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1. Effects of climate on bill morphology within and across Toxostoma thrashers

   https://doi.org/10.1111/jav.02871  

   Probst, Charlotte M.; Ralston, Joel; Bentley, Ian (September 2021, Journal of Avian Biology)

   Nord, Andreas; Nilsson, Janake (Ed.)

   Bird bills possess an important thermoregulatory function as they are a site for environmental heat exchange. Previous studies have demonstrated that birds in warmer climates have larger bills than those living in colder climates, as larger bills can dissipate more heat. Because this dry heat transfer does not incur water loss, it may be additionally advantageous in water‐restricted habitats. Here, we examine the influence of climate on bill morphology inToxostomathrashers, a group of 10 North American species that varied in bill morphology and occupied climate niche, with several species inhabiting arid climates. Past examinations of thrasher bill morphology have only considered foraging, leaving unanswered the role of climate in morphological divergence within this group. We photographed 476Toxostomamuseum specimens encompassing all 10 species and calculated bill measurements from the photos using a MATLAB‐based program. For each species, we calculated occupied climate niche using data from WorldClim describing temperature and precipitation. We found no reliable significant relationships between climate variables and bill morphology across species, suggesting that other factors such as foraging behavior may be more important in shaping bill morphology in this genus. Within species, we found threeToxostomaspecies have significant relationships between bill morphology and climate that follow Allen's rule. However, we also found the relationships between climate and bill morphology varied in strength and direction across species. Notably, we found a negative relationship between maximum temperature of the hottest month and bill surface area in LeConte's thrasher, which occupies the hottest and most arid climates of the thrashers. This adds to the evidence that Allen's rule may reverse in extremely hot climates when the bill may become a heat sink instead of a heat radiator. These results demonstrate the importance of considering the generality of ecogeographical rules across lineages that occupy extreme climates. 

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2. Global intraspecific trait–climate relationships for grasses are linked to a species' typical form and function

   https://doi.org/10.1111/ecog.06586  

   Griffin‐Nolan, Robert J.; Sandel, Brody (May 2023, Ecography)

   Plant traits are useful for predicting how species may respond to environmental change and/or influence ecosystem properties. Understanding the extent to which traits vary within species and across climatic gradients is particularly important for understanding how species may respond to climate change. We explored whether climate drives spatial patterns of intraspecific trait variation for three traits (specific leaf area (SLA), plant height, and leaf nitrogen content (Nmass)) across 122 grass species (family: Poaceae) with a combined distribution across six continents. We tested the hypothesis that the sensitivity (i.e. slope) of intraspecific trait responses to climate across space would be related to the species' typical form and function (e.g. leaf economics, stature and lifespan). We observed both positive and negative intraspecific trait responses to climate with the distribution of slope coefficients across species straddling zero for precipitation, temperature and climate seasonality. As hypothesized, variation in slope coefficients across species was partially explained by leaf economics and lifespan. For example, acquisitive species with nitrogen-rich leaves grew taller and produced leaves with higher SLA in warmer regions compared to species with low Nmass. Compared to perennials, annual grasses invested in leaves with higher SLA yet decreased height and Nmass in regions with high precipitation seasonality (PS). Thus, while the influence of climate on trait expression may at first appear idiosyncratic, variation in trait–climate slope coefficients is at least partially explained by the species' typical form and function. Overall, our results suggest that a species' mean location along one axis of trait variation (e.g. leaf economics) could influence how traits along a separate axis of variation (e.g. plant size) respond to spatial variation in climate. 

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3. A global assessment of environmental and climate influences on wetland macroinvertebrate community structure and function

   https://doi.org/10.1111/gcb.17173  

   Epele, Luis B.; Williams‐Subiza, Emilio A.; Bird, Matthew S.; Boissezon, Aurelie; Boix, Dani; Demierre, Eliane; Fair, Conor G.; García, Patricia E.; Gascón, Stephanie; Grech, Marta G.; et al (February 2024, Global Change Biology)

   Abstract Estimating organisms' responses to environmental variables and taxon associations across broad spatial scales is vital for predicting their responses to climate change. Macroinvertebrates play a major role in wetland processes, but studies simultaneously exploring both community structure and community trait responses to environmental gradients are still lacking. We compiled a global dataset (six continents) from 756 depressional wetlands, including the occurrence of 96 macroinvertebrate families, their phylogenetic tree, and 19 biological traits. Using Bayesian hierarchical joint species distribution models (JSDMs), we estimated macroinvertebrate associations and compared the influences of local and climatic predictors on both individual macroinvertebrate families and their traits. While macroinvertebrate families were mainly related to broad‐scale factors (maximum temperature and precipitation seasonality), macroinvertebrate traits were strongly related to local wetland hydroperiod. Interestingly, macroinvertebrate families and traits both showed positive and negative associations to the same environmental variables. As expected, many macroinvertebrate family occurrences were positively associated with temperature, but a few showed the opposite pattern and were found in cooler or montane regions. We also found that wetland macroinvertebrate communities would likely be affected by changing climates through alterations in traits related to precipitation seasonality, temperature seasonality, and wetland area. Temperature increases may negatively affect collector and shredder functional groups. A decrease in precipitation could lead to reductions in wetland area benefiting drought‐tolerant macroinvertebrates, but it may negatively affect macroinvertebrates lacking those adaptations. Wetland processes may be compromised through broad‐scale environmental changes altering macroinvertebrate family distributions and local hydroperiod shifts altering organism traits. Our complementary family‐based and trait‐based approaches elucidate the complex effects that climate change may produce on wetland ecosystems. 

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4. Identifying the Climate Conditions Associated With Extreme Growth States in Trees Across the Western United States

   https://doi.org/10.1111/gcb.70317  

   Ogle, Kiona; Barber, Jarrett J; Strange, Brandon M; Boone, Rohan D; Formanack, Alicia M; Peltier, Drew_M P (July 2025, Global Change Biology)

   ABSTRACT Climate extremes—e.g., drought, atmospheric rivers, heat waves—are increasing in severity and frequency across the western United States of America (USA). Tree‐ring widths reflect the concurrent and legacy effects of such climate extremes, yet our ability to predict extreme tree growth is often poor. Could tree‐ring data themselves identify the most important climate variables driving extreme low‐ and high‐growth states? How does the importance of these climate drivers differ across species and time? To address these questions, we explored the spatial synchrony of extreme low‐ and high‐growth years, the symmetry of climate effects on the probability of low‐ and high‐growth years, and how climate drivers of extreme growth vary across tree species. We compiled ring widths for seven species (four gymnosperms and three angiosperms) from 604 sites in the western USA and classified each annual ring as representing extreme low, extreme high, or nominal growth. We used classification random forest (RF) models to evaluate the importance of 30 seasonal climate variables for predicting extreme growth, including precipitation, temperature, and vapor pressure deficit (VPD) during and up to four years prior to ring formation. For four species (three gymnosperms, one angiosperm) for which climate was predictive of growth, the RF models correctly classified 89%–98% and 80%–95% of low‐ and high‐growth years, respectively. For these species, asymmetric climate responses dominated. Current‐year winter hydroclimate (precipitation and VPD) was most important for predicting low growth, but prediction of high growth required multiple years of favorable moisture conditions, and the occurrence of low‐growth years was more synchronous across space than high‐growth years. Summer climate and temperature (regardless of season) were only weakly predictive of growth extremes. Our results motivate ecologically relevant definitions of drought such that current winter moisture stress exerts a dominant role in governing growth reductions in multiple tree species broadly distributed across the western USA. 

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5. Intraspecific variation reshapes coral assemblages under elevated temperature and acidity

   https://doi.org/10.1111/ele.14114  

   McWilliam, Mike; Madin, Joshua S; Chase, Tory J; Hoogenboom, Mia O; Bridge, Tom_C L (November 2022, Ecology Letters)

   Abstract Insights into assemblages that can persist in extreme environments are still emerging. Ocean warming and acidification select against species with low physiological tolerance (trait‐based ‘filtering’). However, intraspecific trait variation can promote species adaptation and persistence, with potentially large effects on assemblage structure. By sampling nine coral traits (four morphological, four tissue and one skeletal) along an offshore–inshore gradient in temperature and pH, we show that distantly related coral species undergo consistent intraspecific changes as they cross into warm, acidic environments. Intraspecific variation and species turnover each favoured colonies with greater tissue biomass, higher symbiont densities and reduced skeletal investments, indicating strong filtering on colony physiology within and across species. Physiological tissue traits were highly variable within species and were independent of morphology, enabling morphologically diverse species to cross into sites of elevated temperature and acidity. Widespread intraspecific change can therefore counter the loss of biodiversity and morphological structure across a steep environmental gradient. 

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