Cryptic diversity in the model fern genus Ceratopteris (Pteridaceae)

Abstract

Cryptic species are present throughout the tree of life. They are especially prevalent in ferns, because of processes such hybridization, polyploidy, and reticulate evolution. In addition, the morphological simple body plan of ferns limits phenotypic variation and makes it difficult to detect crypic species in ferns without molecular work. The model fern genus Ceratopteris has long been suspected to harbor cryptic diversity, specifically in the highly polymorphic C. thalictroides. Yet no studies have included samples from throughout the pan-tropical range of Ceratopteris or utilized genomic sequencing, making it difficult to assess the full extent of cryptic variation within this genus. Here, we present the first multilocus phylogeny of the genus using reduced representation genomic sequencing (RADseq) and examine population structure, phylogenetic relationships, and ploidy level variation. We recover similar species relationships found in previous studies, find support for a named cryptic species as genetically distinct, and identify a novel putative species from within C. thalictroides sensu latu in Central and South America.

The biology of C. richardii as a tool to understand plant evolution

“…There are about ten species within Ceratopteris, which can be found throughout the tropics ( Figure 2 ; Masuyama and Watano, 2010; Zhang et al, 2020 ; Yu et al, 2021 ). The classification of these species was made difficult by their inconsistent morphologies, and molecular methods were needed to reconstruct a backbone phylogeny for the genus ( Adjie et al, 2007 ; Kinosian et al, 2020a ). Recent work has shown that cryptic and hybrid species may be quite common in Ceratopteris , warranting a more rigorous evaluation of the relationships between species in the genus (e.g., Kinosian et al, 2020b ).…”

“… ( A ) Phylogenetic reconstruction of Ceratopteris , with the sister genus Acrostichum as the outgroup, based on Kinosian et al, 2020a ; Adjie et al, 2007 ; Yu et al, 2021 Zhang et al, 2020 . Absent from this phylogeny is the Brazilian species C. froesii , for which no genetic sequence data is available.…”

“…Shaded areas show where a species is common, colored dots show where species occur outside their most common range, or multiple species are found in a small area. Location data from Kinosian et al, 2020a ; Lloyd, 1974 ; Masuyama and Watano, 2010 ; Zhang et al, 2020 ; Yu et al, 2021 https://gbif.org/ .…”

Phylogeny and Taxonomy on Cryptic Species of Forked Ferns of Asia

“…Studies on cryptic species throughout the whole tree of life have increased exponentially over the past two decades, fueled in large part by the increasing availability of DNA sequences, which facilitate various genetic approaches to the resolution of cryptic diversity (Sites and Marshall, 2003;Bickford et al, 2007). The prevalence of considerable cryptic diversity has been uncovered in a diverse range of groups, including in plants (Okuyama and Kato, 2009;Carstens and Satler, 2013;Ji et al, 2020;Kinosian et al, 2020;Li et al, 2020) and many animals (Hebert et al, 2004;Oliver et al, 2009;Manthey et al, 2011;Nadler and DE León, 2011;Phiri and Daniels, 2016), suggesting that cryptic species probably represent a significant portion of undiscovered biodiversity (Jörger and Schrödl, 2013;Pante et al, 2015;Loxdale et al, 2016). The ever-increasing cryptic diversity that genetics has resolved poses a taxonomic challenge in terms of what taxonomic ranks should be assigned to cryptic species that can be recognized on a genetic, but not necessarily morphological, basis.…”

Effects of pH on sex organ differentiation and sexual reproduction in the endangered aquatic fern Ceratopteris p teridoides

“…Ceratopteris has been a model plant system in cell biology, biochemistry, genetics, molecular biology [1][2]. There are two species of Ceratopteris in China, including Ceratopteris pteridoides and C. thalictroides [3].…”