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bioRxiv2023

A Practical Approach to Constructing a Knowledge Graph for Soil Ecological Research

With the rapid accumulation of biodiversity data, data integration has emerged as a hot topic in soil ecology. Data integration has indeed the potential to advance our knowledge of global patterns in soil biodiversity by facilitating large-scale meta-analytical studies of soil ecosystems. However, ecologists are still poorly equipped when it comes to integrating disparate datasets into a unified knowledge graph with well-defined semantics. This paper presents a practical approach to constructing a knowledge graph from heterogeneous and distributed (semi-)structured data sources. To illustrate our approach, we integrate several datasets on the trophic ecology of soil organisms into a trophic knowledge graph and show how information can be retrieved from the graph to support multi-trophic studies.

ecology↗

bioRxiv2023

Site-specific length-biomass relationships of arctic arthropod families are critical for accurate ecological inferences

Arthropods play an essential role in terrestrial ecosystems, not least by forming the food base for insectivorous birds. To better understand such trophic interactions, it is essential to monitor seasonal trajectories in arthropod biomass. Because obtaining direct measurements of the body mass of individual specimens is laborious, these data are often indirectly acquired by utilizing allometric length-biomass relationships based on a correlative parameter, such as body length. Studies on insectivorous birds have often used such relationships with a low taxonomic resolution and/or small sample size and/or adopted regressions calibrated in different biomes. Despite the scientific interest in the ecology of arctic arthropods, no site-specific family-level length-biomass relationships have hitherto been published. Here we present 27 family-specific length-biomass relationships from two sites in the High Arctic: Zackenberg in northeast Greenland and Knipovich in north Taimyr, Russia. We show that length-biomass regressions from different sites within the same biome did not affect estimates of phenology but did result in substantially different estimates of arthropod biomass. Estimates of daily biomass at Zackenberg were on average 24% higher when calculated using regressions for Knipovich compared to using regressions for Zackenberg. Our results illustrate that the use of allometric relationships from different sites can significantly alter the biological interpretation of, for instance, the interaction between insectivorous birds and their arthropod prey. We conclude that length-biomass relationships should be locally established rather than being based on global relationships. SubjectsEcology, Entomology, Terrestrial ecology

ecology↗

bioRxiv2023

Geometry of ecological coexistence and niche differentiation

A fundamental problem in ecology is to understand how competition shapes biodiversity and species coexistence. Historically, one important approach for addressing this question has been to analyze Consumer Resource Models (CRMs) using geometric arguments. This has led to broadly applicable principles such as Tilmans R* and species coexistence cones. Here, we extend these arguments by constructing a novel geometric framework for understanding species coexistence based on convex polytopes in the space of consumer preferences. We show how the geometry of consumer preferences can be used to predict species coexistence and enumerate ecologically-stable steady states and transitions between them. Collectively, these results constitute a qualitatively new way of understanding the role of species traits in shaping ecosystems within niche theory.

ecology↗

bioRxiv2023

Connecting higher order interactions with ecological stability in experimental aquatic food webs

Community ecology is built on theories that represent the strength of interactions between species as pairwise links. Higher order interactions occur when the presence of a third (or more) species changes the pairwise interaction between a focal pair. Recent theoretical work has highlighted the stabilizing role of higher order interactions for large, simulated communities, yet it remains unclear how important higher order effects are in real communities. Here we used experimental communities of aquatic protists to examine the relationship between higher-order interactions and community stability (as measured by the persistence of species in a community). We cultured a focal pair of consumers in the presence of additional competitors and a predator and collected time series data of their abundances. We then fitted competition models with and without HOIs to measure interaction strength between the focal pair across different community compositions. We used survival analysis to measure the persistence of individual species. We found evidence that additional species positively affected persistence of the focal species and that HOIs were present in most of our communities. However, persistence was only linked to HOIs for one of the focal species. Our results vindicate community ecology theory positing that species interactions may deviate from assumptions of pairwise interactions, opening avenues to consider possible consequences for coexistence and community stability.

ecology↗

bioRxiv2023

The ecological characteristics of the safe sites for early-stage establishment of Chamaecyparis obtusa var. formosana seedlings in Taiwan

Chamaecyparis obtusa var. formosana is an ecologically and economically important species in Taiwan, with a high affinity for fog immersion. Our study aims to identify possible stress factors that induced seedling mortality and investigate how different ecological factors influence early-stage safe site requirements of the seedlings. We focused on the effect of large-scale climatic variables, small-scale microhabitat conditions, and biotic interactions on seedling survival and establishment by applying seasonal seedling survival monitoring and establishment survey on both regional and local scale. We identified two alternative ways of seedling death, by environmental-induced mortality and by herbivory. Opposite effects of the same environmental factors on different causes of mortality showed that seedlings might need to balance the risks posed by both causes to optimize their growing conditions. On a regional scale, we observed limited effect of regional climatic variables (namely fog frequency) on seedlings establishment and survival but noted a similar seasonal survival pattern among regions. We hypothesize that short-duration droughts during the transition from Plum rain to typhoon season is one of the key mechanisms of environmental-induced mortality. On a local scale, we found that decayed coarse wood debris (CWD) facilitates seedling establishment by providing a "safe site", likely due to increased colonization of small-stature bryophytes and decreased litterfall accumulation. The effect of bryophytes on seedling establishment varies depending on their thickness, with thicker ones having stronger negative effects. Aside from the bryophytes, the accumulation of litter significantly hindered seedling establishment. We argue that to safeguard the regeneration of Chamaecyparis obtusa var. formosana population, preserving CWD in the forest floor as a safe site for the seedlings after tree-replacing disturbance in natural forests is essential, particularly under ongoing climate change where more frequent and prolonged drought events are predicted. HighlightsO_LIOn a local scale, decayed coarse wood debris (CWD) provides "safe site" for the establishment of Chamaecypairs obtusa var. formosana seedlings. C_LIO_LIRegional climatic variables had limited effects on seedlings, but all regions had similar seasonal patterns of seedling mortatlity. C_LIO_LIFacilitation effect of small-stature bryophytes and litterfall avoidance might be the underlying mechanisms behind CWD safe sites. C_LIO_LIPreserving CWD for seedlings is important in the context of predicted prolong drought events under ongoing climate change. C_LI

ecology↗

bioRxiv2023

Assembly archetypes in ecological communities

An instrumental discovery in comparative and developmental biology is the existence of assembly archetypes that synthesize the vast diversity of organisms body plans--from legs and wings to human arms--into simple, interpretable, and general design principles. Here we combine a novel mathematical formalism based on Category Theory with experimental data to show that similar "assembly archetypes" exist at the larger organization scale of ecological communities when assembling a species pool across diverse environmental contexts, particularly when species interactions are highly structured. We applied our formalism to clinical data discovering two assembly archetypes that differentiate between healthy and unhealthy human gut microbiota. The concept of assembly archetypes and the methods to synthesize them can pave the way to discovering the general assembly principles of the ecological communities we observe in nature.

ecology↗

bioRxiv2023

Ecological assessment of the Amazon sailfin catfish (Pterygoplichthys species) within the Indian freshwaters: a mesocosm-based approach

Amazon sailfin catfish is relatively a recent invader to the open waters of India, and studies on ecological assessment of the species within the Indian freshwaters are lacking. In the present study, to assess the ecological impact of catfish, we established mesocosms mimicking the Indian freshwaters within natural ponds of eastern India using three species of native fish, rohu, catla and mrigal, and for two size classes, small (10-20 cm length) and large (20-30 cm length) native fishes. Mesocosms were maintained with (test) and without the catfish (control), and length and weight of native fish, zooplankton abundance, and several hydrological and soil parameters were measured at a monthly interval for a period of 120-days. The catfish had a significant (P<0.05) negative impact on growth of small-size rohu only. However, we found no significant (P>0.05) differences in abiotic parameters and zooplankton abundance between control and test ponds for the small-size class. We speculate that reduced growth of rohu could be due to competition from catfish in the context of feeding, and not due to modification of abiotic environment. Thus, we emphasize upon the need for behavioral studies to further assess the impact of the catfish.

ecology↗

bioRxiv2023

An individual-based simulation framework exploring the ecology and mechanistic underpinnings of larval crowding in laboratory populations of Drosophila

The study of larval competition in laboratory populations of Drosophila, implemented via the crowding of larval cultures, has contributed greatly to the understanding of the ecology of competition, the evolution of larval competitive ability, and formed the basis of rigorous testing of the theory of density-dependent selection. Earlier studies led to the view that the outcomes of larval competition, and resulting evolutionary consequences of crowding-adaptation, could largely be understood by varying the starting density of individuals in a crowded culture. However, recent studies have shown that the results of adaptation to larval crowding may not be well predicted by the total larval density (i.e., total starting individuals/total volume of food). Cultures raised at the same total density but at different egg number and food volume combinations were shown to have different underlying density-specific fitness functions, and crowding-adaptation in each of these cultures was attained through different evolutionary trajectories as well. A recent study showed that cultures with not just the same density, but the same egg and food volume combination, achieved through food columns of differing diameter and height, could also differ greatly in fitness-related trait outcomes. In that study, the density of larvae in the feeding band (volume of food close to the surface in contact with air, to which larval feeding is largely restricted) was a very important factor in predicting the outcomes of larval competition. Given these recent findings, it is important to understand the overall role of feeding band density, and how it influences density-specific fitness functions in different kinds of crowded cultures. As the older models of larval competition are now insufficient to capture current empirical data, we constructed an individual-based simulation framework informed in part by these more recent findings, in order to better understand the evolutionary ecology and mechanistic underpinnings of larval competition, and predict robust experiments for expanding our understanding of the process of larval competition in Drosophila.

ecology↗

bioRxiv2023

Metagenomic analysis of individual mosquitos reveals the ecology of insect viruses

Mosquito transmitted viruses are responsible for an increasing burden of human disease. Despite this, little is known about the diversity and ecology of viruses within individual mosquito hosts. Using a meta-transcriptomic approach, we analysed the virome of 2,438 individual mosquitos (79 species), spanning [~]4000 km along latitudes and longitudes in China. From these data we identified 393 core viral species associated with mosquitos, including seven (putative) arbovirus species. We identified potential species and geographic hotspots of viral richness and arbovirus occurrence, and demonstrated that host phylogeny had a strong impact on the composition of individual mosquito viromes. Our data revealed a large number of viruses shared among mosquito species or genera, expanding our knowledge of host specificity of insect-associated viruses. We also detected multiple virus species that were widespread throughout the country, possibly facilitated by long-distance mosquito migrations. Together, our results greatly expand the known mosquito virome, linked the viral diversity at the scale of individual insects to that at a country-wide scale, and offered unique insights into the ecology of viruses of insect vectors.

ecology↗

bioRxiv2023

A taxonomy of multiple stable states in complex ecological communities

Many natural and man-made systems, from financial markets to ecosystems or the human brain, are built from multiple interconnected units. This complex high-dimensionality hinders our capacity to understand and predict the dynamics, functioning and fragility of these systems. One fragility scenario, particularly relevant to ecological communities of interacting species, concerns so-called regime shifts: abrupt and unexpected transitions from healthy, species-rich communities towards states of degraded ecosystem function and services. The accepted explanation for these shifts is that they arise as abrupt transitions between alternative stable states: multiple stable configurations of a system under the same internal and external conditions. These alternative states are well-understood in low-dimensional systems, but how they upscale with system complexity remains a debated question. In the present work we investigate the emergence of multiple stable states in a number of complex system models. We find that high-dimensional models with random interactions can unfold at least four different regimes of multistability, each emerging under a specific interaction scheme. More importantly, each multistability regime leaves a distinct and quantifiable fingerprint, providing a framework to analyze experimental evidence of abrupt shifts. By bridging previous results and studying multistability regimes, their fingerprints and their correlation with empirical evidence in ecology, our study helps define a common ground to understand and classify multiple stable states in complex systems.

ecology↗

bioRxiv2023

Prioritizing ecological connectivity among protected areas in Colombia using a functional approach for birds

Ecological connectivity among protected areas (PAs) is essential to improve biodiversity conservation and management effectiveness in the long term under global change. Developing strategic plans and identifying spatial priorities are practical actions for establishing and strengthening interconnected networks of PAs. In Colombia, this planning is fundamental to conserve its extraordinary bird diversity in the face of multiple threats, including climate change and deforestation. We develop a connectivity model focused on multiple bird species to identify critical sites to preserve the ecological connections among PAs in Colombia. Based on land cover data and expert knowledge, we created movement resistance surfaces and modeled Least-Cost Corridors among terrestrial PAs for 26 forest-dependent species. We also used circuit and least-cost models to locate conservation priorities and restoration opportunities, estimating the potential gain in connectivity with the Equivalent Connected Area (ECA) index. We found 581,531 km2 belonging to corridors among PAs for all focal species. Priority sites for movement within corridors covered 212,551 km2 and were predominantly located across Andean and Amazonian forests. Restoration opportunities covered 79,203 km2 and were concentrated in agricultural lands of the Andes and Caribbean regions. Restoring these areas could increase the national forest cover by 7% and connectivity by 14%. Our results provide a national-level assessment of functional connectivity priorities to maintain and improve the interconnections among PAs. This assessment could guide efforts related to conservation, restoration, and implementation of management tools that facilitate the movement of native species across transformed lands. These actions are crucial to meet the targets outlined in the post-2020 global biodiversity framework to achieve well-connected systems of PAs during this decade and until 2050.

ecology↗

bioRxiv2023

Vive la difference: why, how, and what trait combinations improve functional community ecology

Analyses of functional trait variation across ecological communities offer valuable insights into the factors that influence and predict trait composition, deepening our understanding of community structure. These analyses also shed light on patterns of trait dispersion, including underdispersion and overdispersion, which are often linked to the mechanisms underlying community assembly. However, striking a balance between characterizing complex phenotypes through the integration of comprehensive set of traits while ensuring the preservation of the distinct signals of overdispersion and underdispersion can pose significant challenges. This is because some trait combinations can result in high functional dispersion or overdispersion, while others may lead to underdispersion within the same community. In this study, we provide a rationale for the importance of trait selection in community ecology and develop a framework that optimizes patterns of functional trait variation among communities. We explored the responses of six trait sets along large-scale environmental gradients, using [~]700 lake-fish communities in Ontario (Canada). We started by adopting the conventional approaches of combining all traits as well as leveraging prior knowledge in fish biology to group traits that are functionally related (Diet, Morphology, Temperature Preference). We contrasted these approaches with a novel computational method to select combinations of traits that maximise overdispersion and minimise underdispersion. We found that separating traits according to their functions or by their patterns revealed signals in communities that appeared random when all the traits were pooled together. Combining our computational approach with environmental models revealed that functional patterns could be very well explained by multiple environmental predictors (model R2 up to 0.7). Our study also outlines future selection procedures to further uncover more complex patterns of species associations based on their traits.

ecology↗

bioRxiv2023

Unifying microorganisms and macrograzers in rocky shore ecological networks

Over the past decades, our understanding of the vital role microbes play in ecosystem processes has greatly expanded. However, we still have limited knowledge about how microbial communities interact with larger organisms. Many existing representations of microbial interactions are based on co-occurrence patterns, which do not provide clear insights into trophic or non-trophic relationships. In this study, we untangled trophic and non-trophic interactions between macroscopic and microscopic organisms on a marine rocky shore. Five abundant mollusk grazers were selected, and their consumptive (grazing) and non-consumptive (grazer pedal mucus) interactions with bacteria in biofilms were measured using 16S rRNA amplicon sequencing. While no significant effects on a commonly used measure of biofilm grazing (Chlorophyll-a concentration) were observed, detailed image analysis revealed that all grazers had a detrimental impact on biofilm cover. Moreover, different grazers exhibited distinct effects on various bacterial groups. Some groups, such as Rhodobacteraceae, Saprospiraceae, Flavobacteriaceae, and Halieaceae, experienced positive effects from specific grazers, while others, like Rhizobiaceae, Rhodobacteraceae, and Flavobacteriaceae were negatively affected by certain grazers. This study presents the first attempt to construct an interaction network between macroorganisms and bacteria. It demonstrates that the strength of trophic and non-trophic interactions varies significantly depending on the mollusk grazer or bacterial group involved. Notably, certain bacterial groups exhibited a generalized response, while others showed specialized responses to specific macroorganisms in trophic or non-trophic interactions. Overall, this work highlights the potential for integrating microbes into ecological networks, providing valuable insights and methodologies for quantifying interactions across Domains. This research complements the previous ecological network, showing that mollusk grazers interact not only trophically but also non-trophically with epilithic biofilms. It identifies three drivers affecting microbial community assembly, crucial for understanding macro-microorganism dynamics in intertidal systems.

ecology↗

bioRxiv2023

Global abundance patterns, diversity, and ecology of Patescibacteria in wastewater treatment plants

BackgroundMicroorganisms are responsible for nutrient removal and resource recovery in wastewater treatment plants (WWTPs), and their diversity is often studied by 16S rRNA gene amplicon sequencing. However, this approach underestimates the abundance and diversity of Patescibacteria due to the low coverage of commonly used PCR primers for this highly divergent bacterial phylum. Therefore, our current understanding of the global diversity, distribution, and ecological role of Patescibacteria in WWTPs is very incomplete. This is particularly relevant as Patescibacteria are considered to be associated with microbial host cells and can therefore influence the abundance and temporal variability of other microbial groups that are important for WWTP functioning. ResultsHere, we evaluated the in silico coverage of widely used 16S rRNA gene-targeted primer pairs and redesigned a primer pair targeting the V4 region of bacterial and archaeal 16S rRNA genes to expand its coverage for Patescibacteria. We then experimentally evaluated and compared the performance of the original and modified V4-targeted primers on 565 WWTP samples from the MiDAS global sample collection. Using the modified primer pair, the percentage of ASVs classified as Patescibacteria increased from 5.9% to 23.8%, and the number of detected patescibacterial genera increased from 560 to 1,576, while the detected diversity of the remaining microbial community remained similar. Due to this significantly improved coverage of Patescibacteria, we identified 23 core genera of Patescibacteria in WWTPs and described the global distribution pattern of these unusual microbes in these systems. Finally, correlation network analysis revealed potential host organisms that might be associated with Patescibacteria in WWTPs. Interestingly, strong indications were found for an association between Patescibacteria of the Saccharimonadia and globally abundant polyphosphate-accumulating organisms of the genus Ca. Phosporibacter. ConclusionsOur study (i) provides an improved 16S rRNA gene V4 region-targeted amplicon primer pair inclusive of Patescibacteria with little impact on the detection of other taxa, (ii) reveals the diversity and distribution patterns of Patescibacteria in WWTPs on a global scale, and (iii) provides new insights into the ecological role and potential hosts of Patescibacteria in WWTPs.

ecology↗

bioRxiv2023

The majority of Germany's small agricultural streams are in poor ecological status

Agricultural pesticides, nutrients, and habitat degradation are major causes of insect declines in lowland streams. To effectively conserve and restore stream habitats, standardized stream monitoring data and societal support for freshwater protection are needed. Here, we sampled 137 small stream sites across Germany, 83% of which were located in agricultural catchments, with more than 900 citizen scientists in 96 monitoring groups. Sampling was carried out according to Water Framework Directive standards as part of the citizen science freshwater monitoring program FLOW in spring and summer 2021, 2022 and 2023. The biological indicator SPEARpesticides was used to assess pesticide exposure and effects based on benthic invertebrate community composition. Overall, 58% of the monitored agricultural stream sites did not achieve a good ecological status in terms of macroinvertebrate community composition and indicated high pesticide exposure (SPEARpesticides status class: 29% moderate, 19% poor, 11% bad). The indicated pesticide pressure in streams was related to the proportion of agricultural land in the catchment area (R2=0.23, p<0.001). With regards to hydromorphology, monitoring results revealed that 65% of the agricultural stream sites failed to reach a good status. The data base produced by citizen science groups was characterized by a high degree of accuracy. This was quantified by a comparative survey of SPEARpesticides index (R2=0.79, p<0.001) and hydromorphology index values (R2=0.72, p<0.001) by citizen scientists and professionals. Such citizen-driven monitoring of the status of watercourses could play a crucial role in monitoring and implementing the objective of the European Water Framework Directive, thus contributing to restoring and protecting freshwater ecosystems. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=82 SRC="FIGDIR/small/564349v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1bbc51aorg.highwire.dtl.DTLVardef@896431org.highwire.dtl.DTLVardef@10e0bborg.highwire.dtl.DTLVardef@121819_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Assessment of ecological status of small agricultural streams in Germany - Pesticides affected invertebrates (bioindicator SPEAR) in 58% of agricultural streams - Failure to reach good hydromorphological status in 65% of agricultural streams - Citizen science monitoring achieves high data accuracy - Citizen science can support European Water Framework Directive monitoring

ecology↗

bioRxiv2023

Environment-organism feedbacks drive changes in ecological interactions

Ecological interactions, the impact of one organism on the growth and death of another, underpin our understanding of the long-term composition and the functional properties of communities. In recent years, the context-dependency of interactions - their tendency to change values in different environments, locations and at different times - has become an increasingly important theme in ecological research. However, an overarching theoretical assumption has been that external environmental factors are responsible for driving these changes. Here, we derive a theoretical interaction framework which teases apart the separate roles played by these extrinsic environmental inputs and the intrinsic environmental changes driven by organisms within the environment itself. At the heart of our theory is the instantaneous interaction, a quantity that captures the feedback between environmental composition and the growth of organisms within it. In the limit that intrinsic, organismdriven environmental change dominates over external drivers, we find that this feedback can give rise to temporal and spatial context-dependencies as organisms modify the environment over time and/or space. We use small synthetic microbial communities as model ecosystems to demonstrate the power of this framework, using it to predict time-dependent intra-specific interactions in a toxin degradation system and to relate time and spatial dependencies in crossfeeding communities. Our framework helps to explain the ubiquity of interaction context-dependencies in systems where population changes are driven by environmental changes - such as microbial communities - by placing the environment on an equal theoretical footing as the organisms that inhabit it.

ecology↗

bioRxiv2023

NPZfc: An ecological relation based fish catch prediction model using Artificial Neural Network

Quantifying interactions of organisms of the various trophic levels is very important in understanding the dynamics of aquatic ecosystems. With regards to fish, as both ecologically and commercially important parts of an ecosystem, predicting their catch in relation to primary producers provides insight into sustainable management. The present paper describes a novel model NPZfc, for nutrients, phytoplankton, zooplankton and fishes, which can predict planktivorous fish catch. Unlike the existing models which deal with the interactions within the system through mathematical equilibrium, the proposed model uses artificial neural network (ANN) to automatically learn inter-dependencies between different related variables and predict the fish catch of a water body. The efficiency of the model was increased by refining the input variables. Here biomass of plankton species population (phyto-plankton and zooplankton) were specifically selected from feeding ecology studies of target fish species as input variable. The study of two of the commercially important fish species, Etroplus suratensis and Nematalosa nasus in Chilika lagoon showed that the model can predict with high accuracy from limited input data. The root mean square error (RMSE) is found to be very satisfactory, ranging from 3.53% to 11.5% for E. suratensis and from 1.63% to 2.22% for N. nasus. Higher accuracy and better predictive ability with a smaller dataset makes this ANN-based NPZfc model more conducive.

ecology↗

bioRxiv2023

FORAGING MECHANISMS IN EXCAVATE FLAGELLATES SHED NEW LIGHT ON THE FUNCTIONAL ECOLOGY OF EARLY EUKARYOTES

The phagotrophic flagellates described as typical excavates have been hypothesized to be morphologically similar to the Last Eukaryotic Common Ancestor and understanding the functional ecology of excavates may therefore help shed light on the ecology of these early eukaryotes. Typical excavates are characterized by a posterior flagellum equipped with a vane that beats in a ventral groove. Here, we combined flow visualization and observations of prey capture in representatives of the three clades of excavates with computational fluid dynamic modelling, to understand the functional significance of this cell architecture. We record substantial differences amongst species in the orientation of the vane and the beat plane of the posterior flagellum. Clearance rate magnitudes estimated from flow visualization and modelling are like that of other similarly sized phagotrophic flagellates. The interaction between a vaned flagellum beating in a confinement is modelled to produce a very efficient feeding current at low energy costs, irrespective of the beat plane and vane orientation and of all other morphological variations. Given this predicted uniformity of function, we suggest that the foraging systems of typical excavates studied here may be good proxies to understand those potentially used by our distant ancestors more than 1 billion years ago. SignificanceHuman sperm reminds us of our ancestry: flagellates, unicellular organisms equipped with a flagellum. The last common eukaryotic ancestor (LECA) was a flagellate. Phylogenetic analyses suggest that Excavates, an assemblage of flagellates, are the living organisms most similar to LECA. They have distinct characteristics in common: a ventral groove within which a vaned flagellum is beating. We show how the shared morphology and foraging behavior among 3 excavate clades is fluid dynamically efficient. A similar flagellar arrangement, potentially homologous to that found in the excavates, is found among flagellates from other deep branches of the eukaryotic tree, suggesting that the typical excavate foraging system studied here may have been used by our distant ancestors more than 1 billion years ago.

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