Ecology Part II r & K Strategists Symbiosis

r-Strategists Many species of life that can reproduce rapidly under ideal conditions are called r- strategists. Included are species like bacteria, insects, some plants, protozoa, Characteristics of this group include, production of many offspring, little if any parental care, and rapid maturity.

R-strategists

K-strategists Many species are much slower growing and tend to live long successful lives with low mortality are called K-strategists. They tend to produce much fewer offspring, population density is low and typically the populations are at or near carrying capacity. Most provide extensive parental support to the young which helps in successful offspring.

Examples include Bears, Whales, Gorillas, Elephants, Bald Eagles and Humans. Many of these species are on endangered species lists because if threatened, it may take many years to grow the population back. (ex. Bald eagles and DDT)

K-strategists

Generalizations-Populations can be K-selected (equilibrium populations) or r-selected (opportunistic populations) Characteristic r-selected K-selected populations populations -Maturation timeshortlong -Lifespanshortlong -Population boom-and-bust growth curve -Death rate high low in young -Investment of time in offspring none some

Characteristic r-selected K-selected populations populations -Number of offspring manyfew -# reproductions per lifetime oneseveral -Timing of first reproductionearly in lifelate in life -Habitat`unstablestable

Symbiosis are two organisms living and interacting together. Types 1. Mutualism-Both species benefit. 2. Commensalism-One species benefits and the other is neither harmed or benefits. 3. Parasitism-One species benefits and the other is harmed.

Mutualism

Commensalism

Parasitism

Biological Niche The role in which an organism plays within its Ecosystem. Examples include, Predator, Producer, Insect Eater, Bottom Feeder, Tree Dweller, Consumer. In short it, is the organisms job and position in the place where it lives. Species often compete for the same Niche or sometimes a Niche may be unoccupied.