Ecological filtering in scrub fragments restructures the taxonomic and functional composition of native bee assemblages

Hung, Keng‐Lou James; Ascher, John S.; Davids, Jessica A.; Holway, David A.

doi:10.1002/ecy.2654

Cited by 26 publications

(27 citation statements)

References 87 publications

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“…Furthermore, anthropogenic landscapes (i.e., urban and agricultural areas) fragment much of the remaining CSS. Loss and fragmentation of CSS has detrimental effects on a variety of animal taxa [22,34,[45][46][47].…”

Section: Study Systemmentioning

confidence: 99%

“…Although no survey was conducted during the drought event, comparisons of native bee assemblages immediately before and after the drought event provide insight into how drought may have modified the assemblages. As the dataset was collected in a series of scrub habitat fragments and large natural reserves in order to examine the responses of bee assemblages to habitat loss and fragmentation [21,22], it also allows us to investigate the joint impacts of drought and habitat fragmentation on bee assemblages.…”

Section: Introductionmentioning

confidence: 99%

“…Third, bee species in our system span at least an order of magnitude in body length [22]. Given the known correlation between bee body size and mobility [31], larger bees may be better able to access flowers growing in drought refugia (e.g., riparian corridors, northfacing slopes, runoff zones of impervious surfaces) and could more quickly recolonize areas where populations were extirpated by drought.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, understanding how the potential tradeoffs of each life history trait translate into realized population dynamics in drought scenarios necessitates examining empirical, assemblage-wide data. Empirical examination is especially important in systems such as ours, which may include both xericadapted and mesic-adapted bee species (based on known life history traits and distributions of the species; see [22]), which may differ in their capacity to respond to drought. If life history traits indeed influence the response of bee species to drought, we expect to detect differences in the species composition of assemblages before versus after drought.…”

Section: Introductionmentioning

confidence: 99%

“…In our case, habitat fragmentation may potentially exacerbate or ameliorate the impacts of drought. On one hand, because bee assemblages in our habitat fragments are taxonomically and functionally depauperate compared to those in relatively intact natural reserves [22], they may be missing many of the taxa that can withstand, avoid (i.e., via extended diapause), or quickly recover from drought (e.g., xeric-adapted species). Also, habitat fragments may fail to encompass drought refugia due to their small size, and their isolation may hinder the recolonization [34] of bees from drought refugia once drought has ended.…”

Section: Introductionmentioning

confidence: 99%

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Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

Hung

Sandoval

Ascher

et al. 2021

Insects

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Global climate change is causing more frequent and severe droughts, which could have serious repercussions for the maintenance of biodiversity. Here, we compare native bee assemblages collected via bowl traps before and after a severe drought event in 2014 in San Diego, California, and examine the relative magnitude of impacts from drought in fragmented habitat patches versus unfragmented natural reserves. Bee richness and diversity were higher in assemblages surveyed before the drought compared to those surveyed after the drought. However, bees belonging to the Lasioglossum subgenus Dialictus increased in abundance after the drought, driving increased representation by small-bodied, primitively eusocial, and generalist bees in post-drought assemblages. Conversely, among non-Dialictus bees, post-drought years were associated with decreased abundance and reduced representation by eusocial species. Drought effects were consistently greater in reserves, which supported more bee species, than in fragments, suggesting that fragmentation either had redundant impacts with drought, or ameliorated effects of drought by enhancing bees’ access to floral resources in irrigated urban environments. Shifts in assemblage composition associated with drought were three times greater compared to those associated with habitat fragmentation, highlighting the importance of understanding the impacts of large-scale climatic events relative to those associated with land use change.

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Section: Study Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

Hung

Sandoval

Ascher

et al. 2021

Insects

Self Cite

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No evidence for environmental filtering of cavity‐nesting solitary bees and wasps by urbanization using trap nests

Xie

Sookhan

Carscadden

et al. 2022

Ecology and Evolution

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Spatial patterns in biodiversity are used to establish conservation priorities and ecosystem management plans. The environmental filtering of communities along urbanization gradients has been used to explain biodiversity patterns but demonstrating filtering requires precise statistical tests to link suboptimal environments at one end of a gradient to lower population sizes via ecological traits. Here, we employ a three‐part framework on observational community data to test: (I) for trait clustering (i.e., phenotypic similarities among co‐occurring species) by comparing trait diversity to null expectations, (II) if trait clustering is correlated with an urbanization graient, and (III) if species' traits relate to environmental conditions. If all criteria are met, then there is evidence that urbanization is filtering communities based on their traits. We use a community of 46 solitary cavity‐nesting bee and wasp species sampled across Toronto, a large metropolitan city, over 3 years to test these hypotheses. None of the criteria were met, so we did not have evidence for environmental filtering. We do show that certain ecological traits influence which species perform well in urban environments. For example, cellophane bees ( Hylaeus : Colletidae) secrete their own nesting material and were overrepresented in urban areas, while native leafcutting bees ( Megachile : Megachilidae) were most common in greener areas. For wasps, prey preference was important, with aphid‐collecting ( Psenulus and Passaloecus : Crabronidae) and generalist spider‐collecting ( Trypoxylon : Crabronidae) wasps overrepresented in urban areas and caterpillar‐ and beetle‐collecting wasps ( Euodynerus and Symmorphus : Vespidae, respectively) overrepresented in greener areas. We emphasize that changes in the prevalence of different traits across urban gradients without corresponding changes in trait diversity with urbanization do not constitute environmental filtering. By applying this rigorous framework, future studies can test whether urbanization filters other nesting guilds (i.e., ground‐nesting bees and wasps) or larger communities consisting of entire taxonomic groups.

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Responses in thermal tolerance and daily activity rhythm to urban stress in Drosophila suzukii

Sato

Takahashi

2022

Ecology and Evolution

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Cities experience changes in abiotic factors, such as warming, increases in noise and light. These changes can lead to phenotypic changes. Several studies have revealed that altered environments change phenotypes in plants and animals in cities. However, limited studies have isolated evolutionary from nongenetic changes. Here, we analyzed the evolution of thermal tolerance and diurnal activity patterns in the urban population of the fruit pest, Drosophila suzukii . Urban and rural isofemale lines were reared under constant conditions. We compared the lower and upper thermal limits (CT min and CT max , respectively), and effects of temperature exposure on the thermal limits of urban and rural populations. Common garden experiments showed that urban populations exhibit a lower CT min than rural populations, suggesting genetic difference in CT min among populations. On the other hand, the difference in CT max between urban and rural populations was not significant. Exposure to cold temperature did not affect CT min in both urban and rural populations. In contrast, exposure to hot temperature increased CT max especially in urban population, suggesting that urban populations evolved in response to urban heat. We also investigated the daily activity patterns of urban and rural populations and the effect of lifelong artificial light at night on daily activity. We found that night‐time light (dim light) reduced the total amount of activity compared to dark night condition. In addition, dim light at night altered the daily rhythm of activity and increased the activity rate at night. The effect of night light on total activity was less in urban than that in rural populations, suggesting that populations in cities evolved to mitigate decreased activity under night light. Our results showed that environmental temperature and artificial light at night evolutionarily and plastically influence ecologically important traits, such as temperature tolerance and diurnal activity.

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Ecological filtering in scrub fragments restructures the taxonomic and functional composition of native bee assemblages

Cited by 26 publications

References 87 publications

Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

No evidence for environmental filtering of cavity‐nesting solitary bees and wasps by urbanization using trap nests

Responses in thermal tolerance and daily activity rhythm to urban stress in Drosophila suzukii

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