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12

The female stood with the tail held sharply to one side, and the quills on the back lying very flat. The male stood on his hind legs, while the front legs grasped the sides of the female. There was no repetition of the act. The male's urethra is 115-120 mm long, and his penis is 75 mm, so the he doesn't need to be as close to the female as one ...


10

No, I don't think auto-regulation explain much in the population sizes of predators. Group selection may explain such auto-reagulation but I don't think it is of any considerable importance for this discussion. You'll be interested in various model of prey-predator or of consumer-ressource interactions. as @shigeta said, what the following says is: predators ...


8

The technical answer is: Because the coloration of skin and hair is done by the two forms of melanin: Eumelanin, which is dark brown to black and Pheomelanin which is yellow to red. This enables colors from white (not pigmentation) to black (dense eumelanin pigmentation) and also colors in between by different ratios of the two pigments. The evolutionary ...


8

Thanks to the other answer for pointing me in the right direction with some references. It seems that two biologists in the early 1990s had a back-and-forth over this topic in The Quarterly Review of Biology.1,2 A statement of the problem: The function of menstruation is a cen tral enigma of mammalian, and especially primate, reproductive physiology. ...


7

Just to add a different dimension to the answer from @Chris. Not all animal colouration is produced by melanin. A whole range of bright colours in insects, birds and reptiles comes under the heading of structural colouration, which basically involves having a repeating structure at the microscopic level to interact with light. This is the basis for macaw ...


5

It is a very nice question. From wikipedia: Though there is some disagreement in definitions between sources, menstruation is generally considered to be limited to primates. Overt menstruation (where there is bleeding from the uterus through the vagina) is found primarily in humans and close evolutionary relatives such as chimpanzees. It is common in ...


3

A dimension not explored by the other (excellent) answers has to do with color perception under trees. Leaves are green while on the tree, which tends to make mostly green light available to the understory. Viewed under green light, a green-furred animal would appear bright green, roughly the same as a white creature viewed under green light. A red or ...


2

One of the possible adjustments of these mathematical models is to introduce a "place to hide", making some (small) percent of the prey population not accessible (or much more difficult to access) for predators. After the number of predators decreases from starvation, prey individuals are relatively safer outside the "place to hide" and can grow over this ...


2

Wikipedia has some revealing information here: Not all puffers are necessarily poisonous; Takifugu oblongus, for example, is a fugu puffer that is not poisonous, and toxin level varies wildly even in fish that are. A puffer's neurotoxin is not necessarily as toxic to other animals as it is to humans, and puffers are eaten routinely by some species of ...


1

You need to add Bell curves to your simulation. The most important curve to simulate is the nutritional quality of the prey though there are plenty more thing to curve like speed and virility for prey and predators both. Nature uses lots of Bell curves so they must be good for something, such as softening the harsh effects of pure exponential growth. I ...


1

Remi.b's answer is an excellent one, and this should be taken as a supplement to it: It's possible your simulation is correct The Lotka-Volterra equations are what is known as a deterministic model, and it describes the behavior of predator-prey systems (in a somewhat simplified fashion) in large populations. Small populations are subject to what is known ...



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