Population Terminology? Flashcards
Defining ecology
Coined by Ernst Haeckel 1896
Extended by Krebs 1972
‘ the scientific study of interactions that determine the distribution, abundance and activity of organisms’
Levels on integration in a community
3 main levels: ecosystems, communities, populations
- explanatory mechanisms are drawn from lower levels and mechanisms of significance are from higher
- everything is always interacting in nature
The issue of defining individuals
Expeditions to the rule: e.g. slime moulds, bacteria with colonies and films, yeasts are chains of buds
Are they multiple individuals?
Autecology
describing growth needs of an individual
E.g. max, min, optimum; PH, temp etc..
Habitat
Where an organism lives
Ecological niche can be split into..
Fundamental
Realised
Practical problems in measuring a niche
- Indefinite number of dimensions with variables that cant be linearly ordered or measured
- often focuses on a set point in time but most interactions dynamic and vary during life cycle e.g. competition
= need 2 or 3D models - models can often only be defined in retrospect
A realised niche
Subset of fundamental niche; is narrower
The niche actually occupied in nature
Nearly impossible to replicate in a lab
Factors in the affects of other species within its habitat e.g. role,of competition
Smaller than fundamental
Fundamental niche
Often the same size or larger than realised niche
All environmental conditions a species could live in
Doesn’t factor in affects such as competition
Define populations
Group of organisms of the same species
Occupying particular space at particular time
- boundary’s arbitrary and fixed by investigator
Features of a population
Size poor density
Age distribution
Genetic composition
Dispersion (in space and time)
How can population SIZE change over time
Birth
Death
Immigration
Emigration
Define communities
Any assemblage of living populations
In a prescribed area or habitat
What affects community structure
- species diversity; components, richness, evenness
- dominance
- relative abundance
- patterns
- intra/inter-specific interactions
Interspecific
Between members of different species
Intraspecific
Between members of the same species
Two ways to classify the interactions between 2 species
- the effects (end result)
- the mechanisms
Neither give perfect results
System of measuring interactions
Odum 1953
- interaction stated as positive, negative or neutral
Different types of interactions
Neutralism Competition Amensalism Parasitism and predation Commensalism Mutualism
Neutralism
Neither pop affects the other
00
Competition
Inhibition of each species by the other
- -
Amensalism
One pop inhibited. The other unaffected
- 0
Parasitism and predation
The predators/parasites increase. The other pop decreases
+ -
Commensalism
One pop increase. The other is unaffected
+ 0
Mutualism
Mutual increase
++
Factor that affect species distribution
Abiotic factors Resource requirements Interspecific interactions.g. Predation Conditions - natural - anthropogenic
Measuring an organisms performance
Often focus on fitness… but hard to measure
Can use simpler measures
- hierarchy of conditions : survival, growth rate, reproduction
Can use long term persistence threshold
- intrinsic rate of increase =/> 0
- reproducing at a rate that balances mortality
Types of response curve
Monotonic
Unimodal
Monotonic response curve
Threshold point = conditions too unfavourable, R below 0
Narrowing chance of reproduction, then growth then survival
Unimodal response curve
Species unable to survive at either end of extremities
Can get multiple peaks with multiple conditions, but not common with one factor
Defining resources
Consumed/used by resources
Leaves potential for competition
Single conditions/resources are a gross simplification
