scholarly journals The Introduction of Entropy and Information Methods to Ecology by Ramon Margalef

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 794 ◽  
Author(s):  
William B Sherwin ◽  
Narcis Prat i Fornells
Keyword(s):  
Information Theory ◽  
Environmental Variables ◽  
Alpha Diversity ◽  
Ecosystem Processes ◽  
Ecological Diversity ◽  
100Th Birthday ◽  
Accessible Form

In ecology and evolution, entropic methods are now used widely and increasingly frequently. Their use can be traced back to Ramon Margalef’s first attempt 70 years ago to use log-series to quantify ecological diversity, including searching for ecologically meaningful groupings within a large assemblage, which we now call the gamma level. The same year, Shannon and Weaver published a generally accessible form of Shannon’s work on information theory, including the measure that we now call Shannon–Wiener entropy. Margalef seized on that measure and soon proposed that ecologists should use the Shannon–Weiner index to evaluate diversity, including assessing local (alpha) diversity and differentiation between localities (beta). He also discussed relating this measure to environmental variables and ecosystem processes such as succession. Over the subsequent decades, he enthusiastically expanded upon his initial suggestions. Finally, 2019 also would have been Margalef’s 100th birthday.

scholarly journals Ecological classification of the freshwater Ostracoda (Crustacea) based on physicochemical properties of waters and habitat preferences

2018 ◽  
Vol 54 ◽  
pp. 26 ◽  
Author(s):  
Okan Külköylüoğlu ◽  
Mehmet Yavuzatmaca ◽  
Derya Akdemir ◽  
Ebru Çelen ◽  
Nurhayat Dalkıran
Keyword(s):  
Electrical Conductivity ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Environmental Variables ◽  
Habitat Preferences ◽  
Habitat Type ◽  
Alpha Diversity ◽  
Abundant Species ◽  
Critical Issue ◽  
Cosmopolitan Species

The relationship between ecological characteristic of freshwater ostracods and their habitat preferences has been a critical issue for understanding of both current and past aquatic conditions. To evaluate this idea, 121 water bodies with 11 different habitat types were randomly sampled in the province of Kütahya. Water quality measurements indicated high to low (Ca2+ > Mg2+ > Na+) cations and relatively low (SO42− > Cl− > F−) anion concentrations with Ca2+ being the dominant ion. Sixteen of 23 species were new reports for the area. Alpha diversity (H′ = 3.64) was found relatively high. Four most abundant species with ca. 93% of similarities contributed highest alpha values in warm to cooler (lower than 25 °C), alkaline (pH 8.22), and fresh to slightly brackish waters. Heterocypris salina and Ilyocypris bradyi also revealed the highest tolerances for electrical conductivity. Based on habitat type, species were clustered into three main groups (I–III). Canonical Correspondence Analyses explained about 57.4% of correlation between species and environmental variables. Redox potential, pH, water temperature and electrical conductivity were found to be the most effective factors on species occurrences while habitat type and dissolved oxygen were not effective. Total number of species showed strong negative and positive relationships with water temperature and dissolved oxygen, respectively. Results clearly showed that cosmopolitan species exhibited relatively wide tolerance ranges to different environmental variables. Accordingly, having wide tolerance ranges seems to provide advantages to cosmopolitan species, increasing their survival chances in a variety of habitats.

scholarly journals Forty years later: monitoring and status of the endangered Coachella Valley fringe-toed lizard

2021 ◽  
pp. 243-257
Author(s):  
Cameron W. Barrows ◽  
Scott A. Heacox
Keyword(s):  
Environmental Variables ◽  
Sand Dune ◽  
Invasive Plant ◽  
Private Property ◽  
Ecosystem Processes ◽  
Coachella Valley ◽  
Management Actions ◽  
Habitat Islands ◽  
Uma Inornata ◽  
Plant Control

The Coachella Valley fringe-toed lizard, Uma inornata, was listed as endangered under the California Endangered Species Act in 1980. By that time, the lizard’s habitat was already reduced by 90%, fragmented into isolated habitat islands on private property among hundreds of landowners. Ecosystem processes that are essential for delivering sand and maintaining the lizard’s sand dune habitat were already compromised. As challenging as it was to protect its habitat under these conditions, populations of this lizard still occur across much of the area where it was found forty years ago. Annual monitoring was designed to assess the ongoing viability of these populations by quantifying the effects of potential threats and stressors and focusing adaptive management actions where they are most needed. Here we demonstrate how hypothesis-based monitoring identified specific locations where invasive plant control and sand corridor management were needed to maintain the lizard’s populations. By monitoring lizard densities within the context of environmental variables that either drive or inhibit population growth, this monitoring approach informs if, when, and where management actions are needed.

Conditional and Weighted Measures of Ecological Diversity

2003 ◽  
Vol 11 (03) ◽  
pp. 283-300 ◽  
Author(s):  
Radu Cornel Guiaşu ◽  
Silviu Guiaşu
Keyword(s):  
Information Theory ◽  
Shannon Entropy ◽  
Supplementary Information ◽  
Conservation Value ◽  
Ecological Diversity ◽  
Simpson Index ◽  
Global Measure ◽  
Absolute Abundance ◽  
Economic Significance ◽  
Respective Species

Shannon's entropy and Simpson's index are the most used measures of species diversity. As the Simpson index proves to be just an approximation of the Shannon entropy, conditional Simpson indices of diversity and a global measure of interdependence among species are introduced, similar to those used in the corresponding entropic formalism from information theory. Also, since both the Shannon entropy and the Simpson index depend only on the number and relative abundance of the respective species in a given ecosystem, the paper generalizes these indices of diversity to the case when a numerical weight is attached to each species. Such a weight could reflect supplementary information about the absolute abundance, the economic significance, or the conservation value of the species.

Assessing alpha and beta diversities of benthic macroinvertebrates and their environmental drivers between watersheds with different levels of habitat transformation in Japan

2019 ◽  
Vol 70 (4) ◽  
pp. 504 ◽  
Author(s):  
Chia-Ying Ko ◽  
Tomoya Iwata ◽  
Jun-Yi Lee ◽  
Aya Murakami ◽  
Junichi Okano ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Benthic Macroinvertebrates ◽  
Environmental Variables ◽  
Species Turnover ◽  
Alpha Diversity ◽  
Freshwater Ecosystems ◽  
Environmental Drivers ◽  
Habitat Transformation ◽  
Β Diversity ◽  
Different Levels

Little is known about differences in species diversity among ecological communities subject to different levels of human-caused habitat transformation and how this disturbance contributes to diversity through symbiotic dependencies with the environment in freshwater ecosystems. We estimated α and β diversities of benthic macroinvertebrates and relationships between diversity and environmental variables in Ado River (natural) and Yasu River (intermediately disturbed) watersheds, Japan. Alpha diversity was consistently slightly higher in the natural river watershed than in the intermediately disturbed one, but the spatial distribution was not equivalent. The opposite pattern was found for β diversity. Significant differences in environmental variables existed between the two river watersheds, with especially high chlorophyll-a concentrations detected in the intermediately disturbed watershed. Alpha diversity was not correlated with specific environmental variables, whereas water temperature and chlorophyll-a concentrations were the two most significant environmental variables influencing β diversity across sites in the two watersheds. These results suggest that diversity patterns in freshwater benthic macroinvertebrates are differentially influenced by levels of human-caused habitat transformation, especially that intermediately disturbed habitats may benefit species turnover, and further understanding how they relate to environmental variables is essential for protecting local to regional diversity and can provide useful information for conservation planning to maximise biodiversity at the watershed scale.

Constructing and Deconstructing Concepts

2016 ◽  
Vol 63 (5) ◽  
pp. 249-262 ◽  
Author(s):  
Charles A. Doan ◽  
Ronaldo Vigo
Keyword(s):  
Information Theory ◽  
Model Performance ◽  
Unsupervised Classification ◽  
Family Resemblance ◽  
Category Membership ◽  
Formal Models ◽  
Human Beings ◽  
One Dimensional ◽  
Relational Patterns ◽  
Optimal Classification

Abstract. Several empirical investigations have explored whether observers prefer to sort sets of multidimensional stimuli into groups by employing one-dimensional or family-resemblance strategies. Although one-dimensional sorting strategies have been the prevalent finding for these unsupervised classification paradigms, several researchers have provided evidence that the choice of strategy may depend on the particular demands of the task. To account for this disparity, we propose that observers extract relational patterns from stimulus sets that facilitate the development of optimal classification strategies for relegating category membership. We conducted a novel constrained categorization experiment to empirically test this hypothesis by instructing participants to either add or remove objects from presented categorical stimuli. We employed generalized representational information theory (GRIT; Vigo, 2011b , 2013a , 2014 ) and its associated formal models to predict and explain how human beings chose to modify these categorical stimuli. Additionally, we compared model performance to predictions made by a leading prototypicality measure in the literature.

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