The genus Hydrocharis L. (Hydrocharitaceae): distribution features and conservation status

Abstract

The genus Hydrocharis L. includes three geographically isolated species. Analysis of the actual data (32 thousand geographical locations and 1946 herbarium sheets) covering the period 1765–2019 made it possible to clarify the nature of the distri- bution of these species and its changes. Hydrocharis morsus-ranae L. has disjunctive Eurasian – North American temperate range, with a massive North American en- clave, the formation of which began in the 1930–1940s. The range of Hydrocharis dubia (Blume) Backer is disjunctive Southeast Asian – Australian subboreal-tropical, Australia enclave began forming in the 1850–1870s. Hydrocharis chevalieri (De Wild.) Dandy is a macrothermal Central African equatorial endemic. Current threat status of all species may be estimated as Least Concern. The mean annual temperature is the most contrasting feature of the distribution areas of the species, water depth, bottom soil type and hydrochemical composition have lower impact. Prognostic models of the potential distribution of the tagged species have been made.

Plastome phylogenomics and historical biogeography of aquatic plant genus Hydrocharis (Hydrocharitaceae)

“…Additionally, paleoclimatic changes may have induced such changes in water bodies that some groups were driven to extinction [43]. This might explain why there are only three extant species, and a majority of fossil groups only occurred in Europe during the Miocene [3]. The area of origin remained uncertain for the genus because several alternative areas with low probabilities were recovered for the deeper nodes (Fig.…”

“…According to the existing distribution patterns of Hydrocharis [1,3], four major areas were identified for biogeographic analysis: A) East and Southeast Asia; B) Europe and Central Asia; C) Central Africa; D) America. The ancestral states were reconstructed using the BioGe-oBEARS package [70] implemented in RASP v. 4.0 [19].…”

“…2 Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, China. 3 Herbarium, Biodiversity Unit, University of Turku, 20014 Turku, Finland. 4 Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China.…”

“…environment [2]. However, due to the deterioration of the aquatic habitats resulting from human activities, H. morsus-ranae and H. dubia have been considered threatened in part of their native distributions [3]. Hydrocharis and the closely related Limnobium are unusual in Hydrocharitaceae by having aerial leaves only, and therefore are important for understanding the evolution of aquatic adaptations in the family [1,4].…”

“…Previous biogeographic analyses suggested that the most recent common ancestor (MRCA) of the Hydrocharis-Limnobium clade originated in the Oriental region approximately 15.9 Ma, and long distance dispersal (LDD) might contribute to its current distributions [4]. However, numerous fossils, including more than 10 Hydrocharis species, which mainly occurred during the Oligocene and Miocene epochs, were discovered in Europe and the Far East [3,[12][13][14][15]. No fossils have been found in Africa.…”