BacR (bacr) wrote,

r-selected organisms

Grzimek's Animal Life Encyclopedia, Edition 2 - Volume 14 - Mammals - Part 3

Humans occupy all terrestrial habitats. Only human ectoparasites
and endoparasites or vermin that attend humans
occupy a comparably broad range of habitats. Yet, humans
have experienced no speciation in spite of a vast array of occupied
habitats. Therefore, the wide distribution of humans
is associated with biological factors underlying good dispersability
and a very broad niche. These factors include a wide
tolerance for habitat diversity and pronounced seasonal variation.
Humans therefore fall into the category of r-selected
organisms, in spite of their large body size, longevity, and low
intrinsic rate of increase.

SEE THE LINK OR SEARCH GOOGLE FOR "r-selected organisms"

Reproductive Strategies: r-selected vs. K-selected

mature rapidly | mature slowly

short-lived: most die before they reproduce | tend to live long lives: low juvenile mortality rate

-------------------| compete well for resources

have many offspring - tend to overproduce | have few offspring at a time

invest little in individual youngsters | care for their young

most pest species are r-selected | most endangered species are K-selected

population not regulated by density:
boom and bust population figures | population stabilizes near carrying capacity

opportunistic -- invade new areas | maintain numbers in stable ecosystems

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