Oviposition Site Selection of the Plateau Frog (Nanorana pleskei) in the Zoige Wetland, China

For oviparous species, oviposition site selection influences adult reproductive success as well as the fitness of the resulting offspring. Females usually choose potential egg-laying sites depending on abundance and quality to maximize their reproductive success. We focused on the oviposition site selection of this plateau frog in Zoige wetland and investigated how the egg-laying pattern of the females influences their offspring＇s survival. We found that shallow waters, decentralized spawning patterns, and egg attachment to appropriate distance to the water surface were the main spawning strategies of Nanorana pleskei endemic to Qinghai-Tibet Plateau. We argued that drought caused by increasing temperature and variable precipitation has probably influenced N. pleskei reproductive success, which may be a crucial reason for its population decline. Our findings have important significance for habitat preservation, increasing embryo survival and establishing practical conservation policies.

Gigantic Genomes Provide Empirical Tests of Transposable Element Dynamics Models

Transposable elements(TEs)are a major determinant of eukaryotic genome size.The collective properties of a genomic TE community reveal the history of TE/host evolutionary dynamics and impact present-day host structure and function,from genome to organism levels.In rare cases,TE community/genome size has greatly expanded in animals,associated with increased cell size and changes to anatomy and physiology.Here,we characterize the TE landscape of the genome and transcriptome in an amphibian with a giant genome—the caecilian Ichthyophis bannanicus,which we show has a genome size of 12.2 Gb.Amphibians are an important model system because the clade includes independent cases of genomic gigantism.The I.bannanicus genome differs compositionally from other giant amphibian genomes,but shares a low rate of ectopic recombination-mediated deletion.We examine TE activity using expression and divergence plots;TEs account for 15%of somatic transcription,and most superfamilies appear active.We quantify TE diversity in the caecilian,as well as other vertebrates with a range of genome sizes,using diversity indices commonly applied in community ecology.We synthesize previous models that integrate TE abundance,diversity,and activity,and test whether the caecilian meets model predictions for genomes with high TE abundance.We propose thorough,consistent characterization of TEs to strengthen future comparative analyses.Such analyses will ultimately be required to reveal whether the divergent TE assemblages found across convergent gigantic genomes reflect fundamental shared features of TE/host genome evolutionary dynamics.