Transcript EVOLUTIONARY ECOLOGY A HISTORICAL PERSPECTIVE

EVOLUTIONARY ECOLOGY
A HISTORICAL PERSPECTIVE
Evolutionary ecology is probably best
described as an approach to the study
of ecology
1.
2.
Recognized by the way in which
ecological problems are conceived and
analyzed using ecological, genetic and
evolutionary principles
Branch that considers how organisms
have evolved to become adapted to
their environment
Take Home Message for Today
Ecology developed considerable autonomy in the first
half of this century, thus the fusion of ecology and
evolutionary biology was a real event.
Three elements led to the emergence of Evolutionary
Ecology
1. Proximate-ultimate perspective (or FunctionalEvolutionary/Historical perspective)
2. Commonness of microevolution
3. Strength with which natural selection was expected to act at
various levels of biological organization
NOW, THE REST OF STORY!
Uniting concepts from ecology
and evolutionary biology
Why would one ask, what is
“nonevolutionary” ecology?
For much of the early history of
ecology and evolution, the
distinction between the fields was
blurred or nonexistant
Nonetheless, ecology developed
considerable autonomy throughout the
first half of this century
Reasons include the following
1.
2.
3.
Perceived need for ecology to gain
respect as an independent science
Adaptive radiation into specialized niches
The core concept of Darwin’s theory,
natural selection, fell into disrepute for
much of the early 20th century
Because ecology did develop
considerable autonomy throughout
the first half of this century, its
conjunction with evolutionary
biology in the 1960’s was a real
event
Orians, G.H. 1962. Natural
selection and ecological theory.
American Naturalist 96:257-263
There were 3 elements that led to the
emergence of evolutionary ecology
1.
2.
3.
Functional-evolutionary or proximateultimate perspective
Commoness of microevolution in
natural communities
Strength with which natural selection
was expected to act at various levels
of biological organization
Functional biologists focus on “how”
biological processes operate
Evolutionary biologists pursue
causation by asking “why” a particular
trait has evolved
Neither alone provides a
complete explanation
Mayr , E. 1961. Cause and effect
in biology. Science 134:15011506.
Four factors need to be considered
1. An ecological cause
2. A genetic cause
3. An intrinsic physiological cause
4. An extrinsic physiological cause
The immediate causes of migration are
the physiological condition of the bird
and the sudden decrease in temperature
These are the proximate causes of the
migration
Mayr contrasts them with lack of food
during the winter and the genotype of
the bird, both of which are ultimate
causes of migration
Ultimate causes are distinguished
primarily by their historical component
Commoness of Microevolution
“increasing evidence has been accumulated to
show that evolutionary, population genetic,
biogeographic, and demographic events are
not on entirely incommensurate time scales”
This condensation of scales was
probably an important factor in the
union of ecological, genetic and
evolutionary theory during and since
the 1960’s
As evolutionary ecology developed
two different approaches were
taken
1.
2.
One approach combined population
genetics and ecology
The adaptationist approach
Level of Selection
V.C. Wynne-Edwards and
Group Selection
vs.
G.C. Williams and
Individual Selection