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