Regeneration niche of three epiphytic species of Gesneriaceae from Chilean rainforests: implications for the evolution of growth habits in Coronanthereae

Abstract

Ecological and evolutionary studies of the epiphytic growth habit in angiosperms are limited. In this article, we assess the relationship between growth habit and regeneration niche in Coronanthereae (Gesneriaceae) and discuss its implications for the evolution of epiphytism in this lineage. In the temperate rainforest of southern Chile, we quantified the vertical distribution and experimentally examined the regeneration niche of three endemic species of Coronanthereae. One species was a holoepiphyte, which was more frequent in the upper canopy, and two species were secondary hemiepiphytes, which decreased in abundance with tree height. Seed germination of the holoepiphyte was higher on tree bark substrates and under open canopy than on forest soil and in the shade. In contrast, seed germination of both secondary hemiepiphytes did not differ between substrates (bark vs. soil) or light conditions (light vs. shade). Seedling survival percentage of secondary hemiepiphytes was higher on forest soil and under a closed canopy, thus behaving as shade‐tolerant species. In turn, the holoepiphyte behaved as a shade‐intolerant species. The reconstruction of the ancestral growth habits and regeneration niches on the inferred phylogenetic tree of Coronanthereae revealed that the specialized regeneration niche of Sarmienta repens, characterized by requirements of shade intolerance and germination on tree bark, was coupled with the evolution of the holoepiphytic growth habit. We conclude that differentiation in the regeneration niche is a key process in the evolution of epiphytic growth habits in Coronanthereae. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170, 79–92.

The systematic distribution of vascular epiphytes - a critical update

“…Genera with both epiphytic and non-epiphytic members seem ideally suited for the study of the ecology and evolution of epiphytism. Indeed, an increasing body of literature puts a focus on epiphytism in a phylogenetic context (Wikström, Kenrick & Chase, 1999;Gravendeel et al, 2004;Monteiro et al, 2010;Givnish et al, 2011;Salinas & Armesto, 2012), whereas other studies deal with the ecology of epiphytism by identifying the anatomical, morphological and physiological attributes that distinguish epiphytic and terrestrial sister taxa (Moreira & Isaias, 2008;Quezada & Gianoli, 2011;Tsutsumi et al, 2011). Clearly, a rigorous definition of 'epiphyte' is essential for unambiguous results in all these studies, whereas the inclusion of a large set of distinct genera and families is needed to come to more general conclusions.…”

“…For example, in KBL virtually all orchid genera with epiphytes were exclusively epiphytic, which suggested that the conquest of tree canopies is unidirectional [e.g. as reported in Coronatherae (Gesneriaceae) by Salinas & Armesto, ] and constitutes an evolutionary dead end. In contrast, in the current list > 50 basically epiphytic orchid genera have a few terrestrial and/or lithophytic members.…”

Confirmation of arboreal habits in Dromiciops gliroides: a key role in Chilean Temperate Rainforests

“…, Celis‐Diez et al. ), including at least two holoepiphytes, which grow in the canopy and never root in the ground, Sarmienta repens (Gesneriaceae) and the bromeliad Fascicularia bicolor (Salinas and Armesto , Ortega‐Solís et al. ).…”

Relación entre la amplitud ecológica de epífitas vasculares y sus respuestas ecofisiológicas a la disponibilidad de luz y humedad en el bosque esclerófilo mediterráneo costero de Chile

“…En Chile la mayoría de los estudios sobre la diversidad de epífitas vasculares se han desarrollado en la zona del bosque templado lluvioso (38ºS a 55°S) (e.g. Muñoz et al 2003, Parra et al 2009, Díaz et al 2010, Salinas & Armesto 2012, Saldaña et al 2014, donde las epífitas presentan su mayor diversidad (Arroyo et al 1995, Armesto et al 1997, por lo que aún existen vacíos de información respecto a la ecología de las epífitas vasculares en otras zonas importantes dentro de su distribución, como por ejemplo en el bosque esclerófilo (32º30'S a 38º30'S) y en la zona de transición mediterráneo-templada, donde se observan cambios sustanciales en el régimen de precipitación, temperatura y estacionalidad respecto a los bosques templados del sur de Chile (Arroyo et al 1988, Luebert & Pliscoff 2006. A escala local, estas diferencias ambientales podrían generar patrones contrastantes de distribución y abundancia de las plantas epífitas, respecto a los observados en el bosque templado lluvioso.…”