Indicator Species (Pollen)
Definition
Pollen taxa with restricted geographic ranges or specific habitat requirements, contrasted with background species that occur everywhere; indicator species provide site-specific geographic evidence.
- Field
- Forensic palynology, soil examination
- Contrast
- Background species vs indicator species
- Value
- Site-specific geographic evidence
Common questions
How do soil examiners use indicator species pollen to link a suspect to a scene?+
A pollen profile from soil on a suspect's shoes or vehicle is compared to the profile at the scene, and a match on restricted-range indicator taxa carries far more weight than a match limited to ubiquitous background pollen found almost anywhere.
Why is background pollen still recorded even though it lacks discriminating power alone?+
The full assemblage, including common species, establishes a baseline that helps confirm the sample is a genuine environmental profile rather than a contaminated or mixed one, and unusual ratios among background species can still support a comparison.
Related terms
- Bromobenzene
- C6H5Br, density 1.50 g/cm3; the lighter component of the forensic density-gradient liquid mixture.
- Bromoform
- CHBr3, density 2.89 g/cm3; the denser component of the forensic density-gradient liquid mixture, used to create the bottom of the density range.
- D-Spacing
- The perpendicular distance between adjacent parallel planes of atoms in a crystal lattice, measured in angstroms or nanometres. Each set of planes...
- Density-Gradient Column
- Glass column filled with stepwise layers of liquids of decreasing density (commonly bromoform 2.89 g/cm3 and bromobenzene 1.50 g/cm3 mixed in known...
- Diatom Frustule
- The siliceous cell wall of a diatom, composed of biogenic opal; species-specific in shape and ornament, and resistant to degradation in soil...
- Forensic Palynology
- The application of pollen and spore analysis to legal investigations. A forensic palynologist identifies the species composition of pollen assemblages from crime-scene...
- Heavy-Mineral Fraction
- The sub-fraction of soil mineral grains with density above 2.85 g/cm3, including pyroxene, hornblende, garnet, zircon, rutile, and tourmaline; particularly diagnostic of...
- Laser Diffraction (PSD)
- A particle-size analysis technique that measures the angular distribution of laser light scattered by suspended particles to produce a continuous grain-size distribution...
- Murray-Tedrow Framework
- The tiered forensic-soil comparison protocol established by Raymond Murray and John Tedrow in their 1992 text 'Forensic Geology,' which organises soil examination...
- Powder XRD
- X-ray diffraction analysis of a finely ground mineral sample, producing a diffractogram with peaks at positions (2θ angles) diagnostic of crystalline mineral...
- Sporopollenin
- The highly chemically inert polymer forming the outer wall (exine) of pollen grains and spores. Resistant to acid, alkali, oxidation, and biological...