ZOO 4910 Lecture Notes - Lecture 8: Feather, Rachis, Hydrophobe
2 May 2018
School
Department
Course
Professor
Defining features of birds -4 level of analysis
•
Unique adaptations across niche
•
Behavioural spectra
•
Integrative biology of flight
•
Outline:
Wing -albatross, bataleur eagle
•
Wing and hind limb -heron, storks, cranes, most shorebirds
•
Hind limb -ratites, tinamous, railks
•
Hind limb and tail -peacocks, pheasants, grouse
•
Tail -lyrebirds, birds of paradise
•
Wing and tail -hummingbirds, nighthawks, frigatebirds
•
Adaptive Radiation:
Hollow tube -barbs -rachis/barbules (downy) -
hooks on barbules -asymmetry
!
Evolution (U) -increasing complexity
1)
Barb and barbule ridges develop -rachis fusion
(central) -sheath degenerates -sheath falls off -
complete
!
Development (P)
2)
Strength
□
Durability
□
Weather proofing
□
Pennaceous -barbs and barbules form a 'zipper
like' mechanism
!
Insulation
□
Soft, light
□
Plumulaceous -barb and barbules trap air
!
Mechanism (P)
3)
As angle of obtuseness increases,
hydrophobicity increases (and wetness
decreases)
□
Cylindrical nature of barbules provide
support to suspend water droplets on air
pockets
□
Hydrophobicity
!
*amount of carotenoids
(vibrance of colour) is associated
with individual health
◊
Beta-carotene -->
canthaxanthin (via
Ketolase CYP2J19)
!
May only be
expressed in certain
areas
–
*this gene acts on a range
on carotenoids
!
Orange/yellow --> red
◊
Carotenoids: accumulated from plants
(red)
!
Melanins: endogenous granules in the
skin (black -brown)
!
Porphyrins: modified amino acids that
fluoresce in the red spectrum when
exposed to UV (pinks, reds, greens)
!
Colour:
□
Changes based on angle of
viewing
◊
Iridescence: feather barbules refract
light (similar to a prism)
!
Barbules lay flat
◊
Costs: iridescent feathers (or patches
on other feathers) are significantly less
hydrophobic due to modifications on
feather structure
!
Structural Colour:
□
Feathers vibrate at a natural
resonance (eyespots don’t move)
◊
E.g. Eyespot on peacock tails
!
Flaps wings behind back to
make noise to attract mates
◊
The pick hits the cone
back and forth with wing
movement (similar to
crickets)
!
Wing feathers are modified to
make a 'pick' and 'cone'
◊
E.g. Club Winged manakin
!
Structural Modifications:
□
Display (mostly males) -Sexual Selection
!
Adaptation (U)
4)
Tinberg's Four Levels of Analysis (Proximate -Ultimate):
•
Tail
○
Wing
○
Semiplume
○
Contour
○
Down
○
Filoplume
○
Bristle
○
Feather types:
•
Pennaceous
○
Plumulaceous
○
Feather composition (see slide):
•
Feathers
Avian Diversity
Friday,*September* 29,*2017
12:24*PM
Document Summary
Defining features of birds - 4 level of analysis. Wing and hind limb - heron, storks, cranes, most shorebirds. Hind limb and tail - peacocks, pheasants, grouse. Tinberg"s four levels of analysis (proximate - ultimate): Hollow tube - barbs - rachis/barbules (downy) - hooks on barbules - asymmetry. Barb and barbule ridges develop - rachis fusion (central) - sheath degenerates - sheath falls off - complete. Pennaceous - barbs and barbules form a "zipper like" mechanism. As angle of obtuseness increases, hydrophobicity increases (and wetness decreases) Cylindrical nature of barbules provide support to suspend water droplets on air pockets. *amount of carotenoids (vibrance of colour) is associated with individual health. *this gene acts on a range on carotenoids. Melanins: endogenous granules in the skin (black - brown) Porphyrins: modified amino acids that fluoresce in the red spectrum when exposed to uv (pinks, reds, greens) Iridescence: feather barbules refract light (similar to a prism)
