Succession Model
Definition
The predictable sequence of arthropod species assemblages that colonise remains as decomposition progresses through fresh, bloat, active decay, advanced decay, and dry stages. Each stage has characteristic indicator species, extending the PMI window beyond what larval development alone can address.
- Field
- Entomological PMI estimation
- Stages covered
- Fresh, bloat, active decay, advanced decay, dry
- Content
- Predictable arthropod species assemblage sequence
- Benefit
- Extends PMI estimation beyond larval-development range
Common questions
Why does the model extend the PMI window beyond larval development alone?+
Larval development windows are tightly linked to the earliest days after death, before certain later-arriving species even reach the body. Tracking which stage of the succession sequence is present lets an entomologist bracket a PMI even weeks after death, once the fly larvae used for precise ageing have already emerged as adults or moved on.
What can disrupt a succession model's reliability in a real case?+
Burial, wrapping, indoor placement, or unusual climate can delay or block the normal arrival order of colonising species, meaning the observed assemblage may not match what the standard sequence predicts for that elapsed time. Investigators check scene conditions for such disruptions before relying on the model.
Related terms
- Accumulated Degree Hours (ADH)
- A temperature-corrected measure of developmental time. Calculated by summing (hourly ambient temperature minus the species-specific base temperature threshold) across the period of...
- Calliphoridae
- The blowfly family: metallic-coloured flies that are typically the earliest colonisers of exposed remains. Forensically important genera include Calliphora, Lucilia, Chrysomya, and...
- COI Barcoding
- DNA-based species identification using a standard 658 bp segment of the mitochondrial cytochrome oxidase subunit I gene. Sequences are matched against reference...
- Instar
- A developmental stage between moults (ecdysis). Blow flies have three larval instars (L1, L2, L3), each ending when the larva sheds its...
- Post-Mortem Interval (PMI)
- The time elapsed between death and discovery or examination of remains. PMI estimation draws on multiple disciplines: soft tissue decomposition stage, insect...