Abstract/Summary

Two sister lineages of Caryophyllales: Droseraceae with 250 species, hermaphrodite flowers, and very little natural interspecific hybridization, and Nepenthaceae with 160 species, dioecious, with numerous fertile hybrids found in the wild are both autotrophic carnivorous plant lineages. This sister relationship offers the opportunity to understand rates and patterns of speciation under challenging environmental conditions, but fundamentally different breeding patterns. Genetic variation and species-level relationships within Nepenthes and Drosera need more investigation to increase our understanding of their evolution. Here, we use affordable genomics approaches to study plastid genomes of 32 Nepenthes species, 31 Drosera species and to recover some mitochondrial genes; to investigate in their phylogenetic perspective. Our results indicate that the next-generation sequencing technology short read data are a good way to sequence the complete plastome in most Nepenthes species. However, with the high degree of Drosera plastid genome rearrangement, using short read data is insufficient for assembling within certain limits for reconstructing plastid genomes. Nanopore Technologies long read sequencing, combined with short reads was demonstrated to produce accurate hybrid assemblies free of structural errors in Drosera. A molecular phylogeny of the Droseraceae supported previously reported sister group relationships among Drosera spp., Dionaea muscipula, and Aldrovanda vesiculosa. These findings provide useful information on molecular evolution about these two families as they have similar autotrophic behaviour; however, plastome rearrangements are much more common in Drosera than in Nepenthes. Furthermore, all Drosera species in this study inhabitant of Brazil, America, New Zealand, and Argentina identify they are clustered next to the species in Africa or Australia, and Drosera regia is sister to all other Drosera species. Moreover, the phylogenetic analysis indicates the sister plant families Nepenthaceae and Droseraceae tend to exhibit variation in the relative rate of DNA mutation and speciation. Quantifying this variation helps us understand how different lineages facing the same challenge, of adaptation to low nutrient habitats, might adapt in different ways. Estimating relative branch length in phylogenetic trees of Nepenthes spp. and Drosera spp.. is one approach to this.