BIO120H1 Lecture Notes - Climax Community, Pioneer Species, Metapopulation

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Published on 13 Apr 2013
School
UTSG
Department
Biology
Course
BIO120H1
Professor
LECTURE 8: Metapopulations, plant community compositions
Nature occurs in patches
Fender’s Blue butterfly depends on one particular plant → Kincaid’s Lupine
Only lays eggs on these plants where caterpillars grow up feeding on it
Only exists on prairie patches
Only exist on prairie patches or die without reproducing
Larger patches can support a population since when they disperse they’d still end up in the area within the
patch
Smaller ones go extinct migration out of patch to agriculture patches without the Kincaid’s Lupine
Small patches near larger ones can sustain due to migration
All depends on quality, size and proximity of patches as well as dispersal
Populations are not easily driven to extinction due to non-equilibrium conditions
Certain species can manage in a certain patch
Migration
Patterns of dispersal (R and K species)
R species weedy plants good at dispersal with high reproduction rate semelparous
K species - more investment in somatic growth, shade tolerant, slow growth iteroperous
Metapopulation theory if death rate = migration rate then the metapopulation will exist indefinitely
Andy Smith distribution of Pika metapopulations lives in patches (north, middle, south)
North: high, stable population due to large stable patches
Middle: ups and downs, can’t sustain very well
South: decline of Pikas
Source disperses population to other places
Sink population that depends on the import and migration of Pikas
Clement species association where a particular pair of species occur in the same piece of vegetation and
has a functional relationship with each other biotic factors
Gleason species are individualistic, does not depend on one another. They are found near each other
because they have the same range of tolerance (abiotic conditions & dispersal) abiotic factors
Gradient analysis Curtis (indirect) & Whittaker (direct)
Davis used pollen data to reconstruct post-glacial migrations of trees did not move in clusters
Proved that each plant is an entity to itself individualistic
Animal communities are less individualistic than plant communities
Lecture 9: Spatial Ecology, Plant Communities, and Disturbance
Succession change of plants through time in a predictable sequence
Soil development and shading is critical
Vegetation changes spontaneously, independent from humans
Classic view of succession:
Starts with pioneer species (R-species weedy perennials)
Goes through temporary equilibrium stages
Ends at climax, stable equilibrium no more changes (K- species competitive, shade tolerant )
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Primary succession new habitat created with no prior vegetation due to large disturbances where all
living individuals and nutrients in soil were removed (volcanic activity, sand dunes, retreating glaciers…)
Secondary succession disturbance of pre-existing vegetation (abiotic disturbances, fire, agriculture…)
Can quickly re-colonize the areas of disturbance
Perennial weeds with seeds in the soil germinate when conditions are wet enough
Dispersal of plants colonize the area slowly develop woody trees species are replaced
Shading becomes a factor taller plants out compete lower plants
Eventually reach a climax with K-species which are shade tolerant and replaces itself
Soil development becomes more complex and organic
Shading starts to occur when there’s many layers of foliage in developing forests
Clement concept of climax communities permanent stage of succession after any disturbances any
ecosystem will return to its characteristic assemblage of species
Super organism concept working together to maintain a stable composure
Not all vegetation will get to a climax stage some will never achieve it
Boreal forest: spruce-fir does not replace itself due to too much shade, makes soil acidic, more
combustible than tropics resulting in fires
Fire dominant communities have no stable climax and no shade tolerant species
Ground fires not that harmful to trees with thick barks good for regrowth
Crown fire more harmful allows seeds in pine cones to disperse
Organisms adapt to a pattern of burning
Gleason communities were individualistic, changes are not as predictable as Clement proposes
Species diversity increases with successional age
Early successional plants have higher rates of photosynthesis & respiration, resource up take and
light compensation points
Habitats are in mosaic patches of different stage of regrowth after disturbance
‘gap phase succession’ when gaps are created for new pioneer species to develop
Occurs through fire (dry forests) or in tropics when large trees fall over to allow new pioneer
species to inhabit the gaps promotes more diversity
Facilitation succession early successional species modify environment for later species to replace them
Tolerance succession later successional species are more long lived and replace earlier species
Inhibition model early colonists dominate until a disturbance removes them and longer lived species
replace them
Change of ratio of resources overtime can shift community composition
Chronosequence of sand dunes bare sand, beach, grasslands, mature forest
Lecture 10: Trophic Relationship in Communities
Primary produces plants, primary consumers herbivores, secondary consumers carnivores who eat
herbivores, tertiary consumers carnivores who eat secondary consumers, and those who eat organic
matter
Insecticide treatment to plants that removes beetles lowers plant diversity
Trophic cascades carnivores limit herbivores so they don’t limit plant growth
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Document Summary

Fender"s blue butterfly depends on one particular plant kincaid"s lupine. Only lays eggs on these plants where caterpillars grow up feeding on it. Only exist on prairie patches or die without reproducing. Larger patches can support a population since when they disperse they"d still end up in the area within the patch. Smaller ones go extinct migration out of patch to agriculture patches without the kincaid"s lupine. Small patches near larger ones can sustain due to migration. All depends on quality, size and proximity of patches as well as dispersal. Populations are not easily driven to extinction due to non-equilibrium conditions. Certain species can manage in a certain patch. Patterns of dispersal (r and k species) R species weedy plants good at dispersal with high reproduction rate semelparous. K species - more investment in somatic growth, shade tolerant, slow growth iteroperous. Metapopulation theory if death rate = migration rate then the metapopulation will exist indefinitely.

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