|Niches to fill.
species has its niche
G. Tyler Miller
Appearance & Species diversity, (2005)
|Diversity to nourish.
An ecologists view
of lifes complexity
based on how a species
... its place in the grand scheme of things.
I. Making a Living
II. Capacity of resources to sustain organisms
III. Reproductive strategies
I Introduction explains
"earning ones keep"
4. competitive quest for food, fuel, fiber & forage
B. niche is defined
"its place in the grand scheme of things"
uses wolf spiders
(Wilson's Storm, in ¶ 4, p. 153)
3: the complexity of a wolf spiders life [but wolf spidering is their
NICHE as "a word borrowed from church architecture"
C contrast between
niche (function) & habitat (place)
to "habitat "as a "physical living place, address or
6: idea of
"niche" helps us understand the "constancy of numbers."
paragraphs to explain "a lifestyle that enables it to survive...."
"The reproductive effort makes no difference to the
II. Limitations inherent
in Carrying Capacity
A. limits are defined
& 8: limitations on the number able to fill a niche
B. carrying capacity
capacity is defined as a functional ability of land to sustain a certain
size population over time without diminishing lifes ability
through individuals to exploit available niches.
III. Competing reproductive
strategies assure survival
A. natural selection
1. twin gambits
a. small - numerous
of eggs (see Zwinger, ¶ 22, p. 104) to show what is necessary
to fill a niche
10, "The actual number of those who will be able to live in
that next generation has been fixed by the environment; we may say
that the population will be a function of the carrying capacity
of the land for animals of this kind in that time & place."
13, "A selfish race of neighbor against neighbor leads to those
thousands of tiny eggs and the early deaths of the babies are the
cost of this selfishness."
b. large young
2. numbers of
eggs and food supply
B. economy of behavior
C. optimization of time, expenditures and resources
Niche is a means to
- the physical
and chemical constraints
- imposed on biological
- by the environments
growing numbers on limited resources.
Colinvaux Every species has its niche (p. 259-264)
the structure of a community in terms of its physical appearance, species
diversity, species abundance, and niche structure.
Differences at boundaries
between two ecosystems result in edge effects.
do species do ecologically?
Species diversity, appearnace of dominance.
on continents declines with distance from the equator (latitude). In marine
communities, species diversity varies with depth and pollution levels.
In terrestrial communities, species diversity increases with increasing
solar radiation, increasing precipitation, decreased elevation, and pronounced
MacArthur and Wilson's
species equilibrium model predicts that species diversity
will increase with island size and with proximity to a mainland. Field
experiments have supported the model.
General Types of Species
species have suffered as a result of the introduction of nonnative
Birds are excellent
indicator species and can serve as an early warning
of damage to a community.
The decline of a keystone
species can cause a ripple effect through an ecosystem.
7-3 Species Interactions:
Competition and Predation
competition can be intense because members of the same species require
the same resources.
The more the niches
of two species overlap, the greater the degree of interspecific
competition. Over time, resource partitioning
may enable similar species to coexist.
benefits a predator at the expense of its prey. Carnivores feed on mobile
prey; herbivores feed on plants. Predators have evolved a variety
of ways to increase their chances of finding food, and prey have evolved
various ways to defend themselves against or avoid predators.
Symbiotic Species: Parasitism, Mutualism, and Commensalism
There are three
types of symbioses among
organisms: parasitism, mutualism,
Ecological Succession: Communities in Transition
The two types of
ecological succession are primary
succession and secondary succession.
With primary succession,
pioneer species colonize an area. Over time, they
may be replaced by early successional plant species,
which may be replaced by midsuccessional plant species.
These species can
give way to late successional plant species. However,
research indicates that we cannot predict the course of succession or
view it as progress toward an ideally adapted climax community.
Disturbances or changes
in environmental conditions disrupt an ecosystem
or community and affect its species diversity and stage of succession.
According to the
intermediate-disturbance hypothesis, communities that experience
fairly frequent but moderate disturbances have the greatest species diversity.
Chapter 7, pp. 140-157
His article is important because:
Creates a structure to understand Wilson, Dillard, Myers, & Leopold.
Introduces game theory in the form of strategies for reproduction.
Is a prerequisite for understanding Hardins The Tragedy of
Calls our attention to constraints on reproduction, dispersal and survival.
The chapter's importance
lies in the fact that it suggests signals we need to read if we are to
understand the fitness of the ecological system to sustain, both human
and non-human needs.
The chapter establishes
two kinds of capacity:
capacity is the absolute number of creatures an ecosystem's vegetation
may sustain without diminishing future needs.
capacity is the quanitity of pollutions, harm, or decay an ecosystem
may sustain before its capacity to nourish additional organisms is depleted.
Paradox of competitive exclusion:
Every family tries to outbreed every other, though the total numbers
remain the same
of ecosystem stability as it emerges out of competitive
behavior, partitioning and symbiotic arrangements to accustom creatures
to adapt to losses of or changes in keystone species.
Adaptive responses are needed to both changes in habitat
and changes in species mixture.