Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Bird Evolution and Classification Dr. Girish Jathar Scientist-in-charge ENVIS Centre BNHS What are birds? • Bipedal • Feathers (diagnostic) – Insulation – Lift and thrust • Toothless bills covered with horny sheath • Wings • Ability to fly • Egg laying and Parental Care • Warm Blooded Characteristics (cont.) • Adaptations associated with flight: – – – – – Skeleton Musculature Physiology Reproductive system Central Nervous System Other features? • Nucleated RBCs • Scales on legs • Ankle in tarsal bones (not between long bones and tarsals) • Bipedal (theropods) • Yolked, polar, cleidoic egg • Females are heterogametic - Female WZ Chromosomes and Male ZZ chromosomes Evolution of Birds Link Between Birds and Reptiles • Lots of morphological, behavioral and physiological similarity between Reptiles and Birds. Archaeopteryx lithographica 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 – 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 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 Ancestor Bird Bird Classification Old Classification • Old Fashion - based on colour - based on type – flying birds/non flying birds - based on food type – insectivorous/piscivor ous/grainivorous/frugi vorous Systematics • Imprint of Linneaus 1758 – Binomial nomenclature • Upupa epops Genus Kingdom Phylum Class Order From Genus species species – Standard English Names (“Common Name”) - In India there is no common naming system for the classification Current Classification • 29 orders • 187 Families • 2000+ Genera • 10000+ species • Rapidly changing Current Classification Molecular Phylogeny • Started in 1990 by Sibley and Ahlquist • DNA-DNA Hybridization • In 2003 Dr. Paul Herbert used mt DNA to Barcode the bird species. • He identified 4 new species of North American birds • This is revolution in the Avian Taxonomy Many Things to come in Future • In India there are only once study on mtDNA i.e. Large-billed Reed Warbler Acrocephalus orinus Thank You