Distinct Reproductive Strategy of Two Endemic Amazonian Quillworts

Abstract

We examined the reproductive strategy of two Amazonian quillworts (Isoëtes cangae and Isoëtes serracarajensis), endemic and threatened species of canga ecosystems. Sexual propagation was examined by in vitro fertilization assays, while asexual propagation was examined by tiller emission. Isoëtes cangae is an outcrossing species that reproduces exclusively by spore germination and is able to propagate by self- and cross-fertilization. Isoëtes serracarajensis reproduces asexually by emitting tillers from the plant corm, despite producing male and female sporangia. These distinct reproductive strategies in the different species may be linked to their contrasting habitats. Isoëtes cangae inhabit a permanent oligotrophic lake with mild environmental changes, while I. serracarajensis are found in temporary ponds facing severe seasonal drought, where asexual propagation may represent an adaptive advantage to the short growth period during access to water. We also observed different relationships between plant growth and reproductive traits between the species, despite their common production of sporophytes with high survival rates. Together, these results are of paramount importance for establishing conservation plans for both species considering the advantages of sexual propagation to maintain the genetic diversity of I. cangae and the diligent management required to do the same with asexually propagated I. serracarajensis.

Mainstreaming Flora Conservation Strategies into the Mitigation Hierarchy to Strengthen Environmental Impact Assessment

“…In the environmental licensing of the project, a set-aside avoidance area was created, as required by the environmental agencies, to circumvent the species occupancy area (IBAMA 2016 ; ICMBio 2018 ). Furthermore, agreements were signed with a research institution and universities to execute a specific Isoetes cangae conservation plan, including ecological and genetic studies, reproduction, flora rescue, germplasm bank deposit, multiplication and relocation (Caldeira et al 2018 , Caldeira et al 2021 ; Campos et al 2021a ; Campos et al 2021b ; Cavalheiro-Filho et al 2021 ; Dalapicolla et al 2021 ; Nunes et al 2018 ; Santos et al 2019 ; Santos et al 2020 ; Zandonadi et al 2019 ; Zandonadi et al 2021 , and many other researches).…”

Aquatic quillworts, Isoëtes echinospora and I. lacustris under acidic stress—A review from a temperate refuge

“…The reproductive success of the extant submerged aquatic quillworts depends exclusively on crossing advantages of heterospory, as vegetative propagation is apparently rare (Eames, 1936), and scarcely reported in some amphibious species (Bray et al, 2018; Caldeira et al, 2021). Our research of Isoëtes echinospora Durieu and I. lacustris L. in severely acidified Bohemian Forest lakes (Czechia) gave the first compelling evidence that these isoetids, seemingly thriving under acidic conditions for more than half a century (Vrba et al, 2003), have in fact suffered.…”