Parallel paths in a miniature world

Authors: Tonkel, Kirk; DIMITRI, LINDSAY - University Of Nevada; Longland, William - Bill; KIRCHOFF, VERONICA - University Of Nevada; Rector, Brian

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2021
Publication Date: 10/1/2021
Citation: Tonkel, K.C., Dimitri, L.A., Longland, W.S., Kirchoff, V., Rector, B.G. 2021. Parallel paths in a miniature world. Ecology. 102(10). https://doi.org/10.1002/ecy.3460.
DOI: https://doi.org/10.1002/ecy.3460

Interpretive Summary: Juniper species have been expanding in range and increasing in density within existing woodlands. In order to better understand seedling recruitment processes underlying these increases, we sought to quantify seed production including seed predation. Very little was previously published regarding arthropods that impact western juniper (J. occidentalis) seed crops, and many of the species and their interactions were previously undocumented. Juniper expansion can decrease forage availability for livestock and wildlife and increase fuel-loads for wildfires, and substantial resources have been aimed at managing these woodlands. Describing the processes that impact seed production is vital to understanding expansion and can aid management. Although this was the original aim of the research, the surprisingly diverse and complex arthropod community we revealed was too interesting to ignore. We collected western (J. occidentalis), Utah (J. osteosperma) and California juniper (J. californicus) berries form 28 sites in California and Nevada. Berries were dissected to collect immatures and notes were taken on immature location and feeding behaviors. Additional berries were also placed in petri dishes to rear adults. Immatures were matched to identified adults using DNA fingerprinting. For those without adult specimens, morphology or feeding ecology were used to identify immatures to the lowest taxonomic unit possible as well as running sequences through GenBank to aid in identification. Our original study focused on western juniper for which we discovered multiple habitats within berries (fruit or pulp, seed, etc.). We then compared this community and the occupied niches to Utah and California juniper berries and uncovered many of the same genera and species occupying the same niches as well as some unique species. Across the three juniper species, we identified 21 phytophages that occupy 7 unique habitats, and 24 predators/parasites. After searching the literature for described juniper berry arthropod communities, we found three other juniper species with enough of the berry-inhabiting arthropod communities described to enable a comparison: eastern juniper redcedar (J. virginiana), distributed in eastern North America; Spanish juniper (J. thurifera), native to mountainous habitats in the western Mediterranean basin; and Phoenician juniper (J. phoenicea), which has a coastal Mediterranean distribution. We found multiple examples of parallel evolution between the three species of junipers we’ve been studying in the western U.S. and the eastern U.S. juniper with the European species. The arthropod communities of most Old and New World junipers have yet to be described, but the patterns we’ve uncovered can be used to predict habitats, niches, interactions and guilds in other juniper species. This knowledge can also be used to inform the management of species in the U.S. that are expanding into shrublands and grasslands as well as providing opportunities for taxonomic descriptions of new species. The diversity of species, niches and habitats within the miniature juniper berry world provides research opportunities in evolution, natural selection and plant-animal interactions at multiple scales, and we hope our work will stimulate future studies.

Technical Abstract: Juniper species have been expanding in range and increasing in density within existing woodlands. In order to better understand seedling recruitment processes underlying these increases, we sought to quantify seed production including seed predation. Describing the processes that impact seed production is vital to understanding expansion and can aid management. Although this was the original aim of the research, the surprisingly diverse and complex arthropod community we revealed was too interesting to ignore. We collected western (J. occidentalis), Utah (J. osteosperma) and California juniper (J. californicus) berries form 28 sites in California and Nevada. Berries were dissected to collect immatures and notes were taken on immature location and feeding behaviors. Additional berries were also placed in petri dishes to rear adults. Immatures were matched to identified adults using DNA fingerprinting. For those without adult specimens, morphology or feeding ecology were used to identify immatures to the lowest taxonomic unit possible as well as running sequences through GenBank to aid in identification. Our original study focused on western juniper for which we discovered multiple habitats within berries (fruit or pulp, seed, etc.). We then compared this community and the occupied habitats and niches to Utah and California juniper berries and uncovered many of the same genera and species functioning in the same capacity along with some unique species. Across the three juniper species, we identified 21 phytophages that occupy 7 unique habitats, and 24 predators/parasites. After a literature search for described juniper berry arthropod communities, we found three other juniper species with enough of the berry-inhabiting arthropod communities described to enable a comparison: eastern juniper redcedar (J. virginiana), Spanish juniper (J. thurifera), and Phoenician juniper (J. phoenicea). We found multiple examples of parallel evolution between the three species of junipers we’ve been studying in the western U.S. and the eastern U.S. juniper with the European species. The arthropod communities of most Old and New World junipers have yet to be described, but the patterns we’ve uncovered can be used to predict habitats, niches, interactions and guilds in other juniper species. This knowledge can also be used to inform the management of species in the U.S. that are expanding into shrublands and grasslands as well as providing opportunities for taxonomic descriptions of new species.