Biology subjects

Hurlbert, A. H.

Publications and source records attributed to Hurlbert, A. H..

7 recordsLinked to original sources

bioRxiv2025

Arthropods on native versus alien woody plants: understanding variation across host plant taxonomy and geography

Alien plants have generally been shown to support reduced arthropod abundance, biomass, and diversity, but inferences have typically come from studies limited in taxonomic and geographic scope. Here, we make use of data from a unique citizen science project, Caterpillars Count!, that consists of nearly 70,000 standardized surveys of woody plant branches across eastern North America on over 100 plant species. From these data we find that caterpillar (i.e. larval Lepidoptera) occurrence was nearly 4 times higher, beetle (order Coleoptera) occurrence was 50% higher, and spider (order Araneae) occurrence was 17% higher on native versus alien plants. The occurrence of hoppers and allies (suborder Auchenorrhyncha) was slightly higher on alien plants, while there was little difference in occurrence on native versus alien plants for ants (family Formicidae) or true bugs (suborder Heteroptera). Species richness of caterpillars, spiders, and beetles was also higher on average on native versus alien plants. The increased occurrence of caterpillars on native plants was consistent across plant families, whereas differences between native and alien plants for the other arthropod groups were highly variable across plant families. Caterpillar occurrence varied widely both within and between plant families, suggesting the importance of other plant species characteristics beyond native versus alien origin. Finally, we show that caterpillar occurrence appears to increase with latitude on alien plants at a faster rate than it does on native plants, but that this difference can be attributed to shifts in the identity and composition of plant species across the latitudinal gradient within our dataset. These findings have implications for how the increased spread of alien plants may impact ecosystems and food webs, and for land managers seeking to mitigate those changes.

ecology↗

bioRxiv2024

Arthropod community composition in urban landscapes is shaped by both environmental filtering and dispersal limitation

We assessed the relative importance of environmental filtering and dispersal limitation in structuring foliage- and ground-dwelling arthropod communities in central North Carolina. We hypothesized that both the local environment and the dispersal distance between sites would predict community composition, but that dispersal distance would be more important for ground arthropods than for foliage arthropods. In both groups, variation in habitat characteristics was important in structuring communities, and the role of dispersal in structuring communities was much greater after accounting for variation in landscape connectivity. Our results demonstrate the importance of both dispersal limitation and environmental filtering in shaping community composition and emphasize the importance of variation in the landscape for modeling these forces. Examining communities of multiple arthropod groups across the same spatial gradient highlights the scale-dependence of these processes and illustrates how variation in the environment can alter the relative abundance of specialist and generalist taxa.

ecology↗

bioRxiv2022

Comparing multiscale, presence-only habitat suitability models created with structured survey data and community science data for a rare warbler species at the southern range margin

Golden-winged Warblers (Vermivora chrysoptera, Parulidae) are declining migrant songbirds that breed in the Great Lakes and Appalachian regions of North America. Within their breeding range, Golden-winged Warblers are found in early successional habitats adjacent to mature hardwood forest, and previous work has found that Golden-winged Warbler habitat preferences are scale-dependent. Golden-winged Warbler Working Group management recommendations were written to apply to large regions of the breeding range, but there may be localized differences in both habitat availability and preferences. Rapid declines at the southernmost extent of their breeding range in Western North Carolina and Georgia necessitate investigation into landscape characteristics governing distribution in this subregion. We describe patterns of Golden-winged Warbler presence in Western North Carolina by examining habitat variables at multiple spatial scales using data from standardized Audubon North Carolina (NC) surveys and unstructured community scientist checklists submitted to eBird. We compared model performance and predictions between Audubon NC and eBird models and found that Golden-winged Warbler presence is associated with sites which, at a local scale (150m), have more young forest, less mature forest, and more road cover, and at a landscape scale (2.5km), have less road cover. eBird and Audubon models had similar parameter estimates for all of the land cover variables and similar overall performance. Based on parameter estimates, road density at the landscape scale (2.5km) is the primary variable driving the difference between Golden-winged Warbler breeding sites and random background sites in Western North Carolina. Our results show that eBird data can produce species distribution modeling results that are similar to results obtained from more standardized survey methods.

ecology↗

bioRxiv2022

Climatic niche conservatism in a clade of disease vectors (Diptera: Phlebotominae)

Sandflies of the family Psychodidae show notable diversity in both disease vector status and climatic niche. Some species (in the subfamily Phlebotominae) transmit Leishmania parasites, responsible for the disease leishmaniasis. Other Psychodidae species do not. Psychodid species ranges can be solely tropical, confined to the temperate zones, or span both. Studying the relationship between the evolution of disease vector status and that of climatic niche affords an understanding not only of the climate conditions associated with the presence and species richness of Leishmania vectors, but also allows the study of the extent to which psychodid flies climatic niches are conserved, in a context with implications for global human health. We obtained observation site data, and associated climate data, for 223 psychodid species to understand which aspects of climate most closely predict distribution. Temperature and seasonality are strong determinants of species occurrence within the clade. We built a mitochondrial DNA phylogeny of Psychodidae, and found a positive relationship between pairwise genetic distance and climate niche differentiation, which indicates strong niche conservatism. This result is also supported by strong phylogenetic signals of metrics of climate differentiation. Finally, we used ancestral trait reconstruction to infer the tropicality (i.e., proportion of latitudinal range in the tropics minus the proportion of the latitudinal range in temperate areas) of ancestral species, and counted transitions to and from tropicality states, finding that tropical and temperate species respectively produced almost entirely tropical and temperate descendant species, a result consistent for vector and non-vector species. Taken together, these results imply that while vectors of Leishmania can survive in a variety of climates, their climate niches are strongly predicted by phylogeny.

evolutionary biology↗

bioRxiv2020

A simulation study of the use of temporal occupancy for identifying core and transient species

Transient species, which do not maintain self-sustaining populations in a system where they are observed, are ubiquitous in nature and their presence often impacts the interpretation of ecological patterns and processes. Identifying transient species from temporal occupancy, the proportion of time a species is observed at a given site over a time series, is subject to classification errors as a result of imperfect detection and source-sink dynamics. We use a simulation-based approach to assess how often errors in detection or classification occur in order to validate the use of temporal occupancy as a metric for inferring whether a species is a core or transient member of a community. We found that low detection increases error in the classification of core species, while high habitat heterogeneity and high detection increase error in classification of transient species. These findings confirm that temporal occupancy is a valid metric for inferring whether a species can maintain a self-sustaining population, but imperfect detection, low abundance, and highly heterogeneous landscapes may yield high misclassification rates.

ecology↗

bioRxiv2019

Genetic diversity and thermal performance in invasive and native populations of African fig flies

During biological invasions, alien populations can suffer losses of genetic diversity that are predicted to negatively impact their fitness/performance. Using genome sequences, we show that invasive populations of the African fig fly, Zaprionus indianus, have lower levels of genetic diversity compared to native populations, and that genetic diversity is lost more in regions of the genome with low recombination rates. However, genetic diversity remains as high or higher in invasive populations than in populations of non-invasive congeneric species. We then use parameter estimates from thermal performance curves measured for 13 species of Zaprionus to show that Z. indianus has the broadest thermal niche of measured species, and that performance does not differ between invasive and native populations. These results illustrate how aspects of genetic diversity in invasive species can be decoupled from measures of fitness, and that a broad thermal niche may have helped facilitate Z. indianuss range expansion.

evolutionary biology↗

bioRxiv2018

Caterpillars Count! A citizen science project for monitoring foliage arthropod abundance and phenology

Caterpillars Count! is a citizen science project that allows participants to collect data on the seasonal timing, or phenology, of foliage arthropods that are important food resources for forest birds. This project has the potential to address questions about the impacts of climate change on birds over biogeographic scales. Here, we provide a description of the projects two survey protocols, evaluate the impact of survey methodology on results, compare findings made by citizen scientist participants versus trained scientists, and identify the minimum levels of sampling frequency and intensity in order to accurately capture phenological dynamics. We find that beat sheet surveys and visual surveys yield similar relative and absolute density estimates of different arthropod groups, with beat sheet surveys recording a higher frequency of beetles and visual surveys recording a higher frequency of flies. Citizen scientists generated density estimates within 6% of estimates obtained by trained scientists regardless of survey method. However, patterns of phenology were more consistent between citizen scientists and trained scientists when using beat sheet surveys than visual surveys. By subsampling our survey data, we found that conducting 30 foliage surveys on a weekly basis led to 95% of peak caterpillar date estimates to fall within one week of the \"true\" peak. We demonstrate the utility of Caterpillars Count! for generating a valuable dataset for ecological research, and call for future studies to evaluate how training and resource materials impact data quality and participant learning gains.

ecology↗