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Chapter 22

BIOLOGY 2F03 Chapter Notes - Chapter 22: Environmental Niche Modelling, Cryptozoology, Macroecology

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D R.Kajura

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Chapter 22 Macroecology
pgs 577-581, pgs 582-586, pgs 586-591, pgs 597-599, pgs 600-604 (summary)
22.1 Ecological Niche Modelling
Goal is to combine a species’ niche requirements with the spatial distribution of
environmental conditions on a landscape or across a region
Making specific predictions about a species:
1. Identify the niche
2. Determine the distribution of environmental conditions throughout area of concern
3. Combine this information to produce a map of potential distributions
Standard approach in ecological niche modelling
1. List of locations where the study organism has been found
2. Spatially explicit environmental information for the region in which the organism is
3. Similar environmental information for areas where the organism has not been found
Predicting the spread of an invasive crab species
When prediction the spread of invasive crab species through north America, they
created a niche equation to the environmental conditions
Resulting map indicated strength of match between niche requires as determined from
its Asian distribution and local environmental conditions of north America
Niche axis: distance to the ocean
Occurrence of crabs were less than 1,261 km from the sea, and 90% of occurrences
were less than 355 km
Issue that could influence invasion risk is the frequency with which this species is
introduced at different locations
Dominant vectors for invasions are ships with ballasts
Problems with niche modelling
oFocuses on where species is found, not where it lives
oUses realized niche, not fundamental
Using ecological niche modelling to predict the distribution of crypto-zoological species
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This would provide scientists with more accurate information on the health populations
of at risk species
Bigfoot (aka a crypto-zoological species) scientists were able to record sightings or
auditory detections and footprints
By combining data sets, they determine environmental conditions
oThis suggests that they were located in the northwest
Real lesson from this: core data used in niche modelling is not accurate, even maps will
be meaningless
22.2 Area, isolation, and species richness
Species richness increases with increases with area and decreases with isolation
Island area and species richness
Scientists show some areas are more diverse than others due to extreme temperature
and precipitation
Habitat patches on continents: mountain islands
Many isolated mountain rangers are not continental islands
When temperature warmed habitats contracted to high mountains
Consequence of these changes: once continuous forest and alpine vegetation was
converted to a series of island like habitat patches associated with mountains =
Lakes as islands
Aquatic environments isolated from other aquatic environments by land
Seepage lakes: receive no surface drainage and are completely isolated, have
stream/inlets and are less isolated
Scientists studied patterns of species composition and richness among fish inhabiting
lakes – all 18 study lakes had similar bottom substrates and similar maximum depths
however the lake spanned a considerable range of surface area
Found that number of species increases with the area of insular environment
Island Isolation and Species richness
Negative relationship between the isolation of an island and the number of species it supports
Marine islands
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