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1. Climate change expected to improve digestive rate and trigger range expansion in outbreaking locusts

   https://doi.org/10.1002/ecm.1550  

   Youngblood, Jacob P.; Cease, Arianne J.; Talal, Stav; Copa, Fernando; Medina, Hector E.; Rojas, Julio E.; Trumper, Eduardo V.; Angilletta, Jr., Michael J.; Harrison, Jon F. (September 2022, Ecological Monographs)

   Abstract Global climate change will probably exacerbate crop losses from insect pests, reducing agricultural production, and threatening food security. To predict where crop losses will occur, scientists have mainly used correlative models of species' distributions, but such models are unreliable when extrapolated to future environments. To minimize extrapolation, we developed mechanistic and hybrid models that explicitly capture range‐limiting processes, and we explored how incorporating mechanisms altered the projected impacts of climate change for an agricultural pest, the South American locust (Schistocerca cancellata). Because locusts are generalist herbivores surrounded by food, their population growth may be limited by thermal effects on digestion more than food availability. To incorporate this mechanism into a distribution model, we measured the thermal effects on the consumption and defecation of field‐captured locusts and used these data to model energy gain in current and future climates. We then created hybrid models by using outputs of the mechanistic model as predictor variables in correlative models, estimating the potential distribution of gregarious outbreaking locusts based on multiple predictor sets, modeling algorithms, and climate scenarios. Based on the mechanistic model, locusts can assimilate relatively high amounts of energy throughout temperate and tropical South America; however, correlative and hybrid modeling revealed that most tropical areas are unsuitable for locusts. When estimating current distributions, the top‐ranked model was always the one fit with mechanistic predictors (i.e., the hybrid model). When projected to future climates, top‐ranked hybrid models projected range expansions that were 23%–30% points smaller than those projected by correlative models. Therefore, a combination of the correlative and mechanistic approaches bracketed the potential outcomes of climate change and enhanced confidence where model projections agreed. Because all models projected a poleward range expansion under climate change, agriculturists should consider enhanced monitoring and the management of locusts near the southern margin of the range. 

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2. Predicting climate change impacts on poikilotherms using physiologically guided species abundance models

   https://doi.org/10.1073/pnas.2214199120  

   Wagner, Tyler; Schliep, Erin M.; North, Joshua S.; Kundel, Holly; Custer, Christopher A.; Ruzich, Jenna K.; Hansen, Gretchen J. (April 2023, Proceedings of the National Academy of Sciences)

   Poikilothermic animals comprise most species on Earth and are especially sensitive to changes in environmental temperatures. Species conservation in a changing climate relies upon predictions of species responses to future conditions, yet predicting species responses to climate change when temperatures exceed the bounds of observed data is fraught with challenges. We present a physiologically guided abundance (PGA) model that combines observations of species abundance and environmental conditions with laboratory-derived data on the physiological response of poikilotherms to temperature to predict species geographical distributions and abundance in response to climate change. The model incorporates uncertainty in laboratory-derived thermal response curves and provides estimates of thermal habitat suitability and extinction probability based on site-specific conditions. We show that temperature-driven changes in distributions, local extinction, and abundance of cold, cool, and warm-adapted species vary substantially when physiological information is incorporated. Notably, cold-adapted species were predicted by the PGA model to be extirpated in 61% of locations that they currently inhabit, while extirpation was never predicted by a correlative niche model. Failure to account for species-specific physiological constraints could lead to unrealistic predictions under a warming climate, including underestimates of local extirpation for cold-adapted species near the edges of their climate niche space and overoptimistic predictions of warm-adapted species. 

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3. Herpetofaunal ecology (often) makes sense in the light of thermal physiology

   Claunch, NM; Goodman, CM; Guralnick RP; Barve, N; Kluever, B. Longo; Reed, RN; Taylor, EN; Romagosa, CM (July 2022, The 55th Scientific Meeting of Australian Society of Herpetologists)

   An underlying rule in biology is that temperature affects physiological processes. This is salient in ectothermic organisms such as herpetofauna, which must cope with the challenges of changing body temperatures. The limitations associated with living in a dynamic thermal environment often translate into patterns of herpetofaunal distribution and behavior. As such, an understanding of thermal physiology and thermal environment are foundational to studies of herpetofauna. Beginning with a brief review of the contributions of Hal Heatwole and Hal Cogger to the field of thermal ecology, I explore how some methodologies and have changed over time with technological improvements to tackle emergent issues including invasion by herpetofauna and understanding of disease processes. I discuss recent applications of thermal ecology in my own research to understand and predict distribution of invasive herpetofauna, and to understand disease processes in wild populations. Specifically, I discuss the predictive value of critical thermal minima on current and future distributions of invasive lizards introduced to Florida, USA (Leiocephalus carinatus and Furcifer pardalis), obtained through different experimental and computational methods. I also discuss planned methodologies to assess the role of thermoregulation in combatting infection of Batrachochytrium dendrobatidis and B. salamandrivorans in plethodontid salamanders. 

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4. Rarity, geography, and plant exposure to global change in the California Floristic Province

   https://doi.org/10.1111/geb.13618  

   Rose, Miranda Brooke; Velazco, Santiago José; Regan, Helen M.; Franklin, Janet (February 2023, Global Ecology and Biogeography)

   Abstract Aim Rarity and geographic aspects of species distributions mediate their vulnerability to global change. We explore the relationships between species rarity and geography and their exposure to climate and land use change in a biodiversity hotspot. Location California, USA. Taxa One hundred and six terrestrial plants. Methods We estimated four rarity traits: range size, niche breadth, number of habitat patches, and patch isolation; and three geographic traits: mean elevation, topographic heterogeneity, and distance to coast. We used species distribution models to measure species exposure—predicted change in continuous habitat suitability within currently occupied habitat—under climate and land use change scenarios. Using regression models, decision‐tree models and variance partitioning, we assessed the relationships between species rarity, geography, and exposure to climate and land use change. Results Rarity, geography and greenhouse gas emissions scenario explained >35% of variance in climate change exposure and >61% for land use change exposure. While rarity traits (range size and number of habitat patches) were most important for explaining species exposure to climate change, geographic traits (elevation and topographic heterogeneity) were more strongly associated with species' exposure to land use change. Main conclusions Species with restricted range sizes and low topographic heterogeneity across their distributions were predicted to be the most exposed to climate change, while species at low elevations were the most exposed to habitat loss via land use change. However, even some broadly distributed species were projected to lose >70% of their currently suitable habitat due to climate and land use change if they are in geographically vulnerable areas, emphasizing the need to consider both species rarity traits and geography in vulnerability assessments. 

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5. Estimating the distribution of Oryzomys palustris , a potential key host in expanding rickettsial tick‐borne disease risk

   https://doi.org/10.1002/ecs2.4445  

   Lippi, Catherine_A; Canfield, Samuel; Espada, Christina; Gaff, Holly_D; Ryan, Sadie_J (March 2023, Ecosphere)

   Abstract Increasingly, geographic approaches to assessing the risk of tick‐borne diseases are being used to inform public health decision‐making and surveillance efforts. The distributions of key tick species of medical importance are often modeled as a function of environmental factors, using niche modeling approaches to capture habitat suitability. However, this is often disconnected from the potential distribution of key host species, which may play an important role in the actual transmission cycle and risk potential in expanding tick‐borne disease risk. Using species distribution modeling, we explore the potential geographic range ofOryzomys palustris, the marsh rice rat, which has been implicated as a potential reservoir host ofRickettsia parkeri, a pathogen transmitted by the Gulf Coast tick (Amblyomma maculatum) in the southeastern United States. Due to recent taxonomic reclassification ofO. palustrissubspecies, we reclassified geolocated collections records into the newer clade definitions. We modeled the distribution of the two updated clades in the region, establishing for the first time, range maps and distributions of these two clades. The predicted distribution of both clades indicates a largely Gulf and southeastern coastal distribution. Estimated suitable habitat forO. palustrisextends into the southern portion of the Mid‐Atlantic region, with a discontinuous, limited area of suitability in coastal California. Broader distribution predictions suggest potential incursions along the Mississippi River. We found considerable overlap of predictedO. palustrisranges with the distribution ofA. maculatum, indicating the potential need for extended surveillance efforts in those overlapping areas and attention to the role of hosts in transmission cycles. 

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