Bassett Maguire

Control of Community Structure by Mosquito Larvae

Observations of communities living in water held in the bracts of flowers of the wild banana, Heliconia bihai, in Puerto Rico show mosquito larvae to have very great influence in determination of community structure. These larvae quickly eliminate all or nearly all Protozoa and micro—Metazoa (other than arthropods) which, in the absence of mosquito larvae, are abundant in Heliconia—held water. Laboratory experiments support this conclusion. See full-text article at JSTOR

Species and Individual Productivity in Phytoplankton Communities

The relative productivity of individual cells in a mixed phytoplankton community has been determined by (14)C autoradiography. These data allow the estimation of the relative contribution of each of the component species to total community production, illustrate the size—specific production of the cells of each of these species, and suggest predictions concerning future successional developments of the community. See full-text article at JSTOR

Monodella Texana N. Sp., an Extension of the Range of the Crustacean Order Thermosbaenacea To the Western Hemisphere 1)

Monodella texana n. sp. ist ein Mitglied der Crustaceen Ordnung Thermosbaenacea, welche bis zur Entdeckung dieser Art in Texas (U.S.A.) nur aus dem Mittelmeer-Gebiet bekannt war.

Lethal Effect of Visible Light on Cavernicolous Ostracods.

Light intensities of the order of 1/20th that of normal sunlight are sufficient to kill ostracods from two different caves. Loss of physiological protection against light has probably occurred through the same mechanism which has resulted in the much better known loss of morphological characters in cave animals.

Ecosystem simulation through use of models of subsystem response structures

Every system has specific kinds and levels of re sponses to conditions as they exist and change in the environment in which the system is immersed. Each response can be expressed quantitatively by a structure in N-dimensional space, where N refers to the number of different environmental factors which operate together to determine the level of that response, and each dimension represents one of the determinative environmental factors. Examination via this response structure of the relationship between environmental factor levels and the systems response permits analysis and modeling of the systems dynamics and allows accurate evaluation of its relationships to other systems. This paper in cludes examples of use of this approach in the modeling of the ecological processes of population growth, competition, predation, and evolution, and it presents a model of a simple hierarchical eco system. Suggestions are made concerning the utiliza tion of this analytical and heueristic approach to examine other, very different systems; brief examples from economics, public health, and social psychology are given.

Crustacea: A Primitive Mediterranean Group also Occurs in North America

A new species of the genus Monodella (class Crustacea, order Thermosbaenacea) has been found in a cave pool in Texas. Previously the order was believed to be restricted to the Mediterranean area. The new evidence indicates that the order is older than was believed, or that invasion of fresh or brackish water has occurred more than once within the order.

Models Based On Response Structure

This paper outlines in very simple form how one may use the response-structure (RS) approach to analyze and model the dynamics of systems. It should be read before my longer article (Ecosystem Simulation through Use of Models of Subsystem Response Structure) which begins on page 149 of this issue. The broad picture presented in this paper will prove very helpful to the reader of the longer article, and it describes the essential feature of a relatively new and very useful technique for modeling and studying systems, including those that contain grow ing or decaying variables.

Analysis and Modeling of Evolutionary Dynamics with the Response Structure/Environmental Structure Approach

This paper illustrates a recently introduced way of visualizing, thinking about, analyzing, and modeling evolutionary and ecological processes. Maps of responses of various phenotypes can be made and then can be used to examine both evolutionary dynamics and the results emergent from the operation of these processes. Perhaps even more important than its considerable analytical power and versatility, this approach has highly useful heuristic characteristics which provide for clear and simple visualization of complex and important biological processes. The following introductory comments will be useful.

MODELING OF ECOLOGICAL PROCESS AND ECOSYSTEMS WITH PARTIAL RESPONSE STRUCTURES: A REVIEW AND A NEW PARADIGM FOR DIAGNOSIS OF EMERGENT ECOSYSTEM DYNAMICS AND PATTERNS

First, existing examples of response structure modelling are briefly outlined, and the computational and heuristic advantages of the approach are reviewed. Then the use of this kind of structure for data organization and presentation suggested, and several examples of use of this kind of visual aid are briefly reviewed. Finally an extension of the analytical model, developed for this paper, is presented. This simple model produced surprising complexity. It permits ready evaluation of the relative effects of various combinations of niche size and the amount of (annual) environmental variation on the dynamics of a simple competitive ecosystem and on some of its emergent properties, including the spatial distribution of its species populations, the pattern of annual fluctuation of those populations, and the stability of the system. The large amount and the details of the complexity generated by the simple ecological interactions of this simple model are instructive.

Megaproblems of megamodel builders

Megamodel builders have major unresolved problems which need much more attention than they are getting. One of these is the difficulty which the modelers have in accepting and then acting on the reality that the human-environmental complex is a single functional system, and that it has critically large (and increasing) amounts of interaction among its various parts. Some of these difficulties obviously are the results of the limits of the mental reach