Evolution, Biological Communities, and Species Interactions
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One of the most important concepts in biology
Adaptation
Two ways of using the term “Adapt”:(2)
• Acclimation • Genetic Traits
When an individual organism can respond immediately to a changing environment
Acclimation
Passed from generation to generation and allow a species to live more successfully in its environment
Genetic Traits
species change over generations because individuals compete for scarce resources
Evolution
The process of better-selected individuals passing their traits to the next generation
Natural Selection
Changes to the DNA Coding sequence of individuals that occurs occasionally, and the changed sequences are inherited by offspring
Mutations
Limitation factors of species: (4)
• Psychological Stress due to inappropriate levels of some critical environment factor • Competition with other species • Predation, including parasitism and disease • Luck
(1) According to the Chemist ___________, the single factor in shortest supply relative to demand is the critical factor determining where a species lives
Justus Von Liebig
Each environmental factor has both minimum and maximum levels, beyond which particular species cannot Survive - “limits where a particular organism can live”
Tolerance Limits - Victor Shelford expanded Liebig’s principle (Critical factor)
“determining where a species lives”
critical factor
can affect the distribution of young differently than they affect adults
Tolerance Limits
the place or set of environmental conditions in which a particular organism lives
Habitat
describes both the role played by a species in a biological community and the set of environmental factors that determine its distribution
Ecological Niche
According to him, each species had a role in a community of species and the niche defined its way of obtaining food.
Charles Elton
The American limnologist who, thirty years laters proposed a more biophysical definition of niche. According to him, every species exists within a range of physical and chemical conditions.
G. E. Hutchinson
species that tolerate a wide range of conditions or exploit a wide range of resources
Generalists
species that have a narrow ecological niche
Specialists
• the development of a new species • As a population becomes more adapted to its ecological niche, it may develop specialized or distinctive traits
Speciation
Two kinds of Speciation: (2)
• Allopatric Speciation • Sympatric Speciation
Speciation that occurs when population are geographically separated
Allopatric Speciation
Speciation that occurs within one geographic area
Sympatric Speciation
When the habitat are far enough apart that population were genetically isolated
Geographic Isolation
When two identical species live in similar habitats but have different mating calls
Behavioral Isolation