Biology subjects

Tanentzap, A. J.

Publications and source records attributed to Tanentzap, A. J..

11 recordsLinked to original sources

bioRxiv2025

Sediment chemistry controls methane emissions from lake littoral zones

Methane emissions from the nearshore zones of lakes are relatively large but can vary by several orders of magnitude. Here we compared predictions for how sediment chemistry and microbial communities influenced methane emissions from 19 littoral sites in the UK varying in organic matter sources and microbial composition. Our approach was to compare multiple predictions to explain methane fluxes from sediment chemistry and microbial composition using path analysis. We found that the prediction that organic matter composition, namely the concentration of polyphenolics, controls methane emissions by changing electrochemical conditions to favour certain methanogen taxa was hundreds of times better supported than predictions involving abundances of all methanogens and methanotrophic bacteria, methanogen diversity, or other physicochemical conditions. Diffusive CH4 fluxes were estimated to increase by 3.1- to 16.6-times (95% confidence interval) with increasing polyphenolic concentrations, almost entirely because they lower reduction-oxidation potentials that shift methanogen composition towards widespread taxa positively associated with methanogenesis. Rather than strongly inhibiting methane-producing microorganisms, our results suggest polyphenolics change reduction-oxidation potentials to favour acetoclastic and methylotrophic methanogens. These results help explain conflicting evidence about the responses of methane to sediment chemistry and can improve future predictions of aquatic carbon cycling. Manuscript HighlightsO_LIPolyphenolics predicted nearshore CH4 fluxes better than other environmental factors C_LIO_LICH4 fluxes increased with polyphenolics that lowered redox to favour methanogenesis C_LIO_LIWe help explain conflicting responses of CH4 to variation in sediment chemistry C_LI

ecology↗

bioRxiv2025

Chemical diversity promotes ecosystem function

Nature benefits people in many ways that rely on how microorganisms and abiotic processes interact with organic matter to influence ecosystem function (EF). Despite many studies evaluating how biodiversity affects EF, most variation in EF remains unexplained. Here, we tested how the variety of organic compounds in the environment, termed chemodiversity, influences EF. Using a laboratory experiment and 101-lake survey spanning Europe, we discovered that chemodiversity, not biodiversity, consistently explained variation in multiple functions related to carbon cycling and ecosystem metabolism. We attributed positive chemodiversity-ecosystem multifunctionality relationships to the accumulation of compounds that could be biochemically transformed in more diverse ways at higher chemodiversity. We estimated chemodiversity will decline by 2100 due to changes in organic matter sources, causing European lakes to emit, on average, 1.6-times more carbon. These findings reframe our understanding of ecosystem functioning and suggest chemodiversity is key to sustain the benefits that nature delivers to people.

ecology↗

bioRxiv2023

Winners and losers under past and future climate change

Understanding the historical and physiological context of species vulnerabilities to climate change is a crucial step in predicting "winners" and "losers" under climate change. However, few studies have compared the magnitude and mechanisms of extant species responses to climate change in both the past and the future. By combining temporally contrasting range and niche projections, we show that range shifts in the next 50 years will need to be more extreme than in the past 6000 years to track climate niches in a large plant radiation. A new subset of physiological niche traits, particularly temperature and radiation tolerance, will be strong filters of range occupancy under anthropogenic compared with Holocene climate change. In the absence of migration, temperature niche shifts tracking the magnitude of climate change will also be required for many species to maintain their present ranges. Where range shifts occur, our results suggest that communities will be restructured differently in different habitats, with widespread range contraction in the mountains and potential latitudinal range expansion in the lowlands. Our study adds to a growing body of evidence that despite the threats posed by climate change to many species, not all species will experience unmitigated loss, and that it may be possible to predict which species are most at risk based on physiological and geographical traits.

ecology↗

bioRxiv2023

Logging disrupts the ecology of molecules in headwater streams

Global demand for wood products is increasing forest harvest. One understudied consequence of logging is that it accelerates mobilization of dissolved organic matter (DOM) from soils to aquatic ecosystems. Here, we tested how logging changed DOM in headwaters of hardwood-dominated catchments in northern Ontario, Canada. We apply a before-after control-impact experiment across four catchments for three years. DOM concentration in streams from logged catchments quadrupled, on average, after the first year post-harvest, but resulting changes to the molecular composition of DOM persisted for at least two-years. Ultrahigh-resolution mass spectrometry revealed that DOM within logged catchments was more energy-rich and chemically diverse than in controls, with novel highly unsaturated polyphenols, carboxylic-rich alicyclic, and nitrogen-containing formulae. The molecular composition of stream DOM measured fortnightly post-harvest was most strongly associated with DOM composition within intermediate and deeper layers of contributing soils, likely due to increased hydrological connectivity post-harvest. We estimate logging increased the total annual flux of dissolved organic carbon in streams by 6.4% of extracted wood carbon, and this carbon was more likely to be released into the atmosphere. Carbon accounting of forestry, including as a natural climate solution, must now consider the transport and fate of DOM from land into water.

ecology↗

bioRxiv2022

Universal microbial reworking of dissolved organic matter along environmental gradients

Soils are losing increasing amounts of carbon annually to freshwaters as dissolved organic matter (DOM), which, if degraded, can accelerate climate change. DOM is more susceptible to degradation closer to its source and becomes increasingly dominated by the same, difficult-to-degrade compounds as degradation proceeds. However, the processes underlying DOM degradation across environments are poorly understood. Here we found DOM changed similarly along soil-aquatic gradients irrespective of differences in environmental conditions. Using ultra-high-resolution mass spectrometry, we tracked DOM along soil depths and hillslope positions in forest headwater catchments and related its composition to soil microbiomes and physical chemistry. Along depths and hillslopes, carbohydrate-like and unsaturated hydrocarbon-like compounds increased in mass, suggestive of microbial reworking of plant material. More than half of the variation in the abundance of these compounds was related to the expression of genes essential for degrading plant-derived carbohydrates. Our results implicate continuous microbial reworking in shifting DOM towards universal compounds in soils. By synthesising data from the land-to-ocean continuum, we suggest these processes can generalise across ecosystems and spatiotemporal scales. Such general degradation patterns can be leveraged to predict DOM composition and its downstream reactivity along environmental gradients to inform management of soil-to-stream carbon losses.

ecology↗

bioRxiv2021

Quantifying microbial associations of dissolved organic matter under global change

Microbes play a critical role in regulating the size, composition, and turnover of dissolved organic matter (DOM), which is one of the largest pools of carbon in aquatic ecosystems. Global change may alter DOM-microbe associations with implications for biogeochemical cycles, although disentangling these complex interactions remains a major challenge. Here we develop a framework called Energy-Diversity-Trait integrative Analysis (EDTiA) to examine the associations between DOM and bacteria along temperature and nutrient gradients in a manipulative field experiment on mountainsides in contrasting subarctic and subtropical climates. In both study regions, the chemical composition of DOM correlated with bacterial communities, and was primarily controlled by nutrients and to a lesser degree by temperature. At a molecular-level, DOM-bacteria associations depended strongly on the molecular traits of DOM, with negative associations indicative of decomposition as molecules are more biolabile. Using bipartite networks, we further demonstrated that negative associations were more specialized than positive associations indicative of DOM production. Nutrient enrichment promoted specialization of positive associations, but decreased specialization of negative associations particularly at warmer temperatures in subtropical climate. These global change drivers influenced specialization of negative associations most strongly via molecular traits, while both molecular traits and bacterial diversity similarly affected positive associations. Together, our framework provides a quantitative approach to understand DOM-microbe associations and wider carbon cycling across scales under global change.

ecology↗

bioRxiv2021

Predictions of biodiversity are improved by integrating trait-based competition with abiotic filtering

All organisms must simultaneously tolerate the environment and access limiting resources if they are to persist. Otherwise they go extinct. Approaches to understanding environmental tolerance and resource competition have generally been developed independently. Consequently, integrating the factors that determine abiotic tolerance with those that affect competitive interactions to model species abundances and community structure remains an unresolved challenge. This is likely the reason why current models of community assembly do not accurately predict species abundances and dynamics. Here, we introduce a new synthetic framework that models both abiotic tolerance and biotic competition by using functional traits, which are phenotypic attributes that influence organism fitness. First, our framework estimates species carrying capacities that vary along abiotic gradients based on whether the phenotype tolerates the local environment. Second, it estimates pairwise competitive interactions as a function of multidimensional trait differences between species and determines which trait combinations produce the most competitive phenotypes. We demonstrate that our combined approach more than doubles the explained variance of species covers in a wetland community compared to the model of abiotic tolerances alone. Trait-based integration of competitive interactions and abiotic filtering improves our ability to predict species abundances across space, bringing us closer to more accurate predictions of biodiversity structure in a changing world.

ecology↗

bioRxiv2019

Angiosperm speciation speeds up near the poles

Recent evidence has questioned whether the Latitudinal Diversity Gradient (LDG), whereby species richness increases towards the Equator, results from higher rates of speciation in the tropics. Allowing for time heterogeneity in speciation rate estimates for over 60,000 angiosperm species, we found that the LDG does not arise from variation in speciation rates because lineages do not speciate faster in the tropics. These results were consistently retrieved using two other methods to test the association between occupancy of tropical habitats and speciation rates. Our speciation rate estimates were robust to the effects of both undescribed species and missing taxa. Overall, our results show that speciation rates follow an opposite pattern to global variation in species richness. Greater ecological opportunity in the temperate zones, stemming from less saturated communities, higher species turnover or greater environmental change, may ultimately explain these results.

evolutionary biology↗

bioRxiv2018

Different macroevolutionary routes to becoming a biodiversity hotspot

Why is species diversity so unevenly distributed across different regions on Earth? Regional differences in biodiversity may stem from differences in rates of speciation and dispersal and colonization times, but these hypotheses have rarely been tested simultaneously at a global scale. Here we uncovered the routes that generated hotpots of mammal and bird biodiversity by analyzing the tempo and mode of diversification and dispersal within major biogeographic realms. Hotspots in tropical realms had higher rates of speciation whereas those in temperate realms received more immigrant species from their surrounding regions. We also found that hotspots had higher spatial complexity and energy availability, providing a link between the environment and macroevolutionary history. Our study highlights how assessing differences in macroevolutionary history can help to explain why biodiversity varies so much worldwide.

evolutionary biology↗

bioRxiv2017

Climate-driven shifts in sediment chemistry enhance methane production in northern lakes

Freshwater ecosystems are a major source of methane (CH4), contributing 0.65 Pg (in CO2 equivalents) yr-1 towards global carbon (C) emissions and thereby offsetting [~]25% of the terrestrial carbon sink. Most CH4 emissions come from littoral sediments, where large quantities of plant material are decomposed. As climate change is predicted to shift plant community composition, and thus change the quality of inputs into detrital food webs, this can affect CH4 production and have far-reaching consequences for global C emissions. Here we find that variation in polyphenol availability from decomposing organic matter underlies large differences in CH4 production in lake sediments. Production was at least 400-times higher from sediments composed of macrophyte litter compared to terrestrial sources (coniferous and deciduous), which we link to the inhibition of methanogenesis by polyphenol leachates. Applying our estimates to projected northward advances in the distribution of Typha latifolia, a widespread and dominant macrophyte, we find that CH4 production could increase by at least 73% in the lake-rich Boreal Shield ecozone solely due to increases in this one macrophyte species. Our results now suggest that earth system models and carbon budgets should consider the effects of plant communities on sediment chemistry and ultimately CH4 emissions at a global scale.\n\nOne-sentence summaryProduction of methane from lakes is at least 400-times lower when 24 sediments receive forest- as opposed to macrophyte-derived (Typha latifolia) litterfall.

ecology↗

bioRxiv2017

Evolutionarily younger and faster diversifying plants are more threatened by extinction

Extinction threatens many species, yet few factors predict this risk across the plant Tree of Life (ToL). Taxon age is one factor that may associate with extinction if occupancy of geographic and adaptive zones varies with time, but evidence for such an association has been equivocal. Age-dependent occupancy can also influence diversification rates and thus extinction risk where new taxa have small range and population sizes. Here we analysed 509 well-sampled genera from across the plant ToL. We found that a greater proportion of species were threatened by extinction in younger and faster-diversifying genera. Repeating our analyses in two large, well-sampled groups, we found that extinction risk increased with evolutionary age in conifer species but not palms. Potential range size decreased in older, non-threatened conifers more strongly than in threatened taxa, suggesting that range size dynamics may explain differing patterns of extinction risk across the ToL with consequences for biodiversity conservation.

evolutionary biology↗