Chapter 5 Sections 1 & 3 ENVIRONMENTAL SCIENCE

HABITATS AND NICHES A NICHE is the role of an organism in the ecosystem A niche is more than a habitat, it is also what the organism does within its habitat A niche includes BIOTIC FACTORS and ABIOTIC FACTORS No two species can share the same niche in the same habitat

HABITATS AND NICHES If two species do, they will COMPETE for RESOURCES The extinction of a population due to direct competition with another species is called COMPETITIVE EXCLUSION Competitive exclusion refers to the extinction of a species in a particular place, not the whole species

HABITATS AND NICHES A FUNDAMENTAL NICHE is the theoretical niche an organism could be in A REALIZED NICHE is where the organism actually is See figure 5.3 NICHE DIVERSITY is relative to the abiotic factors of an ecosystem

HABITATS AND NICHES A PREDATOR is an organism that actively hunts other organisms PREY is the hunted A predator that promotes niche diversity is called a KEYSTONE PREDATOR See Fig 5.4

POPULATION GROWTH Population growth in which the rate of growth in each generation is a multiple of the previous is called EXPONENTIAL GROWTH This can only happen if food and other resources were not limited See fig 5.8

CARRYING CAPACITY The number of individuals of a species that can be supported by an ecosystem is called CARRYING CAPACITY Growth stops when # of births = # of deaths See fig 5.9

LIMITING FACTORS Limiting factors that are dependent on population size are called DENSITY-DEPENDENT LIMITING FACTORS Examples are PREDATION, PARASITISM, DISEASE, FOOD COMPETITION, LIVING SPACE, WATER AVAILABILITY Limiting factors that affect the same percentage of a population, regardless of size are called DENSITY-INDEPENDENT LIMITING FACTOR Examples are CLIMATE, HUMAN DISTURBANCE, AND NATURAL DISASTERS

LIMITING FACTORS Populations controlled by density-dependant factors show an S-shaped curve (fig 5.9) Populations controlled by density-independent factors show a boom and bust curve (see fig 5.11)