chapter1 Flashcards
Ecology: definition
Ecology is the scientific study of the distribution and abundance of organisms, the interactions that determine that distribution and abundance, and the relationships between organisms and the transformation and flux of energy and matter
proximate question
an explanation in terms of the present situation
e.g.
How does a bat transmit echoes?
How do pigeons find their way back?
What is the effect of April frost on seedlings?
ultimate question
an explanation in evolutionary terms
e.g.
Why is a bee brightly coloured?
Why does a bird give parental care?
Why do polar foxes have small ears?
biological scales
Individual
Population
Community
Ecosystem
Landscape
Biosphere
example small scale (individual)
HIV-positive patients infected with GBV-C virus live longer and have fewer HIV viruses in their blood
GBV-C virus may compete with HIV for cells to infect
example big scale (biosphere)
Phytoplankton in the oceans take up carbon dioxide
Part of this fixed carbon dioxide is stored in ocean floor sediments
The oceans slow down global warming
Spatial scales in ecology
Spatial scales ≠ ecological scales!
Individual ecology can take place at global scales
Ecosystem ecology can take place at the smallest scales in the living world
Time scales in ecology
Generation time
Lifespan of organisms
Succession time scales
Generation time
The time from birth to fertility
Varies between 20 minutes (E. coli) to 10.000+ years (endolithic deep-sea bacteria)
E.g. to measure genetic drift in populations
Lifespan of organisms
The time from birth to death
Can vary between a few days (aphids) to 200 years (tortoises)
E.g. to assess different reproductive strategies and overall reproductive success
biological immortality
A stable or decreasing rate of mortality from cellular senescence as a function of chronological age.
Bacteria
Cancer cells
Hydra’s
Lobsters
succession time scales
Succession: The successive and continuous colonization of a site by certain species accompanied by the extinction of others
Can vary from days to 10.000+ years
Observations in the natural environment: Sources of ecological evidence
Observations in the natural environment: spatial and temporal monitoring of species.
Patterns often require explanation that can not be provided by observation alone
Manipulative field experiments, Sources of ecological evidence
Manipulative field experiments: often expensive, difficult and with little control of variables
Laboratory experiments, Sources of ecological evidence
Laboratory experiments: offer a controlled environment
A good way to answer specific questions
Ecological (mathematical) models,Sources of ecological evidence
Ecological (mathematical) models: an artificial environment to test ecological hypotheses
Omit the need to keep living organisms
Hubbard Brook manipulative field experiment
Measurements were made of the quantity and chemical composition of water entering and leaving 6 watersheds.
In one of the watersheds all the trees were felled
The overall export of dissolved anorganic matter rose to 13 times the normal rate
developed small watershed technique to measure the in and output of chemicals from individual forest areas
when tez cut the leaves of one of the parts thez discovered
enormous reduction in transpiring surfaces led to 40% more of the input precipitation being exported again as water in the tsreams, carrzing with it more dissolved substances. secondly as microbes decomposed organic matterand made substances available in solution, the trees no longer were there to assimilate these materials, they were flushed from the system with the exported water
Annual species
complete a whole generation from seed to adult through to seeds again within a year — tend to be good
at increasing in abundance rapidly in relatively empty habitats (the early stages of succession);
perennial species
those that live for several or many years and
may not reproduce in their early years — are slower to
establish but more persistent once they do.
how manz ecological research sites are in america atm
26
catchments
small watersheds
david schindler
whole ecosystem experiment to figure out human impact on lakes.
lake 227 had very low dissolved carbon dioxide they fertallized it with phosphorus and it rapidly became eutrophic. despite low co2 enough became available to support algeal growth.
Phosphorus was the real control on
algal growth and eutrophication in lakes.
eutrophication
excess growth of algae and cyanobacteria as a
result of excessive inputs of nutrients.
Cyanobacteria
A phylum of photosynthetic prokaryotes, also known as “blue-green algae.”
Mesocosm
An enclosed artificial ecosystem designed to mimic natural ecological processes
Phytoplankton
The autotrophic (self-feeding) components of the plankton community
Perennial species
A species with a life cycle of several years
Nitrogen fixation
he conversion of gaseous nitrogen (N₂) into more complex molecules by microorganisms.
Watershed
An area of land that drains all streams and rainfall to a common outlet.
Community
The species that occur together in space and time.
Ecological succession
The nonseasonal, directional, and continuous pattern of colonization and extinction on a site
Migration
The movement of individuals, or entire populations, from one region to another
Biosphere
The totality of all life interacting with the physical environment on the scale of the entire planet.
Ecosystem
A holistic concept of plants, animals, and their physical and chemical environment forming a self-contained entity
Population
A group of individuals of one species in a defined area.
Population dynamics
The study of variations in population sizes and densities and the factors causing these variations
Trophic level
A position in the food chain assessed by the number of energy-transfer steps
Primary productivity
The rate at which biomass is produced per unit area by plants
Dead zone
An area depleted of oxygen
