9/5/2023 0 Comments Tape wormsThey're both the products of a current environment and, at the same time, of a long ancestry reflecting millions of years of association with their hosts." Hoberg's past research includes studies of the systematics and evolution of tapeworms of seabirds, seals, and sea lions. Besides telling us something about their hosts, parasites can tell us about their geographical links to long ago. "Historical studies involving tapeworms contribute to a predictive foundation for understanding today's environments and communities of living things. "The past is the key to the present," Hoberg says. This research, called cospeciation analysis, includes studies of where hosts and parasites occur now and where they originated. National Parasite Collection and his expertise in parasite systematics to examine evolutionary relationships between hosts and parasites. systematic parasitologists who also examine where parasites are distributed geographically and how they co-evolve with their hosts.Looking at Clues From the Past Hoberg uses the vast U.S. "Parasites have characteristic host and geographic distribution, as well as predictable life cycles and transmission patterns," says Hoberg. If we know which order, family, or genus a parasite is in, we can predict-with some certainty-patterns of life history and what effect it will have on hosts within the same or related families. "More importantly," he says, "these classifications help predict species behavior. "These classifications represent everything we know about the relationships among these organisms. 4-7.) "Systematists deal with taxonomy, phylogeny-that is, recognizing evolutionary relationships among species-and ultimately, classification, in which organisms are grouped hierarchically based on their evolutionary relationships," says Hoberg. (See " Searching for Parasitic ‘Roots,’"Agricultural Research, December 1996, pp. As a systematist, Hoberg carefully examines living species of tapeworms and other parasites and describes them by meticulously detailing their distinguishing characteristics-morphological, biochemical, and molecular. The disease caused by tapeworms is known as cestodiasis. Information about carnivorous final hosts, "Our incomplete knowledge and understanding of taxonomy and species-level relationships of these parasites has hindered our full understanding of their host associations-final and intermediate-and their potential for causing disease," says Hoberg. "And although they remain a constant threat to economically important fisheries, livestock, and wildlife, only about one-third have been described or named. "Pathogenic macroparasites, like tapeworms, have parasitized the world's vertebrates and invertebrates for millions of years," says Hoberg. One of his roles as curator is as a systematist-that is, discovering, describing, and developing concepts for the evolution and biodiversity of parasites. It is one of the world's largest collections of parasites of humans and animals-containing several million specimens. National Parasite Collection at Beltsville. By studying the present-day ecology and geographic distribution of these parasites and their hosts, the researchers have uncovered new information about a long ancestry reflecting millions of years of host associations. Their work is based on comparative morphology and DNA sequence analyses of parasites. Alkire at the University of Colorado-Boulder and Arlene Jones at The Natural History Museum in London have uncovered new genealogical evidence that contradicts the traditional theory that humans got these parasites from domesticated animals. But he and colleagues Alan de Queiroz and Nancy L. "Traditionally, scientists believed that about 10,000 years ago-coincidental with the domestication of intermediate hosts such as cattle, swine, and companion carnivores like dogs-three species of taeniid tapeworms became associated with humans," Hoberg says. Zoologist Eric Hoberg examines a specimen. Hoberg, who is in the Biosystematics Unit of the Parasite Biology, Epidemiology, and Systematics Laboratory at Beltsville, Maryland, has made a remarkable discovery-one that contradicts long-held theories. Yet, despite their economic significance, little has been known about how and when these parasites first attacked humans. They occur worldwide, causing malnutrition, sickness, and occasionally the death of their hosts. Tapeworms are among the most disgusting but intriguing parasites of humans and other animals. Out of Africa: The Origins of the Tapeworms
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