Community Assembly Flashcards
What processes influence community structure
Drift Selection Dispersal Speciation Alien species
Describe the current framework for describing community processes
Vallend 2010
Low level processes: Detailed hypothesis around which ecology is built
High level processes: no scale, local to continental
- drift
- selection
- dispersal
- speciation
Drift
- Random fluctuations to population size
- Independent of species identity
- eventually one species dominates: can take long time and the small populations see higher risks
Selection
Higher fitness species = natural selection = moe offspring
- there is always element of chance, not always the fittest
- in small populations the same effect as drift
- as pop size grows the effect of drift decreases and likelihood of 2 species extinction increases
Dispersal
The movement of individs between communities
- immigration or emigration
Mega community approach
- increase dispersal = more stable
- e.g. if one species began to become extinct, individuals from another community would take its niche
Speciation
Mainly of interest at larger spatial scales
Recent research shows can occur quickly e.g. microbial communities
Alien species
- Arrive via dispersal
- increases species richness
- over time there’s selection and drift that alters abundance distribution non community
Traditional view of ecology
Emphasises selection
May ignore dispersal drift and speciation
Niche view
Neutral models of ecology
Ignores selection
Includes speculation, dispersal and drift
Considers all species equal
Is a controversial topic
Very scientific approach that tests predictions
Current thinking in community ecology
That it is a middle ground between traditional and neutral models
- either can be more important in different contexts
- emphasises value of overall framework
