Autecological traits determined two evolutionary strategies in Mediterranean plants during the Quaternary: low differentiation and range expansion versus geographical speciation in Linaria

Abstract

The evolutionary patterns of the Mediterranean flora during the Quaternary have been relatively well documented based on phylogenetic and biogeographic analyses, but few studies have addressed the evolutionary traits that determined diversification and range expansion success during this period. We analysed previously published and newly generated sequences of three plastid noncoding regions (rpl32-trnL(UAG) , trnS-trnG and trnL-trnF), the nuclear ribosomal internal transcribed spacer (ITS) and a low-copy nuclear gene intron (AGT1) of Linaria sect. Supinae, a group of angiosperms that diversified in the Quaternary. The origin and recent colonization dynamics of closely related lineages were inferred by biogeographic reconstruction and phylogeographic analyses, while breeding system experiments coupled with ecological and morphological data were used to test association with range expansion and diversification. A combination of traits, including selfing, short lifespan and the ability to tolerate a wide variety of substrates, were key factors underlying range expansion after long-distance dispersal throughout the Mediterranean basin. By contrast, self-incompatibility may have promoted higher diversification rates in narrow ranges of the Iberian Peninsula. We argue that a few traits contributed to the adoption of two contrasting strategies that may have been predominant in the evolution of Mediterranean angiosperms.

Putative floral brood-site mimicry, loss of autonomous selfing, and reduced vegetative growth are significantly correlated with increased diversification in Asarum (Aristolochiaceae)

“…The inclusion of additional taxa from the Braun clade would undoubtedly reinforce and provide additional significance to our findings, since 46 species from this clade are currently recognized from Japan alone (Sugawara, 2006). Davis et al (2013) warn that BiSSE analyses of trees containing fewer than 300 terminals are prone to Type II error, though published studies have analyzed many fewer species (Johnson et al, 2011;Valente et al, 2011;Blanco-Pastor and Vargas, 2013;Schneider et al, 2013). The majority of p-values reported here are highly significant; this suggests that the phylogenies analyzed did not unduly challenge the BiSSE method.…”

Macroevolutionary dynamics of nectar spurs, a key evolutionary innovation

“…S8). For example, some of the shortest spurs in Linaria are found in species with tiny corollas that appear to have evolved as a result of self‐fertilization (Segarra‐Moragues & Mateu‐Andrés, ; Blanco‐Pastor & Vargas, ). After accounting for corolla size, evolution of the spur : corolla ratio also displays a pattern of recurrent changes with relatively homogeneous rates (Figs S9, S10), and model testing supports a nonphylogenetic model (Table ), indicating a high evolutionary lability.…”

Ecological differentiation, speciation, and rarity: How do they match in Tephroseris longifolia agg. (Asteraceae)?

“…The significant niche differentiation was confirmed for climatic, topographic, pedological, and vascular plant‐based coenotic niches. According to the recent studies (Blanco‐Pastor & Vargas, ; Jaime et al., ; Kreuzer et al., ; Normand et al., ; Pannek et al., ), soil parameters are expected to be among the major predictors of plant distribution at smaller spatial scales, while climate and altitude become increasingly important toward large scales. The indicated morphotype differences in co‐occurring vascular plant species are also important as they support our suggestion on gradual niche divergence within the geographically and climatically distinct areas due to the adaptation to local coenotic conditions.…”

“…Geographic isolation resulting from range shifts during Pleistocene in central Europe could lead to selection and local adaptation to different environments and promote niche differentiation (Jaime et al, 2015;Kreuzer et al, 2014;Thompson et al, 2005). Speciation of outcrossing plants is driven by fine adaptation of ecotypes through extensive recombination and heterozygosity (Blanco-Pastor & Vargas, 2013;Polechová & Storch, 2008). Taxa can adapt to different resources by an independent process of evolutionary optimization, as plant speciation is driven by selection (and subsequent fixation) of novel variants bringing adaptive advantage for plants in novel ecological conditions (Gross & Rieseberg, 2005;Thompson, 1999;Thompson et al, 2005;López-Sepúlveda et al, 2013;Polechová & Storch, 2008).…”

“…Similarly, the expectation of low genetic variation of narrow endemic species (Stebbins, 1980;Walck et al, 2001) has not been universally proved (Matesanz et al, 2009). On the other hand, the biological traits such as understorey grow habit and seed dispersal importantly influenced the breadth of ecological niches (Blanco-Pastor & Vargas, 2013;Fridley et al, 2007;Lavergne et al, 2004;Thompson et al, 2005;Walck et al, 2001;).…”