U2: KA1 Field Techniques for Biologists

Hazards in fieldwork

• adverse weather conditions

• difficult terrain

• problems associated with isolation

• contact with harmful organisms

Sampling should be carried out in a manner that…

minimises impact on wild species and habitats

During sampling of wild organisms, consideration must be given to…

rare and vulnerable species and habitats that are protected by legislation

Point count

• Point count involves the observer recording all individuals seen from a fixed point count location

• This can be compared to other point count locations or with data from the same location gathered at other times

State the two techniques which are used for sampling plants and other sessile or slow-moving organisms

Quadrats, of suitable size and shape, or transects

State the technique used for sampling mobile species

Capture techniques, such as traps and nets,

State the technique used to sample elusive species

Camera traps (direct method) or an indirect method e.g. scat sampling

Taxonomy

Involves the identification and naming of organisms and their classification into groups based on shared characteristics

Phylogenetics

The study of the evolutionary history and relationships among individuals or groups of organisms

Classic taxonomy classification is based on

morphology

Describe what phylogenetics use to make interferences about an organisms evolutionary history and create a phylogenetic tree

Heritable traits such as morphology, DNA sequences, and protein structure

Familiarity with taxonomic groupings allows…

predictions and inferences to be made about the biology of an organism from better-known (model) organisms

Examples of taxonomic groups:

• Nematodes

• Arthropods

• Chordates

Model organisms

Organisms that are either easily studied or have been well studied

Model organisms which have been very important to the advancement of modern biology include:

• the bacterium E. coli

• the flowering plant Arabidopsis thaliana

• the nematode C. elegans

• the arthropod Drosophila melanogaster (a fruit fly)

• the chordates: mice, rats, and zebrafish

Information obtained from model organisms can be…

applied to other species that are more difficult to study directly

Importance of monitoring population of indicator species

Presence, absence or abundance of indicator species can give information of environmental qualities, such as presence of a pollutant

Explain how susceptible and favoured species can be used to monitor an ecosystem

• Absence or reduced population indicates a species is susceptible to some factor in the environment

• Abundance or increased population indicates it is favoured by the

  conditions

Describe the process of mark and recapture

• A sample of the population is captured and marked (M) and released

• After an interval of time, a second sample is captured (C)

• If some of the individuals in this second sample are recaptured (R), then the total population is given by N = MC/R

Mark and recapture assumes that:

• individuals have an equal chance of capture

• there is no immigration or emigration

• individuals that are marked and released can mix fully and randomly with the total population

Methods of marking animals:

• banding

• tagging

• surgical implantation

• painting

• hair clipping

The method of marking and subsequent observation must…

minimise the impact on the study species

Measurements used to quantify animal behaviour:

• latency

• frequency

• duration

Latency

time between the stimulus occurring and the response behaviour

Frequency

the number of times a behaviour occurs within the observation period

Duration

the length of time each behaviour occurs during the observation period

Explain how an ethogram of the behaviours shown by a species in a wild context allows the construction of time budgets

Recording the duration of each of the behaviours in the ethogram, together with the total time of observation, allows the proportion of time spent on each behaviour to be calculated in the time budget

Ethogram

lists species-specific behaviours to be observed and recorded in the study

Importance of avoiding anthropomorphism when analysing behaviour

Anthropomorphism - the attribution of human traits, emotions or intentions to non-human entities - can lead to invalid conclusions

Phylogeny (or phylogenetic tree)

A diagrammatic hypothesis of an organism’s relationships to other organisms

Genetic evidence can reveal…

relatedness obscured by divergent or convergent evolution

Control measures used in field sampling

appropriate:

• equipment

• clothing

• footwear

• means of communication

Identification of an organism in a sample can be made using:

classification guides, biological keys, or analysis of DNA or protein