Explaining the distribution of breeding and dispersal syndromes in conifers

Abstract

The evolution of plants exhibiting different sexes, or dioecy, is correlated with a number of ecological and life-history traits such as woody growth form and animal-dispersed seeds, but the underlying causes of these associations are unclear. Previous work in seed plants has suggested that the evolution of fleshy cones or seeds may favour dioecy. In this study, we use a well-sampled molecular phylogeny of conifers to show that although dioecy and fleshiness strongly co-occur at the species level, this relationship has not resulted from numerous separate origins of this trait combination or from differential rates of diversification. Instead, we suggest that two character combinationsthe ancestral dry-monoecious condition and the derived fleshy-dioecious condition-have persisted in conifers longer than other combinations over evolutionary time. The persistence of these trait combinations appears to reflect differences in the rate of successful transition into and out of these character states over time, as well as the geographical restriction of species with rare combinations and their consequent vulnerability to extinction. In general, we argue that such persistence explanations should be considered alongside 'key innovation' hypotheses in explaining the phylogenetic distribution of traits.

Ecological consequences of contrasting dispersal syndromes in New World Ephedra: higher rates of niche evolution related to dispersal ability

“…Ephedra species (mean 5 mya, HPD: 8.1–1.9 mya). Although shifts between dry and fleshy dispersal syndromes in other gymnosperms are less frequent or occurred only a few times in early diverging clades (Leslie et al ), in NW Ephedra most transitions were observed and they appear in either clades that diverged early on or derived clades.…”

“…Research on dispersal syndromes in higher plants has mainly focused on differences in the traits that are important for disseminating the seeds (Jordano et al , Masaki et al ) or on understanding the association of different dispersal syndromes with biodiversity and ecological patterns at different scales (Tiffney , Jordano , Griz et al , Beaudrot et al ). However, the ecological consequences of different dispersal syndromes have been rarely studied (but see Leslie et al or Verdú and Pausas ).…”

Potential syndromes linking dispersal and reproduction in the hermaphrodite land snail Cornu aspersum

“…At the interspecific level, this prediction is relatively well supported by several comparative analyses, mostly in plants (see, e.g. Leslie et al ., ; and references therein; also Eppley & Jesson, for a study using plants, animals and fungi). However, in hermaphrodites, the allocation to the male or female functions can be highly variable between individuals depending, for example on age, mating opportunities and environmental context (Baeza, ; Vizoso & Schärer, ).…”

Macroevolutionary synthesis of flowering plant sexual systems

“…A third is a combination of sex inconstancy and long-distance dispersal, allowing establishment in a new location (Baker 1955;Lloyd 1975b;Case et al 2008). Empirical evidence for loss of dioecy varies in strength and approach, ranging from observations of particular forms of sex inconstancy (Lloyd 1975a) to direct genetic studies (Wolf et al 2001;Obbard et al 2006) to phylogenetic reconstructions (Case et al 2008;Volz and Renner 2008;Schaefer and Renner 2010;Leslie et al 2013;Villarreal and Renner 2013;McDaniel et al 2013;Njuguna et al 2013). Empirical evidence for loss of dioecy varies in strength and approach, ranging from observations of particular forms of sex inconstancy (Lloyd 1975a) to direct genetic studies (Wolf et al 2001;Obbard et al 2006) to phylogenetic reconstructions (Case et al 2008;Volz and Renner 2008;Schaefer and Renner 2010;Leslie et al 2013;Villarreal and Renner 2013;McDaniel et al 2013;Njuguna et al 2013).…”