Evolution by natural selection can create adaptation, that tangible sense of designed for function But it is also an historical process only works with existing variation, has a characteristic makeshift quality _____________ organs, _____________ genes Pandas thumb The late evolutionary biologist Stephen J. Gould loved to dwell on this historical component of design in nature A favorite example the thumb of the Giant Panda_____bone radial sesamoid Kiwi egg Why would such a little bird have such a big egg? Ratites: Ostrich, cassowary, moa (extinct), rhea, emu, kiwi, tinamou George C. Williams favorite example Williams, G.C Natural selection: domains, levels, and challenges. Oxford Press. Vas deferens My favorite example why is the slime green?? Recall that much of the energy in sunlight is in the _____________ portion of the visible spectrum Does plant greenness relate to the use of this energy? Light energy is obtained by the absorption of photons (light particles) by PIGMENTS Photosynthetic pigment molecules include Chlorophyll a, b, c Carotenoids Phycobilins Each pigment has its own ______________ SPECTRUM The rate of photosynthesis is also a function of wavelength as a result of the pigments __________ SPECTRUM So, plants use light in the visible range where most energy is, but there is a ____ in absorption in the green-yellow range. So thats why plants are green that light is __________, so it is reflected (so we see it). Ok, but this means lots of energy is ____________________? Maybe a mistake? Historical accident? Some _____________ (photosynthetic bacteria) have _____________ If plants were fully utilizing sunlight, what color would they be? So, why the slime is green is still a mystery. 2,3 - chlorophyll a,b 4 - phycoerythrobilin 5 beta-carotene So design by natural selection has a distinctive historical signature While many details of organisms in nature seem beautifully, exquisitely adapted for survival, they also need to be given a history - how did it get there? In fact, many details really dont seem to make much sense without that history Extinction loss of species speciation _______diversity, extinction ________ it The fossil record documents the existence of many species that _________________ Coelacanth Ginkgo Occasionally, a species known first from fossils has been found still existing. Tree of life has many aborted branchesCanidae dogs: many more ______ than ______ Horses (Equidae) Extinction rates have been ________ over time, with occasional _____ extinctions 3.4 Despite this, there have been long term _______ in measures of diversity Often _________ is suspected Adaptive Radiation Speciation rates are ______ as well, especially within groups Adaptive radiation ______ production of descendant species Probably a result of new adaptive opportunity Classic island examples _________ finchesAdaptive radiation Sato et al. 2001 ___________ honeycreepers Fleischer et al 1998 Hawaiian ____________ California _______ Mass extinctions followed by major biotic shifts 1. _________ extinction (250 MYA) 2. __________ extinction (65 MYA) Before -amphibians and ferns After reptiles and gymnosperms Before reptiles and gymnosperms After mammals and angiosperms Adaptive radiation Adaptive innovations Cambrian explosion innovation? Large category, most important traits probably qualify (e.g., photosynthesis, nucleus, multicellularity, flowers) Adaptive radiation By 543 MYA all extant animal phyla 38 body plans from 3 in 20MY Whales (Cetacea) Since