Biological Communities Chapter 18
18-1 How Organisms Interact in Communities Objectives Identify the distinguishing features of symbiotic relationships SCS: B-6.1
Species Evolve in Response to each other Interactions among species Insects/flowers Coevolution Predator/Prey relationships Predation is when one organism feeds on another
Symbiosis When two or more species live together in a close, long-term association.
Parasitism – when one organism feeds on and usually live on or in another Example: Ticks and dogs Ticks benefit, but dogs do not
Mutualism – a symbiotic relationship in which both benefit from the relationship Example: flowers and bees Flowers are pollinated and bees have food
Commensalism – a relationship in which one organism benefits and the other neither is benefits or is harmed Example: Spanish moss and trees Trees are not hurt nor benefit, but the moss benefits from additional sunlight
18-2 How Competition Shapes Communities Objectives Describe the role of competition in shaping the nature of communities Distinguish between fundamental and realized niches Describe how competition affects an ecosystem Summarize the importance of biodiversity SCS: B-6.1, 6.2
Common Use of Scarce Resources leads to competition Organisms compete for food, space, light, minerals, and water Resources must be in short supply if competition occurs Competition can limit how species use resources Competition can lead to extinction or elimination of a species
Niche – the role of a species in a ecosystem How does the organism affect the environment If niches overlap it may cause competition Niches can vary in size
Predation can lesson competition Eliminates those species less adaptive Promotes biodiversity
18-3 Major Biological Communities Objectives Recognize the role of climate in determining the nature of biological communities Describe how elevation and latitude affect the distribution of biomes Summarize the key features of the Earth’s major biomes SCS: B-6.1, 6.2
Climate determines where species lives Climate is the prevailing weather conditions of an area Temperature and moisture Temperature and moisture determine biological communities
Types of Terrestrial Biomes Tundra Taiga Desert Grassland Temperate Forests Tropical Rain Forests
Tundra extremely short growing season (6 to 10 weeks) long, cold, dark winters (6 to 10 months with mean monthly temperatures below 32° F or 0° C.) low precipitation (less than five inches/year) Animals and animals: Musk ox, artic hare and fox, permafrost (permanently frozen ground)
Taiga Long, severe winters and short summers (50 to 100 frost-free days) are characteristic, as is a wide range of temperatures between the lows of winter and highs of summer. Mean annual precipitation is 15 to 20 inches, but low evaporation rates make this a humid climate. Vegetation and Animals: Conifers, beaver, lynx, deer, sparrows…..
Deserts Temperature: Average of 38°C (day), average of -3.9°C (night) Precipitation: About 250 mm of rain per year Vegetation: Cacti, small bushes, short grasses Animals in the desert: coyotes, lizards and snakes, insects, and even some birds) are adapted for burrowing to escape the scorching heat of the desert sun
Grasslands Temperature: Dependent on latitude, yearly range can be between -20°C to 30°C Precipitation: About 500 to 900 mm of rain per year Vegetation: Grasses (prairie clover, salvia, oats, wheat, barley, coneflowers) Animals: bison and antelope
Temperate Forests Temperature: -30°C to 30°C, yearly average is 10°C, hot summers, cold winters Precipitation: 750 to 1,500 mm of rain per year Vegetation: Broadleaf trees (oaks, maples, beeches), shrubs, perennial herbs, and mosses Animals: Deer, raccoons, and salamanders are characteristic inhabitants.
Tropical Rain Forest Temperature: 20°C to 25°C, must remain warm and frost-free Precipitation: 2,000 to 10,000 millimeters of rain per year Vegetation: Vines, palm trees, orchids, ferns Animals and plants: monkeys, cat like mammals, reptiles, insects, diverse flowers, hard wood trees, and medicinal plants