Adaption, Ecology and the
Environment
11.1 The received view in Ecology
11.2 History and Theory in Ecology
11.3 The Balance of Nature
11.4 Niches and Organisms
11.5 Reconstructing Niches
11.6 Unfinished Business
11.1 The Received View in Ecology
Ecology versus Evolutionary Theory
● Ecology as a description of Environment
● The concept of the Niche
●
11.1 Ecology versus Evolutionary
Theory
ecology:
short term view on a local area
or local community
11.1 Ecology versus Evolutionary
Theory
ecology:
short term view on a local area
or local commuity
evolutionary theory:
long term global view
11.1 Ecology
ecology is a way of explaining evolutionary
fitnesses of organisms;
and so it is formulating the source laws of
evolutionary biology;
11.1 Ecology as a description of
Environment
it describes the environment where evolutionary
changes take place;
11.1 The concept of the Niche
Elton's concept of a niche:
a way of making a living in an organic community;
11.1 The concept of the Niche
Elton's concept of a niche:
a way of making a living in an organic community;
different organisms can play the same causal roles in
different communities;
grazers->predators->scavengers->seed eaters...
11.1 The concept of the Niche
Elton's concept of a niche:
a way of making a living in an organic community;
different organisms can play the same causal roles in
different communities;
grazers->predators->scavengers->seed eaters...
still members of the same niche:
communities that are widely scattered in space and
time but functionally similar
11.2 History and Theory in Ecology
Signals sent by history
●Island biogeographie
●
11.2 Signals sent by History
reconstruction of history by its traces in the present
signals in the form of jointly inherited features
convergence and divergence are noise and disturb
the “signal“
11.2 Island Biogeography
an ahistorical view by MacArthur:
diversity only depends on the size of an „island“ and
its distance from immigration sources
11.2 Island Biogeography
an ahistorical view by MacArthur:
diversity only depends on the size of an „island“ and
its distance from immigration sources
=>
time and accidental historical developments play a
minor role
11.2 Island Biogeography
an ahistorical view by MacArthur:
diversity only depends on the size of an „island“ and
its distance from immigration sources
=>
time and accidental developments play a minor role
do islands of the same size and physical similarity
have simular communities?
11.3 The Balance of Nature
communities can get close to reach equilibrium
conditions
but they need internal checks and balances
(competion, predation, parasitism, ...)
there is always the possibility of devastation from
outside
in reality equilibrium is never reached
the return time from disturbance is shorter than the
life span of the community's dominant elements
11.4 Niches and Organisms
Classic view:
organisms are shaped to fit their niche
11.4 Niches and Organisms
Classic view:
organisms are shaped to fit their niche
Lewontin:
organisms construct environments “as much as”(?)
environments construct organisms
niches are defined by their occupants, they do not
exist by themselves
Two concepts of environment
Godfrey-Smith:
properties defined by an organism
(e.g. territory)
other properties
(e.g. temperature)
Three concepts of environment
Robert Brandon:
external environment
(physical factors, biotic and abiotic)
Three concepts of environment
Robert Brandon:
external environment
(physical factors, biotic and abiotic)
ecological environment
(factors that affect the organism's reproductive output)
Three concepts of environment
Robert Brandon:
external environment
(physical factors, biotic and abiotic)
ecological environment
(factors that affect the organism's reproductive output)
selective environment (ctitical for evolutionary
theory)
(factors that differentially affect the reproductive output
across a range of individuals)
11.5 Reconstructing Niches
The authors prefer Lewontin's concept of the Niche
but would make some extensions
11.5 Reconstructing Niches
The authors prefer Lewontin's concept of the Niche
but would make some extensions
The dimensions of the niches should be determined
by the clade and not by the species that belongs to it
=> a more generalistic and long-lasting solution
11.6 Unfinished Business
the nature of ecology's units is problematic
11.6 Unfinished Business
the nature of ecology's units is problematic
communities in small islands can de recognized
but what about an area with a smooth change from
closed forest to woodland and from woodland to
grassland?
there will be no well defined membership in such
communities...