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Several Basic Controls Govern Population Size

Several Basic Controls Govern Population Size - competition...

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Several Basic Controls Govern Population Size Predators kill and consume other organisms. Carnivores prey on animals, herbivores consume plants. Predators usually limit the prey population, although in extreme cases they can drive the prey to extinction. There are three major reasons why predators rarely kill and eat all the prey: 1. Prey species often evolve protective mechanisms such as camouflage, poisons, spines, or large size to deter predation. 2. Prey species often have refuges where the predators cannot reach them. 3. Often the predator will switch its prey as the prey species becomes lower in abundance: prey switching. Symbiosis has come to include all species interactions besides predation and
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Unformatted text preview: competition. Mutualism is a symbiosis where both parties benefit, for example algae (zooxanthellae) inside reef-building coral. Parasitism is a symbiosis where one species benefits while harming the other. Parasites act more slowly than predators and often do not kill their host. Commensalism is a symbiosis where one species benefits and the other is neither harmed nor gains a benefit: Spanish moss on trees, barnacles on crab shells. Amensalism is a symbiosis where members of one population inhibit the growth of another while being unaffected themselves....
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