CALTECH BI 1 - “Study nature, not books” (60 pages)

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“Study nature, not books”



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“Study nature, not books”

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Pages:
60
School:
California Institute of Technology
Course:
Bi 1 - Principles of Biology
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Study nature not books Louis Agassiz Bi 1 Lecture 29 Thursday June 1 2006 Evolution 3 Voyages to the Galapagos The physiology of Diving Mammals 1 Announcements on the Bi 1 Web page http www its caltech edu bi1 schedule html Review Session takes place here today here 4 6 PM Sections meet as usual today and tomorrow The final exam is posted Thursday today 6 PM Due Fri 6 9 4 30PM in the Bi 1 Closet Graduating seniors papers are due today 5 PM in the Bi 1 Closet 2 Acknowledgements It takes a village to teach Bi 1 at Caltech TAs both grads and undergrads Professional staff Dr Jane Mendel Head TA Sections and grading Patricia Mindorff communications David Mathog Molecular Graphics Tim Barnes Webmaster Biology Electronics shop computer support Mike Walsh Tim Heitzman and Pam Fong Guest lecturers Michael McIntosh Christof Koch Cameo appearances from Biology Faculty Advice from other Core Curriculum Resources You the students 3 The Voyage of the HMS Beagle 1831 1836 Charles Darwin born 1809 unpaid naturalist Azores Cape Verde Islands Cocos Islands Tahiti Galapagos Islands 35 day visit Canary Isles Bahia Rio de Janeiro Valparaiso Montevideo Cape of Good Hope King George Sound Tasmania Falkland Islands Cape Horn New Zealand journey out journey home 4 Equator Punta Espinoza Age of the archipelago 1 million yr British Admiralty chart of the Galapagos Islands based on the Beagle s observations 5 Darwin s Finches 5 genera including Geospizia 13 Species each endemic to the islands El Nino poses a survival challenge Highly specialized beaks Observable evolution in beak size Distinctive feeding habits cactus finch ground finch tree finch 6 The voyage of the Beagle convinced Darwin that 1 Members of the same species often change slightly in appearance after becoming geographically isolated from each other 2 Organisms living on oceanic islands often resemble organisms found living on a close mainland 3 Factors other than or in addition to climate play a role in the development of plant and animal diversity 4 Organisms of the past and present are related to one another but there are no fossils in the Galapagos 7 The distribution of the tenants of this archipelago would not be nearly so wonderful if for instance one island had a mocking thrush and a second island some other quite distinct genus But it is the circumstance that several of the islands possess their own species of tortoise mockingthrush finches and numerous plants these species having the same general habits occupying analogous situations and obviously filling the same place in the natural economy of this archipelago that strikes me with wonder Darwin The Voyage of the Beagle http www literature org authors darwin charles the voyage of the beagle chapter 17 html 8 9 Finch family tree based on a 660 nt sequence Molecular Biology and Evolution 18 299 311 2001 Darwin s Galapagos finches 01 change per position 10 Red Footed Booby Ben Lester Blue Footed Booby 11 Masked booby A recently discovered a behavior called siblicide occurs among booby chicks The larger chick always kills the younger chick sometimes aided by the parents Scholars debate the selective advantage of such behavior Perhaps the parents succeed better by insuring the survival of at least one chick 12 Male Frigate Bird Displaying no oil on feathers cannot land on water steals other birds fish 13 Galapagos Waved Albatrosses in Courtship 2 m wingspan 14 Video of Galapagos Waved Albatrosses in Courtship 15 photo by Ben Lester Female Albatross on the nest 16 photo by Ben Lester 17 The Galapagos tortoises reach sexual maturity at the age of 40 and have clutches of 2 26 eggs Eggs hatch at 85 180 d 18 Galapagos Penguins World s Northernmost population of penguins After El Nino in 1983 the population decreased from 12 000 to just 2 000 birds 19 Marine Iguanas 20 Marine Iguana feeding miguana mov Marine iguanas feed once a day The mature lizards swim out through the tidepools to dive to the bottom for algae smaller iguanas feed off the rocks in the tidal zone An iguana may lose up to 10 degrees C of body temperature on these feeding missions Because they are cold blooded ectothermic iguanas must bask on the hot lava rocks throughout the day until they raise their internal temperature 21 The increased rainfall that accompanies El Ni o results in greater food availability for most terrestrial organisms in the Gal pagos but marine life generally suffers from the higher water temperature which decreases the amount of dissolved oxygen Green and red algal species which are the marine iguanas preferred food disappear and are replaced in intertidal areas by brown algae which iguanas find hard to digest Up to 90 of marine iguana populations on islands can die of starvation as a result of these environmental changes During a recent El Ni o event 1997 98 larger individuals of the two island populations shrank more than smaller individuals The scale of the shrinkage up to 20 of body length means that it cannot simply be explained by decreases in cartilage and connective tissue which together make up only 10 of total body length Apparently bone absorption accounts for much of the reduction 22 The fight against salt at Punta Espinoza marine iguanas cormorants sea lions Marine Iguana 23 salt crystals 24 Flightless Cormorant drying its feathers at Punta Espinoza large flightless birds are common on islands e g kiwi New Zealand extinct Great auk north Atlantic dodo Mauritius solitaire Reunion Rodrigues moa New Zealand 25 California Sea Lions 26 short eared owl flies 27 Flamingos in a salt marsh 28 Pelicans 29 Land iguana Conolophus sp 30 Lava lizard doing pushups lizard mov 31 Territorial iguana chase chase mov 32 Sally Lightfoot crab Resembles black crab of Hawaii s Big Island 33 stingless bee 34 Pinnacle Rock on Bartolome Excellent diving lots of marine life 35 The Physiology of Diving 36 Emperor penguins Aptenodytes forsteri 550 m 22 min typical 2 10 min 50 500 m 37 Elephant seal Mirounga leonina 1600 m 120 min typical 20 30 min 200 800 m 38 Weddell seal Leptonychotes weddellii 600 m 82 min 39 Bottlenose dolphin Tursiops truncutus 210 m 5 min typical 30 m 120 s 40 Blue whale Balaenoptera musculus 300 m 50 min 41 Sperm whale Physeter macrocephalus 3000 m 90 min 42 In metabolism electrons move around inside cells until they reach oxygen which has the highest electron affinity of the biological elements Little Alberts 2 7 Garland 43 Diving mammals must store oxygen in order to conduct aerobic


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