There are different ways this “logistic function” typically plays out depending on the species. The two extremes are referred to as K- and r- selected species. K-selected species (e.g. bears) reproduce more slowly and have fewer, but longer-lived, offspring in which the parents invest a lot of time and energy. These offspring have a high chance of survival, tend to adapt to stable ecosystem conditions, and stabilize their populations near the environment’s carrying capacity. In contrast, r-selected species (e.g. rabbits), reproduce rapidly, have short lifespans, have a lot of offspring with little if any parental care, and any given offspring is unlikely to survive to maturity. R- selected species tend to undergo population “booms and busts,” repeatedly overpopulating and then crashing. They do not bother with adapting to a given set of ecosystem conditions because they are optimized to be opportunistic to changing conditions. Nature doesn’t “prefer” one sort of strategy over the other, and, in fact, most species fall somewhere in an intermediate range between being strongly K and r-selected. TaaL: Humans are awfully familiar with species which display so-called “K - selection” because you’ve historically been a K -selected species yourselves. Any species with large brains and self-awareness is K-selected because the lifestyle of an r- strategist wouldn’t allow for the growth of large complex brains! What selects between an environment’s dominance by K - or r-selected species? Environmental stability. K-selected species are very vulnerable to change and are slow to adapt due to their long generation times and low reproductive rates. In contrast, r-selected species thrive on rapid change. This is why abrupt “mass extinction” events ten d to cull out the K- strategists in favor of the small, fecund opportunists. And this is why your warming and acidifying oceans are becoming increasingly devoid of vertebrates and increasingly filled with jellyfish 88 , which is of great concern to marine biologists (and alien anthropologists). Once established, r- selected organisms can be effective at dominating ecosystems against a reversion to K-selected species (as jellyfish have demonstrated).
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