The phylogeny of Syntrichia: An ecologically diverse clade of mosses with an origin in South America

Premise: To address the biodiversity crisis, we need to understand the
evolution of all organisms and how they fill geographic and ecological
space. Syntrichia is one of the most diverse and dominant genera of
mosses, ranging from alpine habitats to desert biocrusts, yet its
evolutionary history remains unclear.    Results: We
found 10 major well-resolved subclades of Syntrichia that possess
geographical or morphological coherence, in some cases representing
previously accepted genera. We infer that the extant species diversity of
Syntrichia likely originated in South America in the early Eocene
(56.5–43.8 mya), subsequently expanded its distribution to the neotropics,
and finally dispersed to the northern hemisphere. There, the clade
experienced a recent diversification (15–12 mya) into a broad set of
ecological niches (e.g., the S. caninervis and S. ruralis complexes). The
transition from terricolous to either saxicolous or epiphytic habitats
occurred more than once and was associated with changes in water-related
traits. Conclusions: Our study provides a framework for understanding the
evolutionary history of Syntrichia through the combination of
morphological and molecular characters, revealing that migration events
that shaped the current distribution of the clade have implications for
morphological character evolution in relation to niche diversity.