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A bug of many hats – The red-shouldered soapberry bug as a pollinating seed-predator

Thu, 06 Nov 2025 06:00:00 GMT

Mattheau S. Comerford, Scott. P. Carroll, and Scott P. Egan: Read the article

Comerford et al. uncover the red-shouldered soapberry bug as the first Hemipteran pollinating seed predator, reshaping our understanding of this guild and its role in evolution and ecological resilience. A discovery bridging natural history and evolution!

When we examine organisms in nature, we tend to typecast them into ecological roles: producers, herbivores, invasives, mutualists, and so on. However, the ecological roles of organisms often vary with circumstances such as the availability of resources and the stability of the environment. Further, the full gamut of their interactions may yet be undescribed by science.

The red-shouldered soapberry bug, Jadera haematoloma, is reminiscent of a male red-winged blackbird: black in colour with eponymous bright red “shoulders”. It is widely distributed across the United States, and its range extends into northern South America. The nymphs and adults are dietary specialists, feeding on the seeds of plants in the soapberry family, Sapindaceae. The authors noticed that this species was often found feeding on the nectar of its host plant’s flowers, so they set out to test if they were viable pollinators.

Until now, it was thought that the members of the true bug subfamily Serinethinae were primarily seed predators of plants in the soapberry family, Sapindaceae. When we think of pollinating seed-predators, the organisms that come to mind are fig wasps or yucca moths, which participate in tightly coevolved partnerships with their plant hosts. The insects provide targeted pollen delivery, while the plant partners sacrifice a few developing seeds as food or lodging for the developing insect offspring. In such cases, the costs and benefits to each partner are clear. From the plant’s perspective, could the pollination benefit, provided by the bugs, although not as targeted, make up for the cost they impose by eating seeds?

Comerford et al. set out to see if the red-shouldered soapberry bug is a different kind of pollinating seed-predator—one that is a generalist nectar feeder, while being a dietary specialist seed-predator. To do this, they examined various records and conducted experiments to test if J. haematoloma consumed nectar, collected host pollen, and contributed to successful seed-set in host plants both in the greenhouse and the field. They also quantified the benefit of consuming nectar to J. haematoloma, and cost of harbouring a pollinating seed-predator to the host plant.

Surveys of museum records, community science databases, online images, and literature revealed widespread nectar feeding in J. haematoloma and some of its relatives worldwide. Experiments confirmed that J. haematoloma consumed nectar, carried pollen and successfully pollinated their host plant, leading to viable seed set. A diet supplemented with synthetic nectar extended insect lifespan, highlighting nectar’s value as a supplement to seeds. However, seed predation experiments showed that offspring consumed far more seeds than the ovules they fertilized, indicating that the interaction with host plants is primarily antagonistic.

These findings reframe our understanding of both the ecology and evolution of this species. Assumed to be exclusively seed feeders until now, these findings suggest that feeding on nectar opportunistically could enable this species to tide over spells of low seed availability and environmental variability. When the flamegold rain tree (Koelreuteria elegans) was introduced to the US from southeast Asia in the 1950s, populations of J. haematoloma were quick to adapt to feed on the seeds of this novel host (Carroll et al. 2001). Considering Comerford et al.’s findings, it’s possible that the ability of this species to feed on nectar may have facilitated its co-expansion into new ranges in tandem with this new host. The findings also prompt us to reconsider the factors shaping the morphology of J. haematoloma’s mouthparts – could nectar consumption be an important driver, in addition to seed predation?

This study also highlights the importance of natural history observations in uncovering surprising aspects of the biology even of well-studied species. In this age of artificial intelligence and big data, observations of organisms in their natural environment continue to serve as wellsprings of inquiry and remain essential to map processes to patterns in ecology, evolution and biodiversity. Studies like this inspire us to don our field biologist hats and just observe our study organisms in nature – who knows what we might discover?

Pooja Nathan is a PhD candidate in the Department of Ecology and Evolutionary Biology at the University of Toronto, where she studies plant-ant mutualisms. Pooja's research focuses on the ecology and evolutionary biology of the mutualism between ants and plants mediated by extrafloral nectaries, but she is excited by all kinds of plants, insects and their interactions. In her free time, Pooja enjoys learning to cook dishes from different cuisines, embroidery, and taking nature walks.

Fire Transforms Landscape Color, Affecting Camouflaging Animals

Thu, 06 Nov 2025 06:00:00 GMT

João Vitor de Alcantara Viana, Rafael Campos Duarte, Carolina Lambertini, Felipe Capoccia, Anna Luiza Oliveira Martins, Camila Vieira, and Gustavo Quevedo Romero: Read the article

Fire events impair animal camouflage. Animals adapt by choosing suitable backgrounds or being polymorphic, reducing predation risks. Our study shows how spiders find the best spots and how grasshoppers and mantises thrive on burned and unburned trunks in a neotropical savanna

Many animals evolved to escape predators by blending into their surroundings – but what happens when their surroundings change? A new study published in 2024 by de Alcantara Viana et al. explores this question in the Cerrado savanna of Brazil, where frequent fires transform the landscape. As fires sweep through the savanna, they produce patches of burned and unburned areas, potentially affecting the ability of local arthropods (a group including insects, spiders, and other relatives) to blend into the background. Their study highlights how camouflaging animals interact with their environment, allowing them to survive even in the face of rapid change.

In their Cerrado savanna system, the authors concentrated on a few arthropod species, including a grasshopper and praying mantis that both produce two color morphs (brown and dark) and a spider that produces a single color morph (dark). Brown arthropods resting on newly burnt, blackened trunks may stand out to predators, increasing mortality. But in varied, patchy environments, even dark arthropods may struggle if they cannot find the appropriate matching background. In the face of such heterogeneous environments, some species evolve multiple color types, or “morphs”.

First, the authors took a bird’s-eye view to test how well the different species and their morphs match both burned and unburned tree trunks from the savanna: They compared the color matching not with human visual systems, but with those of potential bird predators. They found that the dark arthropods blend in better with burned trunks, while brown arthropods blend in better with unburned trunks, with subtle differences depending on species and bird visual systems.

The authors then conducted behavioral tests to determine whether arthropods of different colors could effectively select their matching background by providing brown and dark arthropods the choice of either burned or unburned trunks to rest upon in the lab. Interestingly, they found that only the monomorphic dark spider – the study species most specialized on trees – effectively selected the appropriate background.

To see how the camouflaging plays out in nature, the authors conducted simulated “predation” experiments using human “predators” and artificial arthropod models mimicking the coloration of the actual arthropods. Indeed, they confirmed that brown arthropods evade predation when resting on unburned trunks, while dark arthropods better evade predation when resting on burned trunks.

Overall, the authors found evidence that having different color strategies might help arthropods survive in places with patchy, ever-changing environments. As climate change, pollution, and other human activities continue to transform the planet, animals increasingly face variable, unpredictable habitats. Some species adapt and survive, like the famous peppered moth, which evolved a dark morph in the face of coal-covered trees in industrialized England. But only time will tell whether other arthropod species can evolve polymorphic strategies in time.

Regina A. Fairbanks is a Ph.D. candidate in the Population Biology graduate group at the University of California, Davis. Regina’s research aims to integrate evolutionary genomics with archaeological science to better understand crop domestication and plant-people relationships. For their dissertation, Regina uses population genomic data to study the evolutionary history of maize. In addition to their research, Regina participates in a wide range of science communication and mentorship programs, including Letters to a Pre-Scientist and the UC Davis Evolution & Ecology Graduate School Preview Program. When not staring at a computer screen, Regina can be found in museums, botanical gardens, and farmers markets.

Call for Symposium Proposals for Evolution 2026

Wed, 05 Nov 2025 06:00:00 GMT

The American Society of Naturalists will be participating in a joint meeting with the Society of the Study of Evolution and the Society of Systematic Biologists in May and June 2026! This includes hosting a special symposium during a virtual conference of the three societies on May 20–22.

Have an idea for this special symposium? We want to hear it!

The ASN Symposium Committee invites you to submit proposals for a special symposium. Proposed symposium topics should support the Society’s goal to advance the conceptual unification of the biological sciences and to further knowledge in evolution, ecology, behavior, and organismal biology. Topics could center around important emerging issues in evolution, ecology, or behavior or focus on a pivotal historical paper, tracing its impact and exploring current cutting-edge research inspired by this work.

Proposals should include (1) a title; (2) a description of the symposium topic (up to one page); (3) a list of six speakers, including institutional affiliations, who have agreed to participate in the symposium; (4) a justification for the symposium, explaining why the topic and speakers are appropriate for an ASN symposium (up to one page).

Please submit proposals by email (cas383@miami.edu) no later than midnight Eastern Time on January 15, 2026. Send your proposal as a single pdf attachment, under subject heading “ASN 2026 Virtual Symposium Proposal”.

In line with the ASN's commitment to diversity, we encourage including speakers from groups who have been historically excluded from STEM. Therefore, proposals that include a diverse list of speakers from a range of backgrounds, institutions, career stages, geography, gender, race, etc. are especially encouraged. Further, we especially encourage early career researchers to propose sessions as organizing symposia can advance their careers through building broader scientific networks and a record of scientific leadership.

Additionally, the Society’s selection committee will evaluate proposals based on their potential to attract a substantial audience and stimulate discussion, the significance and timeliness of the topic, and on the topic differing substantively from recent symposia hosted by the Society. Applicants will be notified of the decision before the end of February 2026.

Christopher Searcy
ASN Symposium Committee Chair
Department of Biology
University of Miami
cas383@miami.edu

The ASN is coming to the East Coast!

Wed, 05 Nov 2025 06:00:00 GMT

Save the dates: January 8–10, 2027

The ASN is meeting at The Mansion at Glen Cove, NY

The ASN’s last seven stand-alone meetings have taken place either at the Asilomar Conference Center in Pacific Grove, California, or once virtually during the pandemic. Although we love it at Asilomar, we have also taken to heart participants’ and nonparticipants’ feedback that alternating to a different venue would boost participation and open the conference up to those for whom travel to the West Coast is too much of a reach. We are therefore very excited to announce our 2027 meeting venue, The Mansion at Glen Cove on Long Island, New York—a lovely Georgian manor house designed by Charles A. Platt that once served as a Herber Hoover’s summer White House. The venue is within sight of Long Island Sound and just around the corner from Clark Botanical Gardens, Theodore Roosevelt’s historic home in Oyster Bay, Planting Fields Arboretum, the African American Museum and Center For Education and Applied Arts, whale watching, and more!

More details will be made available in the coming months.

Boy, tell me your favorite song: early mating signal divergence in treehopper evolution

Sat, 18 Oct 2025 05:00:00 GMT

Rafael L. Rodríguez, Thomas K. Wood, Frank W. Stearns, Robert L. Snyder, Kelley J. Tilmon, Michael S. Cast, Randy E. Hunt, and Reginald B. Cocroft : Read the article

How do mating signals diverge early in speciation? Experimental host shifts with Enchenopa treehoppers resulted in subtle but non-trivial signal divergence in a few generations. This was fueled by standing genetic variation and plasticity, and unrelated to host specialization

One of my favorite things to experience at a music concert is hearing an artist change up their song mid-performance by tweaking a lyric or hitting a new note. These changes are often satisfying to the ear, and they almost seem like a love language between that artist and that crowd. After all, the artist went out of their way to make your concert feel unique by crafting a location-specific lyric or singing a new note just for you to enjoy.

For us humans, modifying music like this is a form of entertainment. For many species of animals, though, even minor adjustments to calls, songs, and chirps can be the difference between finding a mate and being single for the rest of the breeding season. Over the course of many generations, these minor adjustments can become fixtures that begin to separate different groups from one another.

For one species to split into two, a lot of changes—ranging from adapting to new locales to only mating within one’s subgroup of the population—need to occur. In their new article, Rodríguez et al. set out to understand the early stages of one species of treehopper bug splitting into multiple and the roles that genetics and the environment play in facilitating that divide.

Male treehoppers produce vibrations to court females, forming a duet if successful. These vibrations are strikingly complex, with an initial elongated whine followed by a rhythm of staccato pulses. Females are particular with which signals they respond to, and even slight deviations in sound characteristics like pitch can take a male from being the talk of the plant to being the lone wolf at the end of the branch.

During a multi-year, collaborative experimental evolution project, Rodríguez et al. raised populations of treehoppers on three different host plants for five generations. Then, they collected eggs and newly hatched nymphs from these treehopper lineages and placed them on either their original host plant species or their new one. Once they reached adulthood, they recorded the treehoppers’ mating signals and analyzed what they heard.

The authors found that when treehoppers were evolving in enclosures with both their original and new plant hosts, any observed changes in the males’ signals when raised on either plant were unique to the identity of the plant on which they evolved. For one host shift, the signals stayed the same between plants. However, in a different shift, signals were different due to 1) changes in the treehoppers’ genetics, 2) changes in which plant the eggs and males were reared on, and 3) changes in genetics that affect how signals vary by which plant they were reared on.

These signal changes were observable after only five generations of being raised on novel host plants. Together with past information about how well treehoppers adapt to new host plants, these authors conclude that sexual divergence (i.e., the changing acoustic signals) occurs very early in the process of one treehopper species diverging into multiple—a process commonly known as speciation— while adaptation to a new host occurs separately and likely later in evolutionary time. This means that as populations start on separate evolutionary trajectories, the first fork in the road may originate in deciding with whom to mate.

So with all this in mind, the next time you’re at a show and the artist sings a note at a different key, you can think to yourself: is this the artist simply being flexible with their range, or could this be the start of an entirely new love language?

Derek Wu is a Ph.D. student in the Population Biology, Ecology, and Evolution program at Emory University in Atlanta, Georgia. Working in Nicole Gerardo’s insect-microbe ecology and evolution lab, he researches the mutualism between squash bugs and their bacterial gut symbiont. He is interested in the environmental, host, and microbial factors that mediate bacterial coinfections in the squash bugs. Outside of lab, he enjoys watching shows and listening to music with his cat, Archie.

Join the American Society of Naturalists Diversity Committee!

Thu, 25 Sep 2025 05:00:00 GMT

The ASN Diversity Committee (DC) seeks to add 2 new members starting in January 2026. The DC works to promote diversity, equity, and inclusiveness to enhance the study of evolution, ecology, and behavior and to foster the career of its developing scientists. We pursue initiatives that support marginalized groups, which include helping to create an inclusive, accessible environment at the Evolution conference, the stand-alone ASN meeting, and our field in general. Members serve a 3-year term, and the committee typically holds two meetings a month to discuss ideas and work on projects collectively.

Apply by November 1!

Old dogs can learn new tricks: revisiting MacArthur’s consumer-resource model

Wed, 17 Sep 2025 05:00:00 GMT

Jawad Sakarchi and Rachel M. Germain: Read the article

Sakarchi & Germain break down MacArthur’s consumer resource model with insights on the mechanistic understanding and biological intuition of how competition and coexistence operate

B iologists have two wolves inside of them – one that craves tractability and simplicity, and another that hungers for complexity and biological realism. Striking a balance between these two desires has proven to be difficult across all fields of biology, and competition theory is no exception. Competition theory assesses how ecological mechanisms mediate coexistence outcomes of two species competing for limited resources. In a recent American Naturalist article, Sakarchi and Germain argue that MacArthur’s consumer-resource model offers a rare middle ground: a biologically rich framework with the tractability and accessibility of simpler competition models. By presenting the model, synthesizing over 40 years of research, linking it to recent theoretical advances, and highlighting its empirical implications and relevance, Sakarchi and Germain demonstrate that this historical model continues to offer valuable insights for competition theory and for ecology and evolution more broadly.

Sakarchi and Germain begin by outlining the structure of the model. MacArthur’s Consumer-Resource Model organizes species into two trophic levels: resources and consumers. For instance, in the classic moose-wolf predator-prey example, moose correspond to resource dynamics while wolves correspond to consumer dynamics. Resource and consumer species exhibit antithetical dynamics. In monoculture, resource species grow toward their carrying capacity, whereas consumer species decay to extinction in the absence of resources. When both are present, the growth rate of the resource species decreases proportionally with consumer density, whereas the growth rate of consumer species increases proportionally with resource density. Sakarchi and Germain ground the mathematical form of the model in biological terms, explaining assumptions made that inform how the model’s results should be interpreted.

Sakarchi and Germain demonstrate how this mechanistic, yet tractable model can be used to understand key processes in community ecology. For instance, they derive the community utilization function – a function that, when minimized, allows for optimal community assembly patterns by ensuring maximized efficiency of resource utilization by consumers. Such metrics help extend ideas from coexistence theory into other areas of community ecology such as assembly theory, demonstrating the flexibility and utility of MacArthur’s consumer-resource model.

By performing a mathematical magic trick, Sakarchi and Germain demonstrate that the mechanistic MacArthur’s consumer-resource model is dynamically equivalent to a classic model in community ecology – Lotka-Volterra. Lotka-Volterra is often considered a phenomenological model, wherein biologically meaningful parameters are sacrificed for simplicity to understand general patterns. Despite this, a redefining of parameters transforms MacArthur’s consumer-resource model into the Lotka-Volterra model. In doing so, Sakarchi and Germain synthesize two seemingly distinct areas of theoretical ecology and demonstrate that a phenomenological, biologically-simplified model can be equivalent to a mechanistic, biologically-detailed one—sometimes, the two wolves take different paths to the same destination. They leverage this connection between models to guide the design of competition experiments, enabling parameterization based on mechanistic rather than traditionally parameterized phenomenological parameters. Such parameterizations can help experimentalists better understand biological mechanisms underpinning outcomes of competition experiments.

Concluding with empirical recommendations, Sakarchi and Germain demonstrate how these theoretical insights can be used to inform empirical studies on consumer-resource dynamics. By compiling 40 years’ worth of research into one concise piece, they highlight both the rich legacy of MacArthur’s consumer-resource model and its ongoing relevance for competition studies. By embracing the complexity associated with the model and highlighting simplifying assumptions, Sakarchi and Germain demonstrate how MacArthur’s consumer-resource model situates itself uniquely in competition theory—offering both mathematical tractability for analytical exploration and the biological complexity and realism to inform empirical work. In striking this delicate balance between simplicity and complexity, MacArthur’s model exemplifies how biologists can indeed satisfy the two wolves within us.

Joe Brennan is a Ph.D. candidate in the Population Biology Graduate Group at the University of California, Davis. Joe's research addresses how ecological communities change over time in response to species invasion and extinction using mathematical and computational models. Outside of the lab, you can find Joe listening to electronic and pop music, appreciating surrealist art, and trying his best at trivia night.

Can temperature explain species ranges?

Wed, 17 Sep 2025 05:00:00 GMT

Zachary K. Lange, Brooke L. Bodensteiner, Daniel J. Nicholson, Gavia Lertzman-Lepofsky, Alexander H. Murray, Edita Folfas, Saúl F. Domínguez-Guerrero, D. Luke Mahler, Martha M. Muñoz, and Luke O. Frishkoff: Read the article

W hat determines the distribution of species? This is a longstanding question in biology, but it is becoming increasingly relevant as climate change and other human-driven factors change environments worldwide. For example, global warming is associated with changes in species’ distributions and survival. This suggests to scientists that temperature may be one of the essential drivers of species’ distributions.

In this study, researchers sought to understand whether the temperature extremes that 21 species of anoles can tolerate, as well as their temperature preferences, are associated with their distribution across Puerto Rico and Hispaniola. To measure the hottest and coldest temperatures the lizards could stand, they gradually increased or decreased the anoles’ body temperatures in the lab until the lizards were no longer able to stand back up after being placed on their backs. The inability of the animal to right itself when placed on its back indicates that they would not be aware enough to escape from harmful situations. So, for example, if a lizard in the experiment could not stand back up at 35 °C, then we would expect this lizard to be unable to escape hot temperatures or hide from predators (likely leading to death for that lizard). Anole temperature preferences were also measured by placing them in an enclosed arena with a gradient of temperatures for them to choose from over three hours.

These values were then compared to the range of temperatures that populations of the corresponding species of anole experience in their natural habitat. This was done to see if the hottest and coldest temperatures the lizards experience in their natural environment could be predicted by the hottest and coldest temperatures the lizards were able to handle in the experiments. The researchers determined these species' distribution limits by visiting various sites across both islands, representing the full range of climates where anoles occur, and searching for anoles in standardized forest plots. Lizards were captured and marked with non-toxic paint before being released. This mark-resight methodology ultimately allowed the researchers to estimate how many individuals of each species were present in each location and, therefore, in each climate. They found that limits measured in the lab and environmental extremes were generally correlated, suggesting that temperature is likely an important factor in determining where species occur. This suggests that as the climate continues to change, we may expect some changes in species distributions.

However, the researchers also found that a species' ability to tolerate a wide range of temperatures in the experiment was not always associated with the species occurring in a wide range of climate conditions. This, along with a relatively large degree of error in the overall model, suggests that other factors, such as competition, predation, and other non-temperature habitat characteristics are partly responsible for setting species’ distributions. The researchers also determined that the conditions where species were most abundant were not best predicted by the temperatures that lizards preferred from lab experiments, demonstrating that the best conditions for population growth may differ from the conditions that individual lizards enjoy the most. While we still don’t know everything that leads to a species’ specific range, this study grants a great deal of insight into the role that temperature may play and the possible limitations of considering just one factor in explaining species’ distributions.

Jamie Cochran is a postdoctoral scholar in Dr. Andrea Durant’s lab at the University of Washington. Jamie’s work lies at the intersection of aquatic entomology, ecotoxicology and organismal physiology and largely looks to understand the interactive effects of stressors on aquatic macroinvertebrate physiology and performance. In her free time, she enjoys traveling, hiking, crocheting, and reading.

Why we aren’t lizards: the evolution of endothermy through optimizing life history

Wed, 17 Sep 2025 05:00:00 GMT

Juan G. Rubalcaba: Read the article

Why do endotherms spend so much energy? A theoretical model shows that species followed one of two possible evolutionary patches: live fast while spending a lot (homeotherms), live slowly and keep your costs low (heterotherms)

A s I write this article, I am huddled at my desk with my portable space heater blasting into my face, warming the soft blanket that I have wrapped around my entire body like a cocoon. It is summer. I just really dislike air conditioning.

Despite my aversion to AC, however, if I were to actually measure my body temperature, it would be relatively consistent with what it always is: about 98 degrees Fahrenheit. This is because I – like all humans – am an endotherm, meaning I maintain a high, stable body temperature using metabolic heat production. This strategy is in contrast to ectotherms, which rely on external sources of heat.

Endothermy has developed in many different types of organisms, including fish, birds, and plants. However, it has a major downside compared to ectothermy—to produce heat, endotherms must burn resources in an inefficient way, costing the organism a lot of energy. Researchers aren’t sure how this ineffective strategy evolved in so many organisms, so Juan Rubalcaba set out to explore which energy balance regulation strategies could feasibly support this energetically costly trait while also still benefitting the organism.

The study of how organisms allocate energy to processes like growth and reproduction in order to maximize their fitness (their ability to survive and reproduce) is known as life history theory. Rubalcaba wanted to determine if an evolutionary stable endothermic strategy could have emerged from organisms optimizing their life history, and so he created a modeling framework to explore the idea. He developed a life history model for the balance between how an organism assimilates energy and how it allocates that energy to survival, growth, thermoregulation, and reproduction. He hypothesized that the temperature-dependent generation of energy performed by endotherms can produce a surplus of energy, which could then be used to fuel both thermoregulation and reproduction.

The results, however, were quite interesting. Although the higher body temperature in endotherms allows them to assimilate more energy, a really large amount of this energy must be allocated to producing heat. Thus, the energy left for growth and reproduction is actually similar to the ectothermic strategy. Contrary to the common argument that endothermy is somehow the “ultimate goal” or more advanced evolutionary strategy, this model suggests that endothermy does not necessarily outperform ectothermy; rather, it simply provides an alternative strategy that would be beneficial in certain environments, like colder regions. Rubalcaba’s model shows that a drop in temperature can force populations to reach a breaking point, allowing endothermy to rapidly expand; while ectothermic organisms would be eradicated once the temperature drops to a certain point, endothermic organisms could continue to thrive in those climates without competition from ectothermic organisms. In this way, birds and mammals have expanded into many new environments that would be far too cold for an ectotherm. There are more details on the formation of the model and its implications in Rubalcaba’s paper.

Me? I might prefer to bask in the sun like a lizard. But if I ever decide to move to Alaska, it’s good to know that my body’s homeothermic strategy will be up to the task of keeping me alive.

Kaleigh Remick is currently a PhD student in the Department of Molecular Biology at Princeton University, where she studies replication of influenza A virus in the Velthuis Lab. She graduated from Cornell University with a B.A. in biological sciences and a minor in English. When she’s not in lab, you can find her bartending, salsa dancing, tutoring at prisons, conferencing at the Writing Center, eating ice cream, or reading a book!

Why food web structure matters for a healthy ecosystem

Wed, 17 Sep 2025 05:00:00 GMT

Dalmiro Borzone Mas, Pablo A. Scarabotti, Patricio Alvarenga, Pablo A. Vaschetto, and Matías Arim: Read the article

How are diversity, food web structure, and ecosystem functioning related? Here Borzone Mas et al. analyze the interrelationship between these three components in predatory fishes of the Paraná River

S cientists are becoming increasingly vocal about the destructive impacts of what has been called a “silent crisis”: the subtle but ultimately devastating creep of biodiversity loss across our planet. From the smallest insects to the most awe-inspiring whales, species on every branch of the tree of life are declining in numbers or disappearing altogether, sometimes without ever being documented by humans. This catastrophe can be difficult to quantify because it has cascading effects. Not only are prey species affected by climate change, habitat loss, and pollution, but their predators are as well. What do you eat when your food source has been wiped out by a potent pesticide, or has migrated further north in search of cooler seas? This effect can be visualized with a food web, where predators and their prey are linked using arrows to show how species interact.

Biodiversity loss, on a larger scale, negatively impacts how well an ecosystem can operate as a unit. This relationship is called the biodiversity-ecosystem functioning relationship. It is measured using species richness (the number of species in an ecosystem), biomass (the weight of organisms produced by a particular ecosystem), energy flows, and ecosystem stability. It indicates that ecosystems are more stable and productive when there are more species present to fill specific niches and provide ecosystem services. When studying this relationship, biomass is considered to be one of the main aspects of ecosystem function. This article takes a new approach by investigating how fish species richness affects food web structure and biodiversity-ecosystem function in the Paraná River.

To conduct this study, scientists compared the stomach contents of fish species from water bodies located within the Paraná River’s floodplain. They created food webs that were each characterized using metrics that describe the species in the web, their linkages, and the web’s complexity. They also measured their catch’s biomass to compare it across each web. During their analysis, they found that as species richness increased, so did the number of linkages per species, the compartmentalization of the web into subgroups, and the number of species that acted as links between subgroups. The more complex the food webs were, with higher linkages per species and more subgroups, the better the ecosystem function. In other words, a greater diversity of species in a system can reshape food webs for the better, making them more complex and therefore more productive.

However, one metric was negatively impacted by increased species richness: nestedness. Nestedness is the number of interactions between species that consume many different types of prey and those that only consume a subset of that prey. In addition, scientists found that the relationship between species richness and biomass is not a straightforward relationship but instead operates indirectly through the three positive pathways and one negative pathway listed above. This result led the authors to conclude that conservation efforts in the future that combat biodiversity loss should not just focus on preserving the number of species but should emphasize preservation of food web complexity. This complexity protects ecosystems by making them more productive and resilient.

This article is a clear example of how ecosystem-based management strategies will be crucial in addressing the biodiversity crisis. Its emphasis on the importance of biodiversity in maintaining a balanced and productive ecosystem through the lens of food webs shows how a more holistic view of the world around us can lead to more effective management. Check out the article for a fresh take on how fish guts can show us a path forward to preserve our biodiverse planet!

Katherine Helmer is a lab technician in the Department of Ecology and Evolutionary Biology at the University of Connecticut, where she studies the decline of flatfish in Long Island Sound. She graduated from the University of Vermont with a B.S. in Environmental Science and shifted to working with marine fisheries in roles at the state level in Massachusetts and Connecticut. At the University of Connecticut, she uses scales and eye lenses to recreate growth and feeding patterns of decades-old fish samples and compare them to current trends. In her spare time, she enjoys bird watching, knitting, watching horror movies, and looking for treasures at thrift stores.

Predator Alerts Before Birth: Lifesaver or a Liability?

Wed, 17 Sep 2025 05:00:00 GMT

Susana Cortés-Manzaneque, Sin-Yeon Kim, Jose C. Noguera, Francisco Ruiz-Raya, and Alberto Velando: Read the article

This study provides strong evidence that prenatal signals of predation risk prepare chicks to cope with predators during their postnatal development, based on findings from a field experiment on the yellow-legged gull

I magine you’re in an egg, you haven’t even hatched yet, but you’re already learning how dangerous the world outside may be. Before a chick even cracks its shell, it’s already listening and learning. Inside the egg, the chick can hear the outside world: the waves, wind, and the calls of its parents and surrounding nesting ground. If those calls include urgent alarm cries, it might mean danger is near. New research shows that these before-hatch warnings can shape how a chick behaves and grows long after it hatches, especially if the warnings turn out to be wrong.

Researchers set-up an experiment on Sálvora Island, Parque Nacional das Illas Atlánticas de Galicia, Spain, where some unhatched yellow-legged gull chicks heard recordings of alarm calls signaling predators were nearby, while others heard only normal colony sounds. After hatching, chicks either experienced “predators” (a stuffed American mink, a real threat to gulls, attached to a remote-controlled toy off-road car) or something harmless (a stuffed European rabbit attached instead). This created a match-mismatch situation where the chicks’ pre-hatch “expectations” —set by the calls they heard in the egg—either matched their post-hatch reality or didn’t.

The results were striking. Chicks that heard alarm calls before hatching spent more time frozen in a “don’t move” defense called tonic immobility. They also crouched faster when they thought danger was near, though only if they did not meet predators later. Chicks that did face predators after hatching begged for food less often, likely to stay hidden from danger. Early on, the chicks all grew at similar rates, and their stress hormone levels didn’t differ much. But weeks later, when the chicks left the nest, those whose early-life predictions didn’t match reality—whether they prepared for danger that never came or faced danger without warning—were smaller in skeletal body size and showed more damage to their DNA, a sign of physical stress. Their bodies also produced more antioxidants, probably trying to repair the damage. On the other hand, chicks that heard alarm calls before hatching ended up heavier in body mass at fledging, no matter what happened afterward.

Why does this matter? It confirms that chicks aren’t passive passengers before hatching. They are already adjusting their bodies and behavior to fit the world they expect. But if that forecast is wrong, it can cost them in growth and health. More research is necessary to fully understand the lifelong consequences of a developmental mismatch and the mechanisms that govern development. As the environment becomes more unpredictable with climate change and human disturbance, such mismatches between early cues and reality could become more common, and more harmful. Yellow-legged gull chicks are born with a kind of weather report for survival. When it is accurate, they are ready. When it is not, they may pay the price. Just like us, their early expectations can shape their future, for better or worse.

Kate Blackwell is a Ph.D. candidate in Ecology and Evolution at Stony Brook University, where she investigates how marine populations are delineated by studying their genetic variation, gene flow, and linking physical traits with ecological roles and environmental adaptation. Her research focuses on identifying the nesting locations of Antarctic petrels using satellite imagery and understanding their connectivity using genetics and morphology. Passionate about intersection of science, policy, and public engagement, Kate collaborates internationally with scientists and policymakers on conservation priorities for the Arctic and Antarctic. During her downtime, she loves traveling with friends and reading a good fantasy or science fiction book.

Are absentee parents a result of evolution?

Tue, 16 Sep 2025 05:00:00 GMT

Xiaoyan Long, Tamas Székely, Jan Komdeur, and Franz J. Weissing: Read the article

As human babies, our survival heavily relies on our caregivers; without them, we would lack food and protection and would likely perish. However, in many other species, young ones receive no parental care and must fend for themselves, such as the beloved baby sea turtle that finds its way to the ocean alone. Other species may have only one parent who stays to provide care, like the pregnant male seahorse. What factors determine whether and which parent offers care?

Historically, scientists believed that the answer to these questions was related to the ratio of males to females in a population; however, this ratio can be defined in three different ways, each yielding very different results. Scientists disagree on which is the true ratio that determines how parents care for their children. Is it the Operational Sex Ratio (the ratio of sexually active males to sexually active females), the Adult Sex Ratio (which represents the ratio of adult males to adult females), or the Maturation Sex Ratio (the ratio of males and females at the time of sexual maturation)?

Researchers Xiaoyan Long, Tamas Székely, Jan Komdeur, and Franz J. Weissing aimed to test which of these ratios is most relevant. By means of computer simulations, they studied how a population's life history affects the evolution of parental care and the three sex ratios. Life history traits include mortality rates at various life stages and maturation rates.

Surprisingly, they found that none of the ratios were the primary driver of parental sex role evolution. Instead, differences between the sexes in life history characteristics acted as the driver of parental sex roles. They concluded that although sex ratios may exert selective pressure in determining parental care patterns, these ratios change over time, altering the direction of selection pressures.

Trade-offs influence parental care patterns, including time, energy, and survival. Parents sacrifice resources for their offspring that could otherwise be used for themselves or to produce more offspring. Therefore, understanding what drives the evolution of parental care is crucial for comprehending the trade-offs that occur within a population and the scenarios in which parents allocate their resources to their children. Understanding care patterns and how they are influenced by sex ratios and life history is essential for identifying the factors that determine a species' overall success.

Julia Dovi is a recently graduated master’s student from the Department of Ecology and Evolution at Stony Brook University. She is passionate about research on animal responses to stress associated with climate change and the genetic mechanisms underlying changes in behavior. She enjoys traveling, playing the piano, and hitting the dance floor.

Till Selection Do Us Part? Testing Sexual Selection’s Role in Speciation

Tue, 16 Sep 2025 05:00:00 GMT

Matheus Januario, Renato C. Macedo-Rego, and Daniel L. Rabosky: Read the article

Januario et al. found no correlation between sexual selection intensity & speciation rates or proxy traits (SSD and dichromatism). Because sexual selection intensity has high intraspecific variation and low phylogenetic signal, its macroevolutionary impacts are weak

Who among us hasn’t mistaken a seal for a sea lion? It’s no wonder the two share a common ancestor. This raises a fundamental question in evolutionary biology: what drives the formation of new species? One long-standing hypothesis suggests that sexual selection, where phenotypic traits evolve due to the dynamics of eager males and elusive females, can accelerate speciation by promoting trait divergence and reproductive isolation.

To test this idea, researchers have traditionally relied on indirect proxies, such as sex-specific differences in body size (sexual size dimorphism) or coloration (sexual dichromatism), assuming these traits reflect the strength of sexual selection. However, characteristics like size and coloration can also be shaped by natural selection, and recent studies suggest they do not reliably correlate with direct measures of sexual selection. Moreover, sexual selection may not always produce obvious physical differences. If these proxies are unreliable, does the assumed link between sexual selection and speciation still hold?

A new study by Matheus Januario and colleagues tackles this question by directly measuring the opportunity for sexual selection (a statistical estimate of how unevenly reproductive success is distributed among individuals) across 82 vertebrate species. Crucially, they asked whether the strength of sexual selection observed in contemporary populations has any predictive power for speciation rates across deep evolutionary timescales.

The results were surprising: despite long-standing assumptions, species experiencing stronger sexual selection in the present do not consistently diversify at faster rates over millions of years. These findings help explain why studies using trait-based proxies have yielded conflicting results. Another key discovery is that sexual selection is highly evolutionarily labile, fluctuating dramatically not just between species, but even within populations over time.

This mismatch across timescales, between the short-term dynamism of sexual selection and the long-term patterns of speciation, lies at the heart of the study. These results offer a new perspective on a long-standing paradox: while sexual selection can drive divergence and reproductive isolation in the near term, its variability may limit it from leaving a lasting macroevolutionary imprint on biodiversity.

If sexual selection is so evolutionarily unpredictable, how much influence does it really have on shaping biodiversity over time? This study suggests that while it may spark short-term evolutionary fireworks, its role in the slow burn of speciation may be more fleeting than foundational.

Pooja Radhakrishnan recently completed her PhD in Ethology at the Laboratoire d'Ethologie Expérimentale et Comparée, Université Sorbonne Paris Nord, where she explored the fascinating world of sex-changing worms. With a Bachelor's Degree in Hotel Management, her late-onset career in science was inspired by a popular science book, which sparked her love for making research more accessible. When she’s not second-guessing every sentence in her manuscript, Pooja enjoys photographing wildlife, taking long bus rides through countryside landscapes, exploring local museums, and of course, French butter.

How moving – or not – as conditions change keeps species alive

Tue, 16 Sep 2025 05:00:00 GMT

Sebastian J. Schreiber: Read the article

Why does one metapopulation decline while another grows? Differences in habitat quality? In movement patterns? To answer these questions, Schreiber quantifies the relative contributions of spatial & temporal variation in demography & dispersal to metapopulation growth rates

No habitat is an island, and that includes islands. Habitat patches exist in networks connected by the species that move between them. For example, a population of seabirds on one island exchanges individuals with any island close enough for the birds to reach. If one island in the network was hit by awful storms and lost all its seabirds, it could be repopulated by its neighboring islands. Due to movement between islands, our seabirds can persist in habitats with consistently bad conditions, so long as a nearby island produces a surplus of seabirds. These networks of habitats ensure that misfortune for one population does not necessarily spell doom for an entire species.

However, these networks are still sensitive to changes in environment. If every island experienced a disaster simultaneously, such as torrential rains brought on by El Niño, no birds would be left to repopulate. Theoretical studies have given us good ideas on how the differences in conditions between habitats over time impact how likely a network is to survive. As demonstrated by our seabirds, the network can survive better when conditions across habitats are different. Conversely, networks with similar conditions over time are more stable than those that fluctuate between good and bad conditions because avoiding decline allows the growth in each year to compound. Essentially, a bird saved is a bird earned. Yet, the mathematical complexity of understanding how variation over time, space, and movement interact makes it challenging to develop effective conservation strategies for real seabirds and other organisms facing environmental change.

Dr. Schreiber set out to face this challenge and determine how combinations of different factors result in the population networks we see in nature. Armed with mathematical models that use the survival, reproduction, and movement of individuals to determine how populations grow. Dr. Schreiber created theoretical networks where he could tweak any factor to see how it impacted the survival of the network. Dr. Schreiber re-confirmed the previously known predictions on what conditions stabilize population networks but also found some surprising exceptions.

If most individuals in a network moved every year, differences in conditions between habitats made the network less likely to survive. This result was due to most individuals now experiencing constantly fluctuating conditions, just like with fluctuating conditions in one habitat over time. However, there were conditions where everyone moving at once stabilized the network. If habitats were perfectly out-of-synch so that good conditions in one lined up with harsh conditions in the other, constantly swapping homes resulted in most individuals spending more time in good conditions. This exception matches real-world examples of migratory species that move between habitats as the seasons make one more desirable than the other. Intriguingly, if one of these perfectly out-of-synch habitats is still, on average, better than the other, networks were equally stable if no individuals moved at all, like real bird species where some individuals migrate while others stay in the breeding habitat all year.

Dr. Schreiber’s work emphasizes that we can’t consider one factor in isolation when determining how populations survive. The unique quirks of environmental change and individual movement have resulted in the wide variety of migration patterns we see in nature. Considering the forces that maintain these patterns is more important than ever now that natural populations are facing unprecedented conditions. Habitat destruction and human infrastructure like roads present new barriers to movement between habitats, which could break up population networks. Managing our impacts could keep habitats connected and prevent islands from becoming alone and vulnerable.

Jeremy Summers is a PhD student at the University of Rochester studying the demographic and genetic consequences of dispersal in birds. They are also interested in long-term human impacts on species and landscapes and in innovative ways of teaching ecology and evolution. When not talking science, Jeremy enjoys hiking, cooking, and playing board games.