PLEASE HELP!!!!!! Part 6. Evolution of Coloration: Multiple considerations The e

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PLEASE HELP!!!!!!

Part 6. Evolution of Coloration: Multiple considerations The evolution of color patterns in animals can be complicated. In the lbiza Wall Lizard, sexual selection is not the only factor that affects coloration. Other selective forces are at work. For example, colorful male lizards may have higher mating success, but colorful males are also more conspicuous to predators. The phenotypes we see in nature are the result of a compromise between selective forces that favor and disfavor a particular trait. Natural and sexual selection often influence individuals of different ages or sexes quite differently. Recall that color brightness and saturation increases with increase in lizard size. 18. If colorful male lizards are more successful, why aren't all the male lizards colorful? 19. What mechanisms could maintain variation for traits that are subject to strong directional selection? List them here. 20. Would color evolve differently if the genes responsible for color were on the autosomal genome versus the sex chromosomes? Why? 21. If bright, saturated color increases male reproductive success, why do young lizards not fully express this trait as early in life as possible? (These lizards can be sexually mature at a relatively small size.)

Explanation / Answer

18Ans: Lizards generally do not express full coloration because the costs associated with being colorful (increased predation, cannibalism, metabolic costs) are much higher for juveniles who do not get any of the reproductive benefits that color affords adult males. As a result, these lizards undergo a dramatic ontogenetic color change. Expression of the color genes is age-dependent.

The species that do change colour the most actually have the most conspicuous social displays. So there's been selection for them to use these really bright, flashy colours in their communication and social displays, therefore there was selection on their ability to change colour.the males to look lijke the most colorful male lizards on Formentera. The remaining males were painted with water as controls

1) the outcome of all male aggressive interactions involving color-enhanced males fighting control males
2) the number of times either color-enhanced or control males courted females
3) the number of times courtship attempts by color-enhanced or control males ended in copulation.
The main reason that many male lizard's are not colourful, because they will not conspicuous male coloration in the result of sexual selection.

20Ans: Yes, the colour evolve differently, the females are only receptive for a very brief period of time, and the males will just continuously harass them. So to escape from that, the females will, as a last resort, flip onto their backs, [which means] they can't actually mate, and they show these bright orange belly patches. The belly patches don't seem to attract the attention of predators, because firstly, predators are quite rare out on these salt pans, and secondly,predators seem to avoid flipped over females with bright orange patches because they've never seen anything like it. They don't even recognise them as potential prey. And when the females are pregnant, the size of the patches increase. So they can use these orange colours to signal that they're receptive, or when they combine it with the flipping over behaviour, to signal that they're not receptive, to try and avoid harassment. So the colours can be used in very different contexts when they're combined with different behaviours?.

21Ans: Most populations have lizards that are shades of green or blue. On the islands with blue or green lizards, conspicuous color increases in both saturation and coverage area on male lizards’ bodies as they increase in age and size: the most conspicuously colored male lizards are also the largestcolorful male lizards may have higher mating success, but colorful males are also more conspicuous to predators. The phenotypes we see in nature are the result of a compromise between selective forces that favor and disfavor a particular trait. Natural and sexual selection often influence individuals of different ages or sexes quite differently.Recall that color brightness and saturation increases with increase in lizard size.

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