolding forms anus

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13
Q

Chordata

A

Notochord
Nerve cord derived from ectoderm and dorsal to notochord
Post anal tail

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14
Q

Vertebrates

A 
Discrete brain 
2+ semicircular canals
Erythrocytes
Neural crest cells and derivatives 
Paired eyes
Nasal placodes
Midline fins
Vertebral elements dorsal or ventral to notochord
Lateral line system
Cartilaginous support for gills
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15
Q

Oldest vertebrate record

A

Haikouichthys ercaicunensis
Early Cambrian
Eyes, paired nasal sacs, optic capsules, vertebral elements

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16
Q

Cyclostomata

A

Myxini
Petromyzontiformes
(Not monophyletic)

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17
Q

Conodonts

A

Teeth like structures in stem gnathostomes

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18
Q

Crown gnathostome features

A

True teeth
Connection of palatoquadrate to brain case
Lower jaw suspended from braincase by hyomandibular element

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19
Q

Chondrichthyes

A 
Uniquely calcified cartilage
Specialised tooth growth and replacement
Claspers (modified pelvic fins) for internal fertilisation 
Micromeric dermal skeleton
Loss of swim bladder
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20
Q

Elasmobranchii

A

Sharks, skates, rays

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21
Q

Holocephalaii

A

Ratfishes

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22
Q

Osteichthyes

A

Dermal opercular bones
Dermal shoulder girdle bones
True endochondal bone
In skull, dermal maxilla, pre-maxilla and dentary

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23
Q

Actinopterygian groups

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A

Polypterus
Chondrosteans
Amia and Lepisosteus (air breathing)
Teleosts

24
Q

Sarcopterygii

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A

Single bone attached to pectoral and pelvic girdles - paired appendages

Actinistia = coelacanths (Latimeria)
Dipnoi = lungfishes
25
Tiktaalik
Basic wrist bones and rays reminiscent of digits Attached to massive shoulder with expanded scapular and corocoid elements, large muscular scars on ventral humerus, mobile distal joints Muscular facets on wrist joint bones (could flex) Spiracle on top of head (lungs and gills) Robust rib cage to support weight and aid breathing Earliest evidence of neck- pectoral girdle separated from skull (hunting)
26
Stem tetrapods
``` Eusthenopteron Panderichthys Tiktaalik Acanthostega Ichthyostega ```
27
Amniotic egg
Chorion - gas exchange Allantois - N waste Amnion - protection Yolk sac - food
28
Ontogeny
Organism history from conception to somatic maturity
29
Cleavage
First post fertilisation stage, cell division produced blastomeres and stops once blastula formed, with an internal hollow blastocoel Amount of cleavage= amount of yolk
30
Holoblastic cleavage
Entire zygote cleaved | Micro (Branchiostoma, eutheria) or mesolecithal (Lampreys, gar fishes, lissamphibians) yolk formed
31
Meroblastic cleavage
Only a portion of zygote cleavage Macrolecithal yolk Elasmobranchs, teleosts
32
Discoidal cleavage
Restricted to small cap on top of macrolecithal, undivided yolk Reptiles, monotremes, some teleosts
33
Neural crest
``` Derived from ectoderm Unique to vertebrates Delaminate ectodermal epithelium at neural folds during gastrulation High BMP, ectoderm --> epidermis Snail TF products, delamination ```
34
Cranial neural crest
Cartilages, bone, cranial neurones, glia, connective tissue of dermal skull In pharyngeal arches, thymic cells, odonotoblasts
35
Trunk neural crest
Anterior of somitic sclerotome, dorsal root ganglia, sympathetic ganglia Later, melanocytes in ectoderm
36
Vagal and sacral neural crest
Nervous system of gut
37
Cardiac neural crest
Values of heart and connective tissue
38
Paraxial mesoderm
Axial skeleton and muscles, back dermis, connective tissues
39
Lateral plate mesoderm
Limbs, sternum, circulatory system, coelom lining, extra amniotic membranes
40
Intermediate mesoderm
Kidneys, gonads
41
Chordamesoderm
Notochord
42
Clock and wavefront model
Morphogens expressed P-->A Fgf8 expressed anteriorly --> Wnt3a --> Notch --> Hairyl --> segmentation (Axin inhibiting Wnt3a loop, restarted by Fgf8 pulse) (Notch --> Mesp2-->Lfringe, inhibits notch = clock) Anterior Fgf8 expression edge = determination front
43
Sclerotome derivatives
Vertebrae and dorsal ribs
44
Myotome derivatives
Axial muscles
45
Dermatome derivatives
Dermis on trunk
46
Three major hard tissues
Cartilage Intamembranous/dermal bone Endochondral bone
47
Cartilage formation
Chondrocytes concentrate and secrete ground substance, deposit collagen --> matrix (spaces for cells = lacunae) Formed by mesoderm and neural crest
48
Chondrichthyian cartilage
Tesserate structure, mineralised with calcium mineral complexes in honeycomb-like pattern on external surfaces
49
Endochondral bone formation and structure
Derived from mesoderm and neural crest Ossification = replacing cartilage -periosteal bone deposited on outer surface, cartilage vascularised, chondrocytes hypertrophy and die -osteoblasts deposited at centre of cartilage and chondroclasts erode it Forms outer shell of layered laminar bone and core of spongy vascular bone Layers in Haversian systems (concentric tubes) Spongy core, tissue in trabeculae that align to resist main compression forces
50
Dermal bone formation
Embryonic origin - ectoderm Condensation &compaction of mesenchyme --> sheet-like membranes Osteoblasts form and secrete ground substance, vascularisation Calcium rich matrix replaces ground substance, internal osteocytes form Repeated addition of new bone layers to matrix
51
Skull skeletal components
Chondrocranium Splanchnocranium Dermatocranium
52
Chondrocranium
Derived from mesoderm Cartilage (chondrichthyians) or endochondral Paired capsules for nose, ears, eyes supported by paired rods Trabeculae at front, parachordal cartilages at back In anterior ethmospenoid and posterior otooccipital elements (intracranial hinge between)
53
Splanchnocranium
Derived from neural crest Branchial, hyoid and mandibular arches Mandibular: palatoquadrate forms upper jaw, Meckel's cartilage lower jaw (chondrichthyians and stem gnathostomes) Hyoid: links to chondrocranium via hyomandibula (also is basihyal and ceratohyal) 5 branchial arches: jointed basket, supports pharyngeal slits
54
Splanchnocranium evolution
Cyclostome gill support Stem Gnathostome and chondrichthyian primary jaw and jaw joints Osteichthyians dermal bone replaces mandibular as tooth bearing element Tetrapods branchial arches support throats and tongue musculature and trachea, hyomandibular --> stapes Mammals, hyoid --> middle ear ossicles
55
Dermatocranium
Derived from neural crest Outer bony casing of skull and pectoral girdle Skull roof, rostrum, lower jaw, palate, gular and opercular bones Basal possessed extensive, reduction in osteichthyians (flexibility and space for musculature)

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