Robert Hershler

Bio: Robert Hershler is an academic researcher from Smithsonian Institution. The author has contributed to research in topics: Pyrgulopsis & Hydrobiidae. The author has an hindex of 28, co-authored 106 publications receiving 3096 citations. Previous affiliations of Robert Hershler include Metropolitan State University of Denver & National Museum of Natural History.

The Global Decline of Nonmarine Mollusks

Abstract: Invertebrate species represent more than 99% of animal diversity; however, they receive much less publicity and attract disproportionately minor research effort relative to vertebrates. Nonmarine mollusks (i.e., terrestrial and freshwater) are one of the most diverse and imperiled groups of animals, although not many people other than a few specialists who study the group seem to be aware of their plight. Nonmarine mollusks include a number of phylogenetically disparate lineages and species-rich assemblages that represent two molluscan classes, Bivalvia (clams and mussels) and Gastropoda (snails, slugs, and limpets). In this article we provide an overview of global nonmarine molluscan biodiversity and conservation status, including several case studies documenting the diversity and global decline of nonmarine mollusks. We conclude with a discussion of the roles that mollusks and malacologists should play in conservation, including research, conservation management strategies, and education and ou...

The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea) : review of classification and supraspecific taxa

Abstract: Kabat, Alan R., and Robert Hershler. The Prosobranch Snail Family Hydrobiidae (Gastropoda: Rissooidea): Review of Classification and Supraspecific Taxa. Smithsonian Contributions to Zoology, number 547, 94 pages, 4 tables, 1993.—A nomenclatural analysis is provided for the 75 family level names and 725 generic-level names in the freshand brackish-water prosobranch gastropod family Hydrobiidae. For the 725 generic-level taxa, 405 are nomenclaturally available and in "current usage"; 51 are junior homonyms; 65 are commonly acknowledged junior synonyms; 24 are nomina nuda or otherwise invalid; and 180 are errors or emendations. The Hydrobiidae are redefined and differentiated from other rissooidean families, and a review of the classification of this family is presented. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging-in-Publication Data Kabat, Alan R. The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): review of classification and supraspecific taxa / Alan R. Kabat and Robert Hershler. p. cm.—(Smithsonian contributions to zoology ; no. 547) Includes bibliographical references (p.) and indexes. 1. Hydrobiidae—Classification. 2. Hydrobiidae—-Nomenclature. I. Hershler, Robert II. Title. III. Series. QU.S54no. 547 [QL430.5.H9] 591 s—dc20 93-11450 [594'.32] CIP ® The paper used in this publication meets the minimum requirements of the American National Standard for Permanence of Paper for Printed Library Materials Z39.48—1984.

A Review of Morphological Characters of Hydrobioid Snails

Abstract: Hershler, Robert, and Winston F. Ponder. A Review of Morphological Characters of Hydrobioid Snails. Smithsonian Contributions to Zoology, number 600, 55 pages, 21 figures, 1998.—We provide herein a description of morphological characters of aquatic gastropods of the family Hydrobiidae and of several other families of Rissooidea that resemble these snails in general features. The hydrobiid gastropods comprise the largest group of freshwater mollusks, with more than 1,000 species and more than 400 Recent and fossil genera. This compilation is a prelude to the first rigorous phylogenetic analysis of the higher taxa of this cosmopolitan, yet poorly understood, group, for which at least 70 family-group taxa have been proposed. It also was prepared to fulfill a need for standardization of terminology and interpretation of characters used in taxonomic descriptions of these small, often morphologically simple, snails. Given that taxonomic study of these animals has long been hampered by reliance on a limited number of morphological features, all aspects of the shell and the soft-part anatomy are reviewed as part of this treatment, and we attempt to be maximally inclusive in listing characters. Emphasis is placed on characters considered potentially useful in recognizing and defining hydrobiid clades, although features having utility for species-rank descriptions are summarized in an appendix. For 202 characters, sufficient information was available to delineate states and tentatively identify plesiomorpbic conditions (based on outgroup comparisons). Features utilized are from the shell (29 characters), operculum (13), external features (32), pallial cavity (10), digestive system (29), life history (6), female reproductive system (52), and male reproductive system (31). Discussion of many characters is augmented by schematic diagrams and in almost all cases by reference to taxa and published figures illustrating given states. Many characters are extensively annotated, and in some cases new concepts of homology and/or division of characters are proposed. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Annals of the Smithsonian Institution. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging-in-Publication Data Hershler, Robert. A review of morphological characters of hydrobioid snails / Robert Hershler and Winston F. Ponder. p. cm. — (Smithsonian contributions to zoology ; no. 600) Includes bibliographical references. 1. Hydrobiidae—Morphology. 2. Mesogastropoda—Morphology. I. Ponder, W. F. II. Title. III. Series. QLI.S54 no. 600 [QL430.5.H9] 590 s—dc21 [571.3' 1432] © The paper used in this publication meets the minimum requirements of the American National Standard for Permanence of Paper for Printed Library Materials Z39.48—1984.

Mitochondrial DNA sequences reveal extensive cryptic diversity within a western American springsnail.

Abstract: We analysed cytochrome c oxidase subunit I and NADH dehydrogenase subunit I sequence variation among 29 populations of a widely ranging southwestern springsnail (Pyrgulopsis micrococcus) and 18 regional congeners. Cladistic analyses of these sequences depict P. micrococcus as a polyphyletic composite of five well-supported clades. Sequence divergences among these clades and subclades imply the possible occurrence of as many as seven or eight cryptic species in addition to P. micrococcus. Our finding that P. micrococcus contains multiple, genetically distinct and geographically restricted lineages suggests that diversification within this highly speciose aquatic genus has been structured in large part by the operation of terrestrial barriers to gene flow. However, these sequence data also indicate that recent dispersal among hydrographically separated areas has occurred within one of these lineages, which we attribute to passive transport on migratory waterbirds.

Are invasive species a major cause of extinctions

Abstract: The link between species invasions and the extinction of natives is widely accepted by scientists as well as conservationists, but available data supporting invasion as a cause of extinctions are, in many cases, anecdotal, speculative and based upon limited observation. We pose the question, are aliens generally responsible for widespread extinctions? Our goal is to prompt a more critical synthesis and evaluation of the available data, and to suggest ways to take a more scientific, evidence-based approach to understanding the impact of invasive species on extinctions. Greater clarity in our understanding of these patterns will help us to focus on the most effective ways to reduce or mitigate extinction threats from invasive species.

The Global Decline of Nonmarine Mollusks

Abstract: Invertebrate species represent more than 99% of animal diversity; however, they receive much less publicity and attract disproportionately minor research effort relative to vertebrates. Nonmarine mollusks (i.e., terrestrial and freshwater) are one of the most diverse and imperiled groups of animals, although not many people other than a few specialists who study the group seem to be aware of their plight. Nonmarine mollusks include a number of phylogenetically disparate lineages and species-rich assemblages that represent two molluscan classes, Bivalvia (clams and mussels) and Gastropoda (snails, slugs, and limpets). In this article we provide an overview of global nonmarine molluscan biodiversity and conservation status, including several case studies documenting the diversity and global decline of nonmarine mollusks. We conclude with a discussion of the roles that mollusks and malacologists should play in conservation, including research, conservation management strategies, and education and ou...

The contribution of headwater streams to biodiversity in river networks

Abstract: The diversity of life in headwater streams (intermittent, first and second order) contributes to the biodiversity of a river system and its riparian network. Small streams differ widely in physical, chemical, and biotic attributes, thus providing habitats for a range of unique species. Headwater species include permanent residents as well as migrants that travel to headwaters at particular seasons or life stages. Movement by migrants links headwaters with downstream and terrestrial ecosystems, as do exports such as emerging and drifting insects.

The Biology of Caves and Other Subterranean Habitats

Abstract: Caves and other subterranean habitats with their often strange (even bizarre) inhabitants have long been objects of fascination, curiosity, and debate. The question of how such organisms have evolved, and the relative roles of natural selection and genetic drift, has engaged subterranean biologists for decades. Indeed, these studies continue to inform the general theory of adaptation and evolution. Subterranean ecosystems generally exhibit little or no primary productivity and, as extreme ecosystems, provide general insights into ecosystem function. The Biology of Caves and other Subterranean Habitats offers a concise but comprehensive introduction to cave ecology and evolution. Whilst there is an emphasis on biological processes occurring in these unique environments, conservation and management aspects are also considered. The monograph includes a global range of examples from more than 25 countries, and case studies from both caves and non-cave subterranean habitats; it also provides a clear explanation of specialized terms used by speleologists. This accessible text will appeal to researchers new to the field and to the many professional ecologists and conservation practitioners requiring a concise but authoritative overview. Its engaging style will also make it suitable for undergraduate and graduate students taking courses in cave and subterranean biology. Its more than 650 references, 150 of which are new since the first edition, provide many entry points to the research literature.