AMPHIBIAWEB






AmphibiaWeb provides information on amphibian declines, natural history, conservation, and taxonomy.






Species of the Week
Bombina bombina | Fire-bellied Toad


Amphibian News Archive
Not all animals have the same amount of DNA in their cells. Among tetrapods, amphibians are remarkable in their genome size variation. In amphibians, larger genome size has been linked to slower development and is hypothesized to impact the formation of late-developing traits like digits, lungs, and brain complexity. Although salamanders are stand-outs with the largest genome sizes in tetrapods (reaching >120 pg or picograms), frogs and toads also have a considerable amount of genome size variation (ranging from 0.95–19 pg). Recently Womack et al. (2019) found that genome size was positively correlated with larval development rate among 90 species, expanding on similar results from previous studies on fewer species. They show that frogs lacking the late-forming middle ear (a repeated evolutionary loss among anurans) often had larger genome sizes than closely-related eared species. They also found that earless species often have very small body sizes at metamorphosis. It could be that middle ear loss is related to slower development (as indicated by larger genome size) and/or developmental constraints related to larger cell sizes and smaller body sizes. Their work provides evidence that increases in frog genome size, although less drastic than those in salamanders, is correlated with the loss of a late-forming and seemingly important sensory trait. They provide a new clue for biologists trying to understand the perplexing evolutionary loss of frog middle ears.

Current number of amphibian species: 8,105 (Dec 11, 2019) Newly added species