Independent Evolutionary Lineages in a Globular Cactus Species Complex Reveals Hidden Diversity in a Central Chile Biodiversity Hotspot.

Heidy M Villalobos-Barrantes,Helmut E Walter,Pablo C Guerrero,Beatriz M Meriño

doi:10.3390/genes13020240

Abstract

Unraveling the processes involved in the origin of a substantial fraction of biodiversity can be a particularly difficult task in groups of similar, and often convergent, morphologies. The genus Eriosyce (Cactaceae) might present a greater specific diversity since much of its species richness might be hidden in morphological species complexes. The aim of this study was to investigate species delimitation using the molecular data of the globose cacti “E. curvispina”, which harbor several populations of unclear evolutionary relationships. We ran phylogenetic inferences on 87 taxa of Eriosyce, including nine E. curvispina populations, and by analyzing three plastid noncoding introns, one plastid and one nuclear gene. Additionally, we developed 12 new pairs of nuclear microsatellites to evaluate the population-level genetic structure. We identified four groups that originated in independent cladogenetic events occurring at different temporal depths; these groups presented high genetic diversity, and their populations were genetically structured. These results suggest a complex evolutionary history in the origin of globular cacti, with independent speciation events occurring at different time spans. This cryptic richness is underestimated in the Mediterranean flora of central Chile, and thus unique evolutionary diversity could be overlooked in conservation and management actions.

Highlights

The planet’s biodiversity is declining at unprecedented rates [1]
Bayesian and Maximum likelihood (ML) inferences retrieved identical topologies of the Horridocactus clade (Supplementary Figures S2 and S3), and strongly support the non-monophyly of the E. curvispina complex; we found that its members clustered in four pairs of taxa distributed across three different clades within Horridocactus in four groups (I-IV, Figure 2; Supplementary Figures S1–S3)
The oldest divergence occurred in Clade A at 3.7 ± 2.3–5.5 Ma (95% confidence interval, IC), separating E. curvispina (Los Molles and Laguna Verde) from Andean populations Putaendo and Escorial

Summary

Introduction

Mediterranean regions are among the most unique and threatened ecosystems, characterized by mild, wet winters and very dry, long, hot summers [2,3], and harboring 20 percent (%) of species even when having a surface less than 5% the of total global landmass [4]. The Mediterranean area in Central Chile is recognized by the high number of endemic species, many of which are heavily threatened [4,5]. Knowledge of the biodiversity of Central Chile has increased in recent decades, there are still important gaps, especially in non-charismatic animal groups and non-woody plants. In the last decade, a large number of angiosperms belonging to different families, such as Alstromeriaceae [7,8], Amarillidaceae [9,10], Brassicaceae [11], Orchidaceae [12] and Cactaceae [13,14], have been described

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