1 Introduction Ecologists usually define a population as… – Characterized by the number of individuals and their density. Additional characteristics of.

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Introduction• Ecologists usually define a population as…

– Characterized by the number of individuals and their density.• Additional characteristics of a population include…

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distribution Limits• _____________________ limits geographic

distribution of a species.– Organisms can only compensate so much for

environmental variation.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Niches• _______: Summarizes environmental factors

that influence growth, survival, and reproduction of a species.– Grinnell’s definition focused on the effects of the

physical environment– Elton’s definition included biotic and abiotic

factors

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Niches• Hutchinson defined niche as:– • n equates the number of environmental factors

important to survival and reproduction of a species.

–___________________- hypervolume

–___________________ includes interactions such as competition that may restrict environments where a species may live.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Kangaroo Distributions and ClimateBIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Tiger Beetle of Cold Climates

• Tiger Beetle (Cicindela longilabris) lives at higher latitudes and elevations than most other species in NA.– Schultz et. al. found metabolic rates of C.

longilabris are higher and preferred temperatures ____________ than most other species.• Supports generalization that the physical environment

limits species distributions.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Tiger Beetle of Cold ClimatesBIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distributions of Plants Along a Moisture-Temperature Gradient

• Encelia species distributions correspond to variations in temperature and precipitation.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distributions of Barnacles Along an Intertidal Gradient

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distributions of Barnacles Along an Intertidal Exposure Gradient

• Organisms living in an intertidal zone have evolved to different degrees of resistance to…

– Barnacles show …

• Connell found Chthamalus stellatus restricted to upper levels while Balanus balanoides is limited to middle and lower levels.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distributions of Barnacles Along an Intertidal Gradient

• Balanus appears to be more vulnerable to _____________, excluding it from the upper intertidal zone.

• Chthamalus adults appear to be excluded from lower areas by _____________ with Balanus.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distribution of Individuals on Small Scales

• _____________: Equal chance of being anywhere.–

• _____________: Uniformly spaced.– –

• _____________: Unequal chance of being anywhere.– –

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distribution of Individuals on Small Scales

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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What pattern? Why?

http://soundwaves.usgs.gov/2004/11/NestingColonyLG.jpg

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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What pattern? Why?

http://i.telegraph.co.uk/telegraph/multimedia/archive/01216/gnu_1216499c.jpg

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Species of aggressive stingless bees that forage over clumped resources… how would you predict they be distributed? How about passive species foraging on regularly spread resources?

http://farm3.static.flickr.com/2359/2459405670_f8082401c0.jpg

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distribution of Tropical Bee Colonies

– As predicted, four species with regular distributions were highly aggressive.• Fifth was non-aggressive and ___________ distributed.

• Prospective nest sites marked with ____________.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Distributions of Desert Shrubs

• Traditional theory suggests desert shrubs are regularly spaced due to competition but….

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Organism Size and Population Density

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

Density decreases as body size…

How does aquatic invertebrate density cmopare to that of other animals of comparable size?

How does mammal density compare to bird density?

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Plant Size and Population Density

• Plant population density ___________ with ____________ plant size.– Underlying details are very different.•

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Commonness and Rarity• Rabinowitz devised commonness classification

based on (3) factors:• • •

• Populations that are least threatened by extinction, have extensive geographic ranges, broad habitat tolerances, and some large local populations. – All seven other combinations create some kind of

rarity.

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Rarity

• Rarity I–

• Peregrine Falcon

• Rarity II–

• Passenger Pigeon

http://falconrytoday.net/news/wp-content/uploads/2009/08/Peregrine-Falcon0014.jpg

http://www.saroffillustration.com/portfolio/page/ns4_pigeon.jpg

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance

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Rarity

• Rarity III–

• California Condor

http://www.dfg.ca.gov/wildlife/hunting/condor/images/condor119.jpg

BIOL 3240 Plant and Animal Ecology – Distribution & Abundance