Vertebrates Midterm 1

Ball State, Dr. Foster

What is the role of the Apical Ectodermal Ridge in limb development

major signaling center that directs limb formation

What is the role of the mesoderm in limb development

Gives rise to bones and determines what limb you get

What is the role of the myotome in limb development?

Gives rise to muscles

5 structures that are formed from the pharynx or pharyngeal pouches in vertebrates that do not have permanent gill slits.

Middle ear bones, parathyroid glands, palatine tonsils, Eustachian tube, thymus

List the 6 shared derived characters of vertebrates

Cranium,

Tripartite brain,

special sensory organs,

gills,

neural crest cells,

multi-chambered heart

“Agnathans” are more derived than urochordates in having which feature?

Visceral arch skeleton, tripartite brain, cranium

Are vertebrae a vertebrate synapomorphy?

No, different types of bone may have evolved independently in different lineages

Describe the 4 primary skeletal adaptations found in birds:

Hollow bones,

reduction number of bones,

keeled sternum,

shortened humerus

Which character evolved on branch A of the cladogram shown below?

Pentadactyly

The phylogenetic tree below is divided into four groups (A,B,C,D).  Which group or combination of groups is polyphyletic (Grouping with no common ancestor)?

C + A

Which feature of the skeleton shown below evolved most recently?

Greatly elongated phalanges

Which feature evolved on branch A?

Limbs with digits

1.     Which statement concerning the middle ear of a frog is correct?

                         i.         The middle ear is triossicular

                       ii.         Sound waves that impinge on the tympanic membrane are amplified by pressure amplification in the middle ear

                      iii.         The columella of the middle ear is homologous to the hyomandibular bone of bony fishes

ii and iii are both true

1.     What can we infer from ventrally grooved ceratobranchials (animal HAD gills) in adult animals belonging to Acanthostegidae and Ichthyostegidae?

                         i.         That these animals possessed gills

                       ii.         That these animals did not possess lungs

                      iii.         That these animals spent much of their time in aquatic environments

i and iii

The tree shown below depicts phylogenetic relationships among eight mammals.  Nodes with filled (black) circles represent mammals without teeth. Terminal and internal nodes with open circles represent mammals with teeth.  The name Adentata refers to a taxonomic group that includes all taxa without teeth.  The name Dentata refers to a taxonomic group that includes all taxa with teeth.  Given this information, which statement is true?

Adentata is a paraphyletic group

Which element in the bird skeleton shown below is homologous to the basal pterygiophore in the pectoral fin of Eusthenopteron?

B

Snake eggs

                                             Yolk- macrolecithal

                                         Cleavage- meroblastic/discoidal

                                           Spindle angle- equatorial

                          Blastocoel- between epiblast and hypoblast, flat

Squirrel eggs

                                               Yolk- microlecithal

                                              Cleavage- holoblastic/radial

                                             Spindle angle- meridional

                                             Blastocoel- large sphere

Tripartite brain

anterior end of dorsal hallow nerve cord enlarged into tripartite brain, mesencephalon

Special Sensory Organs

develop into conjunction w/ cranium & tripartite brain

Gills

efficient at pumping water through pharynx.

Neural crest cells

originate during neurulation; gives rise to receptor cells, sensory nerves, and sensory ganglia.

Multi-chambered heart

more efficient for delivering oxygen to various tissues and organs.

What are the names of the two bones that make up the craniomandibular joint?

Quadrate and Articular

What is the function of the dm muscle?

Causes myotonic dystrophy which causes weakness of voluntary muscles; opens jaw

in proximal/distal axis of limb generation, what gene/molecule levels are required for the humerus/femur

• Proximal/distal axis = shoulder to digits

• Concentrations of retinoic acid, Gli, Fgf, Wnt determine which part of limb is created using Hox genes.

• Hox 9 and 10- high ret and gli, low fgf wnt.

Steps of neuralation

• Neural plate formation where the ectoderm thickens to create a neural plate

• Neural plate folding where the neural plate bends inwards to form a neural groove

• Neural fold elevation where the edges of the neural groove rise up as neural folds

• Neural tube closure where the neural folds meet and fuse together to form a closed neural tube