Global patterns and a latitudinal gradient of flower disparity: perspectives from the angiosperm order Ericales

Abstract

Summary Morphological diversity (disparity) is an essential but often neglected aspect of biodiversity. Hence, it seems timely and promising to re‐emphasize morphology in modern evolutionary studies. Disparity is a good proxy for the diversity of functions and interactions with the environment of a group of taxa. In addition, geographical and ecological patterns of disparity are crucial to understand organismal evolution and to guide biodiversity conservation efforts. Here, we analyse floral disparity across latitudinal intervals, growth forms, climate types, types of habitats, and regions for a large and representative sample of the angiosperm order Ericales. We find a latitudinal gradient of floral disparity and a decoupling of disparity from species richness. Other factors investigated are intercorrelated, and we find the highest disparity for tropical trees growing in African and South American forests. Explanations for the latitudinal gradient of floral disparity may involve the release of abiotic constraints and the increase of biotic interactions towards tropical latitudes, allowing tropical lineages to explore a broader area of the floral morphospace. Our study confirms the relevance of biodiversity parameters other than species richness and is consistent with the importance of species interactions in the tropics, in particular with respect to angiosperm flowers and their pollinators.

Macroevolutionary pattern ofSaussurea(Asteraceae) provides insights into the drivers of radiating diversification

“…This highlights the important roles of morphological diversity in the evolutionary history of Saussurea. Morphological diversity is an essential but often neglected aspect of biodiversity [58]. Our work provides a valuable guide for conservation efforts in the protection of morphological diversity of organisms, especially in the context of exacerbated biodiversity loss due to global warming.…”

Why does pollen morphology vary? Evolutionary dynamics and morphospace occupation in the largest angiosperm order (Asterales)

“…Finally, we echo calls for additional analyses of morphological disparity in plants, both as an important facet of biodiversity in its own right, and as a complementary metric to taxonomic, phylogenetic and functional diversity (Chartier et al ., 2014, 2017, 2021; Oyston et al ., 2016; Clark & Donoghue, 2018). Of particular interest is the distribution and partitioning of morphological disparity across spatial gradients and through time (Lupia, 1999; Wellman et al ., 2013; Mander, 2018; Chartier et al ., 2021), both focusing on individual organs or functional units (i.e. pollen grains and flowers) or combining these into whole plant analyses (e.g.…”

“…Foote, 1992, 1993, 1999; Wills et al ., 1994; Sidlauskas, 2008; Sakamoto & Ruta, 2012; Hopkins & Smith, 2015; Cooney et al ., 2017; Cole & Hopkins, 2021), although similar approaches are increasingly being applied to both extant and fossil plant datasets. These studies have revealed that disparity tends to accumulate quickly early in the history of a clade and is typically decoupled from species richness (Lupia, 1999; Wellman et al ., 2013; Oyston et al ., 2016; Mander, 2018; Chartier et al ., 2021) and that morphological variability is related to both phylogeny (Chartier et al ., 2017; Kriebel et al ., 2017; Clark & Donoghue, 2018; Woutersen et al ., 2018; Clark et al ., 2019; Mander et al ., 2020; Bogotá‐Ángel et al ., 2021) and functional ecology (Chartier et al ., 2017; Kriebel et al ., 2017; Mander et al ., 2020), similar to the trends recorded previously in animal groups (e.g. Foote, 1993, 1994; Friedman, 2012; Hughes et al ., 2013; Hopkins & Smith, 2015).…”

Insights into the drivers of radiating diversification in biodiversity hotspots usingSaussurea(Asteraceae) as a case

“…Although trait dependent analyses showed several adaptive traits driving the increase of speciation rate, some unobserved traits were also important for rapid diversification, highlighting the vital roles of morphological diversity in the evolutionary history of Saussurea. Morphological diversity is an essential but often neglected aspect of biodiversity (Chartier et al, 2021).…”