Modelling and analysis of lifetime data using various failure rate distributions

Abstract

Utricularia, the largest and most species-rich genus in the carnivorous plant family Lentibulariaceae, is distributed globally with 284 taxa. The genus is highly intriguing, possessing inimitable traits that set it apart from other angiosperms. These include a unique body plan, ultra-fast suction trapping mechanism, specialized nutritional acquisition strategy, habitat preferences, genome miniaturization, and dynamic nuclear genomes. Utricularia lacks true roots, stems and leaves, instead relying on rhizoids, stolons, modified leaves and distinctly specialized traps. Known as ‘bladderworts’ these plants use suction-based traps to capture and digest prey. The traps operate beyond human visual perception, demonstrating the remarkable carnivorous adaptation of the genus. Utricularia thrives in nutrient poor, open, wet environments, benefiting from its carnivorous nature, which reduces its photosynthetic cost. Notably, genome downsizing, reported in Genlisea margeretae, G. aurea and Utricularia gibba, highlights the evolutionary significance of this group. This research focuses on the taxonomy of Indian Utricularia, supplemented with micromorphological and molecular evidence. The study recognizes 37 species from India, including two new species and one new distributional record. Extensive fieldwork revealed the high habitat specialization and diverse ecological preferences of Utricularia species. A comprehensive taxonomic account has been provided, including taxonomic keys for species identification within each section. Lectotypes were selected for three names, and the identities and reinstatements of five species were clarified. Six species previously reported from the region were excluded due to inadequate literature, insufficient data, and the need for further collections. Among the 37 recognized species, 16 are endemic to India: 12 endemic to the Western Ghats, two endemic to Peninsular India, one endemic to both Peninsular India and Sri Lanka, and one endemic to the Western Ghats and Sri Lanka. Field studies have revealed several potential threats to the habitats of Utricularia, such as mining, quarrying, commercial development, tourism, land-use changes, landfilling, pollution, grazing, fires, droughts, floods, and landslides. These activities contribute to habitat fragmentation, degradation and loss. The conservation status of 37 species was assessed, with six species categorized as Critically Endangered (CR,) seven as Endangered (EN), two as Vulnerable (VU,) four as Near Threatened (NT), six as Data Deficient (DD), and 12 as Least Concern (LC). The study emphasizes the need for a comprehensive conservation approach, including habitat preservation, ongoing research, monitoring, and raising public awareness to safeguard these plants and their habitats. A micromorphological study of seeds in Indian species revealed diagnostic characters useful for species delimitation. The patterns of seed testa cells, the shape and thickness of anticlinal walls, and ornamentation of the periclinal walls were identified as taxonomically significant, particularly for sectional delimitations and species identification. A strong positive correlation between seed morphology, species habitat and ecology was also observed. Phylogenetic analysis using the nrITS and rps16 intron were carried out to support the morphological data. This is the first comprehensive phylogenetic analysis of Indian Utricularia, including 34 of the 37 recognised taxa sampled across the range of each species. Independent phylogenetic analysis with both nrITS and rps16 datasets confirmed the distinct taxonomic identity of Indian members. The analysis also supported the correct sectional placement of unclassified Indian endemics, confirmed the identity of U. nayarii, U. purpurascens, U. roseopurpurea, synonymisation of U. babui, U. sunilii and U. kamarudeenii, and highlights the distinctiveness of newly described taxa.