Vertebrate Origins And The Integumentary System Flashcards
what are the definitions of the terms:
- function
- biological role
- preadaptation
- how a structure interacts with its environment
- selection pressures leading to the function
- features existing before the adaptation pressure
what are the definitions of the terms:
- homology
- analogy
- convergent evolution (homoplasy)
- synapomorphy
- structures with the same origin, regardless of function
- function, not origin
- similar features which evolved independently of one another
- trait that unifies a group-shared derived group
what are the features of chordates?
- pharyngeal slits
- notochord
- dorsal hollow nerve tube (precursor to the CNS)
- endostyle
- post-anal tail
(first two appear at some point in development if absent)
what is a body plan?
a fundamental structural organisation plan which applies to the entire phylum
body plan = body organisational scheme + phylum-specific traits
chordates have bilateral symmetry - what does this mean?
mirroring about the anterior-posterior axis
what are the 3 main axis?
-left/right
-dorso/ventral
-anterior/posterior
what is segmentation?
repetition of tissues, organs or features along the A-P axis
what is serial homology? name some examples of this
2 or more repeated features within the animal that share similar features. eg:
- muscle
- different vertebrae
what is a coelomic space?
a cavity, is a fluid-filled compartment lined by mesodermal epithelium (is closed and empty)
what are some features of the vertebrate subphylum?
- vertebral column
- cranium
- neural crest
- neurogenic placodes (these two = developmental stem cells)
- brain with 3 divisions
-hypothalamus-pituitary system
what did the duplication of the chordate genome allow for? (hypothesis)
expansion and complexity without destruction of key genes; genes for neural crest, 3-part brain and neurogenic placodes already existed but duplication allowed for diversification
what do pharnygeal arches eventually give way to in vertebrates?
- aortic arch
- cranial nerve
- muscle
- skeletal rod
what is contained within the pleuroperitoneal cavity?
lungs and viscera -this becomes sub-divided in mammals by the diaphragm
list the topological structure of the body walls
- integument (skin)
- fascia
- muscle
- fascia
- coelomic membrane
what are:
-epaxial muscles
-hypaxial muscles
- muscles which lie dorsal to the horizontal septum
- muscles which lie ventral to the horizontal septum
what are the three subphyla within chordates?
- cephalochordates
- urochordates
- vertebrates
what was the original function of the notochord?
a rod to stiffen the spine
what is a gnathostome?
term for jawed fish
define synapomorphy
a common trait shared between two or more groups of organisms
define homoplasy
a feature that has been gained or lost independently in separate lineages
sarcopterygians display ‘flashy fins’ - what is this a preadaptation of?
limbs
synapsid skulls became more fenestrated - what does this allow for?
more muscle attachment
what are some key innovations in mammalian evolution
- tribosphenic molars
- middle ear bones
- diaphragm muscle
- hair
-mammary gland
describe the module duplication theory for the development of fore/hindlimbs
Possible T-box module gene (transcription factor) duplication at gnathostome branch, leading to forelimb (Thx5) and hindlimb (Thx4) fin bud development
