Ecology

Second Part of Student Download

Section 14.2 KEY CONCEPT Organisms interact as individuals and as populations.

Two ways organisms interact: Competition and predation

• Competition: two organisms fight for a resource.

• Predation: one organism captures and eats another.

• The predator population depends on the prey population for survival

(1) Mutualism: both organisms benefit

Symbiotic Relationships

Cactus provides fruit for bat to eat.Bat spreads cactus seeds.

(2) Commensalism: one organism benefits, the other is unharmed

Human Our eyelashes are home to tiny mitesthat feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle.

Demodicids Eyelash mites find all they need to survive in the tiny folliclesof eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope.

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Organism benefits+

Ø

Ø Organism is not affected

Commensalism

(3) Parasitism: one organism benefits, the other is harmed

Organism benefits0

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Organism is harmed

Hornworm caterpillarThe host hornworm will eventually die as its organs are consumedby wasp larvae.

Braconid waspBraconid larvae feed on their host and release themselves shortly before reachingthe pupae stage of development.

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Parasitism

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KEY CONCEPT Biomes are land-based, communities of organisms plus climate. Biomes are identified by their abiotic factors & ecological community .

Earth has six major biomes.

(1) Tropical rain forest biomes produce lush forests.– warm temperature– abundant precipitation all

year

Source: World Meteorological Organization

– Temperate grasslands are dry and warm during the summer; snow in winter.

(2) Grassland biomes:primary plant life is grass.

– Tropical grasslands are warm through the year, with dry and rainy seasons.

(3) Desert biomes are characterized by a very arid climate.– very little precipitation– four types: hot, semi-arid,

coastal, and cold

Tucson, Arizona

Source: National Oceanic Atmospheric Administration

– Temperate rain forests have a long wet season and dry summers.

(4) Temperate forest biomes have seasons.

– Temperate deciduous forests have hot summers and cold winters.

(5) The taiga biome is located in cooler northern climates.– forests– long winters and short summers– little precipitation

Source: Environment Canada

Banff, Canada

(6) The tundra biome is found in the far northern latitudes with long winters.– winter lasts 10 months– limited precipitation– permafrost

Barrow, Alaska

Source: National Oceanic Atmospheric Administration

Polar ice caps and mountains are not considered biomes.• Polar ice caps have no soil, therefore no plant community. • The climate and organisms found on mountains change as the

elevation changes.

Nevada has four Bioregions1. Sierra Nevada

2. Mohave Basin & Range

3. Central Basin & Range

(Great Basin)

4. Northern Basin & RangeBioregion: area that contains unique geologic, hydrologic and biological characteristics

Compared to most states Nevada ranks near the top ten in biodiversity.

Sierra Nevada• Mountain range bordering

California• Mostly granite (igneous

rock cooled slowly)• Alpine forest with several

species of conifers, deer, fox, mountain lions, and jackrabbits.

Mojave Basin & Range• Desert that touches CA, AZ, UT,

southern NV• “High Desert” (3,000-5,000

feet) 10” water• Death Valley (lowest, hottest

place) is here• Joshua tree, sage, cactus,

scorpions, rattlesnakes, lizards, hawks, deer, cougar

Central Basin & Range• Central Nevada (68% of the state)• This bioregion makes up majority of the state• Valleys = basins, Mountains = ranges• Pacific & N. American tectonic plates pulling

apart here; some of thinnest crust on Earth• The shifting tectonic plates create thin crust• Wetter, cooler than Mojave• Sagebrush, salt tolerant plants, pinyon, juniper,

rabbits, hares, deer, mountain lions, etc.

Northern Basin & Range• Northern NV into OR and UT• Volcanic plateaus• Grasslands, aspen forest• Deer, cougar, coyote, eagle, lizards, etc.

Nevada Bioregions