Pleistocene climate oscillations have shaped the expansion and contraction speciation model of the globose Eriosyce sect. Neoporteria cacti in Central Chile.

BACKGROUND AND AIMS: Pleistocene climatic oscillations, characterized by arid (interglacial) and pluvial (glacial) phases, have profoundly impacted the floras of Mediterranean climates. Our study investigates the hypothesis that these climatic extremes have promoted phases of range expansion and contraction in the Eriosyce sect. Neoporteria, resulting in pronounced genetic structuring and restricted gene flow. METHODS: Utilizing nuclear microsatellite markers, we genotyped 251 individuals across 18 populations, encompassing all 14 species and one subspecies within the Eriosyce sect. Neoporteria. Additionally, Species Distribution Models (SDMs) were employed to reconstruct past (Last Interglacial, Last Glacial Maximum, Mid-Holocene) and current potential distribution patterns, aiming to delineate the climatic influences on species' range dynamics. KEY RESULTS: The gene flow analysis disclosed disparate levels of genetic interchange among species, with marked restrictions observed between entities that are geographically or ecologically separated. Notably, E. subgibbosa from Hualpen emerged as genetically distinct, warranting its exclusion for clearer genetic clustering into north, central, and south clusters. The SDMs corroborated these findings, showing marked range expansions during warmer periods and contractions during colder times, indicating significant shifts in distribution patterns in response to climatic changes. CONCLUSIONS: Our findings emphasize the critical role of Pleistocene climatic fluctuations in driving the dynamic patterns of range expansions and contractions that have led to geographic isolation and speciation within the Eriosyce sect. Neoporteria. Even in the face of ongoing gene flow, these climate-driven processes have played a pivotal role in sculpting the species' genetic architecture and diversity. This study elucidates the complex interplay between climatic variability and evolutionary dynamics among Mediterranean cacti in central Chile, highlighting the necessity of considering historical climatic millenial oscillations in conservation and evolutionary biology studies.

Taxonomic dissection based on molecular evidence of the Eriosycecurvispina complex (Cactaceae): identifying nine endemic species from Central Chile.

Chile's distinctive flora, geographical isolation, and complex topography collectively contribute to a notable endemic species diversity, particularly within central regions identified as critical areas for biodiversity conservation. The cactus genus Eriosyce, as currently circumscribed, encompasses seven sections, with Eriosycesect.Horridocatus presenting a notably complex species group. This study investigates the E.curvispina complex, a member of the Notocacteae tribe common in central Chile, by incorporating new populations and examining phylogenetic relationships using four plastid and one nuclear molecular marker. The phylogenetic analysis of sampled individuals identified nine independent lineages, each warranting recognition at the species rank. Despite minimal morphological differences among taxa, morphological characters were utilized to support and stabilize the DNA-based phylogenetic hypothesis. The results highlight the high taxonomic diversity in these cactus lineages and have implications for the classification of the E.curvispina complex, including new combinations and proposals of conservation status.

ResumenLa flora distintiva de Chile, su aislamiento geográfico y topografía compleja contribuyen colectivamente a una notable diversidad de especies endémicas, particularmente dentro de las regiones centrales identificadas como áreas críticas para la conservación de la biodiversidad. El género de cactus Eriosyce, tal como está circunscrito actualmente, abarca siete secciones, presentando Eriosycesect.Horridocatus un grupo de especies notablemente complejo. Este estudio investiga el complejo E.curvispina, un miembro de la tribu Notocacteae común en Chile central, incorporando nuevas poblaciones y examinando las relaciones filogenéticas utilizando cuatro marcadores moleculares del cloroplasto y uno nuclear. El análisis filogenético de las poblaciones muestreadas identificó nueve linajes independientes, cada uno mereciendo reconocimiento a nivel de especie. A pesar de las mínimas diferencias morfológicas entre los taxones, se utilizaron caracteres morfológicos para apoyar y estabilizar la filogenia basada en ADN. Los resultados resaltan la alta diversidad taxonómica en estos linajes de cactus y tienen implicaciones para la clasificación del complejo E.curvispina, incluyendo nuevas combinaciones y propuestas de estado de conservación.