Ward Watt - US grants

This project will examine metabolic, physiological and consequent fitness-related effects in vivo of naturally occurring genetic polymorphism in enzymes of glycolysis. An insect study system (genus Colias; Lepidoptera, Pieridae) will be used. We have already begun to document in vivo effects, at all organizational levels, of a major polymorphism at the phosphoglucose isomerase (PGI) locus. We will complete documentation of this variation's effects on glycolytic intermediate pool sizes, changes in flux through this pathway, etc. in relation to relevant biological variables such as temperature and activity demand. Physiological consequences for flight capacity, and entailed changes in survivorship, flight activity, mating success, and mate choice in the wild will all be documented. Genetic variation at additional glycolytic loci will be put to similar examination as knowledge of it is developed. Available analytical or simulation models will be used or extended to establish continuity of effects among different levels of organization. The overall results will advance understanding of allozyme polymorphisms, lead to progress in evolutionary genetics, and clarify the possible importance of allozyme variation for public health, in direct application to human genetics and indirectly via agricultural implications.

This project will examine metabolic, physiological, and consequent fitness-related effects in vivo of naturally occurring genetic polymorphism in enzymes of glycolysis. An insect study system (genus Colias; Lepidoptera, Pieridae) will be used. We have already begun to document in vivo effects, at all organizational levels, of a major polymorphism at the phosphoglucose isomerase (PGI) locus. We will complete documentation of this variation's effects on glycolytic intermediate pool sizes, changes flux through this pathway, etc. in relation to relevant biological variables such as in temperature and activity level. Physiological consequences for flight capacity, and entailed changes in survivorship, flight activity, mating success, and mate choice in the wild will all be investigated. Genetic variation at additional glycolytic loci will be put to similar study as its basic nature comes to be understood. Analytical and simulation modelling will be used or extended to establish continuity of effects among levels of organization. The overall results will advance understanding of allozyme polymorphisms, lead to progress in evolutionary genetics, and clarify the possible importance of allozyme variation for public health, in direct application to human genetics and indirectly via agricultural implications.

Small strongly flying insects need not fly at high, narrow body temperatures, in terms of the balance of their heat gain or loss. Yet in fact they do so, and even have a variety of complex adaptations for actively regulating body temperature to high and narrow ranges. We will complete the study of how this thermal regulation works during flight itself, and how body temperature variation affects actual flight performance. To do this, we will first complete the construction of a computerized wind tunnel in which to carry out our experiments. Experimental use of this tool to examine a variety of specific issues in the heat-transfer biophysics and the temperature-dependence of flight lift and thrust will follow. We will also test an entirely new concept of why it is that intense animal activity, such as insect flight, is so invariably limited in its range of effective temperatures. This work will be important to a number of issues in basic biology, all revolving around the reasons why animals regulate their body temperatures, the range of ways in which they can do so, and their adaptations for making strenuous and demanding activity more efficient. It may also be extremely important to considering the possible damaging effects of global climate change, especially global warming, which may alter the thermal environments of such sensitive animals on a time scale much shorter than that of their ability to adjust.

Watt 9807609 In the proposed support period the PIs will finish development of a nearly completed method for analyzing metabolites of glycolysis in direct energetic support of insect flight. The PIs will evaluate the effects on flight performance of 10 natural genotypes of a gtycolytic: enzyme, PGI, in the PIs insect study system, using the PIs computerized insect wind tunnel to evaluate lift and thrust output, duration of peak output, and duration of minimal flight sustenance as functions of genotype, brood, and other relevant independent variables. The PIs will test the same genotypes for their effects on flight initiation and sustenance at the behavioral level in outdoor cages, with microclimate monitoring in the cages to establish appropriate control of daily thermal fluctuations. This research, if successful, will lay the foundation for much new progress in the study of adaptive metabolic organization in support of animal locomotion and behavior.

Inheritable variation occurs widely in many different creatures, sometimes over long time periods, forming a persistent part of the organisms' abilities to adapt to their environments. What distinguishes persistent variation from transitory cases? An insect study system will be used to study a persistent case affecting the cellular "machinery" of energy processing common to all living things. How do the chemical and genetic effects of this variation interact with natural environments to maintain the variation, and how the system of variation has evolved as species carrying it have adapted to new habitats? Hopefully, general rules governing evolutionary change will emerge.

These results and their implications will shed important light on problems of concern to human society. For example, energy processing mechanisms in domestic crop animals and plants are no less variable than in these test insects. Many crop species have longer lives and are harder to use for initial study of adaptive principles than the test system. But there is good reason to believe that its results will apply to such crop species, and will assist in selective breeding to maximize food yield in changing agricultural environments. Equally, genetic aspects of conservation of rare species, and of environmental management in general, will be informed by this work in the same ways.

Dr. Watt's research deals with the rise of complex biological adaptations from simpler beginnings. His team uses as a study system a group of insects whose field and lab biology are both well known, allowing for greater analytical power to study the whole process of natural selection, from chemical mechanisms to actual differences in fitness among inheritable variants in the wild. Also, the fact that these insects' energy-demanding flight uses physiology common to all cellular life makes the studies of this "evolutionary model" system of general relevance to many other physiologically active animals (including humans).

Recently, Dr. Watt has found evidence of a historical "innovative step" in the structure of a particular catalytic protein which is central to animal energy processing. This "step" confers sharply increased resistance to heat stress on populations and species which carry it, as compared to other ancestral species. Perhaps as a consequence, in one population of a lowland species, now thermally resistant in this energy processing mechanism, Dr. Watt and his team find a very wide range of new variation experiencing temperature-related natural selection. Further, out of this range of variants, new and more complex combinations are becoming successful. This work will first explore the nature of the processes generating these combinations, and then test the generality of the findings among genes and species.

This work will bear on major conceptual issues in evolutionary biology, such as:
- How living complexity arises from simple beginnings, which has been a central focus since Darwin;
- The likelihood that some living mechanisms may exhibit chronic natural variability, rather than there routinely being one superior "type" which is predominant in populations;
- Clarification of the connections between large-scale, long-term "macroevolution" across populations and species, and local "microevolution" adjusting populations to local conditions in the short term.

Understanding the complexity of adaptation to naturally changed thermal conditions will be important in understanding the stresses placed on these mechanisms by rapid human-caused change of local and global thermal conditions. There are implications here for conservation and environmental management and for agriculture and medicine as the environmental context for both change rapidly.