Plant-animal Interaction Networks
Compared to historical assemblages, contemporary plant communities are novel in a multitude of ways, such as structure, composition, age, diversity and function. These differences are especially true in human-dominated ecosystems where people continuously cultivate plant communities for ecological, economic and cultural services. Novel assemblages can affect trophic relationships in consumers, however, at present, we lack a comprehensive understanding of behavioral, demographic, and community responses of wildlife to altered plant communities. In much of my work I use plant-animal interactions as a means to understand how informed plant selection can help successfully restore and conserve interaction diversity, biodiversity and ecological function in highly managed ecosystems. My ongoing work across the annual cycle explores the role that individual plant species play in the restoration of bird and insect habitat and resources in urban and agricultural ecosystems. I'm particularly interested in the extent that interaction networks vary spatially and temporally and whether some plants are disproportionately important for supporting biodiversity.
My coauthors and I use published host plant-Lepidoptera records across the united states to show that interaction networks are consistently skewed, such that few plant genera support the majority of Lepidoptera species. We also found the shape of this distribution is consistent across biomes, latitudes, diversities and geographies. Across the 25 states included, some plant genera consistently host the highest Lepidoptera richness, support most specialized species and contribute the most to network stability.
Publications:
- Narango, D.L., Shropshire, K.J., and Tallamy, D.W. Few keystone plant genera support the majority of Lepidoptera species. Nature Communications, 11, 5751 (2020). (PDF)
Figure:
a) White-blotched Heterocampa (Heterocampa umbrata) a Lepidopteran from the family Notodontidae. The majority of Lepidopteran caterpillars are constrained to feed on just a few plant genera or families from the total plant diversity available in the landscape (Photo by D. Tallamy)
(b) The 83 United States counties (in green) used in our analyses (map made by KJS using mapchart.net)
(c) Mean % Lepidoptera species hosted by each plant genus across all counties analyzed (n=83). The top 15 genera that supported the most Lepidoptera species are labeled. The average percent Lepidoptera species across all plant genera was 0.36% ± 1.41% (range: 0%-23%). Box plot shows the median (center line), first and third quartile (upper and lower hinges) and 1.5 * interquartile range (whiskers). Data from n=1997 plant genera.
(d) Example histogram of Lepidoptera richness by plant genus with four candidate distributions for the 341 woody and herbaceous plant genera in Oscoda County, Michigan. Most (93%) of the 83 counties included in the dataset had distributions that were best fit by a gamma distribution (solid green line), such that a few plant genera supported high numbers of Lepidoptera species and many plant genera supported few to no Lepidoptera species.
Plants that disproportionately support insect herbivores may also have an inordinate impact on habitat relationships with insectivorous consumers. For example, many birds heavily rely on protein-rich insect prey like caterpillars throughout the year to raise young, make cross-continent migrations and survive the winter. My ongoing work explores the extent that plant diversity is related to animal diversity and whether inclusion of 'foundational' or 'keystone' plant species improves the efficiency and efficacy of restoration in cultivated green spaces. I am also keenly interested in exploring other plant-animal interaction networks (plant-frugivore, plant-pollinator) to understand how temporal and spatial variation in habitat availability & quality affect interaction diversity and evenness.
Infographic of our keystone plant paper. Art by Elsa Cousins
To download, click these links: High-resolution, Low-resolution
To download, click these links: High-resolution, Low-resolution