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Ecology I: Species, Populations, Communities and Ecosystems
Ecology ISpecies interactions, Populations, Communities and Ecosystems
ECOLOGY Ecology: the scientific study of
relationships between organisms and their environment Includes the study of the ecosystem structure
and function
Ecology I: Species, Populations, Communities and Ecosystems
Ecologist vs. Environmentalist Is an ecologist an environmentalist? No, not necessarily An ecologist is a scientist studying how
ecosystems work and the relationship between organisms and their environment
An environmentalist is an individual interested in the environment (and may or may not be a scientist)
Ecology I: Species, Populations, Communities and Ecosystems
Ecology I: Species, Populations, Communities and Ecosystems
Levels of organization in the living world: large scale to small scale
Biosphere
Ecosystem
Community
Population
Organism
The sum total of living things on Earth and the areas they inhabit
A functional system consisting of a community, its nonliving environment, and the interactions between them
A set of populations of different species living together in a particular area
A group of individuals of a species that live in a particular area
An individual living thing
Ecology I: Species, Populations, Communities and Ecosystems
Ecology I: Species, Populations, Communities and Ecosystems
Levels of organization in the living world Organism: an individual living thing
Classified by ancestry into species 1.75 million named so far Maybe 3-100 million total
Why are we still so unsure of the number of species on Earth?
Some areas remain little explored (hydrothermal vents, rainforest canopies, tropical soils).
Many species are tiny and inconspicuous (microbes, roundworms, protists, fungi…).
Some species are very similar in appearance (many taxa, even trees, birds, whales).
Levels of organization in the living world
Ecology I: Species, Populations, Communities and Ecosystems
Species One or more populations
Ecology I: Species, Populations, Communities and Ecosystems
Species One or more populations whose members
actually or potentially interbreed under natural conditions
Ecology I: Species, Populations, Communities and Ecosystems
Species One or more populations whose members
actually or potentially interbreed under natural conditions and produce fertile offspring.
Levels of organization in the living world
Organisms: Population: group of individuals of same
species occupying a given area at the same time
Ecology I: Species, Populations, Communities and Ecosystems
Ecology I: Species, Populations, Communities and Ecosystems
Levels of organization in the living world Organisms: Population: Community: a set of populations of
different species occupying a particular place
Ecology I: Species, Populations, Communities and Ecosystems
Levels of organization in the living world Organisms: Population: Community: Ecosystem: community(ies) interacting
with one another and with the physical environment in a particular place
Ecology I: Species, Populations, Communities and Ecosystems
Levels of organization in the living world
Ecosystems: Include abiotic factors such as climate, water,
minerals and sunlight as well as biotic factors such as organisms
Ecosystems are the fundamental operational unit of ecology
Ecology I: Species, Populations, Communities and Ecosystems
Species: Distribution & Interrelationships
Ecology I: Species, Populations, Communities and Ecosystems
What determines whether a species will occur at any given place and time?
I. It must be able to get there Evolution, Immigration, Introduction
II. It must be able to survive there Biological and Physical Environment
III. It must be able to reproduce there Suitable mates and environment, etc.
Ecology I: Species, Populations, Communities and Ecosystems
I. Getting there
1. Evolution 2. Immigration:
range expansion
Ecology I: Species, Populations, Communities and Ecosystems
I. Getting there 1. Evolution 2. Immigration 3. Introduction
introduced = exotic = alien species versus native and endemic species
Ecology I: Species, Populations, Communities and Ecosystems
Introduction: Exotic Species
•European Starling
Ecology I: Species, Populations, Communities and Ecosystems
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there 1. Physical environment 2. Biological environment
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Habitat An organism’s place or type of place in
which it lives and thrives. Includes food, water, cover, and space
Microhabitat: the part of the habitat the organism is “really” using
Ecology I: Species, Populations, Communities and Ecosystems
Microhabitat: the part of the habitat the organism is the part of the habitat the organism is “really” using“really” using
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Niche
What the organism does in its habitat Includes all the physical and biological
factors and interactions of the organism
Ecology I: Species, Populations, Communities and Ecosystems
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Niche Specialists versus Generalists
Plants and animals with narrow tolerance ranges and/or specific dietary constraints, etc. = Specialists
Plants and animals with wide variety of habitats, foods, etc = Generalists
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Niche Specialists versus Generalists
Which is more prone to extinction?
Wolf Coyote
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Niche Which is more prone to extinction?
The wolf—a specialist (carnivore)? The coyote—a generalist (omnivore)?
Answer: the wolf
Ecology I: Species, Populations, Communities and Ecosystems
Fundamental versus Realized Niches
Wolf Coyote
Removal of wolfAllowed coyotesTo expand to fill
Fundamental niche
Surviving there: Niche
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Physical Environment 1. Range of tolerance
The range of variability in a particular physical factor that an organism can withstand
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Physical Environment
1. Range of tolerance What an organism can tolerate depends
on…Adaptation: (population level) due to
past evolutionAcclimation: (individual level)
Physiological changes within an individual to slowly changing new conditions
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Physical Environment
2. Limiting Factors All it takes is one single factor to be outside
of the range of tolerance to limit population growth
This factor is called the limiting factor
Ecology I: Species, Populations, Communities and Ecosystems
Limiting Factors and Saguaro distribution:saguaros are limited to the north by freezing temperatures and to the south by competition with other plants
Ecology I: Species, Populations, Communities and Ecosystems
II. Surviving there: Biological Environment
Mutualism: both gain Predation: predator gains, prey loses Parasitism: parasite gains, host loses Competition: both lose Commensalism: one species benefits; the
other is unaffected Biological environment=interrelationships
INTERRELATIONSHIPSDifferent ways to get along, or not get along
Predation + -
Competition - -Parasitism + -
Commensalism + o
Mutualism + +
+ = benefit- = harmed0 = unaffected
INTERRELATIONSHIPSMutualism
Which Type?
Both gain
INTERRELATIONSHIPSCompetition
Which Type?Both the bobcat and coyote lose
INTERRELATIONSHIPSParasitism
Which Type?
The parasite gains, the host loses
INTERRELATIONSHIPSPredationWhich
Type?
Predator gains, Prey loses
INTERRELATIONSHIPSCommensalism
Which Type?
Snake gains home, rodent unaffected (hole abandoned long ago)
INTERRELATIONSHIPS: Review
MutualismWhich Type?
Both gain
INTERRELATIONSHIPS: Review
CompetitionWhich Type?
Both lose available
soil moisture
III. Reproduce there
Ecology I: Species, Populations, Communities and Ecosystems
•Must find suitable mate
•Offspring must be able to survive to reproductive age in order to ensure on-going presence of population