Small fortis ate small seeds forced to feed on the

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Small fortis ate small seedsForced to feed on the dreaded tribulusThe dreaded Tribulus (caltrop)usually ignored by the finchesonly fortis and magnirostris can break open its hard spinesextremely sharp spinesDiffering Strategies for eating TribulusMagnirostriscrushes the seeds with its beakrequires 200 newtons of force
can often eat all the seeds in one mericarpgets 2.5x more energy per minute than fortisbut magnirostris is larger and needs more foodeven then they come out on top (2.5 -1 = 1.5x more energy)Fortistoo small to crush the seedsbraces it against a rock to split it openrequires only 54 newtonscost= fewer seeds obtained per mericarpsome even steal from magnirostrisSmall fortis have a marked disadvantageCannot open tribulusHad to eat ChamaesyceHerb with small soft seedsBut exudes a sticky, milky latexSimilar to milkweedGets stuck to their headsFeathers on their heads fall offBald birds die in the hot sunDecline in population size = Decrease in seed abundance = Increase in seed hardnessSurvival is not random; larger birds are more likely to survive than small birdsRole of adaptations (morphology and behavior) may be evident only during times of stress andcompetitionGood years:Variation fills inLess selection on the adaptationsTough years:Adaptations become importantIncreased selectionReduction in variationGenetics of beak morphologyBmp4candidate gene from chickenknown to influence beak depthfinches with deeper beaks have stronger expression of Bmp4Evidence for Evolution: Part 1Chapter 17Evolution is just a theory, not a factScientific theory is different from our everyday usetheory is not a guess or a hunchwell- established, well- supported, well- documented explanations for our observationsTheory > Law
Theories and LawsLaw of gravity- if you drop something it will fall to the groundOnly a description, it does not say whyTheories to explain why: Newton’s Theory of Gravity and also Einstein’s Theory of RelativityLaws described, Theories explainGravity is real, it is true, it can be observed. It can be testedEvolutionThings evolve: populations change over timeEvolution usually happens gradually: populations change over hundreds to thousands of yearsSpeciation occurs: one species splits into two or more speciesAll species share common ancestry: splitting of lineages from one ancestral formMuch of evolution change was caused by natural selection: the sole process producingadaptation, the appearance of designPredictions based on evolutionIf life originated on Earth in the distant past and then evolved, we should see evidence in thefossil recordIf evolution occurred within lineages, and those lineages sometimes split then we should seechange in species or morphology through the fossil recordIf creatures share a common ancestry, then we should see transitional formsWe should see evidence of retrodictions and vestigial characters

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Term
Spring
Professor
KarenWilliams

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