Mingxuan Ge

Abstract

Parnassius clodius, a Snow Apollo butterfly species native to western North America, overwinters as pharate first-instar larvae enclosed within the chorion. Different populations can experience vastly different overwintering temperatures, which are influenced on a microclimatic scale by both snowpack depth and air temperature. Higher elevation populations are likely to experience more moderate overwintering temperatures than lower elevation populations due to the generally greater snowpack volume and stability at higher elevations. Thus, I hypothesized that higher elevation populations would exhibit reduced cold tolerance compared to lower elevation populations, reflected in a higher average egg supercooling point. The results showed that the high elevation population had a supercooling point 0.61 °C warmer than that of the low elevation population (F test, F1,48 = 10.38, P = 0.0023). This pattern supports the hypothesis that overwintering pharate larvae in high elevation populations are less cold-tolerant than their low elevation counterparts and highlights the potential for increased overwintering mortality at high elevations with reduced snowpack under climate change.

The Journal of the Lepidopterists’ Society

https://doi.org/10.18473/lepi.79i3.a6

Louie H. Yang, Elizabeth G. Postema, Heran Arefaine, Fernanda Y. Cohoon, Emma A. Deen, Yvonne L. Durand, Gwendolyn I. Erdosh, Hailey Ma, Courtney N. Mausling, Sarah Solís, Madeline R. Wilson

Abstract

While both daytime and nighttime temperatures are increasing with climate change, few studies have experimentally investigated their differential effects under field conditions. We conducted a factorial field experiment examining how day- and night-warming impact the growth, survivorship, and behavior of cabbage white caterpillars (Pieris rapae). In this experiment, the night-warming only treatment showed the highest rates of caterpillar growth, but also showed the highest mortality, the shortest maximum caterpillar lengths, the least accumulated herbivory, and reduced pupation. Caterpillars in the treatments that were not warmed during the day showed daytime-shifted growth, and caterpillars in the combined day- and night-warming treatment showed strongly night-shifted herbivory. Both biotic (e.g., predation risk) and abiotic (e.g., thermal) factors could have contributed to these results. Broadly, these results show the importance of temperature-mediated behavioral changes in diel activity for caterpillar development and survival. These results also support the emerging hypotheses that periods of reduced activity may be important for successful development, that warmer nighttime conditions could limit a temporal thermal refuge for caterpillars, and that increasing temperatures could increase the likelihood of metabolic meltdown. This experiment also illustrates the value of field studies to provide insights into how ectotherms might respond to ongoing climate change.

Ecology

https://doi.org/10.1002/ecy.70150

Tracie E. Hayes, Léo Lassérès, Louie H. Yang

Abstract

Shifts in abiotic factors such as temperature and moisture can change the availability of resources, especially under climate change. Both abiotic and biotic drivers can have profound, rapid effects on species distribution, survival, and reproduction. Little is known about how abiotic factors affect the availability of ephemeral resources. Burying beetles Nicrophorus spp.) are specialist users of ephemeral resources, as their reproduction requires locating, defending, and burying a small carcass. Environmental moisture, such as coastal fog, could change how quickly carcasses dry out. We tested the role of carcass moisture and interspecific competition with a generalist scavenger, Heterosilpha spp., on reproduction by placing pairs of Nicrophorus guttula in field chambers with control and experimentally dehydrated mouse carcasses. Pairs that were given control mouse carcasses were more likely to carry out reproductive behaviors and produce viable offspring than pairs that were given a partially dehydrated mouse. For those pairs that reproduced, competition limited the number of offspring. These results indicate that shifts in abiotic factors under climate change, along with biotic factors like competition, can reduce the availability and quality of ephemeral resource patches for consumers.

Ecology

https://doi.org/10.1002/ecy.70127

 

Jolene A. Saldivar will be completing her Ph.D. in Plant Biology at UC Riverside this June before starting as a UC Davis Chancellor’s Postdoctoral Fellow in our lab later this summer. Jolene also received an NSF Postdoctoral Research Fellowship in Biology, which she has deferred for a year. Jolene is interested in documenting plant-butterfly interaction networks across a management gradient, using isotopes to learn about the migratory ecology of painted lady butterflies, and developing species distribution models for butterflies and their host plants.

Melanie is a third-year Environmental Science and Management major, working primarily with Tracie on her Pacific Northwest beetle project. Annalee is a first-year Wildlife, Fish, and Conservation Biology major with experience at the UCD Stable Isotope Facility and an interest in butterflies. Annalee will be helping us with a variety projects while developing her research interests.

Kate Cox will be a full-time field assistant on the “Monitoring Monarch Use of Early-Season Milkweeds in the California Coast Range” project this winter/spring. Kate graduated from UC Davis in December 2022 with a major in Plant Biology, and will start with our lab in the new year.

Oriol Lapiedra, Nina Morales, Louie H. Yang, Darío Fernández-Bellon, Sozos N. Michaelides, Sean T. Giery, Jonah Piovia-Scott, Thomas W. Schoener, Jason J. Kolbe, Jonathan B. Losos

Abstract

Foraging decisions shape the structure of food webs. Therefore, a behavioural shift in a single species can potentially modify resource-flow dynamics of entire ecosystems. To examine this, we conducted a field experiment to assess foraging niche dynamics of semi-arboreal brown anole lizards in the presence/absence of predatory ground-dwelling curly-tailed lizards in a replicated set of island ecosystems. One year after experimental translocation, brown anoles exposed to these predators had drastically increased perch height and reduced consumption of marine-derived food resources. This foraging niche shift altered marine-to-terrestrial resource-flow dynamics and persisted in the diets of the first-generation offspring. Furthermore, female lizards that displayed more risk-taking behaviours consumed more marine prey on islands with predators present. Our results show how predator-driven rapid behavioural shifts can alter food-web connectivity between oceanic and terrestrial ecosystems and underscore the importance of studying behaviour-mediated niche shifts to understand ecosystem functioning in rapidly changing environments.

Ecology Letters

https://doi.org/10.1111/ele.14335

Louie H. Yang

Abstract

Recent studies have continued to shed light on the ecology of monarch butterflies (Danaus plexippus) in western North America. These studies have documented a declining overwintering population over several decades, punctuated by unexpected variability in recent years. Understanding this variability will require grappling with the spatial and temporal heterogeneity of resources and risks presented to western monarchs throughout their annual life cycle. Recent changes in the western monarch population further illustrate how interacting global change drivers can create complex causes and consequences in this system. The complexity of this system should inspire humility. However, even recognizing the limits of our current understanding, there is enough scientific common ground to take some conservation actions now.

Current Opinion in Insect Science

https://doi.org/10.1016/j.cois.2023.101078

We are very glad to welcome Mingxuan (Gary) Ge as a new Ph.D. student in our lab! Gary will be in the Entomology Graduate Group starting this fall.

Adam Pepi, Tracie Hayes and Kelsey Lyberger

Abstract

Climate warming directly influences the developmental and feeding rates of organisms. Changes in these rates are likely to have consequences for species interactions, particularly for organisms affected by stage- or size-dependent predation. However, because of differences in species-specific responses to warming, predicting the impact of warming on predator and prey densities can be difficult. We present a general model of stage-dependent predation with temperature-dependent vital rates to explore the effects of warming when predator and prey have different thermal optima. We found that warming generally favored the interactor with the higher thermal optimum. Part of this effect occurred due to the stage-dependent nature of the interaction and part due to thermal asymmetries. Interestingly, below the predator and prey thermal optima, warming caused prey densities to decline, even as increasing temperature improved prey performance. We also parameterize our model using values from a well-studied system, Arctia virginalis and Formica lasioides, in which the predator has a warmer optimum. Overall, our results provide a general framework for understanding stage- and temperature-dependent predator–prey interactions and illustrate that the thermal niche of both predator and prey is important to consider when predicting the effects of climate warming.

Theoretical Ecology

https://doi.org/10.1007/s12080-023-00555-3