Fruit and seed traits of native and invasive plant species in Hawai‘i: implications for seed dispersal by non-native birds

Sperry, Jinelle H.; O’Hearn, Dylan; Drake, Donald R.; Hruska, Amy M.; Case, Samuel B.; Vizentin‐Bugoni, Jeferson; Arnett, Clint M.; Chambers, Tim; Tarwater, Corey E.

doi:10.1007/s10530-021-02473-z

Cited by 22 publications

(29 citation statements)

References 56 publications

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“…The minimum quantities used for each species were 207 mg for lipid, 81 mg for carbohydrates, and 41 mg for protein analyses (details in ref. 53). Plant range.…”

Section: Methodsmentioning

confidence: 99%

Ecological correlates of species’ roles in highly invaded seed dispersal networks

Vizentin‐Bugoni

Sperry

Kelley

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Ecosystems with a mix of native and introduced species are increasing globally as extinction and introduction rates rise, resulting in novel species interactions. While species interactions are highly vulnerable to disturbance, little is known about the roles that introduced species play in novel interaction networks and what processes underlie such roles. Studying one of the most extreme cases of human-modified ecosystems, the island of Oʻahu, Hawaii, we show that introduced species there shape the structure of seed dispersal networks to a greater extent than native species. Although both neutral and niche-based processes influenced network structure, niche-based processes played a larger role, despite theory predicting neutral processes to be predominantly important for islands. In fact, ecological correlates of species’ roles (morphology, behavior, abundance) were largely similar to those in native-dominated networks. However, the most important ecological correlates varied with spatial scale and trophic level, highlighting the importance of examining these factors separately to unravel processes determining species contributions to network structure. Although introduced species integrate into interaction networks more deeply than previously thought, by examining the mechanistic basis of species’ roles we can use traits to identify species that can be removed from (or added to) a system to improve crucial ecosystem functions, such as seed dispersal.

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“…The minimum quantities used for each species were 207 mg for lipid, 81 mg for carbohydrates, and 41 mg for protein analyses (details in ref. 53). Plant range.…”

Section: Methodsmentioning

confidence: 99%

Ecological correlates of species’ roles in highly invaded seed dispersal networks

Vizentin‐Bugoni

Sperry

Kelley

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…From the 20 plant species that we tested, only 4 had higher germination rates following gut passage, 3 of which were non-native and belonged to the genus Rubus (Appendix Table 2); a genus that comprises numerous invasive species worldwide (Caplan and Yeakley 2013). The native and non-native species we examined did not signi cantly differ in seed width for species used in both survival and germination experiments, and broadly, fruit and seed traits are similar between native and non-native plants in Hawaiian forests (Sperry et al 2021). It is currently unclear why native species may be more vulnerable to novel species interactions, and traits not examined here, such as seed-coat thickness (Traveset 1998), may be important for interaction outcomes.…”

Section: Discussionmentioning

confidence: 92%

“…For all plant species tested in seed survival and germination experiments, we recorded seed width and the number of seeds per fruit, measured to estimate the total number of seeds ingested from fruits consumed in trials. Most measurements were taken from Sperry et al (2021), who collected and measured seeds and fruits on O'ahu. For plant species not already measured (42.3% of plant species examined, N = 52), we measured them from fresh samples using the same protocol as Sperry et al (2021).…”

Section: Plant Traitsmentioning

confidence: 99%

“…Most measurements were taken from Sperry et al (2021), who collected and measured seeds and fruits on O'ahu. For plant species not already measured (42.3% of plant species examined, N = 52), we measured them from fresh samples using the same protocol as Sperry et al (2021). In brief, the width of the seed (or other diaspore, such as a hard achene or endocarp) was measured as the second-longest axis of each seed using digital calipers, and a mean value was calculated for each plant species from measures of 10 seeds per species.…”

Section: Plant Traitsmentioning

confidence: 99%

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Introduced galliforms as seed predators and dispersers in Hawaiian forests

et al. 2022

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In altered communities, novel species' interactions may critically impact ecosystem functioning. One key ecosystem process, seed dispersal, often requires mutualistic interactions between frugivores and fruiting plants, and functional traits, such as seed width, may affect interaction outcomes. Forests of the Hawaiian Islands have experienced high species turnover, and introduced galliforms, the largest of the extant avian frugivores, consume fruit from both native and non-native plants. We investigated the impact of two galliform species on seed dispersal processes in Hawaiian forests. Using captive Kalij Pheasants (Lophura leucomelanos) and Erckel's Francolins (Pternistis erckelii), we measured the probability of seed survival during gut passage and seed germination following gut passage. We also examined which seeds are being dispersed in forests on the islands of O'ahu and Hawai'i. We found that galliforms are major seed predators for both native and non-native plants, with less than 5% of seeds surviving gut passage for all plants tested and in both bird species. Gut passage by Kalij Pheasants signi cantly reduced the probability of seeds germinating, especially for the native plants. Further, largerseeded plants were both less likely to survive gut passage and to germinate. In the wild, galliforms dispersed native and non-native seeds at similar rates. Overall, our results suggest the introduced galliforms are a double-edged sword in conservation efforts; they may help reduce the spread of nonnative plants, but they also reduce seed dispersal of native plants. Broadly, we show mutualism breakdown may occur following high species turnover, and that functional traits can be useful for predicting outcomes from novel species' interactions.

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“…Along abiotic gradients, native communities are expected to be less invaded and alien plant species more similar to native communities where abiotic stress is high, while native communities are expected to be more invaded and alien species less similar to native communities where abiotic stress is low (Perelman et al ., 2007; Tecco et al ., 2010; Gross et al ., 2013; González-Moreno et al ., 2014; Sapsford et al ., 2020). Anthropogenic disturbances (or habitats) may also generate context dependent invasion outcomes (González-Moreno et al ., 2014; Jauni et al ., 2015) by favoring non-native species with disturbance-tolerant trait values (Richardson & Rejmánek, 2011; Ni et al ., 2021; Sperry et al ., 2021). Particularly on oceanic islands, island age (or soil age) - which typically has been used to address the macroevolutionary processes underlying native biodiversity patterns (Emerson, 2002; Gillespie, 2016; Whittaker et al ., 2017) - may further strengthen the context dependency of biological invasions by differentially shaping the biodiversity patterns for native (Whittaker et al ., 2008; Craven et al ., 2019) and alien species (Leihy et al ., 2018).…”

Section: Introductionmentioning

confidence: 99%

Interacting abiotic and biotic drivers shape woody invasions across Hawaiian forests

Craven

Chase

Knight

2022

Preprint

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The same features that generate biodiversity patterns across and within oceanic islands over evolutionary time - interactions between isolation, area, and heterogeneity - also influence their vulnerability to biological invasions. Here, we identify the factors that shape the richness and abundance of woody aliens in forest communities across the Hawaiian archipelago, and assess the relative importance of abiotic, biotic, and anthropogenic factors and their interactions on the establishment and dominance of woody alien species. Using a database of 460 forest plots distributed across the six major Hawaiian islands, we examine variation in i) relative alien species richness and abundance as a function of multiple factors (e.g., temperature, aridity, soil age, and the human influence index) and ii) establishment and dominance of alien species as a function of abiotic and anthropogenic factors, as well as phylogenetic and trait distinctiveness. We found that relative alien species richness and abundance were higher in areas where temperature was high and aridity low. Gradients in temperature, aridity, soil age, and human influence also modulated the importance of biotic factors in determining establishment of alien species. In contrast, whether these alien species could become locally dominant was not strongly influenced by abiotic or biotic factors, or their interactions. Our results suggest that environmental filtering mediates the strength of biotic filtering in determining where woody aliens are able to colonize and establish on these oceanic islands, but not whether they become dominant. The strong context dependence of multi-species invasions highlights the complexity of developing management strategies to mitigate the biodiversity and ecosystem impacts of biological invasions.

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Fruit and seed traits of native and invasive plant species in Hawai‘i: implications for seed dispersal by non-native birds

Cited by 22 publications

References 56 publications

Ecological correlates of species’ roles in highly invaded seed dispersal networks

Ecological correlates of species’ roles in highly invaded seed dispersal networks

Introduced galliforms as seed predators and dispersers in Hawaiian forests

Interacting abiotic and biotic drivers shape woody invasions across Hawaiian forests

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