ricklefs_lecture_ppt_ch11-2 - Rick Relyea Robert Ricklefs...

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The Economy of Nature7th editionLecture PowerPointChapter 11Population DistributionsRick Relyea · Robert Ricklefs© 2014 by W. H. Freeman and Company
Chapter 11 conceptsThe distribution of populations is limited to ecologicallysuitable habitats.Population distributions have five importantcharacteristics.Population abundance and density are related togeographic range and adult body size.Dispersal is essential to colonizing new areas.1245Many populations live in distinct patches of habitat.6The distribution properties of populations can beestimated.3
Distributions of populations1Spatial structure: the pattern of density and spacing of individuals in a population.Fundamental niche: the range of abiotic conditions (e.g., temperature, humidity, salinity) under which a species can persist.Competitors, predators, and pathogens may prevent a population from persisting in an area.Realized niche: the range of abiotic and biotic conditions under which a species can persist.Geographic range: a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple).
Distributions of populations1We can test whether species are limited by unsuitable environmental conditions.Example:The Lewis’ monkeyflower lives at high elevations, whereas the scarlet monkeyflower lives at low elevations.When planted outside their natural elevations, the two species grew poorly and experienced lower survival.This suggests that the plants are limited by unsuitable environmental conditions.
Ecological niche modeling1As a general rule, populations can grow larger in more suitable habitats.Understanding the realized niche of a species aids in species conservation and can help to limit the spread of invasive species.Ecological niche modeling: the process of determining the suitable habitat conditions for a species.Ecological envelope: the range of ecological conditions that are predictedto be suitable for a species (differs from the realized niche, which describes conditions in which a species currently exists).Predicting the potential geographic range of a species is difficult when only a few individuals exist; researchers can use historic distributions of species.
Modeling invasive species1Ecological niche modeling can predict the expansion of pest species.Example:The Chinese bushclover was brought to the United States to control erosion, provide cattle feed, and reclaim mined land.Ecologists collected data on the environmental conditions under which bushclover lived in eastern Asia.They used this data to quantify the ecological envelope of bushclover and predicted all locations to which it subsequently spread.Since bushclover has not spread to all predicted locations, other ecological factors may limit its distribution.
Effects of global warming1During the past century, the average temperature of the Earth has increased by 0.8°C.

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