Occurrence of the endangered species Nitellopsis obtusa (Charales, Charophyceae) in western Japan and the genetic differences within and among Japanese populations

Abstract

Summary Nitellopsis obtusa (Charales, Charophyceae) are widely distributed from Europe to Asia; however, this species has been recorded in only the five lakes in central Honshu in Japan. This species was thought to be extinct in Japan, but was rediscovered in limited areas of Lake Kawaguchi in central Honshu. More recently, we discovered more Japanese populations of N. obtusa in Lake Biwa in western Honshu, and it became clear that the species had a broader distribution in Japan than originally believed. In addition, although only male or female thalli have been collected at each lake, both male and female thalli were found from Lake Biwa. This is the first report of a potentially sexual population of N. obtusa in Japan. The DNA sequences of three chloroplast DNA markers, including both coding and non‐coding regions, were identical in all specimens from Lake Kawaguchi and Lake Nojiri (Central Honshu), and differed from those of Lake Biwa and German specimens. Although Japanese and German specimens were genetically similar, Japanese specimens displayed considerable genetic diversity according to locality.

Impact of Nitellopsis obtusa (Desv.) J. Groves, a regionally alien and invasive charophyte, on macrophyte diversity in the species native range

“…In Europe, the species has been recorded from Table 3 Species most frequently co-occurring with Nitellopsis obtusa, based on literature sources: (Dąmbska, 1964;Schloesser et al, 1986;Bailly & Schaefer, 2010;Urbaniak & Gąbka, 2014;Styperek et al, 2014;Midwood et al, 2016;Alix et al, 2017;Brainard & Schulz, 2017;Boissezon et al, 2017;Larkin et al, 2018;this (Urbaniak, 2003;Kabus, 2016;Vesić, 2016;Romanov et al, 2018). In Asia, N. obtusa is known from Turkestan, India, Myanmar, China and Japan (Ling et al, 2000;Urbaniak, 2003;Kato et al, 2005Kato et al, , 2014. Although the species is locally red-listed within its native range, it is common in Western, through Central and Eastern European countries.…”

“…As revised by Larkin et al (2018), the species has been reported from new sites in Europe and its conservations status has locally been lowered. In 2003, N. obtusa was rediscovered in Japan (Kato et al, 2005), after which new populations were found in five lakes, although the species was considered threatened (Kato et al, 2014). The concern was aroused by the fact that the species expanded its range to North America, where for four decades, it has been colonizing new sites bringing the risk of local biodiversity decline (Geist et al, 1981;Escobar et al, 2016;Midwood et al, 2016;Alix et al 2017;Karol & Sleith, 2017).…”

“…Contrary to N. bulbilifera Dontberg, recorded from Argentina and New Mexico (Tindall et al, 1965;Alix et al, 2017), and N. sarcularis Zanevaled, only reported from its type locality on the Indonesian island of Lombok (Alix et al, 2017), N. obtusa is characterised by a wide distribution across the northern hemisphere (Korsch, 2018). Within its native range from Europe to Japan the species is regionally redlisted as near threatened in Switzerland (Auderset Joy & Schwarzer, 2012), vulnerable in Finland (Koistinen, 2010), Sweden (Johansson et al, 2010) and Great Britain (Stewart and Church, 1992), and threatened in Japan (Kato et al, 2014). In Central and Eastern Europe, however, N. obtusa is a common charophyte (Urbaniak & Gąbka, 2014;Kabus, 2016).…”

Realized niche shift associated with the Eurasian charophyte Nitellopsis obtusa becoming invasive in North America

“…Desvaux) J. Groves (starry stonewort) in North America. Nitellopsis obtusa is a dioecious green alga in the Characeae family that is uncommon across much of its native range in Europe and Asia 17 18 and is classified as a priority conservation species in the United Kingdom 19 , near threatened in Switzerland 20 , and endangered in Japan 18 , though there is evidence of expanded distribution in parts of Europe over the past few decades 21 . It occurs in shallow, fresh to brackish water at depths up to 10 m and can reproduce asexually via fragments and star-shaped structures called bulbils 17 .…”

Forecasting distributions of an aquatic invasive species (Nitellopsis obtusa) under future climate scenarios

“…Dense growth may also impair recreational activities such as swimming, fishing, and boating [ 1 , 3 ]. Although populations of starry stonewort in their native distribution in Europe and Japan have been declining [ 5 – 7 ], the species has shown great capacity to spread as an aquatic invasive species in North America [ 3 , 8 , 9 ].…”