ZOOL 4133 1st Edition Lecture 9 Studying AdaptationI. Modes of selectiona. Directional selectioni. The value of a trait consistently increases or decrease fitnessii. The extremes will have the highest or lowest fitnessb. Stabilizing selectioni. The highest fitness comes to individuals with the intermediate values of a traitc. Disruptive selectioni. The highest fitness comes with the extreme values of a traitAdaptationA. Definition of an adaptationa. “a trait, or integrated suite of traits, that increases fitness” II. Zebra hypotheses examplea. What is the significance of the adaptation of zebra stripes?b. Alternative hypotheses:i. Avoiding predationii. Managing heatiii. Protection from fly bitesiv. Concealment (camouflage)c. These need to be testedIII. Important things to remember about adaptationa. Not every trait shown by an organism is an adaptive oneb. Not every adaptation is flawlessc. The origin of a trait is not always represented or reflected in its current usaged. Differences seen in populations are not always adaptationsExperimental approaches to adaptatione. Ex: what is the function of wing- waving movements and markings on wings in Zonosemata (tephritid fly)?i. Form alternative hypotheses1. The flies are not mimicking jumping spiders2. The flies are mimicking jumping spiders only to ward off other (nonspider) predators3. The flies are mimicking jumping spiders in order to ward off jumping spider predationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Set up an experiment involving both flies and jumping spiders in one environment and record the reactions 1. Hypotheses 3 is most strongly supportedObservational studies with studying adaptationiii. Study ectotherms and their behavioral thermoregulation1. Hypothesesa. Particular themperatures are chosen more often than a random pattern of choiceb. “temperature choices are adaptive”2. Observe snakes in a temperature controlled environementa. The factors being :i. Under a rockii. Exposediv. Snakes actively chose rocks that optimized their overnight body temperaturesComparative method of studying adaptationv. “does sperm competition select for larger testes in bats?”1. Hypothesesa. The larger the testes are, the more sperm exist in the race and the higher the chances of fertilization will beb. If there is selection for larger testes, males in species with bigger group sizes would have larger testes size (relative)2. Do a phylogenic compare and contrast3. Trend: size of testes increased when contrasts in group size increasedTrade-offs and constraintsf. Selection can only influence and act upon existing variationsg. Genetic correlation results in genetic constrainth. “developmental programs impose constraints”i. Body plans are constrained by physics and environmentsj. Trade-offsi. Resources may be taken from one aspect of a phenotype in order to provide for