Chapter 3 Classification of Organisms

ECOSYSTEMS An ecosystem includes biotic and abiotic components interacting together.

ABIOTIC = NON-LIVING BIOTIC = LIVING Abiotic elements of a community change over time, affecting organisms and their interactions on all levels. The number and type of species change over time as land is exposed by a melting glacier.

ABIOTIC FACTORS Abiotic factors such as climate, latitude, elevation, temperature, humidity, moisture, salinity, and light affect patterns of distribution of life. Abiotic factors are NONLIVING.

Temperature and Precipitation and their Effects on Biomes of the World

Biomes of the World BIOME – An ecosystem or group of ecosystems in a specific region on Earth that has a particular combination of biotic and abiotic factors; for eg, tundra, desert, rainforest, taiga, etc.

HABITAT A habitat is a place or area within a biome or ecosystem that has a particular set of biotic and abiotic characteristics. It is an organism’s “home”.

RANGE An organism’s range is the geographical area where the organism is found. The hoary marmot (Marmota caligata) feeds on plants found in high altitude meadows. Range of the hoary marmot

NICHE The ecological niche of a population is the role that its members play in an ecosystem. The variety of niches and habitats within an ecosystem allow it to support a diversity of organisms. These two species of ocean barnacles have similar niches, but the two niches differ enough that both species are able to establish populations at different depths of the rocky shore.

LIMITING FACTOR A limiting factor is any biotic or abiotic element that controls the number of individuals in a population. Biotic limiting factors include competition, predation, and parasites. Limiting factors prevent these bacteria from reproducing infinitely.

PREDATORS

COMPETITION For mates, food, territory

COMPETITION Intraspecific competition – competition WITHIN a species (Example: Interspecific competition – competition BETWEEN 2 or more species (Example:

PARASITISM The “parasite” lives and feeds off of a “host” The parasite rarely kills the host, but will weaken it The parasite is generally smaller than the host

ANIMAL PARASITES

HUMAN PARASITES Head lice feeding on a human scalp

ABIOTIC LIMITING FACTORS Abiotic (non-living) factors include:

3.3 Studying Organisms in Ecosystems (cont’d) Organisms can be sampled using transects or quadrats situated randomly in a sample area. From these samples, the density of a population can be estimated. A 5m × 100m transect

Chapter 3 Summary An organism’s environment includes biotic and abiotic components. Organisms affect and are affected by their environment. Organisms are part of a population, a community, an ecosystem(s), and Earth’s biosphere. Abiotic factors in the environment affect the distribution of organisms. Biologists use a hierarchical system to group organisms. Naming and categorization must sometimes be changed to accommodate new discoveries. A universal, two-word naming system is used, giving each organism a genus and species name in Latin.

Chapter 3 Summary (cont’d) Biologists use dichotomous keys to identify organisms. Each step in the key has only two choices. Unequal heating of the Earth creates different climates and distinct biomes that support the growth of certain groups of organisms. Within biomes and ecosystems, there is a great deal of variation in habitats and niches. A population’s growth in a particular habitat is limited by biotic and abiotic factors. Biologists use sampling techniques to estimate population size in large ecosystems. Transects are often used for mobile populations, while quadrats are used for sessile populations, such as plants.