Strictly speaking, a community is composed of all the organisms that live together in a particular habitat. Community structure concerns all the various ways in which the members of such a community relate to and interact with one another, as well as community-level properties that emerge from these interactions, such as trophic structure, energy flow, species diversity, relative abundance, and community stabil­ ity. In practice, ecologists are usually unable to study entire communities, but instead interest is often focused on some convenient and tractable subset (usually taxonomic) of a particular community or series of communities. Thus one reads about plant communities, fish communities, bird communities, and so on. My topic here is the structure of lizard communities in this somewhat loose sense of the word (perhaps assemblage would be a more accurate description); my emphasis is on the niche relationships among such sympatric sets of lizard species, especially as they affect the numbers of species that coexist within lizard communities (species den­ sity). So defined, the simplest (and perhaps least interesting) lizard communities would be those that contain but a single species, as, for instance, northern populations of Eumeces msciatus. At the other extreme, probably the most complex lizard commu­ nities are those of the Australian sandridge deserts where as many as 40 different species occur in sympatry (20). Usually species densities of sympatric lizards vary from about 4 or 5 species to perhaps as many as 20. Lizard communities in arid regions are generally richer in species than those in wetter areas; therefore, because almost all ecological studies of entire saurofaunas have been in deserts (l8, 20, 25), this paper emphasizes the structure of desert lizard communities. As such, I review mostly my own work. Other studies on lizard communities in nondesert habitats are, however, cited where appropriate. Historical factors such as degree of isolation and available biotic stocks (particu­ larly the species pools of potential competitors and predators) have profoundly shaped lizard communities. Thus one reason the Australian deserts support such very rich lizard communities may be that competition with, and perhaps predation pressures from, snakes, birds, and mammals are reduced on that continent (20).

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The structure of lizard communities

The very etymology of Ecology, from the greek 'Qikos', 'the household', implies that ecologists should devote some attention to the 'house' or habitat of the population or community they are studying. However, as Charles Elton (1966) has so forcibly pointed out, 'definition of habitats, or rather lack of it, is one of the chief blind spots in Zoology'. Elton himself has provided us with a qualitative classification of habitats, while another past President, Alex Watt (1947) highlighted the dynamic nature of habitats by his phrase, 'pattern and process'. Elton referred to the need to quantify habitat characteristics. In this Address I will attempt some quantification;however, you will all be aware that in doing this I will not be able to emulate those former Presidents who have been able to provide a definitative synthesis of a field or of their own studies, my offering can be but a small beginning, an indication of the type of characteristics we should quantify. In considering ecosystem patterns and environment R. M. May (1974) writes 'it is to be emphasized that although patterns may underlie the rich and varied tapestry of the natural world, there is no single simple pattern. Theories must be pluralistic'. Indeed, the complexity of the subject is daunting and in any attempt to formulate some type of general framework, one is continually beset with exceptions. In stressing the need for a framework I am echoing a plea of my predecessor Amyan Macfadyen (1975) who cited K. E. F. Watt's (1971) vivid image 'if we do not develop a strong theoretical core that will bring all parts of ecology back together we shall all be washed out to sea in an immense tide of unrelated information'. In some ways I think we may see ourselves at a similar point to the inorganic chemist before the development of the periodic table; then he could not predict, for example, how soluble a particular sulphate would be, or what was the likelihood of a particular reaction occurring. Each fact had to be discovered for itself and each must be remembered in isolation. It is noteworthy that from Dobereiner's early efforts in 1816 it took more than fifty years before Mendeleeff ormulated his Periodic Law (1869) and even after this there were various attempts at rearrangement. Another parallel may be drawn with astronomy before the development of the Hertzsprung-Russell diagram that relates the evolution and the properties of stars. Again in our own subject biology, the situation is somewhat analagous to that before the formulation of the Linnean system of classification; but now from this system of classification, we are able to organize our knowledge of, for example, the functional morphology of organisms and we can even make assumptions, with a high probability

Habitat, the template for ecological strategies?

A behavioral syndrome is a suite of correlated behaviors expressed either within a given behavioral context (e.g., correlations between foraging behaviors in different habitats) or across different contexts (e.g., correlations among feeding, antipredator, mating, aggressive, and dispersal behaviors). For example, some individuals (and genotypes) might be generally more aggressive, more active or bold, while others are generally less aggressive, active or bold. This phenomenon has been studied in detail in humans, some primates, laboratory rodents, and some domesticated animals, but has rarely been studied in other organisms, and rarely examined from an evolutionary or ecological perspective. Here, we present an integrative overview on the potential importance of behavioral syndromes in evolution and ecology. A central idea is that behavioral correlations generate tradeoffs; for example, an aggressive genotype might do well in situations where high aggression is favored, but might be inappropriate...

https://www.jstor.org/stable/10.1086/422893

Behavioral syndromes: An integrative overview

What determines the number and size of the seeds produced by a plant? How often should it reproduce them? How often should a plant produce them? Why and how are seeds dispersed, and what are the implications for the diversity and composition of vegetation? These are just some of the questions tackled in this wide-ranging review of the role of seeds in the ecology of plants. The authors bring together information on the ecological aspects of seed biology, starting with a consideration of reproductive strategies in seed plants and progressing through the life cycle, covering seed maturation, dispersal, storage in the soil, dormancy, germination, seedling establishment, and regeneration in the field. The text encompasses a wide range of concepts of general relevance to plant ecology, reflecting the central role that the study of seed ecology has played in elucidating many fundamental aspects of plant community function.

The ecology of seeds

Invasions by non-native ants are an ecologically destructive phenomenon affecting both continental and island ecosystems throughout the world. Invasive ants often become highly abundant in their introduced range and can outnumber native ants. These numerical disparities underlie the competitive asymmetry between invasive ants and native ants and result from a complex interplay of behavioral, ecological, and genetic factors. Reductions in the diversity and abundance of native ants resulting from ant invasions give rise to a variety of direct and indirect effects on non-ant taxa. Invasive ants compete with and prey upon a diversity of other organisms, including some vertebrates, and may enter into or disrupt mutualistic interactions with numerous plants and other insects. Experimental studies and research focused on the native range ecology of invasive ants will be especially valuable contributions to this field of study.

The Causes and Consequences of Ant Invasions

A simple graphical model for maximization of total lifetime reproductive success is developed using the demographic parameters of current fecundity and residual reproductive value. Trade-offs between present progeny and expectation of future offspring are treated in terms of costs and profits to lifetime reproductive success. Various limitations of the model and some relevant data are presented and discussed. Single-clutched species are distinguished from those that lay multiple clutches each reproductive season, because residual reproductive value in the latter group varies proportionally much more during ontogeny than in the former group. Some difficulties in measuring reproductive effort in a changing environment are pointed out.

Age-Specific Reproductive Tactics

AYALA, S. C. 1970. Lizard malaria in California: Description of a strain of Plasmodium mexicanum, and biogeography of lizard malaria in western North America. J. Parasit. 56:417-425. , AND R. HUTCHINGS. 1974. Hemogregarines as zoogeographical tracers of Galapagos Island lava lizards and marine iguanas. Herpetologica 30:128-132. DESSAUER, H. C., AND W. Fox. 1959. Changes in ovarian follicle composition with plasma levels of snakes during estrus. Amer. J. Physiol. 197: 360-366.

https://www.jstor.org/stable/pdfplus/1442418.pdf

Ecology of Horned Lizards: A Review with Special Reference to Phrynosoma platyrhinos

A Ventral Scale Clipping System for Permanently Marking Snakes (Reptilia, Serpentes)

• The association of tinnitus and vertigo with temporomandibular disorder (TMD) has been debated for many years. The observation that patients with TMD have otologic symptoms is confounded because tinnitus and vertigo are common symptoms in the normal population. The present study was conducted to determine if tinnitus and vertigo are actually more prevalent in patients with TMD than in appropriate age-matched controls. One control group was recruited from patients seeking care for health maintenance and the other from patients seeking routine dental care. We surveyed 1032 patients: 338 had TMD and 694 served as two age-matched control groups. Tinnitus and vertigo symptoms were significantly more prevalent in the TMD group than in either of the control groups. The mechanism of the association of TMD and otologic symptoms is unknown. (Arch Otolaryngol Head Neck Surg. 1992;118:817-821)

https://jamanetwork.com/HttpHandlers/ArticlePdfHandler.ashx?journal=OTOL&articleId=620872&pdfFileName=archotol_118_8_010.pdf

Tinnitus and Vertigo in Patients With Temporomandibular Disorder

SIVILINGHAM, S. 1956. Age and growth in Taeniotica lateralis. Ceylon Jour. Sci., Sec. C. Fish 1 (new series):135-181. SOKAL, R. R., AND F. J. ROHLF. 1969. Biometry. W. H. Freeman and Co., San Francisco. SOULE, M. 1966. Trends in the insular radiation of a lizard. Amer. Natur. 100:47-64. , AND B. R. STEWART. 1970. The "nichevariation" hypothesis: A test and alternatives. Ibid. 104:85-95. TURNER, C. H., E. E. EBERT AND R. R. GIVEN. 1969. man-made reef ecology. Calif. Dept. Fish Game Fish Bull. 146:1-221. VALENTINE, J. W., AND J. H. LIPPS. 1967. Late cenozoic history of the southern California islands. In: Proceedings of the Symposium on the Biology of the California Islands, Santa Barbara Botanic Garden, Santa Barbara, Calif. VAN VALEN, L. 1965. Morphological variation and the width of ecological niche. Amer. Natur. 99: 377-390. WILSON, E. 0. 1959. Adaptive shift and dispersal in a tropical ant fauna. Evolution 13:122-144.

http://www.jstor.org/stable/pdfplus/1443314.pdf

William S. Parker

Papers

Age-Specific Reproductive Tactics

Ecology of Horned Lizards: A Review with Special Reference to Phrynosoma platyrhinos

A Ventral Scale Clipping System for Permanently Marking Snakes (Reptilia, Serpentes)

Tinnitus and Vertigo in Patients With Temporomandibular Disorder

Comparative Ecology of Populations of the Lizard Uta stansburiana