The traits influencing intersexual sexual selection

Info icon This preview shows pages 24–27. Sign up to view the full content.

81) The trait(s) influencing intersexual sexual selection is (are): A) Red tail-spot B) Blue body-color C) cryptic brown body color D) Answers A and B are both correct E) None of these answers are correct 82) The trait(s) influencing intrasexual sexual selection is (are): 83) Suppose that an experiment (that kept juvenile rearing conditions constant) found that the slope of a plot of a sister’s lifetime survival vs. the size of her brother’s red tail spot was positive. This finding would indicate that the red spot most probably evolved due to: 84) Suppose that males brood their mates’ eggs and that this brooding behavior is energetically taxing on the males, causing weaker males to sometimes abandon their clutch of eggs. If the slope of a plot of male brooding success vs. the size of his red color spot was positive, then which sexual selection model is most likely responsible for the evolution of the red tail spot?
Image of page 24

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

85) Suppose that species-T is a member of a clade of fish that lack red tail-spots (except for species-T). Experiments show that attraction to a red tail-spot is a synapomorphy for the clade, but that female preference for this trait was much weaker in species-T. This finding would best support the hypothesis that the red tail-spot evolved via the: A) sensory exploitation model B) sexy sons model C) sexual conflict model D) material benefits model E) good genes model ___________________________________________________________________________________
Image of page 25
Use the following information for the next 4 questions (until you see a solid line): In many invertebrates, (hosts) there are intracellular parasites (bacteria) that are only passed on to the next generation through the egg. This mother-only “vertical” transmission pattern also applies to the mitochondria. Because of mother-only vertical transmission, the bacteria and mitochondria in males are evolutionarily “dead ends” because they are never transmitted to the next generation. Many intracellular bacteria have evolved male-killing phenotypes (i.e., they kill the male that carries them), causing family sex ratios to be strongly female-biased (up to 100% females). Recent studies indicate that the bacteria kill males by targeting a gene on the X chromosome that is only turned on in XY males but not XX females. Killing males increases the fitness of the bacteria when there is competition among siblings for limited resources and/or when the fitness of females is reduced by sib-mating with their brothers (because their offspring experience inbreeding depression). There is also experimental evidence that genes in the genome of some host species have evolved that shut down the male-killing phenotype of the bacteria.
Image of page 26

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 27
This is the end of the preview. Sign up to access the rest of the document.
  • Winter '07
  • Evan
  • Evolution, Sexual Selection, Yucca plant

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern