2.1 - field techniques for biologists

Hazards of fieldwork

adverse weather conditions, difficult terrain, problems associated with isolation, and contact with harmful organisms

Risk

the likelihood of harm arising from exposure to a hazard

Risk assessment

the likelihood of harm arising from exposure to a hazard

Control measures include…

appropriate equipment, clothing, footwear, and means of communication

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.

What sampling technique is used for plants and other sessile or slow-moving organisms

Quadrats of suitable size and shape or transect

Transect

A line along which different samples can be taken using a quadrat

What sampling technique is used for mobile species?

Capture techniques eg traps or nets

What sampling technique is used for elusive species?

directly using camera traps or an indirect method, such as scat sampling

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

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

Taxonomy

involves the identification and naming of organisms and their classification into groups based on shared characteristic

Classic taxonomy classification is based on…

morphology

Phylogenetics

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

How does phylogenetics work?

It uses heritable traits such as morphology, DNA sequences, and protein structure to make inferences about an organism’s evolutionary history and create a phylogenetic tree. Genetic evidence can reveal relatedness obscured by divergent or convergent evolution.

Taxonomic group examples

nematodes, arthropods, chordates

Model organisms from taxonomic groups examples

Bacterium E.coli, flowering plant arabidopsis thaliana, C.elegans, fruit fly, mice, rats and zebrafish

Absence or reduced population indicates…

a species is susceptible to some factor in the environment

Abundance or increased population indicates…

a species is favoured by the conditions

Procedure for mark and recapture

A sample of the population is captured, marked and released. After an interval of time, a second sample is captured. If some of the individuals in this second sample are recaptured, then the total population can be made.

When estimating population size by mark and recapture the following assumptions are made:

All individuals have an equal chance of capture, there is no emigration of marked individuals nor immigration of other individuals, individuals that are marked an released can fully and randomly with the total population

Latency

the 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

What does an ethogram show?

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

Anthropomorphism

Important to avoid when analysing behaviour as it may involve assigning human emotion to animal behaviour and can lead to invalid conclusions