Publications by authors named "Timothy C Bonebrake"

34 Publications

Local adaptation in thermal tolerance for a tropical butterfly across ecotone and rainforest habitats.

Biol Open 2021 Apr 6;10(4). Epub 2021 Apr 6.

Division of Ecology & Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, China

Thermal adaptation to habitat variability can determine species vulnerability to environmental change. For example, physiological tolerance to naturally low thermal variation in tropical forests species may alter their vulnerability to climate change impacts, compared with open habitat species. However, the extent to which habitat-specific differences in tolerance derive from within-generation versus across-generation ecological or evolutionary processes are not well characterized. Here we studied thermal tolerance limits of a Central African butterfly () across two habitats in Cameroon: a thermally stable tropical forest and the more variable ecotone between rainforest and savanna. Second generation individuals originating from the ecotone, reared under conditions common to both populations, exhibited higher upper thermal limits (CTmax) than individuals originating from forest (∼3°C greater). Lower thermal limits (CTmin) were also slightly lower for the ecotone populations (∼1°C). Our results are suggestive of local adaptation driving habitat-specific differences in thermal tolerance (especially CTmax) that hold across generations. Such habitat-specific thermal limits may be widespread for tropical ectotherms and could affect species vulnerability to environmental change. However, microclimate and within-generation developmental processes (e.g. plasticity) will mediate these differences, and determining the fitness consequences of thermal variation for ecotone and rainforest species will require continued study of both within-generation and across-generation eco-evolutionary processes.This article has an associated First Person interview with the first author of the paper.
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http://dx.doi.org/10.1242/bio.058619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053492PMC
April 2021

Behavior-partitioned diversity reveals differential habitat values of gardens to butterfly communities.

Ecol Appl 2021 Mar 23:e02331. Epub 2021 Mar 23.

Division of Ecology & Biodiversity, School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong SAR, China.

Diversity metrics, essential for habitat evaluation in conservation, are often based on occurrences records with little consideration of behavioral ecology. As species use diverse habitats to perform different behaviors, reliance on occurrence records alone will fail to reveal environmental conditions shaping the behavioral importance of habitats with respect to resource exploitation. Here, we integrated occurrence and behavioral records to quantify diversity and assessed how environmental determinants shape the behavioral importance of gardens to butterflies across Hong Kong. We conducted standardized butterfly sampling and behavioral observation, and recorded environmental variables related to climate, habitat quality, and landscape connectivity. We found differential responses of diversity and behavioral diversity metrics to environmental variables. Connectivity increased taxonomic richness based on occurrence and flying across records, while temperature reduced richness based on occurrence, settling and interaction records. Floral abundance increased richness based on nectaring records only. No environmental variable promoted the average number of behavioral types observed in each taxon. Our results suggest that connectivity and temperature determine the richness of butterflies reaching gardens, while floral abundance determines whether butterflies use the sites as nectaring grounds via modifying species behaviors. Our study demonstrates the utility in integrating behavioral and diversity data to reveal how environmental conditions shape behavioral importance of habitats.
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http://dx.doi.org/10.1002/eap.2331DOI Listing
March 2021

Predator presence and recent climatic warming raise body temperatures of island lizards.

Ecol Lett 2021 Mar 6;24(3):533-542. Epub 2021 Jan 6.

Department of Biology, Faculty of Science, Toho University, Funabashi, Chiba, Japan.

In ectothermic predator-prey relationships, evasion of predation by prey depends on physiological and behavioural responses relating to the thermal biology of both predator and prey. On Japan's Izu Islands, we investigated a prey lizard's physiological and thermal responses to the presence of a snake predator over geologic time in addition to recent climatic warming. Foraging lizard body temperatures increased by 1.3 °C from 1981 to 2019 overall, yet were 2.9 °C warmer on snake islands relative to snake-free islands. We also detected snake predator-induced selection on hind leg length, which in turn is a major determinant for sprint speed only in lizard populations exposed to predation by snakes. Accordingly, we found that warmer prey body temperatures result in faster sprint speeds by the prey at temperatures suboptimal for the snake predator, and therefore contribute to escaping predation. Given recent climatic change, further warming could irrevocably alter this and other ectothermic predator-prey relationships.
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http://dx.doi.org/10.1111/ele.13671DOI Listing
March 2021

Author Correction: Land-use change interacts with climate to determine elevational species redistribution.

Nat Commun 2020 07 8;11(1):3485. Epub 2020 Jul 8.

School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, 999077, China.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41467-020-17319-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7343810PMC
July 2020

Climate Change and Thermoregulatory Consequences of Activity Time in Mammals.

Am Nat 2020 07 27;196(1):45-56. Epub 2020 May 27.

Activity times structure the thermal environments experienced by organisms. In mammals, species shift from being nocturnal to diurnal and vice versa, but the thermal consequences of variable activity patterns remain largely unexplored. Here we used theoretical thermoregulatory polygons bounded by estimates of basal metabolic rates (BMR), maximum metabolic rates (MMR), and thermal conductance () in small mammals to explore the metabolic consequences of exposure to global-scale daytime and nighttime temperatures. Model predictions indicated higher metabolic scope for activity for nocturnal species at low latitudes and that reduced minimum and larger body size increased the geographic range in which nocturnality was advantageous. Consistent with predictions, within rodents nocturnal species have low . However, nocturnal mammals tend to be smaller than diurnal species, likely reflecting the importance of additional factors driving body size. Projections of warming impacts on small mammals suggest that diurnal species could lose habitable space globally. Conversely, warming could lift cool temperature constraints on nocturnal species and increase habitable space, suggesting that a shift toward nocturnal niches might be favored in a warming world. Taken together, these findings demonstrate the importance of energetic considerations for endotherms in managing global change impacts on nocturnal and diurnal species.
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http://dx.doi.org/10.1086/709010DOI Listing
July 2020

Past and future decline of tropical pelagic biodiversity.

Proc Natl Acad Sci U S A 2020 06 26;117(23):12891-12896. Epub 2020 May 26.

Faculty of Science, University of the Ryukyus, 903-0213 Okinawa, Japan.

A major research question concerning global pelagic biodiversity remains unanswered: when did the apparent tropical biodiversity depression (i.e., bimodality of latitudinal diversity gradient [LDG]) begin? The bimodal LDG may be a consequence of recent ocean warming or of deep-time evolutionary speciation and extinction processes. Using rich fossil datasets of planktonic foraminifers, we show here that a unimodal (or only weakly bimodal) diversity gradient, with a plateau in the tropics, occurred during the last ice age and has since then developed into a bimodal gradient through species distribution shifts driven by postglacial ocean warming. The bimodal LDG likely emerged before the Anthropocene and industrialization, and perhaps ∼15,000 y ago, indicating a strong environmental control of tropical diversity even before the start of anthropogenic warming. However, our model projections suggest that future anthropogenic warming further diminishes tropical pelagic diversity to a level not seen in millions of years.
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http://dx.doi.org/10.1073/pnas.1916923117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293716PMC
June 2020

Omnivorous ants are less carnivorous and more protein-limited in exotic plantations.

J Anim Ecol 2020 08 30;89(8):1941-1951. Epub 2020 May 30.

School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong SAR, People's Republic of China.

Diets of species are crucial in determining how they influence food webs and community structures, and how their populations are regulated by different bottom-up processes. Omnivores are able to adjust their diet flexibly according to environmental conditions, such that their impacts on food webs and communities, and the macronutrients constraining their population, can be plastic. In particular, omnivore diets are known to be influenced by prey availability, which exhibits high spatial and temporal variation. To examine the plasticity of diet and macronutrient limitation in omnivores, we compared trophic positions, macronutrient preferences and food exploitation rates of omnivorous ants in invertebrate-rich (secondary forests) and invertebrate-poor (Lophostemon confertus plantations) habitats. We hypothesized that omnivorous ants would have lower trophic positions, enhanced protein limitation and reduced food exploitation rates in L. confertus plantations relative to secondary forests. We performed cafeteria experiments to examine changes in macronutrient limitation and food exploitation rates. We also sampled ants and conducted stable isotope analyses to investigate dietary shifts between these habitats. We found that conspecific ants were less carnivorous and had higher preferences for protein-rich food in L. confertus plantations compared to secondary forests. However, ant assemblages did not exhibit increased preferences for protein-rich food in L. confertus plantations. At the species-level, food exploitation rates varied idiosyncratically between habitats. At the assemblage-level, food exploitation rates were reduced in L. confertus plantations. Our results reveal that plantation establishments alter the diet and foraging behaviour of omnivorous ants. Such changes suggest that omnivorous ants in plantations will have reduced top-down impacts on prey communities but also see an increased importance of protein as a bottom-up force in constraining omnivore population sizes.
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http://dx.doi.org/10.1111/1365-2656.13249DOI Listing
August 2020

Increased Suitability of Poleward Climate for a Tropical Butterfly (Euripus nyctelius) (Lepidoptera: Nymphalidae) Accompanies its Successful Range Expansion.

J Insect Sci 2019 Nov;19(6)

School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong, China.

Distribution shifts are a common response in butterflies to a warming climate. Hong Kong has documented records of several new butterfly species in recent decades, comprising a high proportion of tropical species, some of which have successfully established. In this study, we examined possible drivers for the establishment of Euripus nyctelius Doubleday (Lepidoptera: Nymphalidae) by studying its thermal physiology and modeling current climate and future distributions projected by species distribution modeling (SDM). We found that E. nyctelius adults have a significantly higher critical thermal minimum than its local temperate relative, Hestina assimilis Linnaeus (Lepidoptera: Nymphalidae), suggesting a possible physiological constraint that may have been lifted with recent warming. SDMs provide further evidence that a shifting climate envelope may have improved the climate suitability for E. nyctelius in Hong Kong and South China-however, we cannot rule out the role of other drivers potentially influencing or driving range expansion, habitat change in particular. Conclusive attribution of warming-driven impacts for most tropical species is difficult or not possible due to a lack of historical or long-term data. Tropical insects will require a significant advancement in efforts to monitor species and populations across countries if we are to conclusively document climate-driven shifts in species distributions and manage the consequences of such species redistribution. Nevertheless, the warming climate and subsequent increased climatic suitability for tropical species in poleward areas, as shown here, is likely to result in future species redistribution events in subtropical and temperate ecosystems.
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http://dx.doi.org/10.1093/jisesa/iez105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839647PMC
November 2019

Conservation Success through IPBES-Guided Transformative Change.

Trends Ecol Evol 2019 11 7;34(11):970-971. Epub 2019 Oct 7.

School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong; Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia. Electronic address:

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http://dx.doi.org/10.1016/j.tree.2019.08.010DOI Listing
November 2019

Subtropical thermal variation supports persistence of corals but limits productivity of coral reefs.

Proc Biol Sci 2019 07 17;286(1907):20190882. Epub 2019 Jul 17.

The Swire Institute of Marine Science, University of Hong Kong, Hong Kong, People's Republic of China.

Concomitant to the decline of tropical corals caused by increasing global sea temperatures is the potential removal of barriers to species range expansions into subtropical and temperate habitats. In these habitats, species must tolerate lower annual mean temperature, wider annual temperature ranges and lower minimum temperatures. To understand ecophysiological traits that will impact geographical range boundaries, we monitored populations of five coral species within a marginal habitat and used a year of in situ measures to model thermal performance of vital host, symbiont and holobiont physiology. Metabolic responses to temperature revealed two acclimatization strategies: peak productivity occurring at annual midpoint temperatures (4-6°C lower than tropical counterparts), or at annual maxima. Modelled relationships between temperature and P:R were compared to a year of daily subtropical sea temperatures and revealed that the relatively short time spent at any one temperature, limited optimal performance of all strategies to approximately half the days of the year. Thus, while subtropical corals can adjust their physiology to persist through seasonal lows, seasonal variation seems to be the key factor limiting coral productivity. This constraint on rapid reef accretion within subtropical environments provides insight into the global distribution of future coral reefs and their ecosystem services.
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http://dx.doi.org/10.1098/rspb.2019.0882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6661340PMC
July 2019

Integrating Proximal and Horizon Threats to Biodiversity for Conservation.

Trends Ecol Evol 2019 09 23;34(9):781-788. Epub 2019 May 23.

School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China; Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia. Electronic address:

Global conservation promotes solutions to different dimensions of threat and response: land-use change, climate change, pollution, and so forth. Countering each threat has its band of proponents who advocate for their cause as paramount, increasingly, given limited resources, by downplaying the relative importance of others. Not only does this encourage a compartmentalised view of the world, which is ecologically unsound, it allows politicians and others to cherry-pick responses in light of political expediency or local demands. We should instead aim to achieve win-win conservation strategies that address multiple threats to diversity acting at different timescales, as well as 'horizon threats', which occur at large scales and may be the most challenging conservation issues to address in both the present and the future.
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http://dx.doi.org/10.1016/j.tree.2019.04.001DOI Listing
September 2019

Multifunctional behaviour in a sandy shore crab enhances performance in extreme intertidal environments.

Oecologia 2019 Jan 12;189(1):79-89. Epub 2018 Nov 12.

The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China.

Soft sediment shores in the tropics are highly dynamic environments, where behavioural patterns of organisms are constrained by tidal conditions, and environmental temperatures during an organisms' activity periods can exceed their thermal tolerance levels. In such extreme habitats, behavioural responses to environmental changes are key to survival, driving differential performance. We investigated sponging behaviour (water uptake from sediments) of the deposit-feeding crab, Scopimera intermedia, on tropical sandy shores to determine its thermoregulatory function. The thermal physiology of the crabs and their habitat conditions were quantified by measuring thermal performance curves and recording environmental temperatures during the crabs' activity periods. Environmental temperatures were combined with experimental data to investigate the role of sponging on the thermal performances of the crabs by simulating field body temperatures. Sponging rate was strongly and positively correlated with feeding rate, as sponging replenishes water for flotation feeding. Sponging, however, also reduced body temperatures on average by 1.3 °C. Simulated populations of crabs which were unable to sponge had more variable body temperatures, which exceeded the critical thermal maximum of the crabs (~ 39 °C) nearly 2000 times more often than crabs able to sponge. Sponging is, therefore, a multifunctional behavioural trait important for both feeding and thermoregulation. The evolution of such multifunctional traits is likely to be a widespread, but overlooked phenomenon in intertidal species, as maintaining a functional body temperature is energetically costly in habitats where environmental conditions fluctuate strongly such as on tropical shores.
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http://dx.doi.org/10.1007/s00442-018-4299-8DOI Listing
January 2019

Seasonal Polyphenism in Bicyclus dorothea (Lepidoptera: Nymphalidae) Across Different Habitats in Cameroon.

Environ Entomol 2018 12;47(6):1601-1608

Laboratory of Parasitology and Ecology, University of Yaoundé I, Faculty of Science, Yaoundé, Cameroon.

Many organisms exhibit changes in phenotypic traits as a response to seasonal environmental variation. We investigated the role of habitat in generating seasonal polyphenism in different populations of the light bush brown butterfly Bicyclus dorothea (Cramer, 1779) (Lepidoptera: Nymphalidae) in Cameroon. Butterflies were caught during the wet and dry seasons across four localities representing two distinct habitats, namely forest and ecotone (forest-savanna transition zone) over a 2-yr period (2015-2016). We found distinct variation in the wing pattern characteristics of butterflies in response to seasonality and habitat. Specifically we observed that: 1) all wing characters are not seasonally plastic in B. dorothea; 2) populations from ecotone tend to be more variable, with individuals exhibiting wings with large spots during the wet season and very reduced spots in the dry season while in forest populations, individuals exhibit wings with large spots during the wet season, but in the dry season, spots are not as greatly reduced as their ecotone counterparts; 3) this polyphenism in B. dorothea alternated consistently during the wet and dry seasons over the 2 yr of sampling. Bicyclus species have become a textbook example of seasonal polyphenism while this study extends this model system to the unique forest-ecotone gradient of Central Africa and demonstrates the complexity of seasonal forms in different habitats.
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http://dx.doi.org/10.1093/ee/nvy135DOI Listing
December 2018

BioTIME: A database of biodiversity time series for the Anthropocene.

Glob Ecol Biogeogr 2018 Jul 24;27(7):760-786. Epub 2018 Jul 24.

German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

Main Types Of Variables Included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

Spatial Location And Grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km (158 cm) to 100 km (1,000,000,000,000 cm).

Time Period And Grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

Major Taxa And Level Of Measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Software Format: .csv and .SQL.
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http://dx.doi.org/10.1111/geb.12729DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099392PMC
July 2018

Colors of night: climate-morphology relationships of geometrid moths along spatial gradients in southwestern China.

Oecologia 2018 Oct 11;188(2):537-546. Epub 2018 Jul 11.

CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China.

Color lightness of insects is an important ecological trait affecting their performance through multiple functions such as thermoregulation, UV protection and disease resistance. The geographical pattern of color lightness in diurnal insects are relatively well understood and largely driven by thermal melanism through the enhancement of insect activity. In nocturnal insects, however, the ecological function of color lightness in response to climatic factors is poorly understood, particularly at small spatial scales. In this study, we investigated color lightness of nocturnal moth assemblages along environmental gradients. Using geometrid moths collected with comparable methodologies (light trapping), we examined assemblage-level changes in color lightness across elevational gradients and vertical strata (canopy vs understory) across three climatically different locations in Yunnan, China. The results showed that moths are darker in color at higher elevations. Such patterns are most apparent in canopy assemblages. In addition, the strength of the elevational pattern on color lightness varied across location, being most pronounced in the canopy of the subalpine site. These patterns are likely driven by UV protection and/or thermoregulation. Our study highlights the importance of abiotic factors such as temperature and solar radiation in structuring morphological patterns of nocturnal ectothermic assemblages along elevational gradients of climatically harsh environments.
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http://dx.doi.org/10.1007/s00442-018-4219-yDOI Listing
October 2018

Deterred but not preferred: Predation by native whelk Reishia clavigera on invasive bivalves.

PLoS One 2018 16;13(5):e0196578. Epub 2018 May 16.

The Swire Institute of Marine Science, Faculty of Science, The University of Hong Kong, Shek O, Hong Kong, China.

This study tested the potential bio-control role of the common native predatory whelk Reishia clavigera on the invasive bivalves Xenostrobus securis and Mytilopsis sallei and the native Brachidontes variabilis in Hong Kong. Predation experiments were conducted in the laboratory under salinity levels of 22‰ and 32‰, as well as under field conditions. The results indicate that the invasive bivalves are more vulnerable to predation than the native bivalve in environments with high salinity, whereas environments with moderately low salinity (22‰) may reduce predation. Because R. clavigera did not show clear prey preference, the low survival of the invasive species might be due to a lack of effective anti-predatory defenses under experimental conditions. These findings could explain the high abundance of the invasive bivalves in disturbed environments in Hong Kong where predation appears to be lower.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0196578PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5955525PMC
August 2018

Land-Use Change Alters Host and Vector Communities and May Elevate Disease Risk.

Ecohealth 2019 12 24;16(4):647-658. Epub 2018 Apr 24.

School of Biological Sciences, University of Hong Kong, Hong Kong, China.

Land-use change has transformed most of the planet. Concurrently, recent outbreaks of various emerging infectious diseases have raised great attention to the health consequences of anthropogenic environmental degradation. Here, we assessed the global impacts of habitat conversion and other land-use changes on community structures of infectious disease hosts and vectors, using a meta-analysis of 37 studies. From 331 pairwise comparisons of disease hosts/vectors in pristine (undisturbed) and disturbed areas, we found a decrease in species diversity but an increase in body size associated with land-use changes, potentially suggesting higher risk of infectious disease transmission in disturbed habitats. Neither host nor vector abundance, however, changed significantly following disturbance. When grouped by subcategories like disturbance type, taxonomic group, pathogen type and region, changes in host/vector community composition varied considerably. Fragmentation and agriculture in particular benefit host and vector communities and therefore might elevate disease risk. Our results indicate that while habitat disturbance could alter disease host/vector communities in ways that exacerbate pathogen prevalence, the relationship is highly context-dependent and influenced by multiple factors.
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http://dx.doi.org/10.1007/s10393-018-1336-3DOI Listing
December 2019

Land-use change interacts with climate to determine elevational species redistribution.

Nat Commun 2018 04 3;9(1):1315. Epub 2018 Apr 3.

School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, 999077, China.

Climate change is driving global species redistribution with profound social and economic impacts. However, species movement is largely constrained by habitat availability and connectivity, of which the interaction effects with climate change remain largely unknown. Here we examine published data on 2798 elevational range shifts from 43 study sites to assess the confounding effect of land-use change on climate-driven species redistribution. We show that baseline forest cover and recent forest cover change are critical predictors in determining the magnitude of elevational range shifts. Forest loss positively interacts with baseline temperature conditions, such that forest loss in warmer regions tends to accelerate species' upslope movement. Consequently, not only climate but also habitat loss stressors and, importantly, their synergistic effects matter in forecasting species elevational redistribution, especially in the tropics where both stressors will increase the risk of net lowland biotic attrition.
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http://dx.doi.org/10.1038/s41467-018-03786-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883048PMC
April 2018

Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders.

PeerJ 2017 12;5:e4070. Epub 2017 Dec 12.

School of Biological Sciences, The University of Hong Kong, Hong Kong.

Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator-prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings) and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution's disruption of species interactions.
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http://dx.doi.org/10.7717/peerj.4070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731334PMC
December 2017

Managing consequences of climate-driven species redistribution requires integration of ecology, conservation and social science.

Biol Rev Camb Philos Soc 2018 02 1;93(1):284-305. Epub 2017 Jun 1.

Institute of Zoology, Zoological Society of London, NW1 4RY, London, U.K.

Climate change is driving a pervasive global redistribution of the planet's species. Species redistribution poses new questions for the study of ecosystems, conservation science and human societies that require a coordinated and integrated approach. Here we review recent progress, key gaps and strategic directions in this nascent research area, emphasising emerging themes in species redistribution biology, the importance of understanding underlying drivers and the need to anticipate novel outcomes of changes in species ranges. We highlight that species redistribution has manifest implications across multiple temporal and spatial scales and from genes to ecosystems. Understanding range shifts from ecological, physiological, genetic and biogeographical perspectives is essential for informing changing paradigms in conservation science and for designing conservation strategies that incorporate changing population connectivity and advance adaptation to climate change. Species redistributions present challenges for human well-being, environmental management and sustainable development. By synthesising recent approaches, theories and tools, our review establishes an interdisciplinary foundation for the development of future research on species redistribution. Specifically, we demonstrate how ecological, conservation and social research on species redistribution can best be achieved by working across disciplinary boundaries to develop and implement solutions to climate change challenges. Future studies should therefore integrate existing and complementary scientific frameworks while incorporating social science and human-centred approaches. Finally, we emphasise that the best science will not be useful unless more scientists engage with managers, policy makers and the public to develop responsible and socially acceptable options for the global challenges arising from species redistributions.
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http://dx.doi.org/10.1111/brv.12344DOI Listing
February 2018

Higher predation risk for insect prey at low latitudes and elevations.

Science 2017 May;356(6339):742-744

Institute of Entomology, Biology Centre of the Czech Academy of Sciences (CAS), Branisovska 31, 37005 Ceske Budejovice, Czech Republic.

Biotic interactions underlie ecosystem structure and function, but predicting interaction outcomes is difficult. We tested the hypothesis that biotic interaction strength increases toward the equator, using a global experiment with model caterpillars to measure predation risk. Across an 11,660-kilometer latitudinal gradient spanning six continents, we found increasing predation toward the equator, with a parallel pattern of increasing predation toward lower elevations. Patterns across both latitude and elevation were driven by arthropod predators, with no systematic trend in attack rates by birds or mammals. These matching gradients at global and regional scales suggest consistent drivers of biotic interaction strength, a finding that needs to be integrated into general theories of herbivory, community organization, and life-history evolution.
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http://dx.doi.org/10.1126/science.aaj1631DOI Listing
May 2017

Biodiversity redistribution under climate change: Impacts on ecosystems and human well-being.

Science 2017 03;355(6332)

Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.
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http://dx.doi.org/10.1126/science.aai9214DOI Listing
March 2017

The recently introduced bivalve Xenostrobus securis has higher thermal and salinity tolerance than the native Brachidontes variabilis and established Mytilopsis sallei.

Mar Pollut Bull 2017 May 2;118(1-2):229-236. Epub 2017 Mar 2.

The Swire Institute of Marine Science, Faculty of Science, The University of Hong Kong, Cape d'Aguilar Road, Shek O, Hong Kong, China; School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Simon F.S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.

The recently introduced bivalve Xenostrobus securis and the previously introduced Mytilopsis sallei (~30years) are dominant over the native Brachidontes variabilis in estuarine fouling communities in Hong Kong. This study tested whether these introduced species have higher thermal and salinity tolerance than the native species under local subtropical seawater conditions. Survival, attachment, clearance rate and byssal thread production of these three species were examined through 96-h acute temperature and salinity tests. The results indicated that X. securis responded normally over a wide range of temperature and salinity conditions. Though M. sallei exhibited a wide salinity tolerance, its sub-lethal responses decreased in cold-seawater conditions. Brachidontes variabilis had the narrowest tolerance to temperature and salinity. These findings may explain the dominance of the non-native bivalves over B. variabilis. The high tolerance of X. securis enables them to become highly invasive in subtropical regions across Southeast Asia, impacting natural communities and shellfish farming.
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http://dx.doi.org/10.1016/j.marpolbul.2017.02.046DOI Listing
May 2017

Cool habitats support darker and bigger butterflies in Australian tropical forests.

Ecol Evol 2016 Nov 14;6(22):8062-8074. Epub 2016 Oct 14.

Department of Wildlife Ecology and Conservation University of Florida Gainesville FL 32611 USA.

Morphology mediates the relationship between an organism's body temperature and its environment. Dark organisms, for example, tend to absorb heat more quickly than lighter individuals, which could influence their responses to temperature. Therefore, temperature-related traits such as morphology may affect patterns of species abundance, richness, and community assembly across a broad range of spatial scales. In this study, we examined variation in color lightness and body size within butterfly communities across hot and cool habitats in the tropical woodland-rainforest ecosystems of northeast Queensland, Australia. Using thermal imaging, we documented the absorption of solar radiation relative to color lightness and wingspan and then built a phylogenetic tree based on available sequences to analyze the effects of habitat on these traits within a phylogenetic framework. In general, darker and larger individuals were more prevalent in cool, closed-canopy rainforests than in immediately adjacent and hotter open woodlands. In addition, darker and larger butterflies preferred to be active in the shade and during crepuscular hours, while lighter and smaller butterflies were more active in the sun and midday hours-a pattern that held after correcting for phylogeny. Our ex situ experiment supported field observations that dark and large butterflies heated up faster than light and small butterflies under standardized environmental conditions. Our results show a thermal consequence of butterfly morphology across habitats and how environmental factors at a microhabitat scale may affect the distribution of species based on these traits. Furthermore, this study highlights how butterfly species might differentially respond to warming based on ecophysiological traits and how thermal refuges might emerge at microclimatic and habitat scales.
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http://dx.doi.org/10.1002/ece3.2464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108258PMC
November 2016

Cooler performance breadth in a viviparous skink relative to its oviparous congener.

J Therm Biol 2016 Oct 5;61:106-114. Epub 2016 Sep 5.

School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, China. Electronic address:

Susceptibility of species to climate change varies depending on many biological and environmental traits, such as reproductive mode and climatic exposure. For example, wider thermal tolerance breadths are associated with more climatically variable habitats and viviparity could be associated with greater vulnerability relative to oviparity. However, few examples exist detailing how such physiological and environmental traits together might shape species thermal performance. In this study we compared the thermal tolerance and performance of two sympatric skink congeners in Hong Kong that differ in habitat use and reproductive mode. The viviparous Sphenomorphus indicus lives on the forest floor while the oviparous Sphenomorphus incognitus occupies stream edges. We quantified the thermal environments in each of these habitats to compare climatic exposure and then calculated thermal safety margins, potential daily activity times within each species' thermal optimal range, and possible climate change vulnerability. Although we did not detect any differences in thermal tolerance range or thermal environments across habitats, we found cooler performance in S. indicus relative to S. incognitus. Moreover, while optimal activity time increases for both skinks under a warming scenario, we project that the thermal safety margin of S. indicus would narrow to nearly zero, thus losing its buffering capacity to potential extreme climate events in the future. This research is thus consistent with recent studies emphasizing the vulnerability of viviparous reptiles to a warming climate. The results together furthermore highlight the complexity in how environmental and physiological traits at multiple spatial scales structure climate change vulnerability of ectothermic species.
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http://dx.doi.org/10.1016/j.jtherbio.2016.09.003DOI Listing
October 2016

Seasonal heterogeneity provides a niche opportunity for ascidian invasion in subtropical marine communities.

Mar Environ Res 2016 Dec 10;122:1-10. Epub 2016 Sep 10.

School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China. Electronic address:

Implications of changes in environmental conditions caused by seasonality and human alterations on the recruitment of non-native species and their biotic resistance to predation are poorly understood. Here, through the use of experimental recruitment panels and predation exclusion cages, we examined 1) whether a subtropical seasonality (i.e., tropical and temperate conditions) affects the recruitment and abundance of the non-native ascidian Ciona intestinalis, the cryptogenic Styela plicata and Ascidia sydneiensis, and native Hermandia momus in fouling communities in Hong Kong, 2) whether human environmental alterations (i.e., typhoon shelters and sheltered bays with different habitat alteration and seawater quality) affect the abundance of the ascidians, and 3) whether predation reduces the abundance of ascidians under different environmental conditions caused by seasonality and human alteration. Our experimental results indicate that seasonality provides a temporal niche for the recruitment of the ascidians; C. intestinalis and S. plicata recruited mostly in winter, whereas A. sydneiensis and H. momus recruited in summer. Ciona intestinalis was the only ascidian that prospered in anthropogenically altered environments where it monopolized communities. The marked seasonal recruitment of the ascidians obscured the effect of predation between seasons, whereas human alteration did not affect predation. The recruitment of the ascidians in subtropical communities appeared to correspond to their original temperate or tropical distributions, hence Ciona intestinalis, with a temperate native distribution, benefits from a temporal niche opportunity during winter conditions. We argue that seasonality, as an important ecological factor for recruitment and community ecology dynamics, must also be considered in the context of biological invasion.
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http://dx.doi.org/10.1016/j.marenvres.2016.09.001DOI Listing
December 2016

Low frequency dove coos vary across noise gradients in an urbanized environment.

Behav Processes 2016 Aug 3;129:86-93. Epub 2016 Jun 3.

Department of Earth Sciences, University of Hong Kong, Hong Kong. Electronic address:

Urbanization poses a challenge to bird communication due to signal masking by ambient noise and reflective surfaces that lead to signal degradation. Bird species (especially oscines) have been shown to alter their singing behaviour to increase signal efficiency in highly urbanized environments. However, few studies on the effects of noise on song structure have included birds with low frequency vocal signals which may be especially vulnerable to noise pollution due to significant frequency overlap of their signals with traffic noise. We compared the perch coos of spotted doves (Streptopelia chinensis), a species with very low frequency vocalizations, in different background noise levels across urban and peri-urban areas in Hong Kong. We documented a 10% upward shift in the minimum frequency of coos of spotted doves across the noise gradient (a relatively small but significant shift), and a reduced maximum frequency in urban habitats with a higher density of built up area. Hong Kong doves had significantly higher minimum and maximum frequencies than doves from throughout their range (from mostly rural sites). Our results indicate that urban species with extremely low sound frequencies such as doves can alter their vocalizations in response to variable urban acoustic environments.
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http://dx.doi.org/10.1016/j.beproc.2016.06.002DOI Listing
August 2016

From global change to a butterfly flapping: biophysics and behaviour affect tropical climate change impacts.

Proc Biol Sci 2014 Oct;281(1793)

Department of Biology, Stanford University, Stanford, CA 94305, USA.

Difficulty in characterizing the relationship between climatic variability and climate change vulnerability arises when we consider the multiple scales at which this variation occurs, be it temporal (from minute to annual) or spatial (from centimetres to kilometres). We studied populations of a single widely distributed butterfly species, Chlosyne lacinia, to examine the physiological, morphological, thermoregulatory and biophysical underpinnings of adaptation to tropical and temperate climates. Microclimatic and morphological data along with a biophysical model documented the importance of solar radiation in predicting butterfly body temperature. We also integrated the biophysics with a physiologically based insect fitness model to quantify the influence of solar radiation, morphology and behaviour on warming impact projections. While warming is projected to have some detrimental impacts on tropical ectotherms, fitness impacts in this study are not as negative as models that assume body and air temperature equivalence would suggest. We additionally show that behavioural thermoregulation can diminish direct warming impacts, though indirect thermoregulatory consequences could further complicate predictions. With these results, at multiple spatial and temporal scales, we show the importance of biophysics and behaviour for studying biodiversity consequences of global climate change, and stress that tropical climate change impacts are likely to be context-dependent.
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http://dx.doi.org/10.1098/rspb.2014.1264DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4173678PMC
October 2014

Fire management, managed relocation, and land conservation options for long-lived obligate seeding plants under global changes in climate, urbanization, and fire regime.

Conserv Biol 2014 Aug 8;28(4):1057-67. Epub 2014 Mar 8.

Department of Earth Sciences, School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China; Biology Department, University of California, Riverside, CA 92521, U.S.A.

Most species face multiple anthropogenic disruptions. Few studies have quantified the cumulative influence of multiple threats on species of conservation concern, and far fewer have quantified the potential relative value of multiple conservation interventions in light of these threats. We linked spatial distribution and population viability models to explore conservation interventions under projected climate change, urbanization, and changes in fire regime on a long-lived obligate seeding plant species sensitive to high fire frequencies, a dominant plant functional type in many fire-prone ecosystems, including the biodiversity hotspots of Mediterranean-type ecosystems. First, we investigated the relative risk of population decline for plant populations in landscapes with and without land protection under an existing habitat conservation plan. Second, we modeled the effectiveness of relocating both seedlings and seeds from a large patch with predicted declines in habitat area to 2 unoccupied recipient patches with increasing habitat area under 2 projected climate change scenarios. Finally, we modeled 8 fire return intervals (FRIs) approximating the outcomes of different management strategies that effectively control fire frequency. Invariably, long-lived obligate seeding populations remained viable only when FRIs were maintained at or above a minimum level. Land conservation and seedling relocation efforts lessened the impact of climate change and land-use change on obligate seeding populations to differing degrees depending on the climate change scenario, but neither of these efforts was as generally effective as frequent translocation of seeds. While none of the modeled strategies fully compensated for the effects of land-use and climate change, an integrative approach managing multiple threats may diminish population declines for species in complex landscapes. Conservation plans designed to mitigate the impacts of a single threat are likely to fail if additional threats are ignored.
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http://dx.doi.org/10.1111/cobi.12253DOI Listing
August 2014

Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics.

Mol Ecol 2012 Jul 30;21(14):3576-92. Epub 2012 May 30.

Department of Biology, Stanford University, Stanford, CA 94305, USA.

The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.
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http://dx.doi.org/10.1111/j.1365-294X.2012.05618.xDOI Listing
July 2012