Lecture 2 studying ecology Flashcards
Scientific method
Observation
General hypothesis
specific hypothesis
Test
Samples & populations
Biological population
collection of individuals
same species
particular location
same time
Samples & populations
Statistical population
Individuals within specified time or space about which inferences can be made
potential sampling units
Samples & populations
Variable
Characteristics of a population which differ from individual to individual e.g. size
Samples & populations
Observation
measurement provided by each unit in sample
how to quantify error
statistical techniques
population dynamics
patterns and processes of population change over space and time
population dynamics
population size
number of individuals in a population
population dynamics
Density
number of individuals per unit area
population dynamics
Growth
change in population size over time
population dynamics
Dispersal
movement of individuals into (immigration) or out of (emigration) a population
population dynamics
Dispersion
spatial distribution patterns
measuring abundance (estimating population size and range)
small area/population - full census possible
population density for sample area = estimate total population size
sessile organisms - quadrats/transects
mobile organisms - mark recapture
eDNA (environmental DNA e.g. fur) estimating how many unique individuals in a population
Diversity
Abundance
Richness
Eveness
Scales of diversity
ecosystem
species
phenotypic
genetic
Diversity indicies (calculations)
affected by species richness and relative abundance of each species
diversity increases with
number of species
evenness (max diversity all species equally abundant)
distribution
density
dispersion
Spatial distribution
Density
Number of individuals per unit area (or volume)
Percentage cover
Spatial distribution
Dispersion
Pattern of spacing among individuals within the geographic boundaries of the population
Used to understand the structure of a population
Patterns vary according to scale and animals’ interaction with environment
what is spatial distribution of organisms affected by
Abiotic factors: environmental gradients, habitat heterogeneity & fragmentation
Dispersal
Reproductive mode
Behaviour: territoriality, selfish herds
Intraspecific interactions: competition
Interspecific interactions: competition, predation
Stochastic variation in all of the above
patterns of dispersion
clumped/aggregated
Unequal chance of individuals occurring anywhere
High local abundance separated by areas of low abundance
packs & selfish herds
WHY
Patchy resource distribution – attraction to common resource e.g. water
Mutual attraction between individuals
patterns of dispersion
Regular / uniform / hyperdispersed / repulsed
Individuals are uniformly spaced. avoid each other
Exclusive use of area
WHY
competition for resources/mates
Local depletion of resources - depletion zones
Antagonistic interactions - avoid or repel
patterns of dispersion
Random
Equal chance of individuals occurring anywhere
unpredictable spacing
WHY
Neutral interactions between individuals or between organisms and environment
scale of dispersion pattern
dispersion appears different on different scales
What ecologists measure
Variation within and between species
Abiotic interactions
- ecophysiology [how animals adapted to physical world]
- resource use
Biotic interactions
- animal behaviour
- competition
- predation
- altruism [unselfish]
Competition Commensalism Mutualism Predation Succession
Population dynamics
- variation in population size
range and dispersion pattern
over space and time
Abundance
Diversity
Distribution
Life history
