The Contribution of Edaphic Heterogeneity to the Evolution and Diversity of Burseraceae Trees in the Western Amazon

Abstract

Environmental heterogeneity in the tropics is thought to lead to specialization in plants and thereby contribute to the diversity of the tropical flora. We examine this idea with data on the habitat specificity of 35 western Amazonian species from the genera Protium, Crepidospermum, and Tetragastris in the monophyletic tribe Protieae (Burseraceae) mapped on a molecular-based phylogeny. We surveyed three edaphic habitats that occur throughout terra firme Amazonia: white-sand, clay, and terrace soils in eight forests across more than 2000 km in the western Amazon. Twenty-six of the 35 species were found to be associated with only one of three soil types, and no species was associated with all three habitats; this pattern of edaphic specialization was consistent across the entire region. Habitat association mapped onto the phylogenetic tree shows association with terrace soils to be the probable ancestral state in the group, with subsequent speciation events onto clay and white-sand soils. The repeated gain of clay association within the clade likely coincides with the emergence of large areas of clay soils in the Miocene deposited during the Andean uplift. Character optimizations revealed that soil association was not phylogenetically clustered for white-sand and clay specialists, suggesting repeated independent evolution of soil specificity is common within the Protieae. This phylogenetic analysis also showed that multiple cases of putative sister taxa with parapatric distributions differ in their edaphic associations, suggesting that edaphic heterogeneity was an important driver of speciation in the Protieae in the Amazon basin.

Phylogenetic insights into Andean plant diversification

“…These authors argue that the connection between the Andean uplift and the demise of Lake Pebas during the Late Miocene is consistent with colonizations by eastern Andean ancestors into lowland Amazonia from the Late Miocene onwards. Miocene diversification of the rain forest genus Renealmia (Zingiberaceae) also gives support to the idea that its diversification was influenced by the rise of the Andes (Särkinen et al, 2007), similar to what was proposed to several genera of the Annonaceae with Miocene diversifications (Pirie et al, 2006) Diversification of the tribe Protieae (Burseraceae) in the western Amazon was suggested to be associated with the creation of new edaphic habitats during the uplift of the Andes (Fine et al, 2005). However, divergence times for this group (∼40 Ma; Becerra et al, 2012) seem to predate Andean uplift.…”

Time-Calibrated Phylogenies of Hummingbirds and Hummingbird-Pollinated Plants Reject a Hypothesis of Diffuse Co-Evolution

“…In contrast, we do not find evidence that Ruellia contributed to diversification of hummingbirds. Diversification of hummingbirds in the middle to late Miocene, prior to the establishment of Ruellia in the New World, is likely explained by multiple factors, both abiotic (Fine et al 2005;Antonelli et al 2009) and biotic. Over this time span, the Americas were geologically and climatologically dynamic, resulting in a changing mosaic of habitats across latitudinal, elevational, and rainfall gradients over geological time and space (Hoorn et al 2010).…”

“…One of the longest running debates in ecology and evolutionary biology is that of causes of the latitudinal gradient in species diversity (e.g., time and/or area models, speciation and/or extinction rate models ;Wallace 1878;Haffer 1969;van der Hammen 1974;Stebbins 1974;Simpson 1980;Gentry 1982;Prance 1982;Burnham & Graham 1999;Fine et al 2005;Mittelbach et al 2007;Antonelli et al 2009;Pennington et al 2010;Hoorn et al 2010;Rull 2011;see Hughes et al 2013 and other papers in special issue of Bot. J. Linn.…”

Multi-scale comparisons of tree composition in Amazonian terra firme forests

“…In addition, by using species-level phylogenies, it is now possible to examine the relative contribution that habitat specialisation and dispersal events have played in the plant community evolutionary process (e.g. Fine et al, 2005).…”

“…However, at a regional scale within western Amazonia, floristic patterns have been related to dispersal limitation due to geographical distance, the capacity of a few groups of species to dominate large areas ("oligarchies"), large geological units, as well as fine-scale soil heterogeneity (e.g. Pitman et al, 2001;Phillips et al, 2003;Tuomisto et al, 2003a;Vormisto et al, 2004;Fine et al, 2005;Macía and Svenning, 2005;Montufar and Pintaud, 2006;Ruokolainen et al, 2007;Pitman et al, 2008;Duque et al, 2009). Different factors may well be important at different scales but the relative importance of geographical distance and environmental conditions, at both regional and continental scales, has not been studied in Amazonia.…”