Nonmodel

Nonmodel refers to organisms that are not used as standard model systems in biological research. Model organisms are species with extensive historical use in the laboratory, along with well-developed genetic tools, resources, and community knowledge. Classic model systems include mice, fruit flies (Drosophila), nematodes (C. elegans), baker’s yeast, Arabidopsis thaliana, zebrafish, and other well-characterized organisms. Nonmodel organisms span the vast majority of biodiversity and are studied to address questions that models cannot easily answer or to exploit unique biology.

Nonmodel systems are chosen for their ecological relevance, evolutionary interest, or distinctive traits such as regenerative capacity, extreme physiology, or specialized life histories. They enable comparative analyses that reveal the diversity and evolution of biological processes, while also highlighting conserved mechanisms that extend beyond traditional models. The growth of nonmodel research has been accelerated by advances in sequencing, genomics, and imaging, which provide genomic and functional context even in the absence of long-standing laboratory tools.

Challenges associated with nonmodel organisms include limited genetic manipulation methods, fewer standardized husbandry protocols, sparse literature, and incomplete or fragmented genomes. Researchers increasingly overcome these barriers through de novo genome sequencing, transcriptomics, single-cell approaches, and comparative genomics, as well as developing gene-editing and gene-delivery techniques tailored to specific species. Initiatives such as the i5K project and related efforts aim to build community resources for nonmodel taxa.

Overall, nonmodel organisms broaden scientific inquiry by expanding the scope of taxa and traits studied, enriching our understanding of biology beyond traditional model systems.