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opencc-zeroAug 2023View details →

Water loss, not overheating, limits the activity period of an endothermic Sonoran Desert bee

<ol> <li>Desert animals must manage the physiological stresses of heat and desiccation; evaporative heat loss mitigates overheating but exacerbates water stress. Small endothermic flying insects may be particularly vulnerable to overheating and water stress as a result of high surface area to volume ratios, but we lack quantitative understanding of the relative magnitude of these abiotic stressors in flying desert invertebrates, despite their ecological importance.</li> <li>During the hottest and driest weeks of the year, many thousands of males of the Sonoran Desert digger bee (Centris caesalpiniae) flew near-continuously at elevated thorax temperatures for hours at mating aggregation sites, while occasionally fighting other males and digging for females.</li> <li>To determine whether incapacitating high temperatures or water loss limited the activity period of male C. caesalpiniae, we assessed wet and dry body mass and water content through the activity period, crop volume and sugar content, microclimate selection, water loss rate and metabolic water production during flight, critical water content, and maximum critical temperature.</li> <li>Body masses and sizes of males declined through the morning and smaller bees had higher fractional water contents. Crop volume and sugar content did not vary through the day or with bee size.</li> <li>Maximum critical temperature during flight was 51°C, similar to those measured for other bees, and well above temperatures reached in the field, suggesting that avoidance of over-heating does not limit activity in this desert bee.</li> <li>The critical water content of Centris bees averaged 50%. Measures of net water loss rate indicated that males approached lethal water loss limits within four hours, suggesting that desiccation tolerance limits activity. Remarkably, male C. caesalpiniae were not observed to forage at floral or water sources during the activity period, and foraged over multiple days, suggesting selection to maintain reproductive success and that these males have a mechanism to rehydrate when not at the mating aggregation.</li> </ol>

publicAug 2025View details →

Data from: Diet and chemical defenses of the Sonoran Desert toads

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publicAug 2023View details →

Water loss, not overheating, limits the activity period of an endothermic Sonoran Desert bee

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publicMay 2025View details →

Plant responses to anomalous heat and drought events in the Sonoran Desert

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edi36/100

Mycorrhizal diversity and effects on brittlebush in a Sonoran desert urban ecosystem

In this study, the functioning of AM fungi in brittlebush (Encelia farinosa A. Gray ex Torr.) grown at an urban site and a desert site are compared. E. farinosa is a native, desert shrub commonly found in the Sonoran Desert surrounding Phoenix and used as an ornamental shrub in residential and commercial sites in the Phoenix metropolitan area. Because this shrub is common in urban and desert areas, it can be used to compare AM fungal colonization levels between these areas. In addition, the impact of AM fungi on E. farinosa growth and reproductive output was studied by attempting to manipulate the levels of AM fungal colonization using the fungicide methyl-1-(butyl-carbamoyl)-2-benzimidazole (benomyl). This fungicide has been shown to suppress colonization of roots by AM fungi with little phytotoxicity or effect on soil nutrients (Fitter and Nichols 1988; Hartnett and Wilson 2002). Hartnett and Wilson (2002) stated that the best method available to assess the roles and functions of AM fungi in natural communities is through the use of fungicides such as benomyl. Treatment with benomyl should allow for comparisons between plants that have typical levels of mycorrhizal colonization and those with lower, suppressed levels of colonization. The impact of AM fungi on the productivity of brittlebush plants was examined at an urban and desert site. Fungal colonization was greater at the desert site but biomass and reproductive output was higher at the urban site. When mycorrhizal colonization was suppressed, plants had greater vegetative growth, but there was no effect on reproductive output.

openOpenJan 2020View details →

edi36/100

Desert Fertilization Experiment: ecosystem response to nutrient enrichment across an urban airshed in the Sonoran desert

Launched in 2006 with support from the National Science Foundation (NSF) and leveraged by the CAP LTER, the Carbon and Nitrogen deposition (CNdep) project sought to answer the fundamental question of whether elemental cycles in urban ecosystems are qualitatively different from those in non-urban ecosystems. Ecosystem scientists, atmospheric chemists, and biogeochemists tested the hypothesis that distinct biogeochemical pathways result from elevated inorganic nitrogen and organic carbon deposition from the atmosphere to the land. To test the hypothesis, scientists examined the responsiveness of Sonoran desert ecosystems to nutrient enrichment by capitalizing on a gradient of atmospheric deposition in and around the greater Phoenix metropolitan area. Fifteen desert study sites were established, with five locations each west and east of the urban core, and in the urban core in desert preserves. In addition to the gradient of atmospheric deposition in and around the urban core, select study plots at each of the fifteen desert locations receive amendments of nitrogen, phosphorus, or nitrogen + phosphorus fertilizer. Measured variables include soil properties, perennial and annual plant growth, and atmospheric deposition of nitrogen. At the close of the initial grant period, the CAP LTER assumed responsibility for the project, renamed the Desert Fertilization Experiment, which provides a remarkable platform to study the long-term effects of nutrient enrichment on ecosystem properties. This data set features an amalgamation of data from the CAP LTER's long-term Desert Fertilization Experiment. The data presented here bring together many aspects of the project, and are featured in several papers, notably Hall et al. 2009 and 2011, and Sponseller et al. 2012. Investigators interested in other and more recent data from the CAP LTER's long-term Desert Fertilization Experiment should search the data repository for 'desert fertilization experiment'. Citations: Hall, S. J., B. Ah

openCustomJun 2018View details →

dryad32/100

Data from: Shaping species with ephemeral boundaries: the distribution and genetic structure of the desert tortoise (Gopherus morafkai) in the Sonoran Desert region

Aim: We examine the role biogeographical features played in the evolution of Morafka's desert tortoise (Gopherus morafkai) and test the hypothesis that G. morafkai maintains genetically distinct lineages associated with different Sonoran Desert biomes. Increased knowledge of the past and present distribution of the Sonoran Desert region's biota provides insight into the forces that drive and maintain its biodiversity. Location: Sonoran Desert biogeographical region; Sonora and Sinaloa, Mexico and Arizona, USA. Methods: We examined wild tortoises from Mexico (n = 155) and Arizona (n = 78), spanning their known distribution. We used mtDNA sequences to reconstruct matrilineal relationships and 25 microsatellite (STR) loci for Bayesian analyses of gene flow. We performed clinal analyses on both mtDNA and STR loci to determine the position and amount of introgression where lineages co-occur. We used GIS to assess the association of genetic structuring with ecological features. We used these data in a hypothesis-driven approach to assess different models of how genetic diversity is maintained and distributed in G. morafkai. Results: Gopherus morafkai was found to comprise genetically and geographically distinct 'Sonoran' and 'Sinaloan' lineages. Both lineages occurred in a relatively narrow zone of overlap in Sinaloan thornscrub, where it transitions into Sonoran desertscrub. Limited introgression occurred at the contact zone. The best-fit model suggests that these lineages diverged in parapatry where the distribution of genotypes is environment-dependent and introgression is inhibited by exogenous selection. Main conclusions: The historically shifting ecotone between tropical deciduous forest and Sonoran desertscrub appears to be a boundary that fostered divergence between parapatric lineages of tortoises. The sharp genetic cline between the two lineages suggests that periods of isolation in temporary refugia due to Pleistocene climatic cycling influenced divergence. Despite incomplete reproductive isolation, the Sonoran and Sinaloan lineages of G. morafkai are on separate evolutionary trajectories.

opencc-zeroDec 2014View details →

dryad32/100

Data from: Ecological co-associations influence species' responses to past climatic change: an example from a Sonoran Desert bark beetle

Ecologically interacting species may have phylogeographic histories that are shaped both by features of their abiotic landscape, and by biotic constraints imposed by their co-association. The Baja California peninsula provides an excellent opportunity to examine the influence of abiotic vs. biotic factors on patterns of diversity in plant-insect species. This is because past climatic and geological changes impacted the genetic structure of plants quite differently to that of co-distributed free-living animals (e.g., herpetofauna and small mammals). Thus, 'plant-like' patterns should be discernible in host-specific insect herbivores. Here we investigate the population history of a monophagous bark beetle, Araptus attenuatus, and consider drivers of phylogeographic patterns in light of previous work on its host plant, Euphorbia lomelii. Based on mitochondrial and nuclear markers, we found that the evolutionary history of A. attenuatus exhibits similarities to host plant that are attributable to both biotic and abiotic processes. Southward range expansion and recent colonization of continental Sonora peninsula appear to be unique to this taxon pair, and likely reflect influences of the host plant. On the other hand, abiotic factors with landscape-level influences on suites of co-distributed taxa, such as Plio- and Pleistocene-aged marine incursions in the region, also left genetic signatures in beetle populations. Superimposed on these similarities, bark beetle-specific patterns and processes were also evident. Taken together, this work illustrates that the evolutionary history of species-specific insect herbivores may represent a mosaic of influences, including—but not limited to—those imposed by the host plant.

opencc-zeroDec 2012View details →

FIGURE 11 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 11. Geographic distribution of: (A) Pogonomyrmex magnacanthus Cole, (B) Pogonomyrmex hoelldobleri Johnson, Overson & Moreau, and (C) Pogonomyrmex mohavensis Johnson; the larger filled black circle in each panel denotes the type locality. All three maps are drawn on the same geographic area so that distribution patterns are directly comparable.

FIGURE 9 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 9. Photograph of Pogonomyrmex mohavensis Johnson alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 10 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 10. Phylogram of species in the Pogonomyrmex californicus group as inferred through Bayesian analysis for the partitioned dataset. Specimens of P. hoelldobleri are in the dashed box. Branch lengths are proportional to substitution/site as indicated by the bottom legend inset. Clade support greater than 50% is denoted on branches and in the top insert as follows: values above and below branches represent Bayesian posterior probabilities (BPP) and maximum likelihood bootstrap (ML BS), respectively, for the partitioned dataset followed by the single dataset. Clade support of "--" denotes clades not supported in an individual analysis. Numbers following each species name refer to the accession number of the series from which the individual was taken; locale data are given for each series in Table 1. Pogonomyrmex californicus, P. hoelldobleri, and P. magnacanthus occurred sympatrically at one site (designated by an *).

FIGURE 8 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 8. Photograph of Pogonomyrmex hoelldobleri Johnson, Overson & Moreau male: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 7 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 7. Photograph of Pogonomyrmex hoelldobleri Johnson, Overson & Moreau alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 6 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 6. Photograph of Pogonomyrmex hoelldobleri Johnson, Overson & Moreau—HOLOTYPE worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 4 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 4. Photograph of Pogonomyrmex magnacanthus Cole alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 1 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 1. Photograph of Pogonomyrmex magnacanthus Cole—HOLOTYPE worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body.

FIGURE 3 in A New Species of Seed-harvester Ant, Pogonomyrmex hoelldobleri (Hymenoptera: Formicidae), from the Mohave and Sonoran Deserts of North America

FIGURE 3. Bivariate plots for workers: (A) maximum eye diameter versus head width, (B) ocular index versus head width, and (C) malar ratio versus head width (n = 63 for P. magnacanthus Cole, n = 59 for P. hoelldobleri Johnson, Overson & Moreau, plus 16 PARATYPE workers of P. magnacanthus that do not belong to the latter species [see text], n = 25 for P. mohavensis Johnson). Non-type workers were selected to represent the geographic range of each species.