Louie H. Yang, Elizabeth G. Postema, Tracie E. Hayes, Mia K. Lippey, Dylan J. MacArthur-Waltz

Abstract

Global change includes multiple overlapping and interacting drivers: 1) climate change, 2) land use change, 3) novel chemicals, and 4) the increased global transport of organisms. Recent studies have documented the complex and counterintuitive effects of these drivers on the behavior, life histories, distributions, and abundances of insects. This complexity arises from the indeterminacy of indirect, non-additive and combined effects. While there is wide consensus that global change is reorganizing communities, the available data are limited. As the pace of anthropogenic changes outstrips our ability to document its impacts, ongoing change may lead to increasingly unpredictable outcomes. This complexity and uncertainty argue for renewed efforts to address the fundamental drivers of global change.

Current Opinion in Insect Science

https://doi.org/10.1016/j.cois.2021.05.001

Open Access PDF available before July 30, 2021

Lea K. Richardson, M. Kate Gallagher, Tracie E. Hayes, Amanda S. Gallinat, Gretel Kiefer, Kristen Manion, Miriam Jenkins, Greg Diersen, Stuart Wagenius

Abstract

1. Species that persist in small populations isolated by habitat destruction may experience reproductive failure. Self‐incompatible plants face dual threats of mate‐limitation and competition with co‐flowering plants for pollination services. Such competition may lower pollinator visitation, increase heterospecific pollen transfer and reduce the likelihood that a visit results in successful pollination.
2. To understand how isolation from mates and competition with co‐flowering species contribute to reproductive failure in fragmented habitat, we conducted an observational study of a tallgrass prairie perennial Echinacea angustifolia. We quantified the isolation of focal individuals from mates, characterized species richness and counted inflorescences within 1 m radius, observed pollinator visitation, collected pollinators, quantified pollen loads on pollinators and on Echinacea stigmas, and measured pollination success. Throughout the season, we sampled 223 focal plants across 10 remnant prairie sites.
3. We present evidence that both co‐flowering species and isolation from mates substantially limit reproduction in Echinacea. As the flowering season progressed, the probability of pollinator visitation to focal plants decreased and evidence for pollen‐limited reproduction increased. Pollinators were most likely to visit Echinacea plants from low‐richness floral neighbourhoods with close potential mates, or plants from high‐richness neighbourhoods with distant potential mates. Frequent visitation only increased pollination success in the former case, likely because Echinacea in high‐richness floral neighbourhoods received low‐quality visits.
4. Synthesis. In Echinacea, reproduction was limited by isolation from potential mates and the richness of co‐flowering species. These aspects of the floral neighbourhood influenced pollinator visitation and pollination success, although conditions that predicted high visitation did not always lead to high pollination success. These results reveal how habitat modification and destruction, which influence floral neighbourhood and isolation from conspecific mates, can differentially affect various stages of reproductive biology in self‐incompatible plants. Our results suggest that prairie conservation and restoration efforts that promote patches of greater floral diversity may improve reproductive outcomes in fragmented habitats.

Journal of Ecology

https://doi.org/10.1111/1365-2745.13562

Collin B. Edwards and Louie H. Yang

Abstract

Several studies have documented a global pattern of phenological advancement that is consistent with ongoing climate change. However, the magnitude of these phenological shifts is highly variable across taxa and locations. This variability of phenological responses has been difficult to explain mechanistically. To examine how the evolution of multi-trait cueing strategies could produce variable responses to climate change, we constructed a model in which organisms evolve strategies that integrate multiple environmental cues to inform anticipatory phenological decisions. We simulated the evolution of phenological cueing strategies in multiple environments, using historic climate data from 78 locations in North America and Hawaii to capture features of climatic correlation structures in the real world. Organisms in our model evolved diverse strategies that were spatially autocorrelated across locations on a continental scale, showing that similar strategies tend to evolve in similar climates. Within locations, organisms often evolved a wide range of strategies that showed similar response phenotypes and fitness outcomes under historical conditions. However, these strategies responded differently to novel climatic conditions, with variable fitness consequences. Our model shows how the evolution of phenological cueing strategies can explain observed variation in phenological shifts and unexpected responses to climate change.

The American Naturalist

https://doi.org/10.1086/711650

We are listening, learning and taking action. We are committed to this fight, because Black lives matter.

Richard Karban and Louie H. Yang

Abstract

1. Induced plant responses to herbivory are common and we have learned a lot about the mechanisms of induced resistance and their effects on herbivore performance. We know less about their effects on herbivore behavior and especially on spatial patterns of damage.

2. Theoretical models predict that induced responses can cause patterns of damage to become aggregated, random, or even. A recent model predicted that informed herbivore movement coupled with communication between plants would make damage more even within individual plants. We tested these predictions in the field using a specialist beetle (Trirhabda pilosa ) that feeds on sagebrush (Artemisia tridentata ). Both the beetle and the plant are well‐documented to respond to damage‐induced volatile cues.

3. Beetle larvae were more likely to move from damaged leaves and leaves that had been exposed to volatiles from nearby damaged leaves compared to undamaged control leaves. Previous lab results indicated that beetles were more likely to choose undamaged leaves compared to damaged leaves or those exposed to volatile cues of damage.

4. A comparison of damage patterns early in the season and after completion of beetle feeding revealed that variance in damage among branches decreased as the season progressed; i.e., damage became more evenly distributed among the branches within a plant. Larvae damaged many leaves on a plant but removed relatively little tissue from each leaf.

5. Herbivore movement and the spatial patterns of damage that it creates can be important in determining effects on plant fitness and other population processes. Dispersion of damage deserves more consideration in plant‐herbivore studies.

Journal of Animal Ecology

https://doi.org/10.1111/1365-2656.13270

Amber Wright, Louie H. Yang, Jonah Piovia-Scott, David A. Spiller, and Thomas W. Schoener

Abstract

Increases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in shorter response lags and larger magnitude numerical increases. Previous work on large Bahamian islands has shown that lizards (Anolis sagrei) increased in abundance in response to pulses of seaweed deposition, which provide abundant marine-derived prey resources. These numerical responses were associated with rapid diet shifts and aggregation, followed by increased reproduction. These dynamics are likely different on isolated small islands because lizards cannot readily immigrate or emigrate. We evaluated the effects of experimental pulses of seaweed deposition that varied in frequency and magnitude on lizard diet shifts and numerical responses on small islands (n = 16) and in plots on large mainland islands (n = 20) over five years. We found that pulses of seaweed deposition created persistent increases in lizard abundance on small islands regardless of pulse frequency or magnitude, which may have occurred because the initial resource pulse facilitated population establishment, possibly via enhanced overwinter survival. In contrast with a previous experiment, we did not detect numerical responses on mainlands, despite the fact that lizards consumed more marine resources in subsidized plots. This lack of a numerical response may be due to rapid aggregation and disaggregation or stronger suppression of A. sagrei by their predators on mainlands. Our results highlight the importance of habitat connectivity in governing ecological responses to resource pulses and suggest that disaggregation and changes in survivorship may be underappreciated drivers of pulse-associated dynamics.

The American Naturalist

https://doi.org/10.1086/710040

We are glad to welcome Shalom Entner from Howard University to the lab! Shalom will joining the lab as an undergraduate in the UCD-HBCU Graduate Admission Pathways (GAP) Summer Research Program.

We are all glad to welcome Dylan MacArthur-Waltz to the lab! Dylan recently received an NSF Graduate Research Fellowship, and will be joining the Population Biology Graduate Group this fall. Welcome!

We are happy to welcome Gwen Erdosh to the lab! Gwen will be joining the lab as an undergraduate in the Research Scholars Program in Insect Biology (RSPIB).

We are glad to welcome Emily Patterson to the lab! Emily will be joining the lab as an undergraduate in the Research Scholars Program in Insect Biology (RSPIB).