scholarly journals Automated discovery of relationships, models and principles in ecology

2015 ◽  
Author(s):  
Pedro Cardoso ◽  
Paulo A. V. Borges ◽  
José C. Carvalho ◽  
François Rigal ◽  
Rosalina Gabriel ◽  
...  
Keyword(s):  
Species Richness ◽  
Statistical Modelling ◽  
Theoretical Models ◽  
Ecological Systems ◽  
Formal Structure ◽  
Free Form ◽  
List Type ◽  
Complex Data ◽  
Linear Relationships ◽  
Patterns And Processes

ABSTRACTEcological systems are the quintessential complex systems, involving numerous high-order interactions and non-linear relationships. The most commonly used statistical modelling techniques can hardly reflect the complexity of ecological patterns and processes. Finding hidden relationships in complex data is now possible through the use of massive computational power, particularly by means of Artificial Intelligence methods, such as evolutionary computation.Here we use symbolic regression (SR), which searches for both the formal structure of equations and the fitting parameters simultaneously, hence providing the required flexibility to characterize complex ecological systems.First, we demonstrate how SR can deal with complex datasets for: 1) modelling species richness; and 2) modelling species spatial distributions. Second, we illustrate how SR can be used to find general models in ecology, by using it to: 3) develop species richness estimators; and 4) develop the species-area relationship and the general dynamic model of oceanic island biogeography.All the examples suggest that evolving free-form equations purely from data, often without prior human inference or hypotheses, may represent a very powerful tool for ecologists and biogeographers to become aware of hidden relationships and suggest general theoretical models and principles.

scholarly journals Automated Discovery of Relationships, Models, and Principles in Ecology

2020 ◽  
Vol 8 ◽  
Author(s):  
Pedro Cardoso ◽  
Vasco V. Branco ◽  
Paulo A. V. Borges ◽  
José C. Carvalho ◽  
François Rigal ◽  
...  
Keyword(s):  
Species Richness ◽  
Theoretical Models ◽  
Symbolic Regression ◽  
Ecological Systems ◽  
Formal Structure ◽  
Free Form ◽  
Complex Data ◽  
Linear Relationships ◽  
Automated Discovery ◽  
Patterns And Processes

Ecological systems are the quintessential complex systems, involving numerous high-order interactions and non-linear relationships. The most used statistical modeling techniques can hardly accommodate the complexity of ecological patterns and processes. Finding hidden relationships in complex data is now possible using massive computational power, particularly by means of artificial intelligence and machine learning methods. Here we explored the potential of symbolic regression (SR), commonly used in other areas, in the field of ecology. Symbolic regression searches for both the formal structure of equations and the fitting parameters simultaneously, hence providing the required flexibility to characterize complex ecological systems. Although the method here presented is automated, it is part of a collaborative human–machine effort and we demonstrate ways to do it. First, we test the robustness of SR to extreme levels of noise when searching for the species-area relationship. Second, we demonstrate how SR can model species richness and spatial distributions. Third, we illustrate how SR can be used to find general models in ecology, namely new formulas for species richness estimators and the general dynamic model of oceanic island biogeography. We propose that evolving free-form equations purely from data, often without prior human inference or hypotheses, may represent a very powerful tool for ecologists and biogeographers to become aware of hidden relationships and suggest general theoretical models and principles.

scholarly journals Complex community responses underpin biodiversity change following invasion

2021 ◽  
Author(s):  
Alessandra R. Kortz ◽  
Anne E. Magurran
Keyword(s):  
Invasive Species ◽  
Species Richness ◽  
Spatial Scales ◽  
Species Abundance ◽  
Ecological Systems ◽  
Multi Scale ◽  
Mechanistic Approach ◽  
Α Diversity ◽  
Biodiversity Change ◽  
Insight Into

AbstractHow do invasive species change native biodiversity? One reason why this long-standing question remains challenging to answer could be because the main focus of the invasion literature has been on shifts in species richness (a measure of α-diversity). As the underlying components of community structure—intraspecific aggregation, interspecific density and the species abundance distribution (SAD)—are potentially impacted in different ways during invasion, trends in species richness provide only limited insight into the mechanisms leading to biodiversity change. In addition, these impacts can be manifested in distinct ways at different spatial scales. Here we take advantage of the new Measurement of Biodiversity (MoB) framework to reanalyse data collected in an invasion front in the Brazilian Cerrado biodiversity hotspot. We show that, by using the MoB multi-scale approach, we are able to link reductions in species richness in invaded sites to restructuring in the SAD. This restructuring takes the form of lower evenness in sites invaded by pines relative to sites without pines. Shifts in aggregation also occur. There is a clear signature of spatial scale in biodiversity change linked to the presence of an invasive species. These results demonstrate how the MoB approach can play an important role in helping invasion ecologists, field biologists and conservation managers move towards a more mechanistic approach to detecting and interpreting changes in ecological systems following invasion.

Experimental Study on Critical Shear Stress of Cohesive Soils and Soil Mixtures

2021 ◽  
Vol 64 (2) ◽  
pp. 587-600
Author(s):  
Xiaojing Gao ◽  
Qiusheng Wang ◽  
Chongbang Xu ◽  
Ruilin Su
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
Cohesive Soil ◽  
Future Research ◽  
Cohesive Soils ◽  
List Type ◽  
Soil Mixture ◽  
Linear Relationships ◽  
Soil Mixtures

HighlightsErosion tests were performed to study the critical shear stress of cohesive soils and soil mixtures.Linear relationships were observed between critical shear stress and cohesion of cohesive soils.Mixture critical shear stress relates to noncohesive particle size and cohesive soil erodibility.A formula for calculating the critical shear stress of soil mixtures is proposed and verified.Abstract. The incipient motion of soil is an important engineering property that impacts reservoir sedimentation, stable channel design, river bed degradation, and dam breach. Due to numerous factors influencing the erodibility parameters, the study of critical shear stress (tc) of cohesive soils and soil mixtures is still far from mature. In this study, erosion experiments were conducted to investigate the influence of soil properties on the tc of remolded cohesive soils and cohesive and noncohesive soil mixtures with mud contents varying from 0% to 100% using an erosion function apparatus (EFA). For cohesive soils, direct linear relationships were observed between tc and cohesion (c). The critical shear stress for soil mixture (tcm) erosion increased monotonically with an increase in mud content (pm). The median diameter of noncohesive soil (Ds), the void ratio (e), and the organic content of cohesive soil also influenced tcm. A formula for calculating tcm considering the effect of pm and the tc of noncohesive soil and pure mud was developed. The proposed formula was validated using experimental data from the present and previous research, and it can reproduce the variation of tcm for reconstituted soil mixtures. To use the proposed formula to predict the tcm for artificial engineering problems, experimental erosion tests should be performed. Future research should further test the proposed formula based on additional experimental data. Keywords: Cohesive and noncohesive soil mixture, Critical shear stress, Erodibility, Mud content, Soil property.

Modeling and Experiment on Physical and Chemical Liquid Deposition Processes for Rapid Tooling and Manufacturing

2000 ◽  
Author(s):  
Zongyan He ◽  
Jack G. Zhou
Keyword(s):  
Heat Transfer ◽  
Theoretical Models ◽  
Nucleation And Growth ◽  
Free Form ◽  
Technical Problems ◽  
Chemical Liquid Deposition ◽  
Deposition Processes ◽  
Physical And Chemical ◽  
Solid Free Form Fabrication ◽  
Liquid Deposition

Abstract A new solid free-form fabrication (SFF) technique, named Physical and Chemical Liquid Deposition (P/CLD), is introduced in this paper, and then several key technical problems are stated. In order to solve these problems, theoretical models to describe the nucleation and growth of deposits in PLD, the chemical dynamic process in CLD, and the heat transfer in P/LCD are studied. To determine the heat transfer parameters, some experiments are designed and experimental results are presented.

scholarly journals Novelty and emergent patterns in sperm: morphological diversity and evolution of spermatozoa and sperm conjugation in ground beetles (Coleoptera: Carabidae)

2019 ◽  
Author(s):  
R. Antonio Gomez ◽  
David R. Maddison
Keyword(s):  
Ground Beetle ◽  
Morphological Diversity ◽  
Ground Beetles ◽  
Head Width ◽  
Phenotypic Traits ◽  
Sperm Length ◽  
List Type ◽  
History Of ◽  
Morphological Differences ◽  
Patterns And Processes

1.AbstractThe beetle family Carabidae, with about 40,000 species, exhibits enough diversity in sperm structure and behavior to be an excellent model system for studying patterns and processes of sperm evolution. We explore their potential, documenting sperm form in 177 species of ground beetles and collecting data on 1 qualitative and 7 quantitative sperm phenotypic traits. Our sampling captures 61% of the tribal-level diversity of ground beetles. These data highlight the notable morphological diversity of sperm in ground beetles and suggest that sperm in the group have dynamic evolutionary histories with much morphological innovation and convergence. Sperm vary among species in total length from 48-3,400μm and in length and width of the sperm head. Most ground beetles make filamentous sperm with visually indistinct heads, but some or all studied members of the genus Omophron, genus Trachypachus, and tribe Dyschiriini make broad-headed sperm that show morphological differences between species. Most ground beetles package their sperm into groups of sperm, termed conjugates, and ground beetles show variation in conjugate form and in the number and arrangement of sperm in a conjugate. Most ground beetles make sperm conjugates by embedding their sperm in a non-cellular rod or spermatostyle, but some Trechitae make conjugates without a spermatostyle. The spermatostyle is remarkably variable among species and varies in length from 17-41,000μm. Several unrelated groups of ground beetles make only singleton sperm, including Nebriinae, Cicindelinae, many Trechinae, and the tribe Paussini. Given current views about ground beetle relationships, we propose preliminary hypotheses on ground beetle sperm diversification. We hypothesize that spermatostyle and conjugate traits evolve faster than sperm traits and that head width evolves more slowly than head length and sperm length. We propose that conjugation with a spermatostyle evolved early within the history of Carabidae and that it has been lost independently at least three times.Research highlightsGround beetle sperm is morphologically diverse.Most species make sperm conjugates with a spermatostyle, and there is variation in sperm, spermatostyles, and conjugates.Sperm have dynamic evolutionary histories.

scholarly journals Large home range scavengers support higher rates of carcass removal

2020 ◽  
Author(s):  
Cayetano Gutiérrez-Cánovas ◽  
Marcos Moleón ◽  
Patricia Mateo-Tomás ◽  
Pedro P. Olea ◽  
Esther Sebastián-González ◽  
...  
Keyword(s):  
Species Richness ◽  
Home Range ◽  
Functional Diversity ◽  
Ecosystem Functions ◽  
Functional Equivalence ◽  
List Type ◽  
Large Carnivores ◽  
Functional Identity ◽  
Niche Complementarity ◽  
Consumption Rates

AbstractVertebrate scavenger communities vary in species composition across the globe, and include a wide array of species with diverse ecological strategies and life-histories that support essential ecosystem functions, such as carrion removal. While previous studies have mostly focussed on how community aspects such as species richness and composition affect carrion consumption rates, it remains unclear whether this important function of scavengers is better explained by the dominance of key functional traits or niche complementarity as a result of a diverse functional representation.Here, we test three competitive hypotheses to assess if carrion consumption in vertebrate scavenger communities depends on: i) the presence of key dominant traits (functional identity hypothesis), ii) functional diversity that promotes niche complementarity (functional diversity hypothesis), or iii) the accumulation of individuals and species, irrespective of their trait representation (functional equivalence). To explore these hypotheses, we used five study areas in Spain and South Africa, which represent a gradient of scavenger biodiversity, i.e., ranging from communities dominated by facultative scavengers, such as generalists and meso-predators, to those including vultures and large carnivores.Within study areas, traits that characterise obligate scavengers or large carnivores (e.g. mean home range, proportion of social foragers) were positively linked to rapid carrion consumption, while the biomass of functional groups including facultative scavengers were either weakly or negatively associated with carrion consumption.When combining all study areas, higher rates of carrion consumption were related to scavenger communities dominated by species with large home ranges (e.g. Gyps vultures), which was found to be a key trait. In contrast, metrics describing functional diversity (functional dispersion) and functional equivalence (species richness and abundance) had lower predictive power in explaining carrion consumption patterns.Our data support the functional identity hypothesis as a better framework for explaining carrion consumption rates than functional diversity or equivalence. Our findings contribute to understanding the mechanisms sustaining ecosystem functioning in vertebrate communities and reinforce the role of obligate scavengers and large carnivores as keystone species in terrestrial ecosystems.

scholarly journals How to make more from exposure data? An integrated machine learning pipeline to predict pathogen exposure

2019 ◽  
Author(s):  
Nicholas M. Fountain-Jones ◽  
Gustavo Machado ◽  
Scott Carver ◽  
Craig Packer ◽  
Mariana Recamonde-Mendoza ◽  
...  
Keyword(s):  
Machine Learning ◽  
Predictive Performance ◽  
List Type ◽  
Ecological Data ◽  
Linear Relationships ◽  
Animal Populations ◽  
Model Complex ◽  
Non Linear ◽  
Feline Parvovirus ◽  
Pathogen Exposure

AbstractPredicting infectious disease dynamics is a central challenge in disease ecology. Models that can assess which individuals are most at risk of being exposed to a pathogen not only provide valuable insights into disease transmission and dynamics but can also guide management interventions. Constructing such models for wild animal populations, however, is particularly challenging; often only serological data is available on a subset of individuals and non-linear relationships between variables are common.Here we take advantage of the latest advances in statistical machine learning to construct pathogen-risk models that automatically incorporate complex non-linear relationships with minimal statistical assumptions from ecological data with missing values. Our approach compares multiple machine learning algorithms in a unified environment to find the model with the best predictive performance and uses game theory to better interpret results. We apply this framework on two major pathogens that infect African lions: canine distemper virus (CDV) and feline parvovirus.Our modelling approach provided enhanced predictive performance compared to more traditional approaches, as well as new insights into disease risks in a wild population. We were able to efficiently capture and visualise strong non-linear patterns, as well as model complex interactions between variables in shaping exposure risk from CDV and feline parvovirus. For example, we found that lions were more likely to be exposed to CDV at a young age but only in low rainfall years.When combined with our data calibration approach, our framework helped us to answer questions about risk of pathogen exposure which are difficult to address with previous methods. Our framework not only has the potential to aid in predicting disease risk in animal populations, but also can be used to build robust predictive models suitable for other ecological applications such as modelling species distribution or diversity patterns.

scholarly journals Empirical characterization factors assessing the effects of hydroelectricity on fish richness across three large biomes

2019 ◽  
Author(s):  
Katrine Turgeon ◽  
Gabrielle Trottier ◽  
Christian Turpin ◽  
Cécile Bulle ◽  
Manuele Margni
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
Statistical Significance ◽  
Steady States ◽  
Clear Understanding ◽  
List Type ◽  
Characterization Factors ◽  
Alternative Technologies ◽  
The Tropics ◽  
The Impact

AbstractHydroelectricity is often presented as a clean, reliable, and renewable energy source, but is also recognized for its potential impacts on aquatic ecosystem biodiversity. We used empirical data on change in fish species richness following impoundment to develop Characterisation Factors (CF) and Impact Scores (IS) for hydroelectricity production for use in Life Cycle Assessment (LCA). We used data collected on 89 sampling stations (63 upstream and 26 downstream of a dam) belonging to 27 reservoirs from three biomes (boreal, temperate and tropical). Overall, the impact of hydroelectricity production on fish species richness was significant in the tropics, of smaller amplitude in temperate and minimal in boreal biome, stressing for the need of regionalisation. The impact of hydroelectricity production was also quite consistent across scales (i.e., same directionality and statistical significance across sampling stations, reservoirs and biomes) but was sensitive to the duration of the study (i.e., the period over which data have been collected after impoundment), highlighting the need for a clear understanding of transient situations before reaching steady states. Our CFs and ISs contribute to fill a gap to assist decision makers using LCA to evaluate alternative technologies, such as hydropower, to decarbonize the worldwide economy.HighlightsThis paper is the first to develop global and empirically based characterization factors of the impact of hydroelectricity production on aquatic ecosystems biodiversity, to be used in LCA;The impact of hydroelectricity production on fish species richness was significant in the tropics, of smaller amplitude in temperate and minimal in boreal biome;The impact of hydroelectricity production on fish richness was consistent across scales - same directionality and statistical significance across sampling stations, reservoirs and biomes;The impact of hydroelectricity production on fish richness was sensitive to the duration of the study, highlighting the need for a clear understanding of transient situations before reaching steady states in LCA.

scholarly journals Autonomous bird sound recording outperforms direct human observation: Synthesis and new evidence

2017 ◽  
Author(s):  
Kevin Darras ◽  
Péter Batáry ◽  
Brett Furnas ◽  
Irfan Fitriawan ◽  
Yeni Mulyani ◽  
...  
Keyword(s):  
Species Richness ◽  
Signal To Noise Ratio ◽  
Survey Methods ◽  
Meta Analysis ◽  
High Signal ◽  
List Type ◽  
Sound Recording ◽  
Data Types ◽  
Point Counts ◽  
Recording Techniques

Abstract1)Autonomous sound recording techniques have gained considerable traction in the last decade, but the question still remains whether they can replace human observation surveys to sample some animal taxa. Especially bird survey methods have been tested using classical point counts and autonomous sound recording techniques.2)We review the latest information by comparing both survey methods' standardization, verifiability, sampling completeness, data types, compatibility, and practicality by means of a systematic review and a meta-analysis of alpha and gamma species richness levels sampled by both methods across 20 separate studies.3)Although sound recording surveys have hitherto not enjoyed the most effective setups, they yield very similar results in terms of alpha and gamma species richness. We also reveal the crucial importance of the microphone (high signal-to-noise ratio) as the sensor that replaces human senses.4)We discuss key differences between both methods, while richness estimates are closely related and 81% of all species were detected by both methods. Sound recording techniques provide a more powerful and promising tool to monitor birds in a standardized, verifiable, and exhaustive way against the golden standard of point counts. Advantages include the capability of sampling continuously through day or season and of difficult-to-reach regions in an autonomous way, avoidance of observer bias and human disturbance effects and higher detection probability of rare species due to extensive recordings.

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