Side blotched lizard males, pictured at right, have three color morphs that corr

Question

Side blotched lizard males, pictured at right, have three color morphs that correspond to three different mating strategies. Orange morphs are aggressive males that defend large territories, blue morphs are less aggressive and defend smaller territories, and yellow morphs mimic female lizards and sneak matings by stealing females from other males. The dynamics of this system were worked out by Sinervo and Lively in their 1996 paper, where they determined orange males beat blue males, blue males beat yellow males, and yellow males beat orange males (like a game of rock, paper, scissors). a) What form of sexual selection is occurring in this system? b) If sexual selection occurred based on female choice due to good genes/health instead, which color morph do you think would have the highest fitness? Why?

Explanation / Answer

a) The breeding mechanism in male side blotched lizards exhibit "Rock Paper Scissor " mechanism of frequency dependent sexual selection.

Among the three different color throated males the orange throated is ultra dominant,blue throated ones are dominant and yellow throated once are considered to be sneakers.the sexual selection here is said to be frequency dependent sexual selection because here a cycle is created where the least common morph of one breeding season often has the largest number of mature living off springs in the next year as one morph does compete well with the other during mating while with the third type it competes poorly thus it maintains alternative male mating strategy.

B. If sexual selection occurs based on female choice due to good genes /health the yellow color morph would have advantage as the sexual selection exerted by females might be at the origin of fitness intransitivity. The female avoids to mate with the commonly occurring male morphs as it would reduce the fitness of the resulting off spring  due to negative FD competition among adult male morphs, i.e., during inter-generational competition.

Explanation for B

Here the goal of sexual selection by females is to maximize the fitness of the male offspring and its probability of success in future male to male competition,thus if there are two different colors of the male the female would prefer to mate with a male that is less commonly occurring rather than the most common ones thus making sure that the population of less common becomes more in the next generation similarly in the next generation if the third color comes into picture for competition and is less in frequency the female prefers to mate with the less common ones .

assuming that orange and blue color males are coexisting and number of blue throated are less then female prefers to mate with the blue ones similarly when blue and yellow are appearing and yellow are less in number automatically the female prefers yellow ones over blue ones and the game continues.

In case of the three colors coexisting as the yellow ones are sneakers and the other two being dominant and ultra dominant the chance of yellow ones being preferred would be more.

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