Friday, December 7, 2018

[Botany • 2018] Investigating Taxon Boundaries and Extinction Risk in Endemic Chilean Cacti (Copiapoa subsection Cinerei, Cactaceae) Using Chloroplast DNA Sequences, Microsatellite Data and 3D Mapping


The taxa of Copiapoa subsection Cinerei: A – C Copiapoa gigantea; D Ccinerea subsp. cinerea; E C. cinerea subsp. krainziana; F C. cinerea subsp. columna-alba


in Larridon, Veltjen, Semmouri, et al., 2018. 


Photos: A, D, E M.-S. Samain; B, C P. C. Guerrero; F I. Larridon.  facebook.com/KewBulletin

Summary
Copiapoa (Cactaceae) is a genus endemic to the Chilean Atacama Desert. The taxa of Copiapoa subsection Cinerei occur in an area of high species richness and high levels of species endemism of the Central Chilean biodiversity hotspot. Four taxa are usually recognised in this group: Copiapoa gigantea (sometimes placed in C. cinerea as C. cinerea subsp. haseltoniana) and C. cinerea including three subspecies (subsp. cinerea, subsp. krainziana and subsp. columna-alba), one of which is often recognised at species level, i.e. the narrow endemic C. krainziana. Here, we evaluate the taxon boundaries of Copiapoa subsection Cinerei using chloroplast sequences and microsatellite data. We generated sequences of three cpDNA markers (rpl32–trnL, trnH–psbA, ycf1) and as indicated in a previous study, found variation between C. gigantea and C. cinerea on a subsample of 34 individuals. Five microsatellite loci were genotyped for 68 individuals from the known range of Copiapoa subsection Cinerei. In contrast with expectations, we found relatively high levels of genetic diversity (e.g., He = 0.775 – 0.827; Ho = 0.580 – 0.750) and no population structure, even between the two species. Additionally, species distribution models were conducted based on abiotic suitability and transformed to 3D maps to account for topographical complexity. The species distribution models and their 3D projections support an allopatric distribution of the four taxa of Copiapoa subsection Cinerei, with each taxon related to a different range with complex topographical features. The obtained molecular results, combined with the presented species distribution modelling, and calculations of extent of occurrence and area of occupancy for the four taxa of Copiapoa subsection Cinerei, suggest a high extinction risk for most of the taxa. A taxonomic treatment is provided.

Key Words: Atacama Desert, conservation, cpDNA, endemic species, population genetics, species distribution modelling 


Fig. 1. The taxa of Copiapoa subsection Cinerei:
A – C Copiapoa gigantea; D C. cinerea subsp. cinerea; E C. cinerea subsp. krainziana; F C. cinerea subsp. columna-alba.
Photos: A, D, E M.-S. Samain; B, C P. C. Guerrero; F I. Larridon.


Isabel Larridon, Emily Veltjen, Ilias Semmouri, Pieter Asselman, Pablo C. Guerrero, Milén Duarte, Helmut E. Walter, Mauricio A. Cisternas and Marie-Stéphanie Samain. 2018. Investigating Taxon Boundaries and Extinction Risk in Endemic Chilean Cacti (Copiapoa subsection Cinerei, Cactaceae) Using Chloroplast DNA Sequences, Microsatellite Data and 3D Mapping. Kew Bulletin. 73:55. DOI: 10.1007/s12225-018-9780-3  

No comments:

Post a Comment