Slide 1Slide 2Slide 3Slide 4Slide 5Darwin’s Finches (5 genera, including Geospizia)Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Tanks 200 barSlide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 601Bi 1 Lecture 29Thursday, June 1, 2006Evolution 3. Voyages to the Galapagos;The physiology of Diving Mammals“Study nature, not books” (Louis Agassiz)2Announcements on the Bi 1 Web page:http://www.its.caltech.edu/~bi1/schedule.htmlReview 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 ClosetGraduating seniors: papers are due today 5 PM in the Bi 1 Closet3Acknowledgements“It takes a village to teach Bi 1 at Caltech”TAs, both grads and undergradsProfessional staff:Dr. Jane Mendel, Head TA: Sections and gradingPatricia Mindorff, communicationsDavid Mathog, Molecular GraphicsTim Barnes, WebmasterBiology Electronics shop computer support:Mike Walsh, Tim Heitzman and Pam FongGuest lecturers:Michael McIntoshChristof KochCameo appearances from Biology FacultyAdvice from other Core Curriculum ResourcesYou, the students4GalapagosIslands35 day visitAzoresCape Verde IslandsBahiaRio de JaneiroMontevideoFalkland IslandsValparaisoCanary IslesCape HornCocos IslandsNew ZealandThe Voyage of the HMS Beagle 1831-1836Charles Darwin (born 1809), unpaid naturalistjourney outjourney homeCape of Good HopeKing George SoundTasmaniaTahiti5British Admiralty chart of the Galapagos Islands, based on the Beagle’s observationsPunta EspinozaAge of the archipelago:~ 1 million yrEquator6Darwin’s Finches(5 genera, including Geospizia)cactus finchtree finchground finch• 13 Species, each endemic to the islands• El Nino poses a survival challenge• Highly specialized beaks• Observable evolution in beak size• Distinctive feeding habits7The voyage of the Beagle convinced Darwin that1. Members of the same species often change slightly in appearance after becoming geographically isolated from each other2. 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 diversity4. Organisms of the past and present are related to one another (but there are no fossils in the Galapagos)8"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, mocking-thrush, 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 Beaglehttp://www.literature.org/authors/darwin-charles/the-voyage-of-the-beagle/chapter-17.html910Finch family tree based on a 660-nt sequenceMolecular Biology and Evolution 18:299-311 (2001).01 change per position Darwin’s Galapagos finches11Blue-Footed Booby(Ben Lester)Red-Footed Booby12Masked 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.13Male Frigate Bird Displayingno oil on featherscannot land on watersteals other birds’ fish14Galapagos Waved Albatrosses in Courtship2 m wingspan15Video of Galapagos Waved Albatrosses in Courtship16photo byBen LesterFemale Albatross on the nest17photo byBen Lester18The Galapagos tortoises reach sexual maturity at the age of 40 and have clutches of 2 - 26 eggs. Eggs hatch at 85 -180 d.19Galapagos PenguinsWorld’s Northernmost population of penguins. After "El Nino" in 1983 the population decreased from 12,000 to just 2,000 birds.20Marine Iguanas21Marine Iguana feedingMarine 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. miguana.mov22The increased rainfall that accompanies El Niño results in greater food availability for most terrestrial organisms in the Galápagos, 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 Niño 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.23Marine IguanaThe fight against salt at Punta Espinoza: marine iguanascormorantssea lions24salt crystals25Flightless Cormorant drying its feathers at Punta Espinozalarge flightless birds are common on islands, e.g. kiwi (New Zealand)extinct: Great auk (north Atlantic), dodo (Mauritius), solitaire (Reunion, Rodrigues), moa (New Zealand)26California Sea Lions27short-eared owl (flies)28Flamingos in a salt marsh29Pelicans30Land iguana (Conolophus sp)31Lava lizard doing pushupslizard.mov32Territorial iguana chasechase.mov33Sally Lightfoot crabResembles black crab of Hawaii’s Big Island34stingless bee35Pinnacle Rock on Bartolome:Excellent diving, lots of marine life36The Physiology of Diving37Emperor penguins Aptenodytes