Seabird evolution [Compatibility Mode]

Seabird evolution [Compatibility Mode] - 3/10/2010 Seabirds...

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Unformatted text preview: 3/10/2010 Seabirds Seabird Evolution Sphenisciformes -- Penguins Procellariiformes -- tubenoses Pelecaniformes -- Pelicans and relatives Pelecaniformes -and relatives Charadriiformes/Lariformes – Laridae -- Gulls and terns – Alcidae -- Puffins, murres and auks Fossil Record Modern genera (ex. Puffinus) do not Puffinus appear until early Miocene (16-23 mya) (16 Become taxonomically diverse in Middle Become taxonomically diverse in Middle Miocene (11Miocene (11-16 mya) Correlated with permanent East Antarctic ice cap formed in Middle Miocene Structure of Seabird Communities Product of recent and historic processes Ecological time (predation, competition and dispersal) Geological time (plate tectonics and the origin of modern oceanic currents) Dumb luck Historic and pre-historic human preinteractions (e.g., Pacific island faunas) – drop in sea level, increased thermal gradient, increased gyral circulation, coastal and trade winds, and upwelling – Few extinctions, many extirpations The Age of the Reptiles Birds arose in the Mesozoic Preceded in flight by two reptile groups -- dawn lizards and pterosaurs Pterodactylus (‘wing finger’) possessed a keeled breastbone (sternum) supporting muscles suitable for powerful flapping and agile flying Pterosaurs Many forms and many sizes Wingspan up to 20 meters Well toothed mouths toothed mouths – generally size of shorebirds and preyed mainly on fish and squid, but also probed in substrate for inverts like shorebirds, and used filter feeding like flamingos – other anatomical features include hollow long bones, air sacs, and a dense coat of hairhair-like scales (suggesting warm-blooded) warm- Contemporaneous with birds for a while 1 3/10/2010 Fossil birds Archeopteryx (‘ancient wing’) is first known – 2 species, two ‘reptilian’ characters – teeth and a very long and bony tail to Charadriiformes and resembled either a tern or rhinoceros auklet Hesperornis (‘western bird’) was rather loonloonlike, large and flightless Both Ichthyornis and Hesperornis possessed Ichthyornis Hesperornis teeth and jaws modified for catching fish Ichthyornis (‘fish bird’) may have given rise i (‘fi bi Modern seabirds Modern seabirds ... Penguins are the most primitive – Evolution has taken place in Antarctica and the South Pacific Lariformes / Charadriiformes – gulls appear to be only group of marine birds to radiate from the north, Arctic and adjacent North Pacific – Terns may have radiated from tropics or Indian region – Alcids origin is in and around Bering Sea, and they are confined to the Northern Hemisphere The closest relative to the Penguins are the Procellariiformes (Tubinares) – Center of origin is the South Pacific Pelecaniformes radiated from what is now the Indian region -- southeast Asia to Australia Primary vs Secondary Marine Birds Primary marine birds evolved in and spend their entire life cycles in marine environments Secondary marine birds are those belonging to families whose fundamental evolution has probably been non-marine (e.g., waders) or nonwhich are only marine in winter (e.g., grebes and loons) WorldWorld-wide distribution of PMB species (267 total) – Many species belonging to families of primary marine birds have secondarily shifted to inland habitats (e.g., white pelican and Boneparte’s Gull) South Pacific North Pacific North Atlantic South Atlantic South Atlantic Indian Ocean Antarctic Arctic Mediterranean Inland World species 128 species (48%) 107 (40%) 74 (28%) 73 (27%) 73 (27%) 73 (27%) 44 (16.5%) 31 (11.5%) 24 (9%) 7 (2.5%) > 267 (> 100%) 2 ...
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This note was uploaded on 09/13/2010 for the course OCS 4012 taught by Professor Baltz,d during the Spring '08 term at LSU.

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