The role of timing in intraspecific trait ecology

Olivia L. Cope, Laura A. Burkle, Jordan R. Croy, Kailen A. Mooney, Louie H. Yang and William C. Wetzel


Intraspecific trait variation has tremendous importance for species interactions and community composition. A major source of intraspecific trait variation is an organism’s developmental stage; however, timing is rarely considered in studies of the ecological effects of intraspecific variation. Here, we examine the role of time in the ecology of intraspecific trait variation, focusing on plants and their interactions with other organisms. Trait variation due to differences in developmental timing has unique features and dynamics, distinguishing it from variation due to genes or the environment. When time is considered in studies of intraspecific trait ecology, the degree of variability in timing within a population becomes a key factor structuring trait-mediated ecological interactions and community processes.

Trends in Ecology and Evolution (TREE)

Timing of a plant-herbivore interaction alters plant growth and reproduction

Nick L. Rasmussen and Louie H. Yang


Phenological shifts have the potential to change species interactions, but relatively few studies have used experimental manipulations to examine the effects of variation in timing of an interspecific interaction across a series of life-stages of a species. While previous experimental studies have examined the consequences of phenological timing in plant-herbivore interactions for both plants and their herbivores, less is known about their effects on subsequent plant reproduction. Here, we conducted an experiment to determine how shifts in the phenological timing of monarch (Danaus plexippus) larval herbivory affected milkweed (Asclepias fascicularis) host plant performance, including effects on growth and subsequent effects on flower and seed pod phenology and production. We found that variation in the timing of herbivory affected both plant growth and reproduction, with measurable effects several weeks to several months after herbivory ended. The timing of herbivory had qualitatively different effects on vegetative and reproductive biomass: early-season herbivory had the strongest effects on plant size, while late-season herbivory had the strongest effects on the production of viable seeds. These results show that phenological shifts in herbivory can have persistent and qualitatively different effects on different life stages across the season.



Different factors limit early- and late-season windows of opportunity for monarch development

Louie H. Yang, Karen Swan, Eric Bastin, Jessica Aguilar, Meredith Cenzer, Andrew Codd, Natalie Gonzalez, Tracie Hayes, August Higgins, Xang Lor, Chido Macharaga, Marshall McMunn, Kenya Oto, Nicholas Winarto, Darren Wong, Tabatha Yang, Numan Afridi, Sarah Aguilar, Amelia Allison, Arden Ambrose-Winters, Edwin Amescua, Mattias Apse, Nancy Avoce, Kirstin Bastin, Emily Bolander, Jessica Burroughs, Cristian Cabrera, Madeline Candy, Ariana Cavett, Melina Cavett, Lemuel Chang, Miles Claret, Delaney Coleman, Jacob Concha, Paxson Danzer, Joe DaRosa, Audrey Dufresne, Claire Duisenberg, Allyson Earl, Emily Eckey, Maddie English, Alexander Espejo, Erika Faith, Amy Fang, Alejandro Gamez, Jackelin Garcini, Julie Garcini, Giancarlo Gilbert-Igelsrud, Kelly Goedde-Matthews, Sarah Grahn, Paloma Guerra, Vanessa Guerra, Madison Hagedorn, Katie Hall, Griffin Hall, Jake Hammond, Cody Hargadon, Victoria Henley, Sarah Hinesley, Celeste Jacobs, Camille Johnson, Tattiana Johnson, Zachary Johnson, Emma Juchau, Celeste Kaplan, Andrew Katznelson, Ronja Keeley, Tatum Kubik, Theodore Lam, Chalinee Lansing, Andrea Lara, Vivian Le, Breana Lee, Kyra Lee, Maddy Lemmo, Scott Lucio, Angela Luo, Salman Malakzay, Luke Mangney, Joseph Martin, Wade Matern, Byron McConnell, Maya McHale, Giulia McIsaac, Carolanne McLennan, Stephanie Milbrodt, Mohammed Mohammed, Morgan Mooney-McCarthy, Laura Morgan, Clare Mullin, Sarah Needles, Kayla Nunes, Fiona O’Keeffe, Olivia O’Keeffe, Geoffrey Osgood, Jessica Padilla, Sabina Padilla, Isabella Palacio, Verio Panelli, Kendal Paulson, Jace Pearson, Tate Perez, Brenda Phrakonekham, Iason Pitsillides, Alex Preisler, Nicholas Preisler, Hailey Ramirez, Sylvan Ransom, Camille Renaud, Tracy Rocha, Haley Saris, Ryan Schemrich, Lyla Schoenig, Sophia Sears, Anand Sharma, Jessica Siu, Maddie Spangler, Shaili Standefer, Kelly Strickland, Makaila Stritzel, Emily Talbert, Sage Taylor, Emma Thomsen, Katrina Toups, Kyle Tran, Hong Tran, Maraia Tuqiri, Sara Valdes, George VanVorhis, Sandy Vue, Shauna Wallace, Johnna Whipple, Paja Yang, Meg Ye, David Yo, Yichao Zeng


Seasonal windows of opportunity are intervals within a year that provide improved prospects for growth, survival, or reproduction. However, few studies have sufficient temporal resolution to examine how multiple factors combine to constrain the seasonal timing and extent of developmental opportunities. Here, we document seasonal changes in milkweed (Asclepias fascicularis)–monarch (Danaus plexippus) interactions with high resolution throughout the last three breeding seasons prior to a precipitous single-year decline in the western monarch population. Our results show early- and late-season windows of opportunity for monarch recruitment that were constrained by different combinations of factors. Early-season windows of opportunity were characterized by high egg densities and low survival on a select subset of host plants, consistent with the hypothesis that early-spring migrant female monarchs select earlier-emerging plants to balance a seasonal trade-off between increasing host plant quantity and decreasing host plant quality. Late-season windows of opportunity were coincident with the initiation of host plant senescence, and caterpillar success was negatively correlated with heatwave exposure, consistent with the hypothesis that late-season windows were constrained by plant defense traits and thermal stress. Throughout this study, climatic and microclimatic variations played a foundational role in the timing and success of monarch developmental windows by affecting bottom-up, top-down, and abiotic limitations. More exposed microclimates were associated with higher developmental success during cooler conditions, and more shaded microclimates were associated with higher developmental success during warmer conditions, suggesting that habitat heterogeneity could buffer the effects of climatic variation. Together, these findings show an important dimension of seasonal change in milkweed–monarch interactions and illustrate how different biotic and abiotic factors can limit the developmental success of monarchs across the breeding season. These results also suggest the potential for seasonal sequences of favorable or unfavorable conditions across the breeding range to strongly affect monarch population dynamics.

Ecology and Evolution

Open Access PDF

Color under pressure: how multiple factors shape defensive coloration

Elizabeth G. Postema, Mia K. Lippey, Tiernan Armstrong-Ingram


Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field.

Behavioral Ecology

Monarch Summit in Washington, D.C.

A Monarch Butterfly Summit was held June 22-23 at the Capitol in Washington D.C. to discuss western monarch conservation. The summit was organized by Senator Jeff Merkley (OR) and attended by Secretary of the Interior Deb Haaland, Senators Ron Wyden (OR) and Alex Padilla (CA), Congressperson Jimmy Panetta (CA), Assistant Secretary for Fish and Wildlife and Parks Shannon Estenoz, and U.S. Fish and Wildlife Service (FWS) Director Martha Williams. Scientific presenters included Amanda Barth (Western Monarch and Native Pollinator Working Group), Wendy Caldwell (Monarch Joint Venture), Ryan Drum (USFWS) and Wayne Thogmartin (USGS), Cat Darst (USFWS), Cheryl Schultz (Washington State University), Matt Forister (University of Nevada – Reno), Louie Yang (University of California – Davis), Sarah Hoyle (Xerces Society for Invertebrate Conservation), Francis Villablanca (Cal Poly State University), Elizabeth Crone (University of California – Davis), and Sarina Jepsen (Xerces Society for Invertebrate Conservation).

The Department of the Interior announced a $1 million dollar award to the National Fish and Wildlife Foundation’s (NFWF) Monarch Butterfly and Pollinators Conservation Fund, and the Fish and Wildlife Service announced a Pollinator Conservation Center. In addition, two bills to support the Monarch Action, Recovery, and Conservation of Habitat (MONARCH) Act and the Monarch and Pollinator Highway Act were proposed last year; if passed, these acts would support a variety of initiatives focused on monarch research and conservation.

Tracie Hayes receives the Russell J. and Dorothy S. Bilinski Bodega Marine Laboratory Fellowship

The Bilinski Fellowship supports “interdisciplinary, innovative, and highly collaborative” projects at the Bodega Marine Laboratory. Projects must “bridge the natural sciences, social sciences, and/or humanities”. Tracie’s project will support her continued research into the ecology of carrion beetles on ephemeral resource patches, and a collaborative in situ art exhibition along Mussel Point trail at the Bodega Marine Reserve.

Nitrogen increases early-stage and slows late-stage decomposition across diverse grasslands

Allison L. Gill, Peter B. Adler, Elizabeth T. Borer, Christopher R. Buyarski, Elsa E. Cleland, Carla M. D’Antonio, Kendi F. Davies, Daniel S. Gruner, W. Stanley Harpole, Kirsten S. Hofmockel, Andrew S. MacDougall, Rebecca L. McCulley, Brett A. Melbourne, Joslin L. Moore, John W. Morgan, Anita C. Risch, Martin Schütz, Eric W. Seabloom, Justin P. Wright, Louie H. Yang, Sarah E. Hobbie


1. To evaluate how increased anthropogenic nutrient inputs alter carbon cycling in grasslands, we conducted a litter decomposition study across 20 temperate grasslands on three continents within the Nutrient Network, a globally distributed nutrient enrichment experiment

2. We determined the effects of experimental nitrogen (N), phosphorus (P), and potassium plus micronutrient (Kμ) additions on decomposition of a common tree leaf litter in a long-term study (maximum of 7 years; exact deployment period varied across sites). The use of higher-order decomposition models allowed us to distinguish between effects of nutrients on early- versus late-stage decomposition.

3. Across continents, addition of nitrogen (but not other nutrients) accelerated early-stage decomposition and slowed late-stage decomposition, increasing the slowly decomposing fraction by 28% and the overall litter mean residence time by 58%.

4. Synthesis. Using a novel, long-term cross-site experiment, we found widespread evidence that nitrogen enhances the early stages of aboveground plant litter decomposition across diverse and widespread temperate grassland sites, but slows late-stage decomposition. These findings were corroborated by fitting the data to multiple decomposition models and have implications for nitrogen effects on soil organic matter formation. For example, following nitrogen enrichment, increased microbial processing of litter substrates early in decomposition could promote production and transfer of low molecular weight compounds to soils, and potentially enhance stabilization of mineral-associated organic matter. By contrast, by slowing late-stage decomposition, nitrogen enrichment could promote particulate organic matter (POM) accumulation. Such hypotheses deserve further testing.

Journal of Ecology

Biodiversity and infrastructure interact to drive tourism to and within Costa Rica

Alejandra Echeverri, Jeffrey R. Smith, Dylan MacArthur-Waltz, Katherine S. Lauck, Christopher B. Anderson, Rafael Monge Vargas, Irene Alvarado Quesada, Spencer A. Wood, Rebecca Chaplin-Kramer, Gretchen C. Daily


Nature-based tourism has potential to sustain biodiversity and economic development, yet the degree to which biodiversity drives tourism patterns, especially relative to infrastructure, is poorly understood. Here, we examine relationships between different types of biodiversity and different types of tourism in Costa Rica to address three questions. First, what is the contribution of species richness in explaining patterns of tourism in protected areas and country-wide in Costa Rica? Second, how similar are the patterns for birdwatching tourism compared to those of overall tourism? Third, where in the country is biodiversity contributing more than other factors to birdwatching tourism and to overall tourism? We integrated environmental data and species occurrence records to build species distribution models for 66 species of amphibians, reptiles, and mammals, and for 699 bird species. We used built infrastructure variables (hotel density and distance to roads), protected area size, distance to protected areas, and distance to water as covariates to evaluate the relative importance of biodiversity in predicting birdwatching tourism (via eBird checklists) and overall tourism (via Flickr photographs) within Costa Rica. We found that while the role of infrastructure is larger than any other variable, it alone is not sufficient to explain birdwatching and tourism patterns. Including biodiversity adds predictive power and alters spatial patterns of predicted tourism. Our results suggest that investments in infrastructure must be paired with successful biodiversity conservation for tourism to generate the economic revenue that countries like Costa Rica derive from it, now and into the future.