Trait evolution rates shape continental patterns of species richness in North America's most diverse angiosperm genus (Carex, Cyperaceae)

Abstract

Ecological opportunity has been associated with increases in diversification rates across the tree of life. Under an ecological diversification model, the emergence of novel environments is hypothesized to promote morpho-and ecospace evolution. Whether this model holds at the clade level within the most species-rich angiosperm genus found in North America (Carex, Cyperaceae) is yet to be tested. Recent works demonstrate a temporal coupling of climate cooling and widespread colonization of Carex in North America, implicating ecological diversification. In addition, research has consistently found asymmetric patterns of lineage-level diversification in the genus. Why does variation in clade sizes exist in the genus? Is ecological diversification involved? In this study, we tested whether rates of morphological and ecological trait evolution are correlated with clade-level species richness in Carex of North America north of Mexico. We constructed a phylogeny of 477 species-an almost complete regional sample. We estimated rates of evolution of morphological traits, habitat, and climatic niche and assessed whether differences in rates of evolution correlate with species richness differences in replicate non-nested sister clades. Our work demonstrates significant positive correlations between climatic niche rates, habitat and reproductive morphological evolution, and species richness. This coupling of trait and niche evolution and species richness in a diverse, continental clade sample strongly suggests that the ability of clades to explore niche and functional space has shaped disparities in richness and functional diversity across the North American flora region. Our findings highlight the importance of the evolutionary history of trait and niche evolution in shaping continental and regional floras.

Cryptic diversity and significant cophylogenetic signal detected by DNA barcoding the rust fungi (Pucciniaceae) of Cyperaceae–Juncaceae

“…The high rate of ecological niche evolution observed in rapidly radiating lineages of Carex (Pender, 2015; Spalink et al, 2016; Pender et al, 2021 in this issue) may also have played a role in the diversification of their rust fungi, by facilitating the evolution of new aecial host associations or by promoting ecological specialization. As more phylogenetic data accumulate on rust fungi and as taxonomic studies clarify species limits, diversity, and host ranges, it should soon be possible to explicitly test for correlations between rust and host diversification rates.…”

A framework infrageneric classification ofCarex(Cyperaceae) and its organizing principles

“…Additional relevant literature Faulkner (1972), Chater (1980), Cayouette & Morisset (1985), Cayouette (1987), Standley (1987, 1990), Volkova et al (2008), Dragon & Barrington (2009), Korpelainen et al (2010), Jiménez‐Mejías et al (2011, 2012a, 2014b), Nowak et al (2020), Benítez‐Benítez et al (2021), and Pender et al (2021).…”

An Evolutionary Study of Carex Subg. Psyllophorae (Cyperaceae) Sheds Light on a Strikingly Disjunct Distribution in the Southern Hemisphere, With Emphasis on Its Patagonian Diversification

“…Spirostachyae and Uncinia ; Roalson et al, 2021 ) underwent remarkable radiations in NZ, but they could have arrived earlier to the archipelago than NZ-clade of sect. Junciformes (Martín-Bravo et al, 2019 ), perhaps preventing the establishment of its species through high density blocking (Slingsby and Verboom, 2006 ; Pender et al, 2021 ).…”