Cactaceae are the fifth most Threatened group of living organisms to have been evaluated for the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species, with 31% of cactus species Threatened with extinction, primarily from poaching and habitat loss. Including the predicted impacts of climate change, 60-90% of all cactus species are expected to experience anthropogenic threat impacts in the next 50 years. Seed banking, cryopreservation, and living collections for conservation, collectively “ex situ” conservation, are recognized as valuable tools for preventing extinctions. Ex situ conservation entails removing propagules from “in situ” threat impacts and growing or breeding plants for reintroduction to their natural habitats in the future. However, collection trips to gather samples of wild propagules that are sufficiently genetically diverse to preserve the viability of in situ populations can be expensive. At a time when conservation need outpaces conservation budgets, conservation institutions bear a responsibility to plan collection trips strategically to achieve the maximum benefit. This study explores how the Desert Botanical Garden (DBG) in Phoenix, Arizona, can use a project prioritization protocol, a tool from decision science, to best invest resources to minimize extinction across 27 IUCN Threatened and Near-Threatened cactus species in the Sonoran Desert. I developed and applied a novel protocol for estimating cost-efficiency of collection projects for these species. The results suggest that the DBG can achieve 70% of the estimated total conservation benefit by collecting six populations of four species: Grusonia reflexispina, Mammillaria johnstonii, Echinocereus leucanthus, and Echinocereus barthelowanus. All four are Endangered or Critically Endangered species that have few in situ populations and are poorly represented in the DBG. These projects would require two collection trips in Mexico: first to Guaymas, Sonora, and then to the Magdalena and Santa Margarita Barrier Islands, Baja California Sur. This study explores what information is critical to improving decision-making in plant conservation and databases like the IUCN Red List and botanical garden networks. By aiming to unveil the data and assumptions that underpin all decisions, prioritizations are valuable tools for achieving the continuous improvement of conservation decisions.

The genus Buellia remains one of the largest, poorly resolved genera of crustose lichens world-wide. A global revision is challenging because of its enormous diversity .As a step towards a more comprehensive revision, three easily separated groups were examined. Buellia sulphurica is easily recognized by its vivid yellow color, caused by rhizocarpic acid, a secondary metabolite rarely reported from the genus. The species has been considered endemic to the Galapagos, but it is morphologically and anatomically almost identical to B. xanthinula, a taxon previously described from Brazil. Moreover, both have rhizocarpic acid. Additionally, a specimen from Georgia with a similar morphology and anatomy with identical secondary chemistry has been examined here. Based on this research, it is discussed whether all three taxa represent a single species. Another aspect of the research presented here focused on species of Buellia that parasitize other lichens. It is generally assumed that they are strongly host-specific. Parasitic specimens of Buellia recently collected in the Great Basin are morphologically similar to taxa previously reported from Northern Europe, South America, and North America. Preliminary studies, comparing the material with specimens of B. uberior, B. miriquidica, B. malmei and B. imshaugii, suggest that the Great Basin material is best recognized as representatives of distinct, currently undescribed species. Finally, as part of this thesis a group of specimens from the Galapagos containing xanthones has been examined. This heterogeneous group represents an assemblage of taxa that are not necessarily closely related, but easily recognized by their bright yellow to orange UV-fluorescence and orange spot test reaction with sodium hypochlorite. For this group, morphological and anatomical characters were documented, and their secondary chemistry analyzed with thin-layer chromatography. For all three groups, i.e., the Buellia xanthinula-group, the parasitic species, and the ones with xanthones, detailed descriptions are provided.

Understanding the effects of fire on the Sonoran Desert is of critical importance as rising temperatures and changing weather patterns increase the frequency and size of wildfires. Seed banks are an important component in post-fire landscape recovery as the seeds that remain in the soil are an indicator of a landscape’s future trajectory. The purpose of this study is to determine the lasting impacts of fire on the soil seed bank of the Sonoran Desert and to identify potential concerns affecting post-fire recovery and restoration. The study site was located in the Arizona Upland division of the Sonoran Desert, Arizona, United States. Soil samples were collected from five burned sites with increasing time since fire, and five nearby unburned sites used as a control. A seedling emergence test was conducted to investigate the density and richness of the seed bank of burned and unburned sites. Seed densities and species richness for sites were calculated using germination results. Findings were analyzed using non-parametric analyses comparing changes in burned and unburned sites over time. Results found that burn status and time since fire had no significant impact on seed density. Graminoid and forb densities were statistically consistent across burn status and time since fire. While species richness was consistent across both plot types, burned samples typically had fewer species than unburned samples. Burned and unburned plots revealed a dominance of annual species with limited presence of woody perennials. While seed densities and species richness are relatively unchanged across burned and unburned sites over time, the lack of woody perennials in the seed bank raises concerns about landscape recovery trajectories in burned sites. These results suggest that restoration efforts focused on maintaining the presence of woody trees and shrubs in the landscape may have the most impact.

Flowering phenology offers a sensitive and reliable biological indicator of climate change because plants use climatic and other environmental cues to initiate flower production. Drylands are the largest terrestrial biome, but with unpredictable precipitation patterns and infertile soils, they are particularly vulnerable to climate change. There is a need to increase our comprehension of how dryland plants might respond and adapt to environmental changes. I conducted a meta-analysis on the flowering phenology of dryland plants and showed that some species responded to climate change through accelerated flowering, while others delayed their flowering dates. Dryland plants advanced their mean flowering dates by 2.12 days decade-1, 2.83 days °C-1 and 2.91 days mm-1, respectively, responding to time series, temperature, and precipitation. Flowering phenology responses varied across taxonomic and functional groups, with the grass family Poaceae (-3.91 days decade1) and bulb forming Amaryllidaceae (-0.82 days decade1) showing the highest and lowest time series responses respectively, while Brassicaceae was not responsive. Analysis from herbarium specimens collected across Namibian drylands, spanning 26 species and six families, revealed that plants in hyper-arid to arid regions have lower phenological sensitivity to temperature (-9 days °C-1) and greater phenological responsiveness to precipitation (-0.56 days mm-1) than those in arid to semi-arid regions (-17 days °C-1, -0.35 days mm-1). The flowering phenology of serotinous plants showed greater sensitivity to both temperature and precipitation than that of non-serotinous plants. I used rainout shelters to reduce rainfall in a field experiment and showed that drought treatment advanced the vegetative and reproductive phenology of Cleome gynandra, a highly nutritional and medicinal semi-wild vegetable species. The peak leaf length date, peak number of leaves date, and peak flowering date of Cleome gynandra advanced by six, 10 and seven days, respectively. Lastly, I simulated drought and flood in a greenhouse experiment and found that flooding conditions resulted in higher germination percentage of C. gynandra than drought. My study found that the vegetative, and flowering phenology of dryland plants is responsive to climate change, with differential responses across taxonomic and functional groups, and aridity zones, which could alter the structure and function of these systems.

The diverse weevil genus Rhyssomatus Schoenherr, 1837 (Curculionidae: Molytinae: Cleoginini) is currently composed of 175 species throughout the New World (O’Brien et. al 1982; Wibmer et. al 1986). The majority of species are generalist feeders and the group contains many notorious agricultural pests, such as Rhyssomatus nigerimus Fahraeus 1837 and R. subtillis Fiedler 1937 that cause thousands of dollars’ worth of crop damage in South America, Central America, and West Indies (Cazado, 2016; Lopez-Guillen, et. al). Although most notable as a crop pest in the literature, the species Rhyssomatus maginatus Fahraeus has also proven to be a great success in an Integrated Pest Management (IPM), controlling the invasive leguminous tree Sesbenia punicea (Cav.) Benth., in South Africa. (Hoffman & Moran 1991; 1992; 1998; 1999). The last century has seen revisions of the Neotropical species with Central American species revised in 1904 by Champion and the South American taxa treated by Fiedler in the subsequent years of 1937 and 1942 (O’Brien & Wibmer, 1982; Wibmer & O’Brien, 1986). However, North American fauna have not been treated since Casey in 1895 and revision is needed as climate change and global trade have more than likely expanded the distributional range of previously lower latitude Rhyssomatus species northwards.

The weevil genus Pachnaeus Schoenherr, 1826 (Coleoptera: Curculionidae: Entiminae: Eustylini Lacordaire) is revised to accommodate 21 species, including the following 10 new species from the northern Caribbean region: Pachnaeus andersoni sp. nov. (Little Cayman), Pachnaeus eisenbergi sp. nov. (Jamaica), Pachnaeus godivae sp. nov. (Cayman Brac), Pachnaeus gordoni sp. nov. (Jamaica), Pachnaeus howdenae sp. nov. (Bahamas), Pachnaeus ivieorum sp. nov. (Bahamas with adventive records from Florida), Pachnaeus maestrensis sp. nov. (Cuba), Pachnaeus morelli sp. nov. (Haiti), Pachnaeus obrienorum sp. nov. (Cuba and Bahamas), and Pachnaeus quadrilineatus sp. nov. (Jamaica).Pachnaeus can be distinguished from similar, co-occurring taxa such as Exophthalmus quadrivittatus (Olivier, 1807), Exophthalmus roseipes (Chevrolat, 1876), Exophthalmus vittatus (Linnaeus, 1758), and Diaprepes abbreviatus (Linnaeus, 1758) by (1) the presence of postocular vibrissae, (2) endophallus primarily membranous and sac-like proximally, and long (>3 × width), tubular, and sclerotized distally, (3) additional endophallic sclerites typically absent, (4) a never bicarinate, typically tricarinate, rostrum, and several additional characteristics of the pedon, endophallus, pronotal structure, rostral structure, and scaling. Based on these characters, Pachnaeus sommeri (Munck af Rosenschoeld in Schoenherr, 1840) comb, nov. and Pachnaeus gowdeyi (Marshall, 1926) comb. nov. are transferred into the genus from Exophthalmus Schoenherr and Lachnopus Schoenherr respectively. This revision provides genus and species redescriptions, diagnoses, illustrations, and the first comprehensive key to all 21 species within the present circumscription of Pachnaeus, in addition to reviewing the known biology and observed intraspecific variation within species. The complex taxonomic history of the genus is reviewed, and the evolutionary relationships of its presumed constituent clades are proposed through the construction of informal species groups and subgroups based on diagnosable shared traits. Lectotypes for Pachnaeus citri Marshall, Pachnaeus costatus Perroud, and Exophthalmus sommeri Munck af Rosenschoeld in Schoenherr and paralectotypes of P. citri (3 specimens) and E. sommeri (4 specimens) are designated. New state and national records are reported for Pachnaeus azurescens Gyllenhal in Schoenherr for Florida, U.S.A. and new national records are reported for Pachnaeus litus (Germar) for the Bahamas. Validity of the names Docorhinus Schoenherr, 1823 and Pachnaeus Schoenherr, 1826 is treated. Generic placement of Pachnaeus roseipes Chevrolat, 1876 is explored.

The saguaro cactus is vital to the unique biodiversity of the Sonoran Desert. Many animals rely on it for survival and shelter. Due to its thick waxy exterior, it is able to retain a massive amount of water in its succulent stems, making it an ideal habitat for many birds that are native to the region. It also holds a large cultural significance for many native tribes of this region. Thus, it is important to understand how these magnificent plants are affected by changing environmental conditions in order to protect them in the future. Measurements of carbon isotope (13C) signals in saguaros spine tissues have been shown to be a robust approach for evaluating plant responses to climate variation over multiple seasons and years. This study investigated growth and 13C signals in young saguaros (< 2.5 m tall) at a location north of Phoenix to compare with large saguaros (> 4 m tall) that actively flower in the spring. Adolescent saguaros were examined to determine how they responded to variation in moisture between the years 2012 through 2016. As with a previous study by Hultine et al. (2018), this research demonstrated a strong relationship between height growth and precipitation. Stem growth was also highly correlated with the number of areoles produced across both young and old plants. Winter and late summer moisture from the previous year had a significant effect on stem growth, and a legacy effect could be seen in the low growth rates in 2014 which may be a result of low precipitation during the previous fall and winter. This study also established that the adolescent saguaro may be less sensitive to seasonal changes than the mature saguaro. When comparing the large plants with the adolescent plants, spine 13C values were similar between mature and adolescent plants, indicating that perhaps flower does not impose a significant added cost to saguaro water budgets. However, identifying the cost of flowering requires more investigation than that from only spine carbon isotope measurements and coarse measurements of plant productivity.

Weevils are one of the most diverse groups of animals with thousands of species suspected to remain undiscovered. The Conoderinae Schoenherr, 1833 are no exception, being especially diverse and unknown in the Neotropics where they are recognizable for their unique behaviors and color patterns among weevils. Despite these peculiarities, the group has received little attention from researchers in the past century, with almost nothing known about their evolution. This dissertation presents a series of three studies that begin to elucidate the evolutionary history of these bizarre and fascinating weevils, commencing with an overview of their biology and classificatory history (Chapter 1).

Chapter 2 presents the first formal cladistic analysis on the group to redefine the New World tribes Lechriopini Lacordaire, 1865 and Zygopini, Lacordaire, 1865. An analysis of 75 taxa (65 ingroup) with 75 morphological characters yielded six equally parsimonious trees and synapomorphies that are used to reconstitute the tribes, resulting in the transfer of sixteen genera from the Zygopini to the Lechriopini and four generic transfers out of the Lechriopini to elsewhere in the Conoderinae.

Chapter 3 constitutes a taxonomic revision of the genus Trichodocerus Chevrolat, 1879, the sole genus in the tribe Trichodocerini Champion, 1906, which has had an uncertain phylogenetic placement in the Curculionidae but has most recently been treated in the Conoderinae. In addition to redescriptions of the three previously described species placed in the genus, twenty-four species are newly described and an identification key is provided for all recognized species groups and species.

Chapter 4 quantitatively tests the similarity in color pattern among species hypothesized to belong to several different mimicry complexes. The patterns of 160 species of conoderine weevils were evaluated for 15 categorical and continuous characters. Non-metric multidimensional scaling (NMDS) is used to visualize similarity by the proximity of individual species and clusters of species assigned to a mimicry complex in ordination space with clusters being statistically tested using permutational multivariate analysis of variance (PERMANOVA).

Understanding the diversity, evolutionary relationships, and geographic distribution of species is foundational knowledge in biology. However, this knowledge is lacking for many diverse lineages of the tree of life. This is the case for the desert stink beetles in the tribe Amphidorini LeConte, 1862 (Coleoptera: Tenebrionidae) – a lineage of arid-adapted flightless beetles found throughout western North America. Four interconnected studies that jointly increase our knowledge of this group are presented. First, the darkling beetle fauna of the Algodones sand dunes in southern California is examined as a case study to explore the scientific practice of checklist creation. An updated list of the species known from this region is presented, with a critical focus on material now made available through digitization and global aggregation. This part concludes with recommendations for future biodiversity checklist authors. Second, the psammophilic genus Trogloderus LeConte, 1879 is revised. Six new species are described, and the first, multi-gene phylogeny for the genus is inferred. In addition, historical biogeographic reconstructions along with novel hypotheses of speciation patterns within the Intermountain Region are given. In particular, the Kaibab Plateau and Kaiparowitz Formation are found to have promoted speciation on the Colorado Plateau. The Owens Valley and prehistoric Bouse Embayment are similarly hypothesized to drive species diversification in southern California. Third, a novel phylogenomic analysis for the tribe Amphidorini is presented, based on 29 de novo partial transcriptomes. Three putative ortholog sets were discovered and analyzed to infer the relationships between species groups and genera. The existing classification of the tribe is found to be highly inadequate, though the earliest-diverging relationships within the tribe are still in question. Finally, the new phylogenetic framework is used to provide a genus-level revision for the Amphidorini, which previously contained six valid genera and 253 valid species. This updated classification includes more than 100 taxonomic changes and results in the revised tribe consisting of 16 genera, with three being described as new to science.

This project is a revised taxonomic treatment of the tobacco genus, Nicotiana, for the Arizona Flora. The treatment required morphological descriptions of all six species found in Arizona based on measurements and observations from mounted herbarium specimen as well as field collections. Loans from regional herbaria including: Northern Arizona University, Arizona State University, the University of Arizona, Rancho Santa Anna Herbarium, and the Desert Botanical Garden were examined and annotated according to standard herbaria protocols. A dichotomous key was then created based on morphological descriptions for use in identifying species both in the field and from herbarium mounts. Distribution maps were generated using online databases of herbarium vouchers, mapping soft wares, and field excursions. During the course of my field work, I was able to locate all six species and four of them were collected, vouchered, and deposited in the ASU Vascular Plant Herbarium. One species, Nicotiana quadrivalvis was not relocated based on historical records. This treatment will contribute to ongoing revisions of the Arizona Flora via a publication in the regional taxonomic journal Canotia.