Evolution by Natural Selection BIOL 3406

Name: Date: 09/05/2021 Class: BIOL 3413 - 101 Evolution by Natural Selection BIOL 3406 Reading Assignment Due September 6, 2021 Caterpillar instars of Papilio polyxene can be darker in the autumn than the same individual during the summer (Hazel 2002). This is a polyphenism where the individual can change the phenotype with development. In this case, the caterpillar will change from green with narrow black bands in early instars to broad black bands and narrow green bands for 4th and 5th instars. The change in phenotype is in response to photoperiod and temperature (Hazel 2002). (a) How is this polyphenism an adaptation for P. polyxene? The caterpillars must grow rapidly to reach pupal stage so they can _Over- winter _ and be resistance to freezing. During the summer, green banded caterpillars will have _ higher ____ predation rate than dark banded caterpillars. Possibly due to green banded caterpillars being more _ Cryptic _____ than dark band caterpillars during the summer. In the autumn, dark banded caterpillars can maintain _ higher ______ temperature when the environmental temperature is cooler. This would __ speed up ______ development rate so that caterpillar can pupate before freezing conditions. The banding pattern in caterpillars could be a polymorphism where green banding could be found in all instars including the 4th and 5th instars. Another polymorphism could be all instars are dark banded. The dark banded polymorphism would have _ lower ________ probability of survival from predation during the summer but will have _ increased __________ growth during the autumn. The green polymorphism would have _ higher _____ probability of survival from predation during the summer but will have __ decreased _________ growth during the autumn. The phenotype that would have highest fitness (highest probability of reaching adulthood so they can reproduce) is polyphenism from green to dark banding ___ (green banded polymorphism, dark banded polymorphism or polyphenism from green to dark banding). (b) What is required for the polyphenism to evolve in a population? Phenotypic _ variation _______ of polymorphisms and polyphenisms in the population. 2) The phenotypic _ plasticity _______ is _ inherited _______ in part from __ parent ______ to _ offspring __________. 3) Not all caterpillars will _ be able __________ to reach adulthood and _ reproduce __________.

4) The polyphenism with _ Green _______ banded form occurring in individuals during summer and the individuals developing the _ Dark __________ banded form in autumn when the temperatures are lower will have _ higher ________ fitness _ relating _______ to polymorphisms and other polyphenisms. What are these four requirements for the polyphenism to evolve by natural selection called? _ Variation in phenotype between individuals, variations inherited from parent to offspring, struggle for existence, and reproduction _______________________ (c) What is one reason that this polyphenism will not evolve by natural selection in other populations with only polymorphisms? The phenotype that has the _ best ________ absolute reproductive success (optimal phenotype) in this population is not available in the population because the _ mutation __________ for this optimal phenotype is not available. No evolution ________ occurs in population with no _ phenotype __________ for the polyphenism in the gene pool. d) If the environment changes because of climate change and autumn temperatures are higher later in the season, the green banded form would be optimal later in autumn because of higher temperatures. The dark banded form will not be advantage until very late in autumn. Caterpillars could even pupate before the temperatures would decrease enough that the dark banded form would be an advantage. In this case, there are three ways that caterpillars can change: Case 1: A polyphenism that changes the photoperiod cue to a shorter day length to delay development of the dark banded form to later in autumn so the green banded form can occur in 4th and 5th instars in autumn can be optimal in this environment. A polyphenism with shorter day length cue can _ evolve ______ (evolve or develop) in the population, if there are some individual caterpillars that have the polyphenism with a shorter day length photoperiod cue in the population and _ the gene ______ for the polyphenism with shorter day length cue in the gene pool. (c) Case 2: A polyphenism that responds to higher temperatures in autumn by delaying the dark banding form so that green banded form occurs in the 4th and 5th instars in autumn. The polyphenism can respond to higher temperatures by individuals _ Evolving __ (evolving or developing) the green banded form in the 4th and 5th instars in autumn. (d) Case 3: Green banded polymorphism could be optimal in this environment. The green banded caterpillar can _ develop ______ (evolve or develop) in the population, if there are some green banded caterpillars in the population and the green banded polymorphism can be _ inherited ___ from parent to offspring. All these cases can increase survival and maintain development time at higher temperatures so that the caterpillars pupate before freezing conditions. The case that does involve evolution is case(s) _ Case _1 _____ (1, 2, 3, both 1 and 2, both 2 and 3, both 1 and 3, all three (1, 2 and 3). Literature Cited Hazel, W. N. 2002. The environmental and genetic control of seasonal polyphenism in larval color and its adaptive significance in a swallowtail butterfly. Evolution 56:342-348