Climate change and invasive species: a physiological performance comparison of invasive and endemic bees in Fiji

Silva, Carmen R. B. da; Beaman, Julian; Dorey, James B.; Barker, Sarah; Congedi, Nicholas C.; Elmer, Matt C.; Galvin, Stephen; Tuiwawa, Marika; Stevens, Mark I.; Alton, Lesley A.; Schwarz, Michael P.; Kellermann, Vanessa

doi:10.1242/jeb.230326

Cited by 29 publications

(32 citation statements)

References 62 publications

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“…and the results of daSilva et al (2021), our results do not suggest that H. fijiensis is resilient to changing climates. However, H. fijiensis does appear to be more eurythermic (tolerates a broader temperature range) than most other Fijian Chrysodeixis includens, that was perhaps related to human colonization and agriculture.…”

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confidence: 88%

“…given the narrow thermal tolerance of tropical ectotherms (Janzen, 1967;Tewksbury et al, 2008) and the results of da Silva et al (2021), our results do not suggest that H. fijiensis is resilient to changing climates. However, H. fijiensis does appear to be more eurythermic (tolerates a broader temperature range) than most other Fijian Homalictus species (Dorey et al, 2020a).…”

Section: Discussioncontrasting

confidence: 65%

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Holocene population expansion of a tropical bee coincides with early human colonization of Fiji rather than climate change

et al. 2021

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There is substantial debate about the relative roles of climate change and human activities on biodiversity and species demographies over the Holocene. In some cases, these two factors can be resolved using fossil data, but for many taxa such data are not available. Inferring historical demographies of taxa has become common, but the methodologies are mostly recent and their shortcomings often unexplored. The bee genus Homalictus is developing into a tractable model system for understanding how native bee populations in tropical islands have responded to past climate change. We greatly expand on previous studies using sequences of the mitochondrial gene COI from 474 specimens and between 171 and 3928 autosomal (DArTSeq) single nucleotide polymorphism loci from 19 specimens of the native Fijian bee, Homalictus fijiensis, to explore its historical demography using coalescent and mismatch analyses. We ask whether past changes in demography were human‐ or climate‐driven, while considering analytical assumptions. We show that inferred changes in population sizes are too recent to be explained by past climate change. Instead we find that a dramatic increase in population size for the main island of Viti Levu coincides with increasing occupation by humans and their modification of the environment. We found no corresponding change in bee population size for another major island, Kadavu, where human populations and agricultural activities have been historically very low. Our analyses indicate that molecular approaches can be used to disentangle the impacts of humans and climate change on a major tropical pollinator and that stringent analytical approaches are required for reliable interpretation of results.

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confidence: 88%

Section: Discussioncontrasting

confidence: 65%

Holocene population expansion of a tropical bee coincides with early human colonization of Fiji rather than climate change

et al. 2021

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“…This idea is supported by a study that examined trends in upper thermal limits and body mass in grasshoppers, where the largest individuals had the lowest upper thermal limits (Youngblood et al, 2019), however, in other systems, body mass does not explain variation in upper thermal limits, e.g. Fijian bees (da Silva et al, 2021). We were unable to examine how body mass correlates with warming margins and functional groups across geographic space due to a lack of publicly available body mass data for many of the species in our dataset.…”

Section: Discussionmentioning

confidence: 98%

Linking physiology to ecosystem function: how vulnerable are different functional groups to climate change?

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Beaman

Youngblood

et al. 2022

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The resilience of ecosystem function under global climate change is governed by individual species vulnerabilities and the functional groups they contribute to (e.g. decomposition, primary production, pollination, primary, secondary and tertiary consumption). Yet it remains unclear whether species that contribute to different functional groups, which underpin ecosystem function, differ in their vulnerability to climate change. It is important to examine if functional group vulnerability differs across space (e.g. tropical vs temperate latitudes) to determine if some regions will be more vulnerable to loss of ecosystem function than others, and to examine whether localized effects of particular community compositions override global patterns of functional group vulnerability. We used existing upper thermal limit data across a range of terrestrial species (N = 1,743) to calculate species warming margins (degrees distance between a species upper thermal limit and the maximum environmental temperature they inhabit), as a metric of climate change vulnerability, to determine whether species that comprise different functional groups exhibit differential vulnerability to climate change, and if vulnerability trends change across geographic space. We found that primary producers had the broadest warming margins across the globe (mean = 21.85 C) and that tertiary consumers had the narrowest warming margins (mean = 4.37 C), where vulnerability tended to increase with trophic level. Species that contribute towards primary production were more vulnerable in low-latitude than mid-latitude regions, but warming margins across all other functional groups did not differ across regions when evolutionary history was considered. However, when evolutionary history was excluded from the analyses (as closely related species often play similar functional roles within ecosystems demonstrating true variation in functional group warming margins) we found that pollinators are more vulnerable in mid-latitude regions and that primary producers are more vulnerable in low-latitude environments. This study provides a critical first step in linking individual species vulnerabilities with whole ecosystem responses to climate change.

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“…Vertebrates were further represented by the zebrafish Danio rerio (Hamilton, 1822) (CT max only; Morgan et al., 2018) and the toad Alytes obstetricans (Laurenti, 1768) (CT max only; Fernández‐Loras et al., 2019). Invertebrates were further represented by one ant species (CT max and CT min ; Linepithema humile (Mayr, 1868); Jumbam et al., 2008), one weevil species (CT max and CT min ; Bothrometopus elongatus Jeannel, 1940; Klok & Chown, 2003), two bee species (CT max only; Homalictus fijiensis (Perkins & Cheesman 1928) and Braunsapis puangensi (Cockerell, 1929); da Silva et al., 2021) and caterpillars of an emperor moth species (CT max and CT min ; Gonimbrasia belina (Westwood, 1894); Klok & Chown, 1999) as representatives of the juveniles in a field dominated by measurements for adult individuals. To ensure sufficiently large ( n ≥ 50) sample sizes for subsequent subsampling procedures, data from multiple life stages or instars (for the toad and caterpillar datasets respectively), sampling locations (for the toad, weevil and bee datasets) or experimental groups (for zebrafish) were necessarily combined.…”

Section: Methodsmentioning

confidence: 99%

Adequate sample sizes for improved accuracy of thermal trait estimates

et al. 2021

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Thermal traits, such as upper and lower critical thermal limits, are vital indicators of the vulnerability of populations and species to environmental change. Thus, accurate estimates of these traits are needed to explain biological patterns and forecast responses to the changing thermal environment. However, many thermal trait studies measure relatively few individuals to estimate traits for whole populations or species. To ascertain if, and how, sample size affects the accuracy of reported trait means and variances, we applied a subsampling and equivalency testing approach to empirical and simulated trait data to investigate the accuracy of trait estimates relative to sample size and the skew and variance of the trait distribution in the source population. Simulation results indicated that only 7.9% of the 428 critical thermal limit traits documented in a recent synthesis of thermal trait data reported sufficiently large sample sizes, relative to variance, to ensure confidence in the reported mean trait value with negligible (±0.25°C) error. Greater inter‐individual trait variance in the source population requires a larger number of individuals to be measured to accurately estimate the mean and variance of that trait. This pattern is mitigated somewhat by the tendency of thermal traits to exhibit skew‐normal distributions. As measurements of few individuals from a population are unlikely to provide accurate estimates of thermal traits, the propensity towards small sample sizes in thermal trait studies is concerning. Macrophysiological syntheses often use these data to describe, explain and predict broad‐scale ecological patterns. Thus, insufficient sample sizes in the original studies could diminish the robustness of these patterns and predictions. For future studies, we recommend that preliminary data be used to estimate trait variance and calculate minimum sample sizes. If small sample sizes are unavoidable, larger error around the measured trait mean must be assumed and accounted for in subsequent analyses. A free Plain Language Summary can be found within the Supporting Information of this article.

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Climate change and invasive species: a physiological performance comparison of invasive and endemic bees in Fiji

Cited by 29 publications

References 62 publications

Holocene population expansion of a tropical bee coincides with early human colonization of Fiji rather than climate change

Holocene population expansion of a tropical bee coincides with early human colonization of Fiji rather than climate change

Linking physiology to ecosystem function: how vulnerable are different functional groups to climate change?

Adequate sample sizes for improved accuracy of thermal trait estimates

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