The Sagalla caecilian （Boulengerula niedeni） is an endangered amphibian endemic to Sagalla Hill in the Taita Hills. This burrowing worm-like species prefers soft soil with high moisture and organic matter. The major...The Sagalla caecilian （Boulengerula niedeni） is an endangered amphibian endemic to Sagalla Hill in the Taita Hills. This burrowing worm-like species prefers soft soil with high moisture and organic matter. The major threats to the Sagalla caecilian are soil erosion caused by steep slopes, bare ground and water siphoning/soil hardening from exotic eucalyptus trees. The purpose of this study was to get a better understanding of the local people＇s attitude towards this species and how they can contribute to its continued conservation through restoration of its remaining habitat. In this study, it was found that 96% of Sagalla people are aware of the species, its habits and its association with soils high in organic matter. It was also found that 96% of Sagalla people use organic manure from cow dung in their farms. Habitat restoration through planting of indigenous plants was found to be ongoing, especially on compounds of public institutions as well as on private lands. Although drought was found to be a challenge for seedlings development especially on the low elevation sites, destruction by livestock especially during the dry season is also a major threat. In this study, it was recommended that any future habitat restoration initiative should include strong chain-link fencing to protect the seedlings from livestock activity. Recognizing that the preferred habitats for the species are in the valleys, systematic planting of keystone plant species such as fig trees （Ficus） creates the best microhabitats. These are better than general woodlots of indigenous trees.展开更多
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...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.展开更多
基金Foundation items： This study was supported by the Mohamed bin Zayed Species Conservation Fund （MBZ） on the education （project number 11251778） and awareness work by US Fish ＆ Wildlife Service （USFWS） project award number F11AP00359 on habitat restoration work
文摘The Sagalla caecilian （Boulengerula niedeni） is an endangered amphibian endemic to Sagalla Hill in the Taita Hills. This burrowing worm-like species prefers soft soil with high moisture and organic matter. The major threats to the Sagalla caecilian are soil erosion caused by steep slopes, bare ground and water siphoning/soil hardening from exotic eucalyptus trees. The purpose of this study was to get a better understanding of the local people＇s attitude towards this species and how they can contribute to its continued conservation through restoration of its remaining habitat. In this study, it was found that 96% of Sagalla people are aware of the species, its habits and its association with soils high in organic matter. It was also found that 96% of Sagalla people use organic manure from cow dung in their farms. Habitat restoration through planting of indigenous plants was found to be ongoing, especially on compounds of public institutions as well as on private lands. Although drought was found to be a challenge for seedlings development especially on the low elevation sites, destruction by livestock especially during the dry season is also a major threat. In this study, it was recommended that any future habitat restoration initiative should include strong chain-link fencing to protect the seedlings from livestock activity. Recognizing that the preferred habitats for the species are in the valleys, systematic planting of keystone plant species such as fig trees （Ficus） creates the best microhabitats. These are better than general woodlots of indigenous trees.
基金supported by the National Natural Science Foundation of China(Grant No.31570391 to WJ)the National Key R&D Program of China(Grant No.2016YFC0503200)the National Science Foundation of USA(Grant No.1911585 to RLM)
文摘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.
