George Franklin Knowlton

Species’ range size is a fundamental unit of analysis in biodiversity research, given its association with extinction risk and species richness. One of its most notable patterns is its positive relationship with latitude, which has been considered an ecogeographical rule called Rapoport’s rule. Despite this rule being confirmed for various taxonomic groups, its validity has been widely discussed and several taxa still lack a formal assessment. Different hypotheses have been proposed to explain their potential mechanisms, with those related to temperature and elevational being the most supported thus far. In this study, we employed two level of analyses (cross-species and assemblage) to investigate the validity of Rapoport’s rule in spiny lizards (genus Sceloporus). Additionally, we evaluated four environmental-related hypotheses (minimum temperature, temperature variability, temperature stability since the last glacial maximum, and elevation) posed to explain such pattern, contrasting our results to those patterns expected under a null model of range position. Our results provided support for Rapoport’s rule at both levels of analyses, contrasting with null expectations. Consistently, minimum temperature and elevation were the most relevant variables explaining the spatial variation in range size. At the cross-species level, our null simulations revealed that both variables deviated significantly from random expectations. Conversely, at the assemblage level, none of the variables were statistically different from the expected relationships. We discussed the implication of our findings in relation to the ecology and evolution of spiny lizards.

Biodiversity loss amplifies the need for taxonomic understanding at global, regional, and local scales. The United Nations Environmental Programme Sustainable Development Goals are explicit in their demand for greater accountability with respect to ecosystem management, and Sustainable Development Goal 15, Life on Land, specifically calls for a halt to biodiversity loss. Pollinators (bees and butterflies) are two functional groups with public attention for protection, yet little long-term data availability. National Parks, including those in the United States, act as optimal sites to study biodiversity loss, but historic data tends to vary in availability. This study addresses systematic taxonomic and digitalization biases present within historic (museum), modern (citizen science), and non-digitized (private collection) datasets for Yellowstone and Grand Teton National Parks from 1900 to 2021. We find that, although database record availability is representative of butterfly and bumble bee groups known for the area, categories such as data rescue, digitalization/availability, and management/archiving vary across database types. These findings on virtual datasets offer opportunities for conservationists to understand the efficacy of digitized collections in addressing questions of species loss over time, including the strengths and pitfalls of digitized data repositories. Additionally, virtual datasets can be utilized to monitor biodiversity under Sustainable Development Goal 15 targets while also promoting broader access to resources such as museum collections for educational purposes. Natural history collections (NHCs) work to preserve biodiversity but tend to hold taxonomic biases. The rapid digitalization of species occurrence data works to improve biodiversity understanding. Pollinator NHCs can inform conservation targets like SDG 15, but only for a subset of species. Additional funding towards data digitalization will broaden the understanding of lesser-known taxa. Virtual museum resources should become more readily accessible to educate and engage the public in species conservation work; citizen science applications can act as an additional educational tool to promote public conservation interest. International biodiversity sampling efforts should be encouraged to document species decline.

Conservation and management of drylands is a global challenge. Key attributes of these ecosystems, such as dominant vegetation including shrubs, can provide a crucial mechanism to inform conservation strategies. The shrub species Ephedra californica and Larrea tridentata are common native shrub species within the deserts of California and frequently benefit other plant and animal species. Here, we tested the hypothesis that shrubs support reptile and amphibian communities through relative increases in available habitat, estimated through increasing shrub densities at the site level. Reported occurrence data from the Global Biodiversity Information Facility (GBIF) and high-resolution satellite images were used to test for local-to-regional patterns in reptile and amphibian distribution and diversity by shrub densities at sites. At 43 distinct sites, the relationship between shrub density and reported reptile and amphibian communities was also tested. A total of 71 reptile and amphibian species were reported regionally. Increases in shrub density across sites positively influenced the relative abundance and richness of reptiles and amphibians observed. Moreover, increasing shrub density also had a positive influence on species evenness. Aridity differences between sites did not significantly influence the relationship between shrub density and reptiles and amphibians suggesting that the relationship was robust. This study highlights the importance of foundational shrub species in supporting reptile and amphibian communities in arid and semi-arid regions. Large-scale patterns of biodiversity in deserts can be supported by positive plant-animal interactions including small islands of fertility and resources for animals in the context of a warming climate.

The global threat of invasive alien species (IAS) being introduced into new habitats is concerning, particularly in agricultural crops as invasive insect species are continuing to expand their distribution through anthropogenic activities and climate changes. Pea aphids (Acyrthosiphon pisum Harris) are an economic threat to numerous legume crops as they can reproduce parthenogenetically, damage crops directly, and vector over 30 plant viruses as the insect's distribution continues to spread. There are no existing pea aphid-specific risk maps that identify the habitat suitability of pea aphids at either a regional or global scale. Here, we used Species Distribution Models (SDMs) to evaluate which climatic variables influence pea aphid distribution, identify regions of potential distribution, and analyze the global distribution of pea aphids under current and future climate change scenarios (SSP 126, 245, and 370) by utilizing presence-only SDMs based on Maximum Entropy (MaxEnt). The modeling results indicate suitable conditions are relevant for pea aphid establishment in six out of seven continents, with significant range expansion in western Canada, the United States of America, and across Europe. We identified human influence to be the most prominent predictor in determining the distribution of pea aphids, supporting the fact that invasive species distributions are heavily impacted by human activities.

Pleurodonta is an ancient, diverse clade of iguanian lizard distributed primarily in the Western Hemisphere. Although the clade is a frequent subject of systematic research, phylogenetic resolution among the major pleurodontan clades is elusive. That uncertainty has complicated the interpretations of many fossil pleurodontans. I describe a fossil skull of a pleurodontan lizard from the Palaeogene of Wyoming that was previously allocated to the puzzling taxon Aciprion formosum , and provide an updated morphological matrix for iguanian lizards. Phylogenetic analyses using Bayesian inference demonstrate that the fossil skull is the oldest and first definitive stem member of Crotaphytidae (collared and leopard lizards), establishing the presence of that clade in North America during the Palaeogene. I also discuss new or revised hypotheses for the relationships of several early pleurodontans. In particular, I examine potential evidence for crown-Pleurodonta in the Cretaceous of Mongolia ( Polrussia ), stem Pleurodonta in the Cretaceous of North America ( Magnuviator ) and a stem anole in the Eocene of North America ( Afairiguana ). I suggest that the placement of the fossil crotaphytid is stable to the uncertain phylogeny of Pleurodonta, but recognize the dynamic nature of fossil diagnosis and the potential for updated systematic hypotheses for the other fossils analysed here.

Globally, insects have been impacted by climate change, with bumble bees in particular showing range shifts and declining species diversity with global warming. This suggests heat tolerance is a likely factor limiting the distribution and success of these bees. Studies have shown high intraspecific variance in bumble bee thermal tolerance, suggesting biological and environmental factors may be impacting heat resilience. Understanding these factors is important for assessing vulnerability and finding environmental solutions to mitigate effects of climate change. In this study, we assess whether geographic range variation in bumble bees in the eastern United States is associated with heat tolerance and further dissect which other biological and environmental factors explain variation in heat sensitivity in these bees. We examine heat tolerance by caste, sex, and rearing condition (wild/lab) across six eastern US bumble bee species, and assess the role of age, reproductive status, body size, and interactive effects of humidity and temperature on thermal tolerance in Bombus impatiens. We found marked differences in heat tolerance by species that correlate with each species' latitudinal range, habitat, and climatic niche, and we found significant variation in thermal sensitivity by caste and sex. Queens had considerably lower heat tolerance than workers and males, with greater tolerance when queens would first be leaving their natal nest, and lower tolerance after ovary activation. Wild bees tended to have higher heat tolerance than lab reared bees, and body size was associated with heat tolerance only in wild‐caught foragers. Humidity showed a strong interaction with heat effects, pointing to the need to regulate relative humidity in thermal assays and consider its role in nature. Altogether, we found most tested biological conditions impact thermal tolerance and highlight the stages of these bees that will be most sensitive to future climate change.

The current ecological crisis stemming from the loss of biodiversity and associated ecosystem services, highlights the urgency of documenting diversity and distribution. Bees are a classical example of an ecologically and economically important group, due to their high diversity and varied ecosystem services, especially pollination. Here, two common biodiversity indices, namely species richness and phylogenetic diversity, are evaluated geographically to determine the best approach for selecting areas of conservation priority. The model organisms used in this study are the North American species belonging to the bee genus Diadasia (Apidae). Based on the results obtained by analyzing distributional records and a molecular phylogeny, we can see that species richness and phylogenetic diversity are closely linked, although phylogenetic diversity provides a more detailed assessment of the spatial distribution of diversity. Therefore, while either one of these commonly used indices are valid as far as selecting areas of conservation priority, we recommend, if possible, to include genetic information in biodiversity and conservation studies.

The tribe Astereae (Asteraceae) displays an American Amphitropical Disjunction. To understand the eco-evolutionary dynamics associated with a long-distance dispersal event and subsequent colonization of extratropical South America, we compared the climatic and geographic distributions of South American species with their closest North American relatives, focusing on the diverse South American Astereae genus, Haplopappus. Phylogenetic analysis revealed that two South American genera are closely related to seven North American genera. The climatic niche overlap (D = 0.5) between South and North America exhibits high stability (0.89), low expansion (0.12), and very low unfilling (0.04). The distribution of the North American species predicted the climatic and geographic space occupied by the South American species. In central Chile, Haplopappus showed a non-random latitudinal gradient in species richness, with Mediterranean climate variables mainly explaining the variation. Altitudinal patterns indicated peak richness at 600 m, declining at lower and higher elevations. These findings support climatic niche conservatism in shaping Haplopappus species distribution and diversity. Two major endemism zones were identified in central Chile and the southern region, with a transitional zone between Mediterranean and Temperate macro-bioclimates. Our results indicate strong niche conservatism following long-distance dispersal and slight niche expansion due to unique climatic variables in each hemisphere.

Advances in technology have equipped paleobiologists with new analytical tools to assess the fossil record. The functional traits of vertebrates have been used to infer paleoenvironmental conditions. In Quaternary deposits, birds are the second-most-studied group after mammals. They are considered a poor paleoambiental proxy because their high vagility and phenotypic plasticity allow them to respond more effectively to climate change. Investigating multiple groups is important, but it is not often attempted. Biogeographical and climatic niche information concerning small mammals, reptiles, and birds have been used to infer the paleoclimatic conditions present during the Late Pleistocene at San Josecito Cave (~28,000 14C years BP), Mexico. Warmer and dryer conditions are inferred with respect to the present. The use of all of the groups of small vertebrates is recommended because they represent an assemblage of species that have gone through a series of environmental filters in the past. Individually, different vertebrate groups provide different paleoclimatic information. Birds are a good proxy for inferring paleoprecipitation but not paleotemperature. Together, reptiles and small mammals are a good proxy for inferring paleoprecipitation and paleotemperature, but reptiles alone are a bad proxy, and mammals alone are a good proxy for inferring paleotemperature and precipitation. The current paleoclimatic results coupled with those of a previous vegetation structure analysis indicate the presence of non-analog paleoenvironmental conditions during the Late Pleistocene in the San Josecito Cave area. This situation would explain the presence of a disharmonious fauna and the extinction of several taxa when these conditions later disappeared and do not reappear again.

Ceratitis capitata (Wiedemann), the Mediterranean fruit fly or medfly, is one of the world's most serious threats to fresh fruits. It is highly polyphagous (recorded from over 300 hosts) and capable of adapting to a wide range of climates. This pest has spread to the EPPO region and is mainly present in the southern part, damaging Citrus and Prunus. In Northern and Central Europe records refer to interceptions or short‐lived adventive populations only. Sustainable programs for surveillance, spread assessment using models and control strategies for pests such as C. capitata represent a major plant health challenge for all countries in Europe. This article includes a review of pest distribution and monitoring techniques in 11 countries of the EPPO region. This work compiles information that was crucial for a better understanding of pest occurrence and contributes to identifying areas susceptible to potential invasion and establishment. The key outputs and results obtained in the Euphresco project included knowledge transfer about early detection tools and methods used in different countries for pest monitoring. A MaxEnt software model resulted in risk maps for C. capitata in different climatic regions. This is an important tool to help decision making and to develop actions against this pest in the different partner countries.