COS 227-1 - Tardigrades of Belize

Abstract: Tardigrades are aquatic invertebrates found in marine, freshwater, and moist terrestrial habitats with global ubiquity. Limited studies indicate Central American tardigrades appear unique and specific, while North and South America share some species not found in Central America. This suggests complex biogeographic processes in Central America not explained by the Great American Biotic Interchange hypothesis alone. The phylum Tardigrada encompasses over 1400 species which have been discovered and described in the literature, yet researchers believe this is a fraction of tardigrades in existence. Current biogeographical distribution patterns may simply be an artifact of the paucity of sampling within the Americas. One country with no previous record of tardigrades is Belize, a tropical country situated on the Yucatan Peninsula facing the Caribbean Sea. This research serves to increase the knowledge of tardigrade biogeography in Central America and to further understand the drivers of species distributions.

Samples were collected in June 2022 across four regions in Central Belize: Mountain Pine Ridge Forest Reserve, Chiquibul National Park, Cockscomb Basin Wildlife Sanctuary, and Monkey Bay Wildlife Sanctuary. GPS data, substrate, and habitat type were recorded for each sample. Moist moss and lichen habitat was scraped into a labeled paper bag and dried thoroughly. Specimens were collected from rehydrated samples with an Irwin Loop under stereomicroscopy. Each specimen was permanently mounted on slides for morphometric analysis under differential interference microscopy and keying to species. Tardigrade abundance per sample was standardized to dry weight sample and rehydration volume. Additional specimens were committed to SEM imaging and DNA barcoding. Molecular analysis involved extracting single tardigrade DNA using Lucigen Quick Extract, PCR amplification of COI and 28SrRNA genes, and both forward and reverse Sanger sequencing of gene amplicons. DNA sequences were compared to others in GenBank using NCBI BLAST and all potential matches analyzed using MEGA11 software.

Presently, over 820 tardigrade specimens have been identified. Of the 18 species to date, Heterotardigrades encompass four species, four genera, and a single family; Eutardigrades include 14 species, eight genera, and four families. GPS, distribution, and molecular data analysis is ongoing. The results will be compared to prior studies to support or offer new insights to current understanding for tardigrade biogeography across the Americas. In closing, this is the first tardigrade biodiversity study in Belize, Central America, and it contributed knowledge to the global distribution of tardigrades. All results will be provided to the Belize Forest Department and National Biodiversity Office.