Rhipsalis(Cactaceae): loss and gain of floral rewards is mirrored in range sizes and distribution patterns of species

Abstract

Autogamous species are usually distinguishable from xenogamous relatives by smaller flowers, fewer or even no floral rewards and lower pollen-ovule (P/O) ratios. Many Rhipsalis spp. are small flowered, selfing and include the most widespread species in Cactaceae. However, Rhipsalis also includes a large number of narrowly endemic species and is most diverse in the Atlantic rainforests of Brazil. To investigate the evolution of floral function and the correlation between floral function and range size, we analysed display size, floral reward and P/O ratios of Rhipsalis and its closest relatives, reconstructed ancestral traits and related these patterns to the distributions and range sizes of the species. Display size and sugar amount are reduced in subgenera Goniorhipsalis and Rhipsalis and secondarily increased in Phyllarthrorhipsalis, whereas the P/O ratio is decreased in subgenera Rhipsalis and Phyllarthrorhipsalis. We interpret this pattern as a switch from a predominantly xenogamous to an autogamous reproductive system, followed by a return to a predominantly xenogamous system. None of the floral parameters shows significant correlations with range size, except for display size. Nevertheless, those species with the smallest flowers, lowest sugar amounts per flower and lowest P/O ratios occur either outside southeastern Brazil and/or have comparatively large distribution ranges. Almost all Rhipsalis spp. occurring outside the Atlantic rainforests are restricted to the clade formed by subgenera Rhipsalis and Phyllarthrorhipsalis. Thus, we believe that the evolution of an autogamous reproduction system enabled this lineage of Rhipsalis to diversify and spread in the Atlantic rainforests, in the rest of the Neotropics and even spread to the Old World, where it is the only member of the family.

Breeding systems in Balsaminaceae in relation to pollen/ovule ratio, pollination syndromes, life history and climate zone

“…Tate & Simpson ; Grosse‐Veldmann et al . ), which must have occurred at least four times in Balsaminaceae in a variety of temperate and tropical ecosystems. However, we did not find a relation between breeding system and climate zone in Balsaminaceae.…”

“…; Grosse‐Veldmann et al . ). Changes in breeding system from outcrossing to autonomous selfing are also often coupled with changes in life history ( e.g .…”

“…; Grosse‐Veldmann et al . ). However, autogamy bears the risk of inbreeding depression and increases the risk of genetic drift (Kalisz & Vogler ; Culley & Klooster ).…”

Functional Dioecy in Echinocereus: Ontogenetic Patterns, Programmed Cell Death, and Evolutionary Significance

“…Its floral diversity is observed in variations in whorl size, color, and shape and in its breeding systems. This variation and the ecological importance of this family make it an interesting model to study the evolution of floral and morphological diversity (Wolf and Martínez del Rio 2003;Casas et al 2006;Mandujano et al 2010;Hernández-Hernández et al 2011;Grosse-Veldmann et al 2016).…”

Espécies brasileiras de Tacinga Britton & Rose (Cactaceae): morfoanatomia e estratégias reprodutivas

“…estudo de caracteres e estratégias reprodutivas foi embasado principalmente na metodologia deGrosse-Veldmann et al (2016), analisando-se os seguintes parâmetros: tamanho do display floral, quantidade média de óvulos por flor, estimativa de número de grãos de pólen por flor e razão grão de pólen/óvulo. Além disso, foi incluída a avaliação do período de floração das espécies.…”