The amazing evolutionary diversity of a taxon: Genome sizes of twenty Antarctic amphipod species

Polar ecosystems feature among the last pristine areas of planet Earth, but also among the fastest changing due to global change. The long isolation history of the Southern Ocean has led to high levels of endemism, resulting in a hotspot of biodiversity for many taxa, including crustaceans (Malacostraca). Genomes represent the blueprint of this long evolution. Geographic isolation in combination with harsh and challenging sampling conditions, has left considerable biological knowledge gaps in the Southern Ocean. Closing these knowledge gaps is challenging for Antarctic amphipods because their genome sizes are highly variable and they are hard to sample. Genome size of amphipods are widely varying, ranging from 0.68 to 64.62 pg with an average of 12.85 pg (± 4.46 pg). Unfortunately, information on the genome size of amphipods remains limited, especially from polar regions. Just 65 records of amphipod genome sizes are listed in the Animal Genome Size Database, of which 17 marine species. To close the knowledge gap, I used flow cytometry to estimate the genome size of 32 Antarctic amphipod species. I successfully estimated genome sizes for 20 species, ranging from 0.45 pg to 57.28 pg (> 120-fold difference). Preliminary analyses do not show any significant correlation between depth and genome size or body size and genome size. The results provide a valuable addition to the inventory of the genome size of amphipods, especially from extreme environments.

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