Abstract Detail

Conservation Biology

Breslin, Peter [1], Albuquerque, Fabio [2].

Habitat Suitability and Potential Future Range Contraction of Cochemiea halei (Cactaceae), a Pacific Island Endemic of Baja California Sur.

          Cochemiea halei is an island endemic cactus in Baja California Sur, closely related to the more widespread, peninsular species, Cochemiea poselgeri. It is of conservation concern, listed as threatened on the International Union for the Conservation of Nature Red List and as a species of special concern under Mexican federal law, and, along with the rest of the Cactaceae, on the Convention in International Trade of Endangered Species appendix II. C. halei only occurs on the island archipelago in Bahía Magdalena, except for six individuals on the adjacent peninsula, with a known extent of occurrence of approximately 50 km by 20 km. The oceanic islands where C. halei occurs are characterized by rugged terrain, consisting in part of ultramafic crustal rock such as serpentinite, amphibolite and ophiolite, but also of basalt and sand. The heterogeneous geography, geology and climate of the islands play a strong role in determining habitat suitability for this species. The goals of this study are to 1). estimate the current suitable habitat for Cochemiea halei, 2). identify which environmental variables determine the habitat suitability for the species, 3). Clarify the role of ultramafic soils in the distribution of the species and 4). predict future trends in the distribution of the species based on climate change scenarios. We used WorldClim variables at 30 arcsecond resolution and multiple species distribution modeling methods to identify important environmental variables driving current habitat suitability. The best model of current suitability is used to predict possible effects of four climate change scenarios based on best case to worst case representative concentration pathways, with projected climate data from two general circulation models, over two time periods. The occurrence of the species is found to be strongly correlated with ultramafic soils, as well as annual temperature range, the mean temperature of the warmest quarter of the year, and biseasonal summer and winter precipitation typical of the Sonoran Desert. The most important climate predictor for habitat suitability is annual temperature range, significantly lower than on the adjacent peninsula. The species is shown to be unlikely to migrate back to the peninsula. Within its extent of occurrence on the islands, the probability of occurrence of the species varies widely, including distinct regions of unsuitable habitat. Under climate change, the species is predicted to undergo range contractions between 21% and 53%, depending on the scenario and time period of the projection.

1 - 172 E Bonita Way, Tempe, AZ, 85281, United States
2 - Arizona State University, Gilbert, AZ, 85281, United States

none specified

Presentation Type: Oral Paper
Number: 0004
Abstract ID:501
Candidate for Awards:None

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