Cacti (Cactaceae)
Cactaceae systematics
Currently, a collaborative project is underway to build a unifying phylogenetic framework for systematics and evolution of Portulacineae (Anacampserotaceae, Basellaceae, Cactaceae, Didiereaceae, Halophytaceae, Montiaceae, Portulacaceae, and Talinaceae) using the Angiosperms353 targeted sequencing baits. This effort is led by Jurriaan de Vos and is funded through the Kew's Plant and Fungal Trees of Life programme.
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Echinopsis chiloensis
Recently, a collaborative project led by Carmen Gloria Ossa from the Universidad de Valparaiso in Chile focussed on the taxon Echinopsis chiloensis, an endemic cactus from arid and semiarid regions of Central Chile. The aim was to develop microsatellite markers using high-throughput sequencing as a tool to study population structure, genetic diversity and effective population size. We developed 12 polymorphic microsatellite markers for E. chiloensis and tested them in 60 individuals from six sites, covering all the latitudinal range of this species. Using these microsatellite markers, we then examined the response of this xerophytic species to quaternary glacial cycles to determine the genetic patterns and climatic niche of Echinopsis chiloensis var. chiloensis.
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Relevant publications
Ossa CG, Larridon I, Montenegro P, Pérez F (2019) Response of xerophytic plants to glacial cycles in southern South America. Annals of Botany 124(1): 15–26. Available online.

Ossa CG, Larridon I, Peralta G, Assselman P, Pérez F (2016) Development of microsatellite markers using Next-Generation Sequencing for the columnar cactus Echinopsis chiloensis (Cactaceae). Molecular Biology Reports 43(12): 1315-1320. Available online.
Copiapoa, Eriosyce & Eulychnia
The highly endemic flora of the Chilean biodiversity hotspot is increasingly threatened by habitat loss due to anthropogenic causes and climate change. My postdoctoral research at Ghent University (2012-2015) focused on threatened cactus species of which the evolution and genetic diversity have not yet been studied using molecular approaches.

In this project, fundamental plant biodiversity research, conservation genetics and analyses of species distributions were applied to species of Copiapoa, Eriosyce and Eulychnia. Molecular tools were used to delimit species and assess the genetic diversity at species and population level. This knowledge not only helps to understand general patterns of evolution in the studied genera, but is also of great value towards long-term in situ and ex situ conservation as it can be used to recommend specific conservation actions.
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Relevant publications
Guerrero PC, Walter HE, Walter; Arroyo MTK, Peña CM, Tamburino Í, De Benedictis M, Larridon I (2019) Molecular phylogeny of the large South American genus Eriosyce (Notocacteae, Cactaceae): Generic delimitation and profound changes at infrageneric and species ranks. Taxon 68(3): 557-573. Available online.

Larridon I, Veltjen E, Semmouri I, Asselman P, Guerrero PC, Duarte M, Walter HE, Cisternas MA, Samain MS (2018) Investigating taxon boundaries and extinction risk in endemic Chilean cacti (Copiapoa subsection Cinerei) using chloroplast DNA sequences, microsatellite data and 3D mapping. Kew Bulletin 73: 55 (17 pages). Available online.

Larridon I, Walter HE, Rosas M, Vandomme V, Guerrero PC (2018) Evolutionary trends in the columnar cactus genus Eulychnia (Cactaceae) based on molecular phylogenetics, morphology, distribution and habitat. Systematics and Biodiversity 16(7): 643-657. Available online.

Larridon I, Walter HE, Guerrero PC, Duarte M, Cisternas MA, Peña Hernández C, Bauters K, Asselman P, Goetghebeur P, Samain MS (2015) An integrative approach to understanding the evolution and biodiversity of Copiapoa (Cactaceae), a threatened endemic Chilean genus from the Atacama Desert. American Journal of Botany 102(9): 1506-1520. Available online.

Larridon I, Shaw K, Cisternas MA, Sharrock S, Oldfield S, Goetghebeur P, Samain MS (2014) Is there a future for the Cactaceae genera Copiapoa, Eriosyce and Eulychnia? A status report of a prickly situation. Biodiversity and Conservation 23(5): 1249-1287. Available online.
Main collaborators
Helmut E. Walter