Basic Characteristics, Evolution of Birds, Form and Function, 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 Standard English Names (“Common Name”) In NA, both established by AOU Kingdom Phylum Class Order From Genus species species Genus

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) Turacos (Musophagidae) Woodhoopoes (Phoeniculidae) Larks (Alaudidae) Sunbirds (Nectariniidae) 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 Stochastic extinction events Regional Bird Community Local Bird Community Speciation Habitat selection 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 D E F OTUs Tips Nodes Branches Extinct taxa Speciation “Reading” the tree B time

Based on shared, derived characteristics

middle ear bones

Diversity of Birds 100,000 species! Pg 47 - Heritable variation in a population due to mutation - Some variation leads to differential reproductive success (if expressed) Due to : Phyletic evolution Cladistic evolution (speciation) Extinction – “termination of a lineage” c b a c b c b d b Time a a 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 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 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? To help escape from predators To help catch flying or speedy prey To help move from place to place (leaping or gliding) Vigilence Migration, etc… Nomadism To free the hindlegs for use as weapons

and diversity of living species From Bemis 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 Pros Lots of fossils 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. Thecodont Ancestry Pros Tree dwellers 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) 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 Inductive interaction between the epidermis and the dermal mesenchyme Leads to a formation of a dermal papilla Mitotic divisions in the stratum germinativum near the base of the papilla form a crown of barbs Covered by a horny sheath of epidermis Cells on one side of the of the papilla divide more rapidly than others Formation of shaft that extends upward carrying the barbs that are formed in the collar The base of the feather recedes into the skin with layers of epithelial cells that form the feather follicle Scaleless hen

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) 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 Barb ridges of epithelial Surrounding dermal core of connective tissue Space of the follicle Epithelial tissue of follicle Associated musculature This slide displays an avian feather follicle in cross section. Notice the barb ridges of epithelium surrounding a core of areolar connective tissue. Observe that the feather follicles are surrounded by dense connective tissue, which is part of the dermis. Thus, feather follicles are within the dermis. Also take note of the muscles surrounding each feather follicle. These are feather muscles which control the positioning of feathers.

Melanins

Carotenoids

Porphyrins

Structural colors