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Research in the YEP Lab primarily aims to understand how physiological processes scale up to produce ecological patterns. Our core hypothesis is that integrating physiological mechanisms into ecological models will improve our ability to predict organismal responses to climate change. Using insects (mainly grasshoppers) as a model system, we rigorously test this hypothesis through a combination of laboratory experiments, field observations, and computational modeling.
Research in the YEP Lab primarily aims to understand how physiological processes scale up to produce ecological patterns. Our core hypothesis is that integrating physiological mechanisms into ecological models will improve our ability to predict organismal responses to climate change. Using insects (mainly grasshoppers) as a model system, we rigorously test this hypothesis through a combination of laboratory experiments, field observations, and computational modeling.
Ongoing Projects
Ongoing Projects
Investigating how temperature-nutrient interactions affect the physiological performance of insect herbivores
Biodiversity and agriculture are threatened by two main impacts of climate change: rising air temperatures and declining plant nutrients. However, current models do not account for these combined impacts, limiting our ability to predict and mitigate the outcomes of climate change. Students are conducting laboratory experiments with caterpillars of Manduca sexta and grasshoppers of Melanoplus ascensus to test the hypothesis that body temperature and dietary nutrition interactively shape organismal performance. Preliminary results indicate that malnutrition slowed the growth of caterpillars more severely at optimal temperatures than it did at low temperatures, confirming the interactive effects of temperature and nutrition (Figure 1). Future research will apply the geometric framework of nutrition to evaluate how dietary nutrition (quantity and quality of macronutrients) influences the feeding behavior and physiological performance of insects at different temperatures.
Figure 1. Temperature and nutrition interacted to affect the growth of caterpillars. Circles represent mean growth rate for every temperature-nutrition treatment, and bars represent 95% confidence intervals. Blue and red symbols represent data from caterpillars feeding on 50% and 100% nutrition, respectively. Data collected by SOU undergraduate Claire Klocksieben.
Monitoring the diversity and distribution of grasshoppers (Orthoptera: Acrididae) in the Klamath-Siskiyou ecoregion
Insect herbivores such as grasshoppers are vital to their ecosystems, playing central roles as both primary consumers and food sources. Although insect herbivores make up an estimated 27% of Earth’s biodiversity, our knowledge of this biodiversity is relatively poor. This point is especially true for grasshoppers, one of the most ancient lineages of chewing herbivorous insects that tend to be the dominant herbivore in grassland ecosystems. To address this knowledge gap, the YEP Lab started in 2023 a grasshopper monitoring program in Cascade-Siskiyou National Monument, the only national monument set aside specifically for its biodiversity. With the generous support of the nonprofit organization Friends of the Cascade-Siskiyou National Monument, students in the YEP Lab monitor the weekly relative abundance and species richness of grasshoppers living along a 4000-feet elevation gradient in the Monument. The YEP Lab has a special interest in documenting the range and phenology of the endemic Siskiyou short-horned grasshopper (Chloealtis aspasma) (Figure 2), which is listed as a Species of Special Status by the BLM and USFS.
Figure 2. Photograph of the Siskiyou short-horned grasshopper (Chloealtis aspasma), a focal species of the YEP Lab. This species can be identified by the following combination of traits: slanted face, gray speckled body, short wings that do not extend past the abdomen, orange tibia, and a diamond-shaped “nose” (not visible).
Building mechanistic models of physiological performance and geographic distributions
Scientists have modeled the performance and distributions of numerous species by correlating environmental variables and species occurrences. However, this approach is not reliable when extrapolating to future environments that are outside the range of current environments. Research in the YEP Lab works to improve ecological models by incorporating biological mechanisms such as behavioral thermoregulation and digestion rate (Figure 3). Our previous research centered on the South American locusts (Schistocerca cancellata), demonstrating that climate change will expand the geographic range of this locust and that this range expansion will be driven by increased digestion rates at high latitudes (Youngblood et al. 2022). Current research in the YEP Lab centers on parameterizing this mechanistic model for other economically important species such as the migratory grasshopper (Melanoplus sanguinipes). Furthermore, we are working to improve the mechanistic models by incorporating the interactive effects of temperature and nutrition. We anticipate that current models underestimate the impacts of climate change by ignoring the combined impacts of temperature and nutrition.
Figure 3. Spatial distribution of the energy assimilated by a South American locust (Schistocerca cancellata) during the wet season (September to March), assuming either thermoregulation (left) or randomly selected shade (right). Each pixel is color-coded based on the energy assimilated (kJ per wet season) at that location. Minimum to maximum values are colored white to green, respectively. For reference, black dots denote known occurrences of Schistocerca cancellata (N = 627). Figure from Youngblood et al. 2022 published in Ecological Monographs.
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