Biosystematic Study of Himalayan Carex L. (Cyperaceae)

Abstract

Diversification patterns within the Himalayan region have been paramount to the understanding of worldwide biodiversity. Apart from recent wide scale report, a hyperdiverse genus of the temperate region under angiosperm—Carex L. (Cyperaceae), consists of ca. 2100 species globally has not been examined in the Himalayan region, which covers 189 Himalayan Carex taxa. The timing, phylogenetic relationship and ecological diversification of Himalayan lineage in this remarkable genus were aimed to infer. Particularly inspected whether priority and adaptation to this ecological system, or both enlighten the success of radiation from the Kobresia clade (~ 60 species, among which ca. 40 are the Himalayan) of Himalayan Carex. The Phylogenetic patterns were evaluated employing maximum likelihood method (ML) of two (ITS and ETS) nrDNA regions and one (matK) plastid gene; the ML tree was used for time-calibration under penalized likelihood approach and with a fossil calibrated at the base of the tree. The estimation of phylogeographical reconstruction for ancestral ranges and historical processes was achieved with the model, dispersal-extinction-cladogenesis (DEC) implemented in BioGeoBEARS and reciprocal impacts of diversification were analyzed employing the model, geographic state speciation and extinction (GeoSSE). The climatic niche for all Carex species with available mapped georeferenced specimen data were assessed along with climatic records from WORLDCLIM, and therefore, niche evolution was estimated with a group of two models for adaptive range shift and inferring ancestral character states under Ornstein-Uhlenbeck (O-U) models and a Brownian motion model, respectively. During the exploration of Carex flora across the Western Himalayan range Carex simpliciuscula Wahlenb. (1803: 141), previously with doubtful record in the Flora of xiv Pakistan, was confirmed for the region. The Himalayan taxa appears in three of the five reported major Carex clades, and characterized by multiple origins within each major clade. The oldest Himalayan Carex radiation was dated back to ~ 20 Ma, close the period of Himalayan orogeny, contributed to now abundant the Kobresia clade through longdistance migration from the region Nearctic. The Carex taxa in the Himalayas represents a heterogeneous model of diversifications derived from all through the cosmopolitan, however mostly temperate radiations. Several Himalayan radiations are relatively recently evolved, on the other hand, the most widespread and diverse Himalayan Kobresia radiation appeared at the lower Miocene. The timing and predominance of Hiamalayan taxa in Kobresia clade distributed in great elevation Himalayan meadows reveals that Kobresia may have eliminated other Carex taxa (non Kobresia) due to the consequence of mainly priority, competitive exclusion and historical contingency. A significant biodiversity needs to be discovered in order to explore new flora for the region. Around seventy specimens of 19 species collected with GPS reading of collecting sites from Western Himalayas (Pakistan) and 21 species requested from different herbaria, collectively made 40 for this study. Carex simpliciuscula, a new flora and numerous new collection localities for this region were explored. Additionally, morphological characters of pistillate scales studied particularly under scanning electron microscope seem to contribute to identifying taxa for the region. Therefore, these findings encourage further research on micro- and macromorphological studies of pistillate scales in Carex.