So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

The evolution of "niche breadth," or "niche width," was a more popular topic in the evolutionary ecological literature of the 1960s and 1970s than it has been recently (109, 118, 120, 134, 155, 156). This review summarizes current hypotheses on the evolution of specialization and generalization and suggests areas in which future research might be rewarding. The topic is so broad that every area of biology bears on it. We cannot hope to offer an exhaustive review of evidence and in particular have slighted much of the ecological literature to emphasize genetic and evolutionary perspectives. We limit our discussion almost entirely to animals. We adopt Hutchinson's (86) representation of a population's ecological niche as an n-dimensional hypervolume, the axes of which are environmental variables or resources. Along each of these, the population displays a wide or narrow tolerance or pattern of utilization, relative to other populations or species. Specialization and generalization must be defined with reference to particular axes (e.g. temperature, range of food particle sizes). Brown (9) suggests that niche breadth along different axes is positively correlated and that this explains positive correlations across species between local abundance and breadth of geographic range. Multidimensional specialization might be expected if species arise in localized regions that differ in several ecological respects from those occupied by parent species. Cody (20), however, suggested that the breadth of habitat is negatively correlated with diet breadth among certain bird species. In practice, quantitative measurement of niche breadth can be difficult (22,

The Evolution of Ecological Specialization

Half of all insect species are dependent on living plant tissues, consuming about 10% of plant annual production in natural habitats and an even greater percentage in agricultural systems, despite sophisticated control measures. Plants are generally remarkably well-protected against insect attack, with the result that most insects are highly specialized feeders. The mechanisms underlying plant resistance to invading herbivores on the one side, and insect food specialization on the other, are the main subjects of this book. For insects these include food-plant selection and the complex sensory processes involved, with their implications for learning and nutritional physiology, as well as the endocrinological spects of life cycle synchronization with host plant phenology. In the case of plants exposed to insect herbivores, they include the activation of defence systems in order to minimize damage, as well as the emission of chemical signals that may attract natural enemies of the invading herbivores and maybe exploited by neighbouring plants that mount defences as well.

Insect-plant biology

Parasitoids and predators of herbivores have evolved and function within a multitrophic context. Consequently, their physiology and behavior are in­ fluenced by elements from other trophic levels such as their herbivore victim (second trophic level) and its plant food (first trophic level) (126) . Natural enemies base their foraging decisions on information from these different trophic levels, and chemical information plays an important role. This review is restricted to the ecology of chemical information from the first and second trophic levels. The importance of so-called infochemicals, a subcategory of semiochemicals, in foraging by parasitoids and predators has been well documented (e.g. reviewed in 31, 78, Il l , 183, 185) , and we do not intend to repeat the details. But because of a lack of testable hypotheses, all this research is conducted rather haphazardly: the total puzzle of infochemical use has not been solved for any natural enemy species. Here we approach the use of infochemicals by natural enemies from an evolutionary and ecological standpoint. Our basic concept is that information from the first and second trophic levels differs in availability and in reliability, a difference that shapes the way infochemicals are used by a species. We generate hypotheses on (a)

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Ecology of infochemical use by natural enemies in a tritrophic context.

When individuals of two species interact, they can adjust their phenotypes in response to their respective partner, be they antagonists or mutualists. The reciprocal phenotypic change between individuals of interacting species can reflect an evolutionary response to spatial and temporal variation in species interactions and ecologically result in the structuring of food chains. The evolution of adaptive phenotypic plasticity has led to the success of organisms in novel habitats, and potentially contributes to genetic differentiation and speciation. Taken together, phenotypic responses in species interactions represent modifications that can lead to reciprocal change in ecological time, altered community patterns, and expanded evolutionary potential of species.

https://science.sciencemag.org/content/sci/294/5541/321.full.pdf

Phenotypic plasticity in the interactions and evolution of species.

Our objective in compiling a series of chapters on the chemical ecology of insects has been to delineate the major concepts of this discipline. The fine line between presenting a few topics in great detail or many topics in veneer has been carefully drawn, such that the book contains sufficient diversity to cover the field and a few topics in some depth. After the reader has penetrated the crust of what has been learned about chemical ecology of insects, the deficiencies in our understanding of this field should become evident. These deficiencies, to which no chapter topic is immune, indicate the youthful state of chemical ecology and the need for further investigations, especially those with potential for integrating elements that are presently isolated from each other. At the outset of this volume it becomes evident that, although we are beginning to decipher how receptor cells work, virtually nothing is known of how sensory information is coded to become relevant to the insect and to control the behavior of the insect. This problem is exacerbated by the state of our knowledge of how chemicals are distributed in nature, especially in complex habitats. And finally, we have been unable to understand the significance of orientation pathways of insects, in part because of the two previous problems: orientation seems to depend on patterns of distri- bution of chemicals, the coding of these patterns by the central nervous system, and the generation of motor output based on the resulting motor commands.

Chemical Ecology of Insects

Odor plumes and how insects use them , Odor plumes and how insects use them , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

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Odor plumes and how insects use them

Male moths generally find their mates by following the females' pheromone plume to its source. A formulated copy of this message is used to regulate mating of many important pests, including the pink bollworm (Pectinophora gossypiella), the oriental fruit moth (Grapholita molesta), and the tomato pinworm (Keiferia lycopersicella). How synthetic disruptant interrupts normal orientation is uncertain, but the most probable mechanisms invoke adaptation and habituation, competition between point sources of formulation and females, and a camouflage of a female's pheromone plume by the formulation. The efficacy of this technology is related principally to the motility of mated females into the area to be managed, the initial population levels of the pest, and the release characteristics of the formulation. In most cases, implementation of this technology necessitates a sophisticated monitoring and management program. Area-wide management schemes are ideal vehicles for using disruptants. Future acceptance of this...

CONTROL OF MOTH PESTS BY MATING DISRUPTION: Successes and Constraints

Awarded Best Reference by the New York Public Library (2004), Outstanding Academic Title by CHOICE (2003), and AAP/PSP 2003 Best Single Volume Reference/Sciences by Association of American Publishers' Professional Scholarly Publishing Division, the first edition of Encyclopedia of Insects was acclaimed as the most comprehensive work devoted to insects. Covering all aspects of insect anatomy, physiology, evolution, behavior, reproduction, ecology, and disease, as well as issues of exploitation, conservation, and management, this book sets the standard in entomology. The second edition of this reference will continue the tradition by providing the most comprehensive, useful, and up-to-date resource for professionals. Expanded sections in forensic entomology, biotechnology and Drosphila, reflect the full update of over 300 topics. Articles contributed by over 260 high profile and internationally recognized entomologists provide definitive facts regarding all insects from ants, beetles, and butterflies to yellow jackets, zoraptera, and zygentoma. * 66% NEW and revised content by over 200 international experts * New chapters on Bedbugs, Ekbom Syndrome, Human History, Genomics, Vinegaroons * Expanded sections on insect-human interactions, genomics, biotechnology, and ecology * Each of the 273 articles updated to reflect the advances which have taken place in entomology research since the previous edition * Features 1,000 full-color photographs, figures and tables * A full glossary, 1,700 cross-references, 3,000 bibliographic entries, and online access save research time * Updated with online access

Encyclopedia of insects.

The diminutive size of most parasitoids undoubtedly has limited their choice as subjects for behavioral study, despite their great diversity in lifestyles and reproductive strategies The present chapter addresses their foraging behavior as influenced by learning Most of their adult life female parasitoids search for host insects which, in turn, are under selection to avoid being found and devoured This scenario sets the stage for the evolution of diverse hide-and-seek games played by parasitoids and their victims, most often herbivores That parasitoids are successful in their quest for hosts is evidenced by the vast number of parasitoid species and their importance in insect management

Ring T. Cardé

Papers

Chemical Ecology of Insects

Odor plumes and how insects use them

CONTROL OF MOTH PESTS BY MATING DISRUPTION: Successes and Constraints

Encyclopedia of insects.

Parasitoid foraging and learning.