Ornithology Basic Characteristics Evolution of Birds Form and

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 – 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 Order Piciformes Family Picidae Genus Picoides Colaptes Species pubescens villosus auratus

Current Classification • • 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 47 100, 000 species! • - Heritable variation in a population due to mutation - 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 b a c b d Time b a a

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 • 2 nd 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 • • • 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? • • Trees-down…maybe Largely historical debate • 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) • • • 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 • • • 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 • 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 & Bmp 2 – 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) • Major Types: – Contour • Insul. , Flight • Vanes symmetrical • Vanes asymmetrical – Semiplumes and • Rachis > barbs – Down • • • 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