Species Complex
Definition
A group of closely related species that are nearly identical in morphology but behaviourally or ecologically distinct. Molecular methods are often the only way to separate them, and incorrect identification within a complex can shift a PMI estimate by hours.
- Field
- Forensic entomology, taxonomy
- Defining trait
- Near-identical morphology, distinct behaviour or ecology
- Resolution method
- Molecular identification (DNA sequencing)
- Casework impact
- Misidentification can shift a PMI estimate by hours
Common questions
Why can two species in a complex give different PMI estimates?+
Species within a complex can differ in development rate at a given temperature even though they look alike, so assigning the wrong species to a larval sample carries the wrong growth-rate data into the postmortem interval calculation.
Why not just rely on morphology under a microscope?+
Morphological features overlap so closely between species in a complex that visual keys cannot separate them reliably, which is why DNA barcoding is used as the standard resolution method in casework.
Related terms
- BOLD
- Barcode of Life Data System, an international curated database linking COI sequences to verified voucher specimens with collection locality and taxonomic annotation....
- COI (Cytochrome C Oxidase I)
- A mitochondrial gene encoding subunit I of the respiratory enzyme cytochrome c oxidase. Its intermediate evolutionary rate makes it the primary barcode...
- Cytochrome B (Cyt B)
- A mitochondrial protein-coding gene widely used in forensic species identification before COI barcoding was standardised. Still used because its reference database for...
- DNA Barcoding
- Species identification using a short, standardised region of the mitochondrial genome. For animals, the primary barcode marker is a 648-base-pair segment of...
- Morphological Identification
- Species determination based on external or internal physical features. Reliable and cheap for adults and many late-instar larvae, but fails on early...