California supports more than 60,000 insect species, according to a new DNA barcoding study that raises earlier estimates of the state’s insect diversity. Researchers say roughly one third of those species have not been formally described. The work, published in the journal Ecography and led by the Natural History Museum of Los Angeles County, also found that almost every location sampled hosted its own distinct insect community.
That second result matters for conservation. Places with similar climates and landscapes can support different species, so no single protected area is likely to capture the state’s insect diversity. Protecting that diversity will require safeguarding a wide range of habitats.
A statewide barcode library
The paper is the first publication from the California Insect Barcode Initiative (CIBI), a $6 million project that aims to collect and identify every insect species in the state. Insects are the most diverse group of animals on land, yet they remain underrepresented in large-scale conservation assessments.
The team applied DNA barcoding to more than one million specimens. The method compares short DNA sections to separate species, which helps reveal diversity that appearance alone can hide.
Partners in the effort included the California Department of Food and Agriculture, UC Berkeley, UC Riverside, the San Diego Natural History Museum and the California Academy of Sciences. Material came from three sources: tissue samples from museum collections, Malaise traps deployed across 72 ecoregions, and collecting expeditions to 454 additional locations around the state.
Volunteers sustained the fieldwork
Malaise traps collect insects passively, but emptying and maintaining them takes steady effort. Study co-author Giar-Ann Kung, the museum’s entomology collections manager, said volunteers made continuous weekly sampling possible by managing traps, something the research team could not have done itself. Some kept sites running for years.
Kung singled out Sara Fairchild and Michael Nance, who maintained a trap at a high desert site for more than three years. It is the longest continuous site in the project.
Every region has its own insects
To compare diversity across the state, the researchers used Level 3 ecoregions, the areas the Environmental Protection Agency groups by shared ecosystem characteristics. These include the Mojave Basin and Range, the Southern California Mountains and the Sierra Nevada. The Mojave Basin and Range had the highest number of insect species.
Regional patterns did emerge. Megan Barkdull, a study author, noted that the deserts resemble one another more than they resemble other regions, and that the mountains of northern California are somewhat alike. Even so, every part of the state hosted a distinctly different insect fauna.
The differences also held at finer scales, with individual collecting sites inside the same ecoregion harboring different communities. The study’s richness map is built on rule-based spatial range interpolation, constrained by ecoregion and vegetation type for each species in the dataset. Some ecoregions have been sampled but not yet sequenced, and others lack insect samples, so the picture is still incomplete.
The study, “DNA barcoding of more than one million insect specimens indicates that at least one third of California’s insect biodiversity remains undiscovered,” lists Austin J. Baker as first author and Brian V. Brown and Laura Melissa Guzman among its senior authors.
Source: scitechdaily.com
