Benjamin T. Wilder

Assessing the Geological and Climatic Forcing of Biodiversity and Evolution Surrounding the Gulf of California

The biota of the lands has had a restless place and has endured displacements, inundations, extinctions, and has been forced into migrations with the coming and going of the sea, with the submergence or emergence of mountains, and with the concomitant changes of local climate. Close study of the plant and animal life, when directed by a correlating intelligence, should reveal a course of evolution, expressed jointly by plant and rock, hardly equaled in plant geography.

Succulent Plant Diversity Of the Sonoran Islands, Gulf Of California, Mexico

Abstract Succulent life forms are a prominent feature of the Sonoran Gulf of California islands (Alcatraz, Cholludo, Dátil, Patos, San Esteban, San Pedro Mártir, San Pedro Nolasco, and Tiburón). Among a total flora of 378 species of vascular plants, there are 62 succulent taxa (16%) in 16 families and 33 genera, which we place in three categories: xerophytic succulents (32), semisucculents (22), and halophytic succulents (8). Succulent plant distribution on each island is unique and reflects the shaping climatic, biotic (including herbivores), soil, and topographical features of each of these microcosms. Cactaceae is the most diverse family (25 taxa), with six endemic species, all small cacti, found on Islas San Esteban, San Pedro Nolasco, Dátil, and Cholludo. The smaller islands in the region have a significantly higher percentage of succulent species. Here we present a discussion of the different succulent categories and a detailed floristic listing for all succulent species, which represents the first specimen-based flora of succulents from Gulf of California islands.

Local Extinction and Unintentional Rewilding of Bighorn Sheep (Ovis canadensis) on a Desert Island

Bighorn sheep (Ovis canadensis) were not known to live on Tiburón Island, the largest island in the Gulf of California and Mexico, prior to the surprisingly successful introduction of 20 individuals as a conservation measure in 1975. Today, a stable island population of ∼500 sheep supports limited big game hunting and restocking of depleted areas on the Mexican mainland. We discovered fossil dung morphologically similar to that of bighorn sheep in a dung mat deposit from Mojet Cave, in the mountains of Tiburón Island. To determine the origin of this cave deposit we compared pellet shape to fecal pellets of other large mammals, and extracted DNA to sequence mitochondrial DNA fragments at the 12S ribosomal RNA and control regions. The fossil dung was 14C-dated to 1476–1632 calendar years before present and was confirmed as bighorn sheep by morphological and ancient DNA (aDNA) analysis. 12S sequences closely or exactly matched known bighorn sheep sequences; control region sequences exactly matched a haplotype described in desert bighorn sheep populations in southwest Arizona and southern California and showed subtle differentiation from the extant Tiburón population. Native desert bighorn sheep previously colonized this land-bridge island, most likely during the Pleistocene, when lower sea levels connected Tiburón to the mainland. They were extirpated sometime in the last ∼1500 years, probably due to inherent dynamics of isolated populations, prolonged drought, and (or) human overkill. The reintroduced population is vulnerable to similar extinction risks. The discovery presented here refutes conventional wisdom that bighorn sheep are not native to Tiburón Island, and establishes its recent introduction as an example of unintentional rewilding, defined here as the introduction of a species without knowledge that it was once native and has since gone locally extinct.

Island Specialists: Shared Flora of the Alta and Baja California Pacific Islands

Abstract. The floristic connection between the mediterranean region of Baja California and the Pacific islands of Alta and Baja California provides insight into the history and origin of the California Floristic Province. We present updated species lists for all California Floristic Province islands and demonstrate the disjunct distributions of 26 taxa between the Baja California and the California Channel Islands. These 26 plant taxa are found among the 16 Pacific islands without occurring on the intervening mainland of Alta California. Separate species lists for each island group (8 California Channel Islands and 8 Baja California Islands) were compiled. These lists were compared to the mainland California flora to identify species that occur on the California Islands and either the Baja California Pacific Islands or the mediterranean region of the Baja California Peninsula, but not the mainland of Alta California. This first compilation of the flora of the Baja California Islands and nomenclatural updates for the Channel Islands provide a platform for future research and conservation planning.

Near Colonization of a Desert Island by a Tropical Bird: Military Macaw (Ara militaris) at Isla San Pedro Nolasco, Sonora, Mexico

Abstract In 2000, military macaws (Ara militaris) arrived on Isla San Pedro Nolasco, a desert island near the coast of Sonora, Mexico. The last one was seen in 2009. This is the first report of this macaw on an island in the Gulf of California, Mexico.

Report to Arizona-Nevada Academy of Science on the Project: Vascular Flora of Isla Tiburón and Satellite Islands, Gulf of California, Mexico

To the Board of Governors of the Arizona Nevada Academy of Science (ANAS), I am pleased to report considerable success thus far on my floris tic project focused on Isla Tibur?n and its satellite islands (Islas San Esteban, D?til, Cholludo, Alcatraz, and Patos) in the Gulf of California, Mexico. This work represents a collaborative effort between myself; Dr. Richard Feiger, Executive Director of Drylands Institute; Humerto Romero, Comc?ac (Seri people) collaborator; and Jss?s Sanch?z-Escalante, Curator of the University of Sonora Herbarium (USON). Additional Assistance has been received from Dr. Betsy Arnold, my project advisor who is an ANAS member. The project commenced in August of 2005 and since receiving funding from ANAS, December 15,2005, I have completed four field expeditions to the study area and developed a working relationship with Humberto Romero. I have collected >200 signifi cant plant specimens from the islands, representing 130 different species (Appendix 1). I presented the project to an international audience at the Fifth International Symposium on the Native Flora of Arid Lands in Hermosillo, Mexico, 29-31 March 2006.1 have completed searching the University of Arizona Herbarium (ARIZ) for voucher specimens from the islands, and have initiated work on several publications. All of the field work on the islands is being carried out under Mexican federal collecting permits, with specimens collected being deposited at ARIZ, with duplicates to the Herbario de la Universidad de Sonora (USON), the San Diego Natural History Museum Herbarium (SD), and other appropriate institutions in Mexico and the US. The goal of the project is to produce a compre hensive treatment of the flora of Isla Tibur?n and its