Phylogenetics of hopbushes and pepperflowers (Dodonaea, Diplopeltis - Sapindaceae), based on nuclear ribosomal ITS and partial ETS sequences incorporating secondary-structure models

Abstract

Hopbushes and pepperflowers (Dodonaea, Diplopeltis – Sapindaceae) are important components of Australia’s arid zone and sclerophyll and temperate forests and woodlands. Phylogenetic analyses of nuclear ribosomal ITS and partial ETS sequences for near-complete sampling of both genera were performed using a Bayesian statistical method and RNA specific models of nucleotide evolution that incorporate secondary structure (separate models for stems and loops). Diplopeltis is paraphyletic. Diplopeltis stuartii is not closer to other species of the genus than it is to species outside the genus. There are also several evolutionary elements in the molecular data that support D. stuartii as distinct from the other members of the genus. The monophyly of Dodonaea as redefined here to include all species of Distichostemon is unequivocally supported by the molecular data and the morphological synapomorphies of petal-less flowers with a highly reduced intrastaminal disk that is absent in staminate flowers. There do not appear to be any obvious evolutionary trends in the morphological characters (leaf and capsule form, presence or absence of aril, or breeding system) that have been previously used to group taxa. However, there are some morphological characters that may be useful to delineate some of the clades recovered in the present molecular study. New combinations in Dodonaea are made for all species of Distichostemon.

Macroevolutionary synthesis of flowering plant sexual systems

“…Previous conclusions in these genera include transitions away from hermaphroditism and toward dioecy (↑SD; Miller and Venable 2000;Venter 2000;Malcomber 2002;Weigend et al 2002;Senters and Soltis 2003;Navajas-Pérez et al 2005;Miller et al 2008;Wallander 2008;Martine et al 2009;Soza and Olmstead 2010;Himmelreich et al 2012;Soza et al 2012Soza et al , 2013 and away from dioecy and toward hermaphroditism (↓SD; Becerra and Venable 1999;Sweeney 2008;Soza and Olmstead 2010). In particular, the confident outcomes from our statistical analysis provide renewed support for transitions from hermaphroditism to monoecy and dioecy in Thalictrum, transitions both to and from dioecy in Galium, and transitions away from dioecy in Bursera and Dodonaea (compare, respectively, with Soza et al 2012;Soza and Olmstead 2010;Becerra and Venable 1999;Harrington and Gadek 2010). Our broad dataset additionally yielded confident conclusions in a few genera in which sex system evolution has apparently not previously been extensively investigated.…”

“…Our stochastic mapping results yielded 20 species in which loss of dioecy was inferred with at least 85% confidence to occur on the external branch leading to them (Table S3). However, others are from genera in which sexual system evolution has not been heavily investigated (Allocasuarina, Rhus) or in which previous results have been equivocal (Dodonaea, Piper, Ribes; see respectively Harrington and Gadek 2010;Jaramillo and Manos 2001;Senters and Soltis 2003). However, others are from genera in which sexual system evolution has not been heavily investigated (Allocasuarina, Rhus) or in which previous results have been equivocal (Dodonaea, Piper, Ribes; see respectively Harrington and Gadek 2010;Jaramillo and Manos 2001;Senters and Soltis 2003).…”

Flora da Serra do Cipó, Minas Gerais: Sapindaceae

“…Cápsula septífraga, cartácea, suborbicular, porção seminífera central, rodeada por ala arredondada; sementes lenticulares, 1 por lóculo (a outra é abortada), arilo ausente, embrião curvo. Dodonaea é predominantemente australiano, com aproximadamente 68 espécies, das quais 61 são endêmicas da Austrália (West 1984, Harrington & Gadek 2010. Dodonaea viscosa é a única espécie que ocorre no Brasil.…”

Low siring success of females with an acquired male function illustrates the legacy of sexual dimorphism in constraining the breakdown of dioecy

“…). For instance, dioecy was lost several times in the large and successful Cucurbitaceae family (Volz & Renner ; Schaefer & Renner ), as well as in the genera Bursera (Becerra & Venable ), Garcinia (Sweeney ), Gallium (Soza & Olmstead ) and Dodonaea (Harrington & Gadek ). Within genera, Goldberg et al .…”

“…Phylogenetic analysis of clades in which both dioecy and functional hermaphroditism occur indicates that dioecy has not always been derived from, but may also be ancestral to, hermaphroditism or monoecy (Goldberg et al 2017;Kafer et al 2017). For instance, dioecy was lost several times in the large and successful Cucurbitaceae family (Volz & Renner 2008;Schaefer & Renner 2010), as well as in the genera Bursera (Becerra & Venable 1999), Garcinia (Sweeney 2008), Gallium (Soza & Olmstead 2010) and Dodonaea (Harrington & Gadek 2010). Within genera, Goldberg et al (2017) found that transitions towards combined sexes were no less common than those towards separate sexes.…”