Libertini et al. 2008

Libertini A, Trisolini R, Rampin M. 2008. Chromosome number, karyotype morphology, heterochromatin distribution and nuclear DNA content of some talitroidean amphipods (Crustacea: Gammaridea). European Journal of Entomology 105: 53-58.

These authors report genome size and other genomic phenotypes for 10 species of amphipods in the infraorder Talitrida, which includes family Hyalellidae and family Talitridae. Talitridae includes intertidal, supralitoral, and fully terrestrial species. The cytogenetics of this group of amphipods are poorly understood, with few species receiving significant scientifica attention to date.

Genome size and AT-content were measured by flow cytometry. Cell suspensions were prepared as in Libertini et al. (2000), primarily of either late embryos or pooled internal organs of adults. Genome sizes were larger in more terrestial species. Additionally, two species with the largest genomes in their respective families, that inhabit the high intertidal in the Mediterranean, shifted their habitats inland to fully terrestial in northern locations such as Iceland.

These patterns support the hypothesis applied to other amphibious or terrestrial-colonizing groups such as gastropods and sarcopterygian fishes, that large genome size is a pre-adaptation or associated with other pre-adaptations to terrestrial life. Additionally, the authors associate the harsh terrestrial environment, large genomes, and the harsher environments of higher latitudes, citing in particular Rees et al. (2007) and the discovery of very large amphipod genomes in Arctic environments.