Cytogenetic features and associated microbiome of Belgica antarctica Jacobs, 1900 (Diptera: Chironomidae)

Chironomids are widely used in genetic and ecological studies. However, the Antarctic endemic midge Belgica antarctica Jacobs, 1900 has received more limited attention to date. This species is extremely pertinent given its endemism to a region subject to extreme environmental conditions and also to some of the most rapid climatic changes globally in recent decades. We present the first standard polytene chromosome map of B. antarctica. We show that, despite the rapid recent climate warming in the Antarctic Peninsula region, inversions are present in populations of B. antarctica, which were first documented as much as 40 years ago. We also report two new inherited inversions. The data analysis showed the presence of somatic aberrations that have not been investigated before and may provide an informative method for assessing pollution, which has been growing rapidly in parts of the Antarctic in recent decades. Associated microbiota have a key influence on the survival of organisms under harsh and changing climatic conditions. Analyzing 34 whole-genome sequences of B. antarctica available in the NCBI database, we identified 14 bacterial taxa associated with this chironomid or with its substrate. Separately, did not identify endosymbiotic bacteria such as Wolbachia or Spiroplasma using PCR (44 specimens from seven locations were tested) and metagenomic analysis. Our data suggest low bacterial diversity in the B. antarctica microbiome. The data obtained provide a basis for further population studies of B. antarctica.

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