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Flashcards in Biodiversity, Ecology and Conservation Deck (260)
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Definition of ecology

Interaction between organisms (biotic) and their environment (biotic and abiotic)


Definition of biological species

Two organisms which cannot breed to produce viable, fertile offspring


Definition of population

A group of individuals of 1 species living and interacting in one area at a given time


Definition of community

Associations of populations of 2 or more different species in the same area


Definition of ecosystems

Community and physical environment and the transfer between different trophic levels in the whole environment


Definition of landscapes

Areas with considerable differences e.g. multiple ecosystems


Definition of biosphere

All the world's ecosystems i.e. all living organisms and their environment


Definition of assemblages

A group of similar animals e.g. an assemblage of birds


Definition of population dynamics

How population size varies through time


Basic population equation and what it is used to calculate

Nt+1 = Nt + B - D + I - E
To calculate population size for animals with annual breeding cycles


Definition of geometric growth

Species population changes in size by a constant proportion in discrete time steps


Definition of exponential growth

Species population with continuous reproduction changes in size by a constant proportion at each instant in time


When does unlimited population growth occur?

- no competition and unlimited resources
- in small populations
- Newly colonised regions
- e.g. Muskox, Alaska


Important population measures

1. Population size i.e. number of individuals
2. Population density i.e. number of individuals/ area or vol


What are area-based counts

Count sessile individuals or vegetation using quadrats or aerial surveys for large mammals in a known area


What are distance-based counts

Measure distances individuals seen from a transect line/ point to estimate relative number of individuals/ unit area


Definition of relative population size

Number of individuals in time/ place relative to a number in another


Methods used to measure population sizes

1. Area-based counts
2. Distance-based counts
3. Capture, mark, release, recapture


Capture, mark, release, recapture equation to estimate population size

Total population (N) = (Number marked first catch (M) x total caught second catch (C) / number marked second catch (R)
N = (M x C)/R


Assumptions and issues with capture, mark, release, recapture

1. No B, D, I or E between M and R i.e. equal chance of capture
2. No harm during process
3. Marks do not fade
4. Overestimate if animals learn to avoid recapture
5. Underestimate if animals get preferentially caught


Definition of intraspecific competition

Competition within members of the same species as similar resource requirements i.e. demand>supply


Definition of interspecific competition

Competition between different species where both suffer negatively


Definition of carrying capacity (K)

The upper sustainable limit of a population


Begon et al. (1996) intraspecific comp. characteristics

1. Effect is a measurable reduction in an individual's contribution to future generations
e.g. a) fecundity (Cain 2011) - song sparrow breeding pairs and offpsring survival b) survivorship (van Balen 1980) - supplementary feeding and great tit breeding pairs
2. Resources must be in limited supply
3. Reciprocity e.g. bird of prey chicks, spadefoot toad phenotypic plasticity
4. Density dependent e.g. Tribolium confusum, soybean survivorship


Population growth models

1. Exponential growth equation
2. Discrete logistic growth equation


Exponential growth equation

Nt+1 = reproductive rate x Nt

(Nt = pop. size)


Discrete logistic growth equation

Represents intraspecific competition
Nt+1 = reproduction rate x Nt (1 - Nt/K)
- calculate N at different time phrases
- plot Nt (y) against time (x) to see population growth


Characteristics of density dependence

- closely linked to intraspecific competition
- regulates population sizes around an optimum K value


Population regulation

1. Regulating equilibrium around K by DD factor regulation (pop. often fluctuates)
2. DD factors do not regulate if there is a time delay or if it only regulates in certain environmental conditions
3. Different factors, e.g. food, waste, predation, may cause DD


What is cobwebbing (Ricker-Moran plots), how to use them and features?

Graphical method to predict the results of intraspecific competition and show population dynamics
- plot curve represented by the discrete logistic growth equation
- plot straight line to present unchanging population around K
- plot graph N against time
Changes to curve shape can majorly impact population stability and dynamics
Patterns vary i.e. cycles, oscillations, fluctuations