Transcript Ornithology

Ornithology
Basic Characteristics, Evolution of
Birds, Form and Function,
Intro/Basic Characteristics
What are birds?
• Taxonomy
– Kingdom Animalia
• Phylum Chordata
– Class Aves
Characteristics
• Bipedal
• Feathers (diagnostic)
– Insulation
– Lift and thrust
• Toothless bills covered with horny sheath
• Wings
• Ability to fly*
Characteristics (cont.)
• Adaptations associated with flight:
– Skeleton
– Musculature
– Physiology
– Reproductive system
– CNS
– etc…
Adaptive Radiations (within
adaptive radiations)
• Evolution of ecological diversity within a
rapidly multiplying lineage (Schluter, 2000)
• 150-160 MYA
• >10,000 species extant
– Fraction of what has existed
Ur bird ancestor
Hawaiian
Honeycreepers
• Radiations within
smaller groups
• Radiation in body
parts
A note on Avian Classification
• Imprint of Linneaus 1758
– Binomial nomenclature
• Upupa epops
Genus
Kingdom
Phylum
Class
Order
From
Genus
species
species
– Standard English Names (“Common Name”)
– In NA, both established by AOU
Classification of three species of
woodpeckers
Taxon
Downy Woodpecker Hairy Woodpecker Northern Flicker
Class
Aves
Aves
Aves
Order
Piciformes
Piciformes
Piciformes
Family
Picidae
Picidae
Picidae
Genus
Picoides
Picoides
Colaptes
Species
pubescens
villosus
auratus
Current Classification
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29 orders
187 Families
2000+ Genera
10000+ species
• Rapidly changing
Interesting biogeograpy
• Each faunal region
has its characteristic
birds – endemics
Biogeography (cont.)
Regions
Endemic (non-passerines)
Representative Family Radiation
Holarctic
Incl. Nearctic and
Palearctic
Loons, (Gaviidae)
Auks (Alcidae)
Accentors (Prunellidae)
NW warblers (Parulidae)
OW warblers (Sylviidae)
Neotropical
Rheas (Rheidae)
Sunbittern (Eurypygidae)
Motmots (Momotidae)
Hummingbirds (Trochilidae)
Tyrant-flycatchers (Tyrannidae)
Ethiopian
Ostrich (Struthionidae)
Larks (Alaudidae)
Turacos (Musophagidae)
Sunbirds (Nectariniidae)
Woodhoopoes (Phoeniculidae)
Oriental
None
Leafbirds (Irenidae)
Pheasants (Phasianidae)
Flowerpeckers (Dicaeidae)
Australasian
Emus (Dromiceidae)
Kiwis (Apterygidae)
Monarch-flycatchers (Monarchidae)
Birds-of-paradise (Paradisaeidae)
Biogeography (cont.)
• Most bird communities or faunas are
mosaics of species of various ages from
various historical backgrounds
• + factors affecting species richness
Immigration / Invasion
Speciation
Regional
Bird Community
Stochastic extinction events
Habitat
selection
Local
Bird Community
Competitive exclusion
From Ricklefs and Miller, 2000
Mass extinction events
Predatory exclusion
1998
Evolution of Birds
Note on Phylogenetics
• Phylogenetics – History of the evolution of a group
• Cladistics – defining groups based on shared
characteristics not found in ancestors (derived)
• Cladogram – “tree-like” hypothesis of the hierarchical
evolutionary relationships of a group
A
C
time
B
D
E
F
OTUs
Tips
Nodes
Branches
Extinct taxa
Speciation
“Reading” the tree
Based on shared, derived
characteristics
middle ear bones
Diversity of Birds
Pg 47
- Heritable variation in a
population due to mutation
100,000 species!
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- Some variation leads to
differential reproductive
success (if expressed)
Due to :
1. Phyletic evolution
2. Cladistic evolution (speciation)
3. Extinction – “termination of a lineage”
c
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Time
d
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Shared, derived characters with
anything?
Other features?
• Nucleated RBCs
• Scales
• Ankle in tarsal bones (not between long
bones and tarsals)
• Bipedal (theropods)
• Yolked, polar, cleidoic egg
• Females are heterogametic
• etc…
Link Between Birds and Reptiles
• Lots of morphological, behavioral and
physiological similarity between Reptiles
and Birds.
• Which reptiles???
Founding of Archaeopteryx
• Lithograph Quarrymen – Jurassic limestone
• Single feather impression – 1861, Bavarian
Quarry
• Complete skeletal impression – Few months
later
• 2nd complete skeleton – 1877, quarry near
Eichstatt, Germany
• Herman von Meyer
– Archaeopteryx lithographica
Archaeopteryx
• Debates
– Support of Darwinian evolution
• Darwin predicted transitional fossils in 1859
• ‘one of the best links between two taxa’ (Feduccia, Ostrom, etc.)
– Creation / Evolution debate (pg 27)
– Evolution of feathers (flight or insulation first?)
– Evolution of homeothermy in birds
– Evolution of flight
• Ground-up vs. Trees down
Could it fly?
The ‘historical’ evolution of flight
debate
• Two main hypotheses:
– Ground-up (cursorial hypothesis)
– Trees-down (arboreal hypothesis)
Ground-up
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Assume biped, cursorial ancestor
Has to be bipedal to use wings at all
Large legs for running muscle attachment
Bones of legs are long
Once running:
– Use feathers for other things
• Catch insects
• Pick up minimum speed for lift: Flight
Trees-down
• Assume semi-bipedal leaping and gliding
ancestor
• Use of claws to scale trees, then glide to ground
• Claws retained in winged appendages
• Short hand wing (power), relatively long arm
wing (lift)
• Claw geometry (Feduccia’s study)
• Large attachment sites for downstroke on
humerus but no keeled sternum
• Flying squirrels?
Winner?
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Trees-down…maybe
Largely historical debate
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More productive???
– Why evolve flight?
(1) To help escape from predators
(2) To help catch flying or speedy prey
(3) To help move from place to place (leaping or gliding)
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Vigilence
Migration, etc…
Nomadism
(4) To free the hindlegs for use as weapons
Craniate phylogeny
and diversity of living species
From Bemis
http://www.bio.umass.edu/biology/bemis
1/31/06
• Lab tomorrow – in the field (Briar Creek Lake)
– Bring
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Clothes
Binoculars
Waterproof notebook
Time to meet?
Lab Activities BWSV
Read Taking Field Notes Handout
– Lecture Today
• End Evolution
• Start Form and Function
– Feathers
Fig. 3.25
Fig. 3.20
Alternative Hypotheses?
• Overhead from Feduccia
Leading alternative hypotheses
• Theropod Ancestry
• Thecodont Ancestry
– Pros
– Pros
• Lots of fossils
• Tree dwellers
– Some with feathers
• Bone morphology
– Foot with 3 digits
» Embryology (birds w/5)
– Sholder joint similarity
» Facilitates wings held at sides
• Eggs in nest structure
– Cons
• Theropod adapted for running (how
could flyer and runner share
ancestry?
• Feathers? (Old argument)
– Theropod fossils – yes
– Used for insulation
» Exapted for flight.
– Glider forms
– In the trees
• “More parsimonious argument
that flight feathers evolved
from gliding stabilizers rather
than insulation”
– Cons
• Fossil Evidence is missing
Form and Function
Feathers
• Most conspicuous
integumental derivative
• Keratin
• Function
– Flight
– Heat Conservation
• Reduced convective and
evaporative heat loss
• Increased insulation
Feather Development
Bird scales
Lizard scales
• Development triggered by an interaction b/w
epidermis and dermal mesenchyme
• Formation of dermal papilla (placode)
Scaleless hen
• Mitotic divisions in a collar zone of the stratum
germinativum near the base of the papilla form a
crown of barbs
• Covered by a horny sheath of epidermis
Feather Development
• As development proceeds:
– Differential cell division on one side of the papilla
• Timing of expression of two proteins: Shh & Bmp2
– These cells form a shaft away from the body
• carrying the barbs that are formed in the collar
– The base of the feather recedes into the skin
• Accompanied by layers of epithelial cells
• Feather follicle
– Degeneration of epidermal sheath
Feather morphogenesis
• Movie
Morphology of a Feather
Morphology of a feather (cont)
Morphology of a feather (cont)
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Major Types:
– Contour
• Insul., Flight
• Vanes symmetrical
• Vanes asymmetrical
– Semiplumes and
• Rachis > barbs
– Down
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Rachis < barbs
Insul.
Adult down
Natal down (lost)
Powder down
– Grooming
– waterproofing
– Bristles
• Little or no vane
– Filoplume
• Monitor pennaceous
feathors
• Attached to sensory
corpuscles
Pennaceous
Plumulaceous
Contour feathers
• Wings
Contour feathers
• Tail
Semiplume
• ostrich
Down
natal
powder
adult
Filoplume
Bristles
• Whip-poor-will
Cross-section of feather follicle
1. Barb ridges of
epithelial
2. Surrounding
dermal core of
connective tissue
3. Space of the
follicle
4. Epithelial tissue of
follicle
5. Associated
musculature
Melanins
Carotenoids
Porphyrins
Structural colors