Colonization Of Species Research Articles

Seeding roadsides is necessary but not sufficient for restoring native floral communities

Abstract The plant community in roadside right‐of‐ways is an important component of transportation infrastructure. Revegetation after construction is an opportunity to improve the plant community and create pollinator habitat. However, native seed mixes are substantially more expensive than those used in conventional roadside plantings, and transportation agencies often lack resources for management. Here, we compare the actively flowering plant community across a growing season in roadside plots seeded with native seed mixes versus non‐native seed mixes in Minnesota, USA. Plots varied in age from 2 to 20 years old. We demonstrate that native seeded plots had more native flowering forbs than non‐native seeded plots, as native flowers were rare in the non‐native seeded plots. However, despite some native species establishing well, many species in native seed mixes had poor or non‐existent establishment. Furthermore, the native and non‐native seeded plots converged in the makeup of their floral communities after a few years; part of this pattern is due to colonisation of species that were never seeded at either type of plot. Practical implication. If the goal of revegetation is to produce diverse, native dominated floral communities in roadsides, agencies must invest more in long‐term management. Managers could also alter seed mixes to remove species that fail to establish, which would reduce the cost of the seed mix, but not the diversity of the plant community that ultimately establishes. The use of such streamlined seed mixes across more land area would increase the availability of pollinator habitat without substantially altering current budgets or management plans.

Use of acoustic signals in Cape fur seal mother-pup reunions: individual signature, signal propagation and pup home range.

The Cape fur seal (Arctocephalus pusillus pusillus) is one of the most colonial mammals, with colonies of up to hundreds of thousands of individuals during the breeding season. During the lactation period, mothers and pups are regularly separated as females undertake multi-day foraging trips at sea. Mothers and pups use a mutual vocal recognition system to reunite after separation. Such communication is highly constrained by both high background noise and risk of individual confusion owing to the density of seals. This study aimed to experimentally assess the acoustic features relevant for mother-pup vocal identification and the propagation properties of their calls. Playback experiments revealed that mother and pup individual vocal signatures rely on both temporal and frequency parameters: amplitude and frequency modulations, timbre and fundamental frequency (f0). This is more parameters than in any colonial species studied so far. The combinational use of acoustic features reinforces the concept that both environmental and social constraints may have acted as selective pressures on the individual vocal recognition systems. Theoretical propagation distances of mother and pup vocalisations were estimated to be below the range of distances at which mother-pup reunions can occur. This suggests that Cape fur seals may have strong abilities to extract vocal signals from the background noise, as previously demonstrated in the highly colonial king penguin. Investigating the transmission of information throughout the propagation of the signal as well as the ability of the receiving individual to decipher vocal signatures is crucial to understanding vocal recognition systems in the wild.

The crystal structure of the N-terminal domain of the backbone pilin LrpA reveals a new closure-and-twist motion for assembling dynamic pili in Ligilactobacillus ruminis.

Sortase-dependent pili are long surface appendages that mediate attachment, colonization and biofilm formation in certain genera and species of Gram-positive bacteria. Ligilactobacillus ruminis is an autochthonous gut commensal that relies on sortase-dependent LrpCBA pili for host adherence and persistence. X-ray crystal structure snapshots of the backbone pilin LrpA were captured in two atypical bent conformations leading to a zigzag morphology in the LrpCBA pilus structure. Small-angle X-ray scattering and structural analysis revealed that LrpA also adopts the typical linear conformation, resulting in an elongated pilus morphology. Various conformational analyses and biophysical experiments helped to demonstrate that a hinge region located at the end of the flexible N-terminal domain of LrpA facilitates a new closure-and-twist motion for assembling dynamic pili during the assembly process and host attachment. Further, the incongruent combination of flexible domain-driven conformational dynamics and rigid isopeptide bond-driven stability observed in the LrpCBA pilus might also extend to the sortase-dependent pili of other bacteria colonizing a host.

Invasibility framework to predict the early colonization of alien Sonneratia in mangrove: Implications for coastal area management

Invasibility, or an ecosystem's susceptibility to invasion, plays a critical role in managing biological invasions but is challenging to quantify due to its dependence on specific ecosystem variables. This limitation restricts the practical application of this concept in the control of alien species. This study aims to simplify invasibility into measurable components and develop an applicable framework to predict early colonization of alien plants within the coastal mangrove ecosystem. We used the unchanneled path length (UPL), a widely applied hydrological connectivity-related indicator, to assess the accessibility of the mangrove. The enhanced vegetation index (EVI), positively correlated with above-ground biomass, was used to evaluate the potential competitive intensity. Firstly, building on existing studies, we developed a four-quadrant concept model integrating the effects of EVI and UPL on the early colonization of the alien species Sonneratia apetala. Our results revealed significant differences in EVI and UPL values between colonized and uncolonized areas, with colonized regions displaying markedly lower values (P < 0.001). Additionally, logistic regression showed a significant negative association between the probability of successful colonization by S. apetala and both indicators (P < 0.001). These results validate the effectiveness of our conceptual model. Furtherly, we identified four key niche opportunities for exotic species in mangrove: mudflats outside the mangrove forest, tidal creeks, canopy gaps, and unmanaged abandoned aquaculture ponds. Overall, this study provides important insight into the ecological processes of alien S. apetala colonization and practical information for management of coastal areas susceptible to invasion. Additionally, it presents a case study on the practical application of the concept of invasibility in the management of alien species.

Breeding ecology of the Asian openbill in eastern Nepal: Larger trees support higher fledgling success.

Colonial nesting waterbirds in agricultural landscapes have historically received limited research attention, especially in South Asia. For example, the Asian openbill (Anastomus oscitans) is a colonial species that extensively utilizes agricultural landscapes, yet there is a notable lack of substantial studies despite increasing urbanization across these landscapes. We investigated the factors affecting the breeding ecology of Asian openbills in eastern Nepal. We used a grid-based approach to locate stork colonies and monitored them throughout the breeding season from May to November for three consecutive years (2020-2022). Altogether, we observed a total of 67 active colonies, comprising 4020 active nests, which successfully fledged a total of 7566 chicks. Additionally, most of the colonies were located within areas of human settlements (40%), followed by community forests (33%) and agricultural land (27%). The Asian openbills primarily preferred large trees, such as Bombax ceiba (72%), for nesting. The mean height of nesting trees was approximately 4 m taller, the diameter at breast height was twice as large, and the canopy cover area was three times greater than that of non-nesting trees. The canopy cover area of trees positively influenced the colony size, while colony size positively influenced the fledgling's success. Our study underscores the significance of large trees in providing sufficient space for accommodating a substantial number of openbill nests and fledglings. These findings have significant implications for conservation efforts to protect large trees along with wetlands and agricultural lands, as crucial measures to ensure the sustainable breeding of this nationally vulnerable species.

Urban colonization of invasive species on islands: Mus musculus and Rattus rattus genetics of establishment on Cozumel Island

Humans and wildlife experience complex interactions in urban ecosystems, favoring the presence of commensal species, among which invasive species are particularly successful. Rodents are the main vertebrate group introduced to oceanic islands, where the invasion process and dispersal patterns strongly influence their evolutionary and genetic patterns. We evaluated the house mouse Mus musculus and the black rat Rattus rattus on Cozumel Island, Mexico. We assessed genetic diversity and structure, connectivity, gene flow, relatedness and bottleneck signals based on microsatellite loci. Our genetic findings suggest that introduction of individuals of different geographic sources to the island promotes high allelic diversity and the effective establishment of migrants. We identified a clear genetic structure and low connectivity for the two species, tightly linked with anthropogenic and urban features. Notably, we found that the genetic structure of the house mouse sampled within the city of San Miguel Cozumel is associated with the historical human population growth pulses accompanying the urbanization of the city. At the fine-scale genetic level, the main urban drivers of connectivity of the house mouse were both the impervious land surfaces, i.e. the urban landscape, and the informal commerce across the city (a proxy of resources availability). Chances of a secondary invasion to natural environments have been relatively low, which is crucial for the endemic taxa of the island. Nonetheless, improving urban planning to regulate future expansions of San Miguel Cozumel is of the outmost importance to prevent these invasive species to disperse further.

Population Trend of Colonially Nesting Heron Species in Greece

Heron colonies are dynamic components of wetlands. Therefore, their systematic monitoring is important for the management of both birds and wetlands. During the period 1988–2018, we counted breeding pairs of seven colonial breeding heron species at 65 colonies across 37 wetlands in Greece. We considered as annual variables of a population: (a) years since 1988, (b) Natura 2000 network inclusion, (c) protected area management authority overseeing, (d) wetland type (new or restored), and (e) new colonies (established after 2003). The Cattle Egret Bubulcus ibis and the Squacco Heron Ardeola ralloides had a positive breeding population trend. The Black-crowned Night Heron Nycticorax nycticorax, Little Egret Egretta garzetta, and Grey Heron Ardea cinerea had a negative trend, while the Purple Heron Ardea purpurea population was stable. The Great White Egret Ardea alba bred sporadically at only a few sites which precluded the evaluation of its population trend. The informative population variables differed among species, even of those at the same colony, which suggests trends are also affected by conditions at wintering grounds. The study highlights the need for the systematic monitoring of heron colonies and the protection of foraging/breeding areas in order to reverse the observed negative population trends.

Homogenization of soil seed bank communities by fire and invasive species in the Mojave Desert

Soil seed banks help maintain species diversity through temporal storage effects and function as germination pools that can optimize fitness across varying environmental conditions. These characteristics promote the persistence of native plant communities, yet disturbances such as fire and associated invasions by non-native species can disrupt these reserves, fundamentally altering successional trajectories. This may be particularly true in deserts, where native plant communities are less adapted to fire. While studies of fire effects on desert plant communities are not uncommon, information regarding the short- and long-term effects of fire on seed banks is less available. To better understand the influence of fire and invasive species on desert seed banks, we investigated soil seed bank biodiversity from 30 wildfires that burned between 1972 and 2010 across the Mojave Desert ecoregion of North America. We assessed how characteristics of fire regimes (frequency, time since fire, and burn severity) interacted with climate and invasive plants on measures of α-, β-, and γ-diversities. Because β-diversity is a direct measure of community variability and reveals important information about biodiversity loss, we further examined the nestedness and turnover components of β-diversity. Mean α- and γ-diversities were generally higher for burned locations than in unburned reference sites, however individual fire variables had little influence on patterns of seed bank diversity. Burned area seed banks tended to be dominated by non-native invasive species, primarily two grasses, (Bromus rubens, Bromus tectorum), as well as an invasive forb (Erodium cicutarium). The most striking pattern we observed was a collective sharp decline in α-, β-, and γ-diversities with increased invasive species dominance, indicating the homogenization of seed bank communities with the colonization of invasive species after fire. Evidence of homogenization was further supported by reduced turnover and increased nestedness in burn areas compared to reference areas indicating potential biodiversity loss. Our findings highlight how biological processes such as plant invasions can combine with disturbance from fire to alter patterns of seed bank composition and diversity in desert ecosystems.

Proteomic profiling of Botryllus schlosseri, an emerging model organism

Botryllus schlosseri is a colonial chordate species that exhibits robust stem cell-mediated regeneration capacities throughout life. It grows through a process of colonial budding known as blastogenesis, in addition to its sexual reproduction mode, embryogenesis. In natural conditions, colony growth peaks in the summer and drastically decreases in the winter due to various seasonal factors. We have established and optimized a method to rear B. schlosseri animals in landlocked laboratories where the controlled conditions allow colonies to grow continuously and exponentially through asexual reproduction under constant temperature, salinity, light, and nutrient conditions. During the weekly blastogenic cycle, all asexually derived parental zooids synchronously regress within one day and are replaced by a new generation. To enable comprehensive molecular phenotyping of this species we established a quantitative proteomics workflow and spectral library for Liquid chromatography/Tandem mass spectrometry (LCMS) data-independent acquisition (DIA). In this study, we quantified the relative abundances of several thousand proteins representing molecular phenotypes of B. schlosseri. This workflow enables us to use proteomics to characterize zooid development during its regenerative cycle, including the short critical period of the takeover stage, during which degenerating zooids undergo massive apoptosis while succeeding buds quickly mature and migrate into place. From this data, protein networks associated with regeneration and degeneration can be created, offering insights into tissue developmental pathways in vivo and future cell immortalization strategies in vitro. Furthermore, the establishment of quantitative proteomics workflows for B. schlosseri coupled with its unique life cycle features promotes the use of this model organism for the study of phenotypic plasticity and evolution of aging, stem cells, and mechanisms of regeneration and cell differentiation. This project is funded by NSF Grant MCB — 2127516. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Influence of habitat features on the colonisation of native and non-indigenous species

Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure.

Biofilm of petroleum-based and bio-based microplastics in seawater in response to Zn(II): Biofilm formation, community structure, and microbial function

Microplastic biofilms are novel vectors for the transport and spread of pathogenic and drug-resistant bacteria. With the increasing use of bio-based plastics, there is an urgent need to investigate the microbial colonization characteristics of these materials in seawater, particularly in comparison with conventional petroleum-based plastics. Furthermore, the effect of co-occurring contaminants, such as heavy metals, on the formation of microplastic biofilms and bacterial communities remains unclear. In this study, we compared the biofilm bacterial community structure of petroleum-based polyethylene (PE) and bio-based polylactic acid (PLA) in seawater under the influence of zinc ions (Zn2+). Our findings indicate that the biofilm on PLA microplastics in the late stage was impeded by the formation of a mildly acidic microenvironment resulting from the hydrolysis of the ester group on PLA. The PE surface had higher bacterial abundance and diversity, with a more intricate symbiotic pattern. The bacterial structures on the two types of microplastics were different; PE was more conducive to the colonization of anaerobic bacteria, whereas PLA was more favorable for the colonization of aerobic and acid-tolerant species. Furthermore, Zn increased the proportion of the dominant genera that could utilize microplastics as a carbon source, such as Alcanivorax and Nitratireductor. PLA had a greater propensity to harbor and disseminate pathogenic and drug-resistant bacteria, and Zn promoted the enrichment and spread of harmful bacteria such as, Pseudomonas and Clostridioides. Therefore, further research is essential to fully understand the potential environmental effects of bio-based microplastics and the role of heavy metals in the dynamics of bacterial colonization.

Biological and functional responses of the benthic surf zone community to different beach types

In this study, we analyzed the biological descriptors and functional traits of the benthic community inhabiting the water/bottom layer in the surf zones of three sandy beaches: a tide-dominated flat, and two intermediate beaches, from tide-modified to wave-dominated. Samples were collected seasonally in the inner surf zone by hand-towing a benthic sledge equipped with two nets, one above the other, across transects parallel to the shore, capturing the benthic community in two levels, close to the seafloor. A total of 116 species were collected, with a total of 327,678 specimens. Arthropods were 99.63% of all individuals caught across the three beaches, mainly represented by peracarid crustaceans. An important species turnover was detected along the shore, with a significant change in community composition. The biological descriptors and some functional traits vary among beaches: the total density, the density of individuals of small (5–10 mm length) and very small sizes (<5 mm length), the density of larval forms, and the presence of colonial species were higher in the tide-dominated flat (sometimes also in the tide-modified beach). More arthropods and more mobile individuals were found in those beaches, while mollusks and sedentary individuals were found in high number in the wave-dominated beach. Stratification was present across the three studied beaches, with higher densities in the near-bottom layer. In the tide-dominated beach, there was also a higher richness in this layer, with a nested community between levels. In the wave-dominated beach, similar richness was registered between levels, with a different community composition (and some differences in functional traits), indicating that some species can maintain their position close to the bottom despite the turbulent conditions experienced on this beach. Differences in wave conditions among beach types could be an important factor driving the biological descriptors and functional traits of the benthic community in surf zone ecosystems. Therefore, acknowledging their role is crucial in deciphering global patterns in surf zone biodiversity.

Facilitating early boreal forest succession on waste rock using Ramial Chipped Wood mulch: A five-year study

After a mine is closed, waste rock storage areas must be revegetated to facilitate the return of ecosystem services and meet legal and social expectations. The restoration of forest ecosystems on waste rock through spontaneous colonization associated with primary succession can take decades and is still poorly studied. Adding a mulch of ramial chipped wood (RCW) could improve the physicochemical properties and microclimate conditions of waste rock, thus facilitating substrate colonization by plants. In 2016, a fully randomized block design was installed on waste rock from a closed gold mine located in the boreal forest in Abitibi-Témiscamingue, Quebec, Canada. The design included four treatments: scarified waste rock as the control (WR), 2 cm of RCW mulch on top of scarified waste rock (RCW/WR), and 10 cm layer of sand on top of scarified waste rock with or without 2 cm of RCW mulch (RCW/S and S, respectively). Over a period of five years, we followed the natural colonization of forest species as well as abiotic (substrate microclimate conditions and physicochemistry) and biotic (herbaceous plant colonization) factors influencing woody plant colonization success. Six boreal woody species spontaneously colonized the area (five individuals per m2, on average, all species combined). Salix sp. and Picea glauca seedlings were more abundant on substrates with RCW mulch (especially sand) than those without mulch, and P. glauca had greater aerial biomasses with RCW mulch. Substrate water content during the growing season and the presence of the weed species Tussilago farfara were determining environmental factors in substrate colonization by Abies balsamea. In the absence of Tussilago farfara, RCW mulch increased A. balsamea colonization. RCW mulch increased the total cover of colonizing herbaceous plants (23.3–58.2%) as compared to mineral substrates alone (4.78–52.3%), which negatively affected the number of A. balsamea individuals. The colonizing herbaceous species were mostly primary succession species, Pilosella caespitosa, Anaphalis margaritacea, and Tussilago farfara being dominant; no exotic species were observed. The results highlight the potential of RCW mulch in promoting forest recolonization on waste rock, including mid-successional species like Picea sp., which could be useful for facilitating ecosystem succession in post-mining landscapes.

Larger and structurally complex woodland creation sites provide greater benefits for woodland plants

Abstract Reforestation initiatives are underway across the world. However, we know relatively little about the ecological consequences of creating and restoring forest ecosystems, and there is a lack of studies examining the drivers of species colonisation and establishment across appropriate temporal and spatial scales to inform conservation practice. Using data from a long‐term natural experiment (the WrEN project), we explore ground plant species occurrence and community composition in 102 woodland creation sites (10–160 years since planting), and 27 old growth woodlands (&gt;250 years). We conducted field surveys to collect data on occurrence of plant species (classified into woodland specialist, woodland generalist, or non‐woodland) and used Structural Equation Modelling to investigate the influence of local (age, size, woodland structure) and landscape‐level (amount of surrounding woodland) attributes on species richness. Woodland generalists are readily colonising woodland creation sites to similar levels found in old growth woodlands. However, there were fewer woodland specialist and more non‐woodland plants in creation sites than in old growth. Specialists and generalists were more likely to be present in larger woodlands and those with higher variation in tree size (which was higher in older woodlands) and did not appear to be influenced by features of the surrounding landscape. Some plant communities in older creation sites (80–160 years) were similar to old growth, suggesting colonisation of a typical old growth flora over time; however, some sites were shifting away from this trajectory. Specialists are slow to colonise woodland creation sites and their occurrence was low relative to old growth woodlands even after &gt;80 years. However, woodland management to increase structural complexity may enhance the establishment of woodland plants. The lack of influence of the surrounding landscape on species occurrence is likely due to most of the study sites being relatively isolated resulting in limited colonisation. This suggests that new woodlands need to be adjacent or very near to existing woodland to receive the benefits of increased colonisation. Our results highlight the importance of creating large and structurally complex woodlands, close to existing woodlands to facilitate the colonisation and establishment of woodland plants.

Modelling metabolic fluxes of tomato stems reveals that nitrogen shapes central metabolism for defence against Botrytis cinerea.

Among plant pathogens, the necrotrophic fungus Botrytis cinerea is one of the most prevalent, leading to severe crop damage. Studies related to its colonization of different plant species have reported variable host metabolic responses to infection. In tomato, high N availability leads to decreased susceptibility. Metabolic flux analysis can be used as an integrated method to better understand which metabolic adaptations lead to effective host defence and resistance. Here, we investigated the metabolic response of tomato infected by B. cinerea in symptomless stem tissues proximal to the lesions for 7 d post-inoculation, using a reconstructed metabolic model constrained by a large and consistent metabolic dataset acquired under four different N supplies. An overall comparison of 48 flux solution vectors of Botrytis- and mock-inoculated plants showed that fluxes were higher in Botrytis-inoculated plants, and the difference increased with a reduction in available N, accompanying an unexpected increase in radial growth. Despite higher fluxes, such as those involved in cell wall synthesis and other pathways, fluxes related to glycolysis, the tricarboxylic acid cycle, and amino acid and protein synthesis were limited under very low N, which might explain the enhanced susceptibility. Limiting starch synthesis and enhancing fluxes towards redox and specialized metabolism also contributed to defence independent of N supply.

Immobilised antimicrobial peptides in downregulation of biofilm.

Colonisation of sessile bacterial species on biotic and abiotic surfaces is responsible for the development of various infections in humans. At present, biofilm-associated chronic infections have been a prime concern among the healthcare practitioners since they are impermeable to drugs, resulting in the development of antibiotic resistance or multi-drug resistance. For a few decades, a lot of research activity has been performed in the development of alternative therapeutics to combat biofilm-associated chronic infections. The presence of extracellular polymeric substance (EPS) prevents the permeation of most of the drugs rendering drug failures. The use of small molecules has been necessary to penetrate easily through the EPS and act on the targeted cells. In present days, the use of antimicrobial peptides (AMPs) has gained immense importance as alternative therapeutics since they exhibit a novel class of antibiotics exhibiting a wide spectrum of activity and possess a low rate of development of resistance. In the last few decades, a large number of AMPs have been identified from varied groups of organisms as effector molecules for innate immune system acting as an important line of defence. In this review, we will discuss the use of AMPs as effective agents to combat various biofilm-associated chronic infections.

Food preference for native and invasive prey in the naive lancehead pitviper

AbstractThe presence of invasive species in the environment can be highly detrimental. The success of these species depends on their interaction with native ones. The prey–predator relationship between invasive and native species can result in biodiversity loss or the introduction of new food items for local predators. Due to its tropical and extensive nature, Brazil is vulnerable to the colonization of invasive species. Snakes are a group of animals that can act as both predators and prey for invasive species. The pitviper Bothrops jararaca is an abundant and widely distributed native species on the Brazilian coast. Based on this, we conducted a study on the feeding preferences of naive B. jararaca juveniles regarding invasive and native prey. We found that this species exhibits a greater preference for native anurans compared to Rana catesbeiana, an invasive amphibian associated with significant environmental impacts. Additionally, the gecko Hemidactylus mabouia, a prey that triggered intense predatory responses from the pitviper, reveals that this species, even with a short period of coexistence with B. jararaca, has established an intense prey–predator relationship. The negative correlation between prey size and feeding interest, guided solely by olfactory cues, adds a layer of complexity to understanding the feeding choices of B. jararaca, providing valuable insights for conservation and environmental management strategies.Abstract in Portuguese is available with online material.

Abstract 2176: Differences in gut microbial composition alter pancreatic tumorigenesis

Abstract Pancreatic ductal adenocarcinoma (PDAC) is predicted to become the second leading cause of cancer-related deaths by 2030, and currently has a 5-year survival rate of roughly 10%. With long-term survival rates in patients being exceedingly low, understanding what factors delineate survival is imperative. When comparing spontaneous transgenic mouse models of pancreatic cancer housed in geographically distinct vivaria, regardless of a common lineage, we observed drastically different phenotype states in the respective locations. We hypothesize that the gut microbiome results in different gene expression profiles, leading to alterations in pancreatic tumorigenesis. Using various sequencing techniques, including 16s rRNA and RNA sequencing of the gut, we identified unique signatures at these respective institutions. Subsequent fecal microbiota transplantation and single bacterial species colonization experiments were performed to evaluate the ability of microbiomes/specific microbiota to alter the rate of tumorigenesis. In addition to probing the gut microbiome, circulating metabolites from individual mice were quantified, and correlated to phenotype state. Following identification of potentially tumorigenic bacterially derived metabolites, single bacteria colonization experiments were utilized to determine the downstream effects of identified metabolites as well as the ability of directly altering the metabolic landscape to drive tumorigenesis. Additionally, murine derived pancreatic cancer cells were exposed to both identified bacteria alone or bacterially produced metabolite and analyzed by metrics such as proliferation and relative expression of transcription factors associated with cancer development in vitro. Taken together, these data demonstrate the ability of distinct gut microbiomes to directly alter the metabolic landscape in mice, thus differentially altering the progression of pancreatic lesions. By better understanding the factors that stratify survivorship, we can begin to employ clinically actionable methodologies in the treatment or prevention of pancreatic cancer. Citation Format: Rian M. Howell, Jose Enriquez Ortiz, Olivia Le Roux, Vidhi Chandra, Le Li, Pratip K. Bhattacharya, Florencia McAllister. Differences in gut microbial composition alter pancreatic tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2176.

Data-driven prediction of colonization outcomes for complex microbial communities

Microbial interactions can lead to different colonization outcomes of exogenous species, be they pathogenic or beneficial in nature. Predicting the colonization of exogenous species in complex communities remains a fundamental challenge in microbial ecology, mainly due to our limited knowledge of the diverse mechanisms governing microbial dynamics. Here, we propose a data-driven approach independent of any dynamics model to predict colonization outcomes of exogenous species from the baseline compositions of microbial communities. We systematically validate this approach using synthetic data, finding that machine learning models can predict not only the binary colonization outcome but also the post-invasion steady-state abundance of the invading species. Then we conduct colonization experiments for commensal gut bacteria species Enterococcus faecium and Akkermansia muciniphila in hundreds of human stool-derived in vitro microbial communities, confirming that the data-driven approaches can predict the colonization outcomes in experiments. Furthermore, we find that while most resident species are predicted to have a weak negative impact on the colonization of exogenous species, strongly interacting species could significantly alter the colonization outcomes, e.g., Enterococcus faecalis inhibits the invasion of E. faecium invasion. The presented results suggest that the data-driven approaches are powerful tools to inform the ecology and management of microbial communities.

No city for wetland species: habitat associations affect mammal persistence in urban areas.

The fast rate of replacement of natural areas by expanding cities is a key threat to wildlife worldwide. Many wild species occur in cities, yet little is known on the dynamics of urban wildlife assemblages due to species' extinction and colonization that may occur in response to the rapidly evolving conditions within urban areas. Namely, species' ability to spread within urban areas, besides habitat preferences, is likely to shape the fate of species once they occur in a city. Here we use a long-term dataset on mammals occurring in one of the largest and most ancient cities in Europe to assess whether and how spatial spread and association with specific habitats drive the probability of local extinction within cities. Our analysis included mammalian records dating between years 1832 and 2023, and revealed that local extinctions in urban areas are biased towards species associated with wetlands and that were naturally rare within the city. Besides highlighting the role of wetlands within urban areas for conserving wildlife, our work also highlights the importance of long-term biodiversity monitoring in highly dynamic habitats such as cities, as a key asset to better understand wildlife trends and thus foster more sustainable and biodiversity-friendly cities.