Biology subjects

Hof, C.

Publications and source records attributed to Hof, C..

9 recordsLinked to original sources

bioRxiv2026

Size- and colour-based mechanisms shape the phenological structure of butterfly communities

O_LISeasonal patterns of species appearances constitute a major component of diversity variation. Theory attributes this phenological structuring of communities to the alignment of life cycles to suitable moments and to constraints of seasonality on development, yet the specific mechanisms operating across taxa remain largely unresolved. In insects, body size and colour are key functional traits that contribute to driving spatial community assembly through their link to thermoregulatory performance and development. C_LIO_LIHere we analyse variation in mean body size and colour lightness of 483 butterfly assemblages across Great Britain and throughout the season to test whether trait alignment with seasonal environment and developmental constraints may shape the phenological structuring of communities. C_LIO_LIBoth body size and body colour varied more along season than across space, emphasizing the importance of phenology on diversity variation. Body size was larger early and late in the season, i.e. under conditions of low temperature and solar radiation. This pattern contrasted with the spatial trends found and was driven by species overwintering as adults, which we interpret as being likely due to energetic constraints. Body colour, conversely, was darker early and late in the season, mirroring the spatial pattern found, and suggesting a thermoregulatory alignment with seasonal conditions. Furthermore, covariation between body size and colour suggests a thermoregulatory interaction between both traits. C_LIO_LIOur findings suggest that life-cycle constraints and seasonal thermoregulatory alignment contribute to shaping the phenological structure of insect communities. C_LI

ecology↗

bioRxiv2025

Metabolic ecology and habitat stability explain the disproportionately high species richness in standing waters

The Metabolic Theory of Ecology (MTE) conceptualizes that temperature is the primary driver of species richness, a pattern well supported in terrestrial taxa but less certain for freshwater organisms. Limited global-scale evidence and frequent violations of MTEs assumptions, particularly the stationarity of body size and abundance, further obscure its applicability. In freshwater systems, body size and abundance are tightly linked to dispersal and range size, which differ markedly between running-water (lotic) and standing-water (lentic) species, as proposed by the Habitat-Stability-Dispersal Hypothesis (HSDH). Adaptations to habitat stability may therefore generate distinct biogeographical trait patterns and modify richness-temperature relationships predicted by MTE. Utilizing comprehensive global functional, phylogenetic, and distributional data on dragonfly and damselfly species (83%) and habitat information (46%), we tested MTE predictions for lentic versus lotic species. Lotic species richness followed MTE expectations (slope: -0.469) more closely than lentic species richness (slope: -0.283). The proportion of lentic species in an assemblage was the strongest predictor of deviation in the species richness-temperature relationship (R2 = 38%). Assemblages dominated by lentic species clustered in climatically unstable regions and mainly including smaller-bodied species with larger ranges. Phylogenetic comparative analysis shows a strong phylogenetic signal in habitat preference, with the most species rich and northernly distributed families comprising predominately lentic species. Our findings suggest that adaptations to habitat stability facilitated the colonization and persistence of lentic species in harsh and fluctuating climates both past and present causing largely divergent species richness patterns of lentic and lotic odonates. Integrating HSDH-related traits (body and range size) not only substantially improves the explanatory power of the MTE, but also reveals a trait syndrome with broad implications for the biogeography and climate change responses of freshwater communities.

ecology↗

bioRxiv2024

Future climate and land use change will equally impact global terrestrial vertebrate diversity

Aim: Terrestrial biodiversity is impacted by both climate and land use change. Yet, future biodiversity projections have rarely considered these two drivers in combination. In this study, we aim to assess the individual and combined impact of future climate and land use change on global terrestrial vertebrate diversity under a "sustainability" (SSP1-RCP2.6) and an "inequality" (SSP4-RCP6.0) scenario. Location: Global land, excluding Antarctica. Time period: 1995, 2080 Major taxa studied: Amphibians, birds, and mammals. Methods: We combined global climate-driven species distribution model (SDM) projections of 13903 vertebrates (amphibians, birds, and mammals) with future and present land use projections from the Land Use Harmonization 2 (LUH2) project. We refined the SDM outputs by the habitat requirements of each species using a land use filtering approach. We then analyzed future species richness changes globally, per region, and per land use category, and looked at taxon-specific effects. Results: Under both scenarios, decreases in future species richness dominate at low and mid-latitudes, with climate and land use change playing an equally important role. Land use change can be either an alleviating (SSP1-RCP2.6) or an exacerbating (SSP4-RCP6.0) factor of climate-induced biodiversity loss. Sub-Saharan Africa is projected to become a high-risk area for future land use-driven biodiversity loss under the SSP4-RCP6.0. Under SSP1-RCP2.6, forested and non-forested land areas increase, while SSP4-RCP6.0 leads to higher rates of deforestation and pasture expansion. Mammals experience the largest climate-driven losses, affecting 56.4% of land area under SSP4-RCP6.0, while amphibians are particularly vulnerable to land use-driven losses, especially under SSP4-RCP6.0. Main conclusions: Our results suggest that both climate and land use pressures on biodiversity will be highest in lower latitudes, which harbor the highest levels of biodiversity.

ecology↗

bioRxiv2024

FT-IR micro-spectroscopy for imaging the extracellular matrix composition in biofilms

Microorganisms form granules by embedding themselves in an extracellular matrix through the secretion of extracellular polymeric substances (EPS). The extracellular matrix is a complex structure comprising of e.g. proteins, polysaccharides, lipids, and extracellular DNA. Understanding the function of individual EPS components within the matrix not only requires knowledge on the composition of the extracellular matrix, but also on the spatial distribution of said components. Molecular imaging like e.g. fluorescence microscopy have been used for the visualization of the extracellular matrix, but these target specific molecules. Untargeted approaches like FT-IR micro-spectroscopy would allow for a broader exploration. In this study FT-IR micro-spectroscopy analysis was implemented on sliced anaerobic granular sludge to explore the EPS distribution. Visualization of single wavenumber absorbance showed a higher polysaccharide content in the EPS at the granule perimeter, shifting to a higher protein concentration toward the centre. The boundary of this shift was approximately 150 {micro}m from the surface, which was in accordance with the layer of fermentative bacteria described in literature. The complexity in the polymer composition meant that many functional groups were overlapping, making FT-IR annotation challenging. To address this, principal component analysis and two-dimensional correlation spectroscopy analysis were included in the analysis. These methods enabled the identification of overlapping functional groups and correlations between functional groups. Positive correlations between protein and polysaccharide functional groups suggested the presence of glycoproteins, which has been regularly described in chemical EPS analysis studies. Additionally, correlations between sulfated compounds and protein/polysaccharide functional groups indicated potential co-localization in the extracellular matrix. Differences in positive correlations of sialic acids with polysaccharides suggest variations in polysaccharide compositions, possibly caused by differences in the microbial community.

microbiology↗

bioRxiv2022

Potential future climate change effects on global reptile distribution and diversity

AimUntil recently, complete information on global reptile distributions has not been widely available. Here, we provide the first comprehensive climate impact assessment for reptiles on a global scale. LocationGlobal, excluding Antarctica Time period1995, 2050, 2080 Major taxa studiedReptiles MethodsWe modelled the distribution of 6,296 reptile species and assessed potential global as well as realm-specific changes in species richness, the change in global species richness across climate space, and species-specific changes in range extent, overlap and position under future climate change. To assess the future climatic impact on 3,768 range-restricted species, which could not be modelled, we compared the future change in climatic conditions between both modelled and non-modelled species. ResultsReptile richness was projected to decline significantly over time, globally but also for most zoogeographic realms, with the greatest decrease in Brazil, Australia and South Africa. Species richness was highest in warm and moist regions, with these regions being projected to shift further towards climate extremes in the future. Range extents were projected to decline considerably in the future, with a low overlap between current and future ranges. Shifts in range centroids differed among realms and taxa, with a dominating global poleward shift. Non-modelled species were significantly stronger affected by projected climatic changes than modelled species. Main conclusionsWith ongoing future climate change, reptile richness is likely to decrease significantly across most parts of the world. This effect as well as considerable impacts on species range extent, overlap, and position were visible across lizards, snakes and turtles alike. Together with other anthropogenic impacts, such as habitat loss and harvesting of species, this is a cause for concern. Given the historical lack of global reptile distributions, this calls for a reassessment of global reptile conservation efforts, with a specific focus on anticipated future climate change.

ecology↗

bioRxiv2022

How to resolve conflicting conservation objectives: A decision support tool for the global selection of multi-purpose protected areas

The establishment and maintenance of protected areas (PAs) is viewed as a key action in delivering post-2020 biodiversity targets. PAs often need to meet multiple objectives, ranging from biodiversity protection to ecosystem service provision and climate change mitigation, but available land and conservation funding is limited. Therefore, optimizing resources by selecting the most beneficial PAs is vital. Here, we advocate for a flexible and transparent approach to selecting protected areas based on multiple objectives, and illustrate this with a decision support tool on a global scale. The tool allows weighting and prioritization of different conservation objectives according to user-specified preferences, as well as real-time comparison of the selected areas that result from such different priorities. We apply the tool across 1347 terrestrial PAs and highlight frequent trade-offs among different objectives, e.g., between species protection and ecosystem integrity. Outputs indicate that decision makers frequently face trade-offs among conflicting objectives. Nevertheless, we show that transparent decision-support tools can reveal synergies and trade-offs associated with PA selection, thereby helping to illuminate and resolve land-use conflicts embedded in divergent societal and political demands and values.

ecology↗

bioRxiv2020

Climate change impacts on the phylogenetic diversity of the world's terrestrial birds: more than species numbers

Ongoing climate change is a major threat to biodiversity and impacts on species distributions and abundances are already evident. Heterogenous responses of species due to varying abiotic tolerances and dispersal abilities have the potential to further amplify or ameliorate these impacts through changes in species assemblages. Here we investigate the impacts of climate change on terrestrial bird distributions and, subsequently, on species richness as well as on different aspects of phylogenetic diversity of species assemblages across the globe. We go beyond previous work by disentangling the potential impacts on assemblage phylogenetic diversity of species gains vs. losses under climate change and compare the projected impacts to randomized assemblage changes. We show that climate change might not only affect species numbers and composition of global species assemblages but could also have profound impacts on assemblage phylogenetic diversity, which, across extensive areas, differ significantly from random changes. Both the projected impacts on phylogenetic diversity and on phylogenetic structure vary greatly across the globe. Projected increases in the evolutionary history contained within species assemblages, associated with either increasing phylogenetic diversification or clustering, are most frequent at high northern latitudes. By contrast, projected declines in evolutionary history, associated with increasing phylogenetic over-dispersion or homogenisation, are projected across all continents. The projected widespread changes in the phylogenetic structure of species assemblages show that changes in species richness do not fully reflect the potential threat from climate change to ecosystems. Our results indicate that the most severe changes to the phylogenetic diversity and structure of species assemblages are likely to be caused by species range shifts rather than range reductions and extinctions. Our findings highlight the importance of considering diverse measures in climate impact assessments and the value of integrating species-specific responses into assessments of entire community changes.

ecology↗

bioRxiv2020

Global impacts of climate change on avian functional diversity

Climate change is predicted to drive geographical range shifts in many taxa, leading to the formation of novel species assemblages and fluctuations in species richness worldwide. However, the effect of these changes on functional diversity is not yet fully understood, in part because comprehensive species-level trait data are generally lacking at global scales. Here we use morphometric and ecological trait data for 8269 terrestrial bird species to compare functional diversity (FD) of current and future bird assemblages under a medium emissions scenario. We show that future assemblages are likely to undergo substantial shifts in trait structure, with the direction and magnitude of these shifts varying with geographical location and trophic guild. Specifically, invertivore FD is projected to increase at higher latitudes with concurrent losses at mid-latitudes, reflecting poleward shifts in range, whereas frugivore FD is projected to fluctuate in many tropical regions with major declines in much of South America and New Guinea. We show that these projected changes in FD are generally greater than expected from changing species richness alone, indicating that projected FD changes are primarily driven by the loss or gain of functionally distinct species. Our findings suggest that climate change will drive continental-scale shifts in avian functional diversity, with potentially far-reaching implications for ecosystem functions and resilience.

ecology↗

bioRxiv2017

Metabolism constrains bird and mammal ranges and predicts shifts in response to climate change

AimWe test whether physiological constraints on maximum metabolic rate and the factor by which endotherms can elevate their metabolism (metabolic expansibility) govern cold range limits for mammal and bird species.\n\nLocationGlobal\n\nMethodsWe examine metabolic expansibility at the cold range boundary (MEO_SCPLOWCRBC_SCPLOW) and its trait predictors and then use MEO_SCPLOWCRBC_SCPLOW to project range shifts for 210 mammal and 61 bird species.\n\nResultsWe find evidence for metabolic constraints: the distributions of metabolic expansibility at the cold range boundary peak at similar values for birds (2.7) and mammals (3.2). The right skewed distributions suggest some species have adapted to elevate or evade metabolic constraints. Mammals exhibit greater skew than birds, consistent with their diverse thermoregulatory adaptations and behaviors. Mammal and bird species that are small and occupy low trophic levels exhibit high levels of MEO_SCPLOWCRBC_SCPLOW. Mammals with high MEO_SCPLOWCRBC_SCPLOW tend to hibernate or use torpor. Predicted metabolic rates at the cold range boundaries represent large energetic expenditures (>50% of maximum metabolic rates). We project species to shift their cold range boundaries poleward by an average of 3.9{degrees} latitude by 2070.\n\nMain conclusionsOur analysis suggests that metabolic constraints provide a viable mechanism for projecting cold range boundaries and range shifts in response to climate change for endotherms.

ecology↗