Exam 1 Flashcards
(45 cards)
Scaptia Beyonceae
Fly with big golden booty like Beyonce.
Xenopus Laevis
- Volcano frog
- Genes associated with tail regeneration associated with reactive oxygen species (high concentrations of hydrogen peroxide found at point of regeneration).
- Reactive oxygen species (typically associated with cell death) required for regeneration.
Ph. Chordata
(Subphylums)
Vertebrata
Urochordata
Cephalochordata
Urochordata
- Tunicates, sea squirts
- adults – primarily sessile
- look more like other chordates as larvae
- Attach as larvae to substrate and become completely attached within 5 minutes
- contract notochord, dorsal hollow nerve chord, axial muscular tissue
- Within 18 hours goes from tadpole like organism to sea squirt adult
- Larvaceans
- produce huge mass of gelatin that they live within
Cephalochordata
lancelets, amphioxus, Branchiostoma sp.
Shared Characteristics of Chordates
Dorsal Hollow Nerve Tube
Notochord
Pharyngeal Gil Slits
Post Anal Tail
Endostyle
Dorsal Hollow Nerve Tube
Hollow tube dorsal to notochord, later evolves into brain and spinal chord.
Notochord
(primitive backbone) – flexible rod for support, structure, and movement (point of attachment for muscle groups)
Pharyngeal Gil Slits
Filter feeding organs.
In non-vert chordates, lined with mucus (collects particles) and cilia (moves mucus into esophagus).
Primarily for feeding in chordates but in most verts associated with respiration.
Post Anal Tail
Assists with locomotion and movement.
Endostyle
(thyroid gland) – ciliated groove on the wall of the pharynx that produces mucus to gather food particles and critical for iodine metabolism. (also found in larval lampreys but lost as they become adults)
- *Vertebrata** (craniata)
- *Shared Characteristics**
(separate from other chordates)
Bony or Cartilagenous Vertebral Column
Cranium
Bony or Cartilagenous Vertebral Column
(function)
Allows increased body size, organized locomotion, and increased stability of body frame (provides muscle attachment points and support).
Cranium
- surrounds/protects brain and associated sensory structures
- bony, cartilagenous, or fibrous
- allows for expansion of sensory centers
- greater range of behavior, activity, and responses to stimuli
Note: Hagfish
Have cranium but no vertebrae (still considered vertebrate).
Possess a calcium management system that allows for calcium homeostasis.
Ontogenetic
Relating to growth and development of the organs.
Ontogenetic Characteristics of Vertebrata
Duplication of the HOX gene complex (other animals possess one)
Neural Crest Cells
HOX Gene Complex
Master Genes
Control body system development
Transcription factors turn genes on/off during development
Urochord/Cephalochord
Jawed vertebrates have 4 hox gene clusters
Gene duplication overcomes genetic constraints on the elaboration of vertebrate body plan
Allows for increased potential for mutation, natural selection, and genetic drift.
Accounts for subsequent modifications in the body.
Neural Crest Cells
Cells arising from the sheet of cells forming the DHNT
Migrate around embryo, settle, and develop into…
- peripheral nervous system
- parts of central nervous system
- range of endocrine glands (e.g. Pituitary, thyroid, parathyroid)
- range of skeletal/connective tissues in head (gill arches in fish, teeth, jaws)
Walter Garstang
Larval Forms:
An early mechanism for vert. (chordate) origins.
Larvae battle two opposing selective pressures:
- Dispersal
- To avoid competition
- Longer dispersal requires longer larval periods
- Predation risk increases with time
- Pressure to shorten larval period and decrease vulnerability
- To reach sexual maturity and reproduce
paedomorphosis
Juvenile/embryonic characters are retained into adulthood.
e.g. Develop mature gonads while still swimming
Echinoderm larvae kept swimming (starfish/early chordates)
Tunicate-like ancestors
Early fossil finds that may related to early chordates:
- Conodont elements mineralized
- Well-preserved into fossil record
- Conodont apparatus [1983] (lined up like it would appear in living organism)
- similar to gill arches (pharyngeal teeth) lining the throat
- likely associated with foraging
- Sensory organs
- Swelling at end of notochord (enhanced CNS)
Gans & Northcutt
Hypothesis based on neural crest cells
NCC gave vert. Flexibility to build a new type of body
NCC associated with complex sensory organis, big brains, jaws with teeth, powerful pumping throats (pharyngeal teeth)
Relates to better feeding and increased activity
No longer would they be passive filter feeders
Now possible to be a larger, more active predator