scispace - formally typeset
Search or ask a question
Author

Gerald W. Esch

Other affiliations: University of Toronto
Bio: Gerald W. Esch is an academic researcher from Wake Forest University. The author has contributed to research in topics: Population & Helisoma anceps. The author has an hindex of 38, co-authored 172 publications receiving 7233 citations. Previous affiliations of Gerald W. Esch include University of Toronto.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, an ad hoc committee was established to establish working definitions of a few terms used and misused by parasitological ecologists as a guide for authors submitting papers to The Journal of Parasitology.
Abstract: In February 1981, ASP President Elmer Noble on recommendation from the Editor, Austin Maclnnis, appointed an ad hoc committee \"to establish working definitions of a few terms used and misused by parasitological ecologists\" as a guide for authors submitting papers to The Journal of Parasitology. Appointed to the committee were Drs. Gerald Esch, John Holmes, Armand Kuris, Gerhard Schad, and Leo Margolis (Chairman). As a starting point the committee examined the recommendations (Margolis et al., 1982) prepared by a similar committee established by the Parasitology Section of the Canadian Society of Zoologists. The Canadian Committee concerned itself only with terms required to express concepts related to the number of hosts in a sample infected with a particular species of parasite, and to the number of individuals of a particular parasite in each host in a sample. As noted below the present committee also dealt with several other ecological terms that are not now being used in a consistent manner in parasitological literature. The following are the committee's recommendations, annotated as required:

1,923 citations

Book
01 Mar 2001
TL;DR: Parasitism in other metazoan groups 10.
Abstract: Reflecting the enormous advances made in the field over the past ten years, this text synthesizes the latest developments in the ecology and evolution of animal parasites against a backdrop of parallel advances in parasite systematics, biodiversity and life cycles. This second edition has been thoroughly revised to meet the needs of a new generation of parasitology students. Balancing traditional approaches in parasitology with modern studies in parasite ecology and evolution, the authors present basic ecological principles as a unifying framework to help students understand the complex phenomenon of parasitism. Richly illustrated with over 250 figures, the text is accompanied by case study boxes designed to help students appreciate the complexity and diversity of parasites and the scientists who study them. This unique approach, presented clearly and with a minimum of jargon and mathematical detail, encourages students from diverse backgrounds to think generally and conceptually about parasites and parasitism.

591 citations

Journal ArticleDOI
TL;DR: In this article, a detailed overview of patterns and processes in helminth parasite communities is presented. But the authors focus on the processes of forming a guild of larval trematode parasites in molluscan hosts: prevalence, dominance and significance in competition.
Abstract: 1 Patterns and processes in helminth parasite communities: an overview.- 2 Host populations as resources defining parasite community organization.- 3 Spatial scale and the processes structuring a guild of larval trematode parasites.- 4 Guild structure of larval trematodes in molluscan hosts: prevalence, dominance and significance in competition.- 5 Helminth communities in marine fishes.- 6 Helminth communities in freshwater fish: structured communities of stochastic assemblages?.- 7 Helminth communities of amphibians and reptiles: comparative approaches to understanding patterns and processes.- 8 Helminth communities in avian hosts: determinants of pattern.- 9 Helminth community of mammalian hosts: concepts at the infracommunity, component and compound community levels.- 10 Models for multi-species parasite-host communities.- 11 Free-living communities and alimentary tract helminths: hypotheses and pattern analyses.- 12 Concluding remarks.

384 citations

Journal ArticleDOI
TL;DR: Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminth communities.
Abstract: Examples of the apparently stochastic nature of freshwater fish helminth communities illustrating the erratic and unpredictable occurrence and distribution of many species are provided for six species of fish from several localities throughout Britain. By focussing on parasite colonization strategies two categories of helminths are recognized: autogenic species which mature in fish and allogenic species which mature in vertebrates other than fish and have a greater colonization potential and ability. Three groups of fish are distinguished: salmonids, in which helminth communities are generally dominated by autogenic species which are also responsible for most of the similarity within and between localities; cyprinids, in which they are dominated by allogenic species which are also responsible for most of the similarity within and between localities; and anguillids, whose helminth communities exhibit intermediate features with neither category consistently dominating nor providing a clear pattern of similarity. Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation, and their period of residence in a locality, whether transient or permanent, provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminths. Comparison with other parts of the world indicates that colonization is a major determinant of helminth community structure.

220 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols used xiii 1.
Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

14,171 citations

01 Jan 2007

4,037 citations

Journal ArticleDOI
TL;DR: In this paper, an ad hoc committee was established to establish working definitions of a few terms used and misused by parasitological ecologists as a guide for authors submitting papers to The Journal of Parasitology.
Abstract: In February 1981, ASP President Elmer Noble on recommendation from the Editor, Austin Maclnnis, appointed an ad hoc committee \"to establish working definitions of a few terms used and misused by parasitological ecologists\" as a guide for authors submitting papers to The Journal of Parasitology. Appointed to the committee were Drs. Gerald Esch, John Holmes, Armand Kuris, Gerhard Schad, and Leo Margolis (Chairman). As a starting point the committee examined the recommendations (Margolis et al., 1982) prepared by a similar committee established by the Parasitology Section of the Canadian Society of Zoologists. The Canadian Committee concerned itself only with terms required to express concepts related to the number of hosts in a sample infected with a particular species of parasite, and to the number of individuals of a particular parasite in each host in a sample. As noted below the present committee also dealt with several other ecological terms that are not now being used in a consistent manner in parasitological literature. The following are the committee's recommendations, annotated as required:

1,923 citations

Journal ArticleDOI
TL;DR: Overall studies of parasite communities suggest that the action of processes determining species richness of parasite assemblages becomes less detectable as focus shifts from parasite faunas to infracommunities.
Abstract: Parasite communities are arranged into hierarchical levels of organization, covering various spatial and temporal scales. These range from all parasites within an individual host to all parasites exploiting a host species across its geographic range. This arrangement provides an opportunity for the study of patterns and structuring processes operating at different scales. Across the parasite faunas of various host species, several species-area relationships have been published, emphasizing the key role of factors such as host size or host geographical range in determining parasite species richness. When corrections are made for unequal sampling effort or phylogenetic influences, however, the strength of these relationships is greatly reduced, casting a doubt over their validity. Component parasite communities, or the parasites found in a host population, are subsets of the parasite fauna of the host species. They often form saturated communities, such that their richness is not always a reflection of that of the entire parasite fauna. The species richness of component communities is instead influenced by the local availability of parasite species and their probability of colonization. At the lowest level, infracommunities in individual hosts are subsets of the species occurring in the component community. Generally, their structure does not differ from that expected from a random assembly of available species, although comparisons with precise null models are still few. Overall studies of parasite communities suggest that the action of processes determining species richness of parasite assemblages becomes less detectable as focus shifts from parasite faunas to infracommunities.

1,479 citations

Journal ArticleDOI
01 Feb 1999-Oikos
TL;DR: It is argued that ecology has numerous laws in this sense of the word, in the form of widespread, repeatable patterns in nature, but hardly any laws that are universally true.
Abstract: The dictionary definition of a law is: "Generalized formulation based on a series of events or processes observed to recur regularly under certain conditions; a widely observable tendency". I argue that ecology has numerous laws in this sense of the word, in the form of widespread, repeatable patterns in nature, but hardly any laws that are universally true. Typically, in other words, ecological patterns and the laws, rules and mechanisms that underpin them are contingent on the organisms involved, and their environment. This contingency is manageable at a relatively simple level of ecological organisation (for example the population dynamics of single and small numbers of species), and re-emerges also in a manageable form in large sets of species, over large spatial scales, or over long time periods, in the form of detail-free statistical patterns - recently called 'macroecology'. The contingency becomes overwhelmingly complicated at intermediate scales, characteristic of community ecology, where there are a large number of case histories, and very little other than weak, fuzzy generalisations. These arguments are illustrated by focusing on examples of typical studies in community ecology, and by way of contrast, on the macroecological relationship that emerges between local species richness and the size of the regional pool of species. The emergent pattern illustrated by local vs regional richness plots is extremely simple, despite the vast number of contingent processes and interactions involved in its generation. To discover general patterns, laws and rules in nature, ecology may need to pay less attention to the 'middle ground' of community ecology, relying less on reductionism and experimental manipulation, but increasing research efforts into macroecology.

1,349 citations