Southern South American Proteaceae thrive on young volcanic substrates, which are extremely low in plant-available phosphorus (P). Most Proteaceae exhibit a nutrient-acquisition strategy based on the release of carboxylates from specialized roots, named cluster roots (CR). Some Proteaceae colonize young volcanic substrates which has been related to CR functioning. However, physiological functioning of other Proteaceae on recent volcanic substrates is unknown. We conducted an experiment with seedlings of five Proteaceae (Gevuina avellana, Embothrium coccineum, Lomatia hirsuta, L. ferruginea, and L. dentata) grown in three volcanic materials. Two of them are substrates with very low nutrient concentrations, collected from the most recent deposits of the volcanoes Choshuenco and Calbuco (Chile). The other volcanic material corresponds to a developed soil that exhibits a high nutrient availability. We assessed morphological responses (i.e., height, biomass, and CR formation), seed and leaf macronutrient and micronutrient concentrations and carboxylates exuded by roots. The results show that G. avellana was less affected by nutrient availability of the volcanic substrate, probably because it had a greater nutrient content in its seeds and produced large CR exuding carboxylates that supported their initial growth. Embothrium coccineum exhibited greater total plant height and leaf P concentration than Lomatia species. In general, in all species leaf macronutrient concentrations were reduced on nutrient-poor volcanic substrates, while leaf micronutrient concentrations were highly variable depending on species and volcanic material. We conclude that Proteaceae from temperate rainforests differ in their capacity to grow and acquire nutrients from young and nutrient-poor volcanic substrates. The greater seed nutrient content, low nutrient requirements (only for G. avellana) and ability to mobilize nutrients help explain why G. avellana and E. coccineum are better colonizers of recent volcanic substrates than Lomatia species.

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Aims Embothrium coccineum is a pioneer tree that produces cluster roots (CR) induced by phosphorus (P) or nitrogen (N) deficiency, but the role which both N and P play in CR formation for different E. coccineum populations is still unknown. We hypothesized that in E. coccineum, N influences the CR formation response, primarily induced by P limitation. However, this response depends on local adaptations to their specific conditions of geographic origin. M e t h o d s S e e d l i n g s f r o m t h r e e c o n t r a s t i n g edaphoclimatic conditions (Northern, Central and Southern populations) were grown in hydroponic culture under high and low N supply and at five different P

The South American temperate forests have been subjected to drastic past topographic and climatic changes during the Pliocene – Pleistocene linked to Andean orogeny and glacial cycles. These changes are common drivers of genetic structure and adaptation process. Embothrium coccineum, a member of the Proteaceae family and an emblematic tree of the South American temperate forest with a distribution spanning 20° of latitude, has been strongly affected by these topographic and climatic changes. Previous studies have shown that the species presents a marked genetic structure with distinct ecotypes described; yet, little is known about their adaptive genetic responses. The main goal of this study was to investigate the effects of historical and contemporary landscape features affecting the genetic diversity and connectivity of E. coccineum throughout its natural distribution. Using more than 2000 SNPs, two genetic groups (North and Center-South) that have diverged some 2.8 million years ago were observed. The level of genetic structure was higher between populations within the North genetic group than within the Center-South group. We propose that these contrasting patterns of genetic structure are related to differences in pollinator’s assemblage and evolutionary histories between genetic groups. Moreover, we observed the existence a strong patter of isolation by environment in E. coccineum, suggesting that selection could have leaded to adaptive divergence among localities. We propose that, within the Chilean temperate forest, the patterns of genetic variation in E. coccineum reflect both a Quaternary phylogenetic imprint and the impact of selection to the strong environmental gradient.

The South American temperate forests were subjected to drastic topographic and climatic changes during the Pliocene‐Pleistocene as a consequence of the Andean orogeny and glacial cycles. Such changes are common drivers of genetic structure and adaptation. Embothrium coccineum (Proteaceae) is an emblematic tree of the South American temperate forest (around 20°S of latitude) that has strongly been affected by topographic and climatic events. Previous studies have shown a marked genetic structure in this species, and distinct ecotypes have been described. Yet, little is known about their adaptive genetic responses. The main goal of this study was to investigate the effects of historical and contemporary landscape features affecting the genetic diversity and connectivity of E. coccineum throughout its current natural distribution. Using over 2000 single nucleotide polymorphisms (SNPs), we identified two genetic groups (a Northern and a Central‐Southern group) that diverged around 2.8 million years ago. The level of genetic structure was higher among populations within the Northern genetic group than within the Central‐Southern group. We propose that these differences in genetic structure may be due to differences in the assemblages of pollinators and in the evolutionary histories of the two genetic groups. Moreover, the data displayed a strong pattern of isolation by the environment in E. coccineum, suggesting that selection could have led to adaptive divergence among localities. We propose that in the Chilean temperate forest, the patterns of genetic variation in E. coccineum reflect both a Quaternary phylogenetic imprint and signatures of selection as a consequence of a strong environmental gradient.