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8/12/2019 EVOLUTION,SPECIES, INTERACTIONS AND BIOLOGICAL COMMUNITIES.pps
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EVOLUTION, SPECIES, INTERACTIONSAND BIOLOGICAL COMMUNITIES
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How does a polar bear endure the long, sunless and supercold artic winter?
Adaptation Acclimation
Darwin theory of evolution by natural selectionis Most organisms produce more offspring than can survive. Better attributes = + chances to survive
Those that survive pass on fit traits to offspring
Mutations(DNA) may give individuals advantages underthe selection pressures of their environment.
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Some giraffes had long
necks, some short
Those with long necks
reached the food, thosewith short starved
Long necks mate and
produce population of
long necked giraffes.
http://www.youtube.com/watch?v=XKnq
j3YFXU8
http://www.youtube.com/watch?v=XKnqj3YFXU8http://www.youtube.com/watch?v=XKnqj3YFXU8http://www.youtube.com/watch?v=XKnqj3YFXU8http://www.youtube.com/watch?v=XKnqj3YFXU88/12/2019 EVOLUTION,SPECIES, INTERACTIONS AND BIOLOGICAL COMMUNITIES.pps
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Environmental factors Selection pressure
Influence the fitness of individuals and theiroffspring.
Examples: Physiological stress, competition with
other species, predation, luck.
Liebig- proposed that the singleenvironmental factor in shortest supply relativeto demand is the critical determinant in speciesdistribution bamboo
Shelford- added to Liebig's work by proposingthat the single environmental factor closest totolerance limits determines where a particular
organism can live
Environmental Indicators: requirements andtolerance of species determine specific
environmental characteristics and ecosystems
health. Example: Trout speciesSaguaro cactus very sensitive to lowtemperatures
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Tolerance Limits: levels beyond which species cannot survive Several factors determine species distri ution: temperature extremes, Salt
concentration, Competitors, Food availability
Tolerance limits also affect the distributionof young differently than adults Environmental gradient stepwise increase or decrease in an environmental factor
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Habitat - place /environmental conditions in which a particular organism lives. Ecological niche
Role played by a species in a biological community
Set of environmental factors that determine species distribution.
Ecological niche alterations
Species exist within a range of physical and chemical factors as well as biologicalinteractions.
Generalists vs Specialists
Endemic species: specifically found in a certain habitat. Resource partitioning: species coexisting in the same habitat Law of Competitive Exclusion
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What is Taxonomy? Binomials to classify them
Organization of specimens How they have descendent from ancestors
Six kingdoms: animals, plants, fungi, protists, bacteria and
archaebacteria.
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Predation and Competitionantagonistic relationships Competition: shapes a species population and biological community
Intraspecific: members of the same species
Interspecific: members of different species
Mechanisms to reduce intraspecific competition Young of the year can disperse plants
Strong territoriality
Resource partitioning between generations
Predation: feed directly on another living organism, whether or not this kills the prey. Life cycles of predators and species
Specialized food obtaining mechanisms
Evolutionary adjustment behavior and body characteristics (camouflage)
Predator mediated competition cooperation Predators and prey relation affect directly human needs
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Toxic chemicals, body armor, extraordinary
speed, ability to hide strategies to protect
from predators
Chemical defenses: distinct coloration and
patterns
Coevolution: physical an behavioral changescan become mutually beneficial
Batesian Mimicry
Mllerian mimicry
Poison dart native to Central and South America.
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Non-antagonistic interaction and even
beneficial, with their fates linked
Mutualism: enhance survival of one orboth partners, combining tissues to
mutual benefit.
Commensalism: one member clearlybenefits and the other apparently is
neither benefited nor harm.
Parasitism: a form of predation whereparasite depend on the host.
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A species or group of species whoseimpact on a community are much larger
than would be expected from mereabundance.
Change competitive relationships
change in food availability
Maintain the balance of ecosystems
Example: tropical figs/ Groups fungi Keystone species common in aquatic
habitat than terrestrial ones
Keystone species increase niche diversity
Giant Brown Alga
Tropical Figs
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Exponential growth- theunrestricted increase in a populationbut possess a distinctive shaped
when graphed over time.
Logistic growth:with unlimitedresources may, they may growth
exponentially but this slows as carryingcapacity is approached or exceeded
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Species deal with limiting factors in their environment
R-selected species:depend on a high rate of reproductionOvershoot carrying capacity then experience population crushes
Grow exponentially, expend energy in giving birth to progeny, highmortality
Low trophic levels in their ecosystems niche generalists
K-selected species: slower growth conditions near the carryingcapacity
Crucial - ability to compete for limited resources
Grow logistically, expend energy raising progeny
Live in stable biological communities, such as late-successional orclimax forests
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Properties of biological communities andecosystems
Diversity vs abundance Community structure and patchiness
Individuals /species spaced differently
Arranged over a large geographic area or landscape
Meet relatively uniforms interiors and edges
Distribution of members of a population in a given space can be:
Random- individuals live wherever resources are available Uniform - often the result of biological competition Clustered- individuals of a species cluster together for protection,
mutual assistance, reproduction, or to gain access to a particularenvironmental resource
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Communities distributed in patterns across a Landscape Land with patches of different colors and
shapes Each patch - biological community with
its own set of species and environmental
conditions
Largest patches contain core habitat Ecotone: outside habitat cores, species
encounter different habitat or border between
communities
Rich in species - individuals from both
environments occupy the boundary area
edge effects) Environmental conditions blend and the
species and microclimate of one
community cant penetrate the other
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Community properties
Complexity: refers to thenumber of trophic levels in
a community, groups ofspecies performing and to
the number of species at
each of those trophic
levels.
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Community properties Resilience: either resist or recovers quickly for disturbance.
Complexity - less resilient
Community diversity - resilience
Stability:communities resist changes despite disturbance. Three kinds of stability or resiliency in ecosystems:
Constancy - lack of fluctuations in composition or functions
Inertia - resistance to perturbations
Renewal - ability to repair damage after disturbance
Primary productivity - a community's rate of biomass production, or theconversion of solar energy into chemical energy stored in living
Net primary productivity =primary productivity - energy lost (resp.) High productivity: tropical forests, coral reefs, bays, estuaries
(abundant resource supply) Low Productivity: desert and tundra lack of water limits
photosynthesis and productivity is low.
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Climax community: the community that
developed last and lasted the longest
Process as a relay: species replace each
other in predictable groups and in a fixed
regular order.
Climax community determinate by climate
Maturation of an organism
Succession:organisms occupy a site and
change the environmental conditions
Primary succession:land is bare as soil and
then is colonized by living organisms where
none lived before
Secondary succession: a existing community
is disturbed and a new one develops from
the biological legacy of the old.
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Disturbances within communities Disturbance: any force that disrupts the established patterns of species
diversity and abundance, community structure or properties People and animals create disturbances
Extensive changes take centuries to recover
Breaking the grip of a super-competitor helpful role of disturbances
Examples:landslides, mudslides, hailstorms, earthquakes, hurricanes,tornados, tidal waves, wildfires and volcanoes
Landscapes with unstable Climax Characterized by periodic disturbances
Made up of disturbance-adapted species Fires able to suppress competitors, prepare ground for seed to germinate,
split thick seeds coats and release seeds. Disturbances essential for maintaining a ecosystem
Floods help to maintain food-plains and river health
Reset the successional clock in every community
Stability over the long run