Phylogenetic biogeography reveals the timing and source areas of the Adiantum species (Pteridaceae) in the West Indies, with a special focus on Cuba

Abstract

Aim The processes that shaped the West Indian fern flora remain poorly understood. We attempt to investigate earlier biogeographical patterns described for the region using the genus Adiantum as model. These patterns propose that the West Indian fern flora has (1) an essentially continental rather than insular character, having a rich representation of species occurring in tropical America; (2) the Greater Antilles have a higher fern diversity and higher endemism than the Lesser Antilles, and (3) adaptive speciation has been an important process in shaping the fern diversity of the Greater Antilles. Location West Indies. Methods Adiantum is a subcosmopolitan genus that comprises 200–225 species of which 33 occur in the West Indies. We compiled the most comprehensive molecular dataset of Adiantum available to date, including the chloroplast markers rbcL, atpA, atpB and trnL‐F of 407 accessions belonging to 101 species, 24 of which occur in the West Indies. Maximum likelihood and Bayesian inference approaches were applied to generate phylogenetic hypotheses. Divergence times were estimated using published substitution rates. Ancestral areas were estimated using BioGeoBEARS. Results The extant West Indian Adiantum species originate from at least 17 predominantly Miocene immigration events, 11 from South America and six from Central America, in combination with two cladogenetic events. The Cuban endemics Adiantum alomae and A. sericeum, as well as the Greater Antillean A. deltoideum, A. cristatum and A. pyramidale first appeared during the Pleistocene. The emergence of A. alomae and A. deltoideum coincides with the formation of the karstic relief of the Cuban coasts. Main conclusions Immigration, rather than cladogenesis, governed the evolution of the West Indian Adiantum species. Our results concur with theoretical models proposed for island communities, suggesting that geologically younger and smaller island assemblages mainly derive from immigration, whereas cladogenesis plays an important role in older and larger islands.

A worldwide phylogeny of Adiantum (Pteridaceae) reveals remarkable convergent evolution in leaf blade architecture

“…Several were first resolved by Lu & al. (2012), and these were also confirmed by Regalado & al. (2017) using new and previously published plastid sequences.…”

“…More recently, four taxon-specific, multigene studies have been carried out, but these were limited to specific monophyletic clades within Adiantum (McCarthy, 2012;Hirai & al., 2016;Kuo & al., 2016;Wang & al., 2017). To date, the most extensive studies of Adiantum focused on Chinese taxa (48 species), with limited sampling from other regions (Lu & al., 2012), and on the Antillean archipelago (Regalado & al., 2017), which had a more comprehensive sampling (101 species). Here, we sampled 146 Adiantum taxa, two-thirds of known species, with an aim to rigorously determine relationships that previously may have been obscured by morphological homoplasy.…”

“…(2012), however, who undertook the first multigene phylogenetic analysis that included a broad sample of Adiantum species, with a focus on those found in China. Recently, Regalado & al. (2017) examined the biogeography and origins of Antillean species and assembled a comprehensive dataset of 101 species using new and previously published plastid sequences (rbcL, atpA, atpB, trnL-F).…”

Elucidating species richness in lichen fungi: The genus Sticta (Ascomycota: Peltigeraceae) in Puerto Rico

“…For instance, many of the non‐flying terrestrial vertebrate groups (Hedges, 2006; Marivaux & al., 2020) and even some invertebrates (e.g., McHugh & al., 2014) have their closest relatives in South America. Less evidence is available for plants, but recent work suggests that most West Indian Adiantum L. species originated from immigration events from that continent during the Miocene (Regalado & al., 2018).…”

Heinrichsia cheilanthoides gen. et sp. nov., a fossil fern in the family Pteridaceae (Polypodiales) from the Cretaceous amber forests of Myanmar

“…Our divergence time estimates under UCLN largely concur with the younger age estimates obtained in previous studies (Schuettpelz & Pryer, 2009;Rothfels et al, 2015), rather than older estimates (Testo & Sundue, 2016;Lehtonen et al, 2017), for all Pteridaceae subfamily lineages except the above-mentioned groups (Table 1). On the other hand, divergence time estimates of vittarioids and adiantoids within Vittarioideae under RLC are equivalent to the values inferred by Regalado et al (2018a) using local clocks for vittariods, adiantoids, and cheilanthoids based on relative rates published by Rothfels & Schuettpelz (2014), and assigning the standard substitution rate for plastid data 0.0005 (Palmer, 1991) to cheilanthoids.…”