Elsa Youngsteadt

Elsa Youngsteadt
Sigma Xi, The Scientific Research Honor Society

About

52
Publications
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848
Citations
Introduction
Skills and Expertise
Featured research
Article
Full-text available
As cities expand, conservation of beneficial insects is essential to maintaining robust urban ecosystem services such as pollination. Urban warming alters insect physiology, fitness, and abundance, but the effect of urban warming on pollinator communities has not been investigated. We sampled bees at 18 sites encompassing an urban warming mosaic within Raleigh, NC, USA. We quantified habitat variables at all sites by measuring air temperature, percent impervious surface (on local and landscape scales), floral density, and floral diversity. We tested the hypothesis that urban bee community structure depends on temperature. We also conducted model selection to determine whether temperature was among the most important predictors of urban bee community structure. Finally, we asked whether bee responses to temperature or impervious surface depended on bee functional traits. Bee abundance declined by about 41% per °C urban warming, and temperature was among the best predictors of bee abundance and community composition. Local impervious surface and floral density were also important predictors of bee abundance, although only large bees appeared to benefit from high floral density. Bee species richness increased with floral density regardless of bee size, and bee responses to urban habitat variables were independent of other life-history traits. Although we document benefits of high floral density, simply adding flowers to otherwise hot, impervious sites is unlikely to restore the entire urban pollinator community since floral resources benefit large bees more than small bees.
Article
Full-text available
Because carnivorous plants rely on arthropods as pollinators and prey, they risk consuming would-be mutualists. We examined this potential conflict in the Venus flytrap (Dionaea muscipula), whose pollinators were previously unknown. Diverse arthropods from two classes and nine orders visited flowers; 56% of visitors carried D. muscipula pollen, often mixed with pollen of coflowering species. Within this diverse, generalized community, certain bee and beetle species appear to be the most important pollinators, on the basis of their abundance, pollen load size, and pollen fidelity. Dionaea muscipula prey spanned four invertebrate classes and 11 orders; spiders, beetles, and ants were most common. At the family and species levels, few taxa were shared between traps and flowers, yielding a near-zero value of niche overlap for these potentially competing structures. Spatial separation of traps and flowers may contribute to partitioning the invertebrate community between nutritional and reproductive functions in D. muscipula.
Article
Full-text available
The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the negative effects of hurricanes remains an open question. Here, we consider two hypotheses about the simultaneous consequences of acute disturbances from hurricanes and chronic stress from urbanization for the structure of urban arthropod communities. The tipping point hypothesis posits that organisms living in high stress habitats are less resilient than those in low stress habitats because they are living near the limits of their environmental tolerances; while the disturbance tolerance hypothesis posits that high stress habitats host organisms pre-adapted for coping with disturbance, making them more resilient to the effects of storms. We used a before-after-control-impact design in the street medians and city parks of Manhattan (New York City, New York, USA) to compare arthropod communities before and after Super Storm Sandy in sites that were flooded and unflooded during the storm. Our evidence supported the disturbance tolerance hypothesis. Significant compositional differences between street medians and city parks before the storm disappeared after the storm; similarly, unflooded city parks had significantly different arthropod composition while flooded sites were indistinguishable. These differences were driven by reduced occurrences and abundances of arthropods in city parks. Finally, those arthropod groups that were most tolerant to urban stress were also the most tolerant to flooding. Our results suggest that the species that survive in high stress environments are likely to be the ones that thrive in response to acute disturbance. As storms become increasingly common and extreme, this juxtaposition in responses to storm-associated disturbance may lead to diversity loss in cities, potentially leading entire urban landscapes to mirror the reduced diversity of street medians.

Publications

Publications (52)
Article
Wild bees can be essential pollinators in natural, agricultural, and urban systems, but populations of some species have declined. Efforts to assess the status of wild bees are hindered by uncertainty in common sampling methods, such as pan traps and aerial netting, which may or may not provide a valid index of abundance across species and habitats...
Article
Prescribed burning is a common silvicultural practice used in the management of longleaf pine (Pinus palustris Mill., Pinales: Pinaceae) savannas to reduce hardwood encroachment and ground cover and to maintain biodiversity. We investigated the response of the native bee community (Hymenoptera: Apoidea: Anthophila) in the Sandhills of North Carolin...
Article
Dioecy is rare among flowering plants, and is associated with a high frequency of threatened species. Dioecious plants are often pollinated by wind or insects, but are susceptible to pollination failure should male and female plants become spatially separated, or should pollinator abundance decline. Here we characterize the plant–pollinator interac...
Article
Management of natural habitats is an important strategy for rare plant conservation. One common tool for managing natural habitats is the use of controlled fire. Rare plants in fire-dependent ecosystems often rely on frequent fires to increase nutrient availability, initiate germination, and limit cover from light competitors. Fire can also alter a...
Article
Low cost temperature sensors are increasingly used by ecologists to assess climatic variation and change on ecologically relevant scales. Although cost-effective, if not deployed with proper solar radiation shielding, the observations recorded from these sensors will be biased and inaccurate. Manufactured radiation shields are effective at minimizi...
Article
Full-text available
As cities expand, conservation of beneficial insects is essential to maintaining robust urban ecosystem services such as pollination. Urban warming alters insect physiology, fitness, and abundance, but the effect of urban warming on pollinator communities has not been investigated. We sampled bees at 18 sites encompassing an urban warming mosaic wi...
Article
Full-text available
Because carnivorous plants rely on arthropods as pollinators and prey, they risk consuming would-be mutualists. We examined this potential conflict in the Venus flytrap (Dionaea muscipula), whose pollinators were previously unknown. Diverse arthropods from two classes and nine orders visited flowers; 56% of visitors carried D. muscipula pollen, oft...
Article
A foundation of integrated pest management (IPM) in urban landscapes is to put the right plant in the right place. This preventive tactic can reduce plant stress, pest infestations, and subsequent pesticide applications. Many urban tree species have more insect and mite pests in urban landscapes than in surrounding natural areas. This is due in par...
Article
Full-text available
The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the neg...
Article
Full-text available
In light of global climate change, ecological studies increasingly address effects of temperature on organisms and ecosystems. To measure air temperature at biologically relevant scales in the field, ecologists often use small, portable temperature sensors. Sensors must be shielded from solar radiation to provide accurate temperature measurements,...
Article
Full-text available
Honey bees are the most important managed pollinators as they provide key ecosystem services for crop production worldwide. Recent losses of honey bee colonies in North America and Europe have demonstrated a need to develop strategies to improve their health and conserve their populations. Previously, we showed that feral honey bees—colonies that l...
Article
Full-text available
Changes in community composition are an important, but hard to predict, effect of climate change. Here,we use a wild-bee study system to test the ability of critical thermal maxima (CTmax, a measure of heat tolerance) to predict community responses to urban heat-island effects in Raleigh, NC, USA. Among 15 focal species, CTmax ranged from 44.6 to 5...
Article
Biological effects of climate change are expected to vary geographically, with a strong signature of latitude. For ectothermic animals, there is systematic latitudinal variation in the relationship between climate and thermal performance curves, which describe the relationship between temperature and an organism's fitness. Here we ask whether these...
Article
A substantial amount of global carbon is stored in mature trees. However, no experiments to date test how warming affects mature tree carbon storage. Using a unique, citywide, factorial experiment, we investigated how warming and insect herbivory affected physiological function and carbon sequestration (carbon stored per year) of mature trees. Urba...
Article
Full-text available
“ Each species must be known by one name only, throughout the entire extent of its range. This systematic study is the foundation upon which all the other work of seemingly more practical importance is based ” [T. B. Mitchell (1946)][1] [1]: #ref-10
Article
Full-text available
Trees provide ecosystem services that benefit humans and the environment. Unfortunately, urban trees often do not provide maximum services due to abiotic stress and arthropod herbivores and borers. These problems often originate from trees being planted in unsuitable conditions. Cities are warmer than natural areas because impervious surfaces absor...
Article
Timeline of response variable measurements. This shows when treatments were implemented and insect and tree growth and photosynthesis data were collected.
Article
Timeline of response variable measurements. This shows when treatments were implemented and insect and tree growth and photosynthesis data were collected.
Article
Detailed statistics. Relevant statistical information not included in the main manuscript is included here. In all mixed effects models, "Site" was specified as the random effect. In GLMER, sample ID was also included as a random effect
Article
Detailed statistics. Relevant statistical information not included in the main manuscript is included here. In all mixed effects models, "Site" was specified as the random effect. In GLMER, sample ID was also included as a random effect
Article
Full-text available
Given the role of infectious disease in global pollinator decline, there is a need to understand factors that shape pathogen susceptibility and transmission in bees. Here we ask how urbanization affects the immune response and pathogen load of feral and managed colonies of honey bees (Apis mellifera Linnaeus), the predominant economically important...
Article
Full-text available
The biological diversity and composition of microorganisms influences both human health outcomes and ecological processes; therefore, understanding the factors that influence microbial biodiversity is key to creating healthy, functional landscapes in which to live. In general, biological diversity is predicted to be limited by habitat size, which f...
Article
Urban green spaces provide ecosystem services to city residents, but their management is hindered by a poor understanding of their ecology. We examined a novel ecosystem service relevant to urban public health and esthetics: the consumption of littered food waste by arthropods. Theory and data from natural systems suggest that the magnitude and res...
Article
Full-text available
Global urbanisation is rapidly expanding and most of the world's humans now live in cities. Most ecological studies have, however, focused on protected areas.To address this issue, we tested predictions from studies of protected areas in urban ecosystems.Because most cities are heterogeneous habitat mosaics which include habitats with varying level...
Article
Cities experience elevated temperature, CO 2 , and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the...
Conference Paper
Background/Question/Methods: The frequency and intensity of extreme weather events are increasing globally, while urbanization is rapidly expanding worldwide. However, we have a poor understanding of how these simultaneous global changes interact to influence local community dynamics and ecosystem services. Home to more than half of the world’s hum...
Data
Full-text available
Composition of blends mentioned in Table S1. (PDF)
Data
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Results of exploratory seed-carrying assays with sugars and with combinations of sugars, amino acids and volatile compounds. (PDF)
Data
Full-text available
Ant response to (a) dilute A. gracile extract (0.1 seed-equivalent per test seed) alone or with the addition of glucose (G) and fructose (F), sucrose (S) or a combination of the three. Addition of sugars did not enhance ant preference for test seeds. Because sugars were presented by weight rather than by their respective molarity, non -preference f...
Data
Full-text available
Results of ANOVA on ranks, testing for effects of treatment (dilute A. gracile extract alone or with the addition of glucose and fructose, sucrose or a combination of the three, matched for weight of sugar per seed) on the order in which ants retrieved test seeds. (PDF)
Data
Full-text available
Results of ANOVA on ranks, testing for effects of treatment (dilute A. gracile extract alone or with the addition of glucose and fructose or sucrose, matched for moles of sugar per seed) on the order in which ants retrieved test seeds. (PDF)
Data
Full-text available
Results of exploratory seed-carrying assays with volatile compounds, presented individually and in blends. (PDF)
Article
Full-text available
In lowland Amazonian rainforests, specific ants collect seeds of several plant species and cultivate them in arboreal carton nests, forming species-specific symbioses called ant-gardens (AGs). In this obligate mutualism, ants depend on the plants for nest stability and the plants depend on ant nests for substrate and nutrients. AG ants and plants a...
Article
Camponotus femoratus is an abundant and behaviorally dominant ant in lowland Amazonian rainforests, where this species participates in a complex and obligate seed-dispersal mutualism. C. femoratus typically cohabits with another ant species Crematogaster levior in an apparently amiable but poorly understood interaction. Despite these outstanding ch...
Article
Throughout Amazonia, the ant Crematogaster levior is known for its participation in a complex ant-garden mutualism with the ant Camponotus femoratus and several species of epiphytic plants for which it plays an important role in seed viability. We isolated nine polymorphic microsatellite loci for C. levior from a genomic library enriched for di-, t...
Article
Full-text available
Throughout lowland Amazonia, arboreal ants collect seeds of specific plants and cultivate them in nutrient-rich nests, forming diverse yet obligate and species-specific symbioses called Neotropical ant-gardens (AGs). The ants depend on their symbiotic plants for nest stability, and the plants depend on AGs for substrate and nutrients. Although the...
Article
Classic genetic model organisms--fruit flies, zebrafish, and roundworms--are popular newcomers in sleep research laboratories, although debate continues about how much their dozing relates to human slumber.
Article
VIROLOGYA study out this week suggests that in addition to predisposing carriers to Alzheimer's disease, the defective lipid transporter apolipoprotein E4 also hastens the death of people infected with HIV, possibly by allowing the virus easy entry into cells.
Article
Researchers have discovered an environmental hiding place for the bacteria that cause a devastating disease known as Buruli ulcer. The accomplishment marks a major milestone in efforts to understand and control one of the world's most neglected tropical diseases.
Article
Full-text available
Seed dispersal mutualisms are essential for the survival of diverse plant species and communities worldwide. Among invertebrates, only ants have a major role in seed dispersal, and thousands of plant species produce seeds specialized for ant dispersal in “diffuse” multispecies interactions. An outstanding but poorly understood ant–seed mutualism oc...
Article
Embryos of the viviparous cockroach Diploptera punctata accumulate large amounts of hydrocarbon (HC) of either maternal or embryonic origin. HC synthesis and its accumulation in maternal and embryonic tissues were measured over the course of gestation. Female abdominal integument was the only tissue that synthesized appreciable amounts of HC in vit...
Article
Full-text available
Neotropical ant-gardens: Behavioral and chemical ecology of an obligate ant-plant mutualism

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