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23 Cards in this Set

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Define succession.

The process by which species composition of a community changes over time.

Define seral stage.

Each stage of community change during succession.

Define pioneer species.

The earliest species to arrive at a site; typically are able to disperse long distance and arrive quickly at disturbed sites.

Define climax community.

The final seral stage in the process of succession; generally composed of organisms that dominate in a given biome.

Define a chronosequence.

A sequence of communities that exist over time and a given location.

Define primary succession.

The development of communities in habitats that are initially devoid of plants and organic soil such as dunes, lava flows and bare rock.

Define secondary succession.

The development of communities in disturbed habitats that contain no plants but still contain organic soil e.g., ploughed fields or forests uprooted by a hurricane.

Define priority effect.

When the arrival of species at a site affects the colonization of other species; often occurs through inhibition.

Define tolerance.

A mechanism of succession in which the probability that a species can become established depends on its dispersal ability and its ability to persist under the physical conditions of the environment.

What are transient climax communities?

A climax community that is not persistent; occurs when a site is frequently disturbed so a climax community cannot persist.

What is a fire-maintained climax community?

A successional stage that persists as the final seral stage due to periodic fires.

What is grazer-maintained climax community?

When a successional stage persists as the final seral stage due to intense grazing.

What is landscape ecology?

The field of study that considers the spatial arrangement of habitats at different scales and examines how they influence individuals, populations, communities and ecosystems.

What are legacy effects?

The long lasting influences of historical processes that affect the ecology of an area.

What is a species-area curve?

A graphical relationship in which increases in area (A) are associated with increases in the number of species (S).




S = cA>z

What are stepping stones?

Small intervening habitat patches that dispersing organisms can use to move between large areas of favourable habitat, useful for flying organisms that do not need continuous corridors to disperse.

What is equilibrium theory of island biogeography?

A theory stating that the number of species on an island reflects a balance between the colonization of new species and the extinction of existing species.

What is the theory of island biogeography?

Smaller islands should have higher extinction rates; islands nearer to a source of habitat should have higher colonization rates.

Where do oceans have increased species richness?

At lower latitudes.

What are the hypothesises for patterns of diversity?

1) Species are continually created over time and without limit; because tropical regions have not experienced glaciation therefore these areas have had more time to accumulate species.


2) The number of species in an area reflects an equilibrium between the processes of speciation and extinction.

What is the energy-diversity hypothesis?

Sites with higher amounts of energy are able to support more species and higher abundances of individual species.

What is Laurasia?

The northern landmass that separated from Pangaea 150 Mya and split into North America, Europe and Asia.

What is Gondwana?

The southern landmass that separated from Pangaea and split into South America, Africa, Antarctica and India.