Are cancers newly evolved species?

(PhysOrg.com) -- Cancer patients may view their tumors as parasites taking over their bodies, but this is more than a metaphor for Peter Duesberg, a molecular and cell biology professor at the University of California, Berkeley.

Scientists prove key aspect of evolutionary theory

Evolutionary theory predicts that pairs of chromosomes within asexual organisms will evolve independently of each other and become increasingly different over time in a phenomenon called the 'Meselson effect'.

Feeding bluebirds helps fend off parasites

If you feed the birds in your backyard, you may be doing more than just making sure they have a source of food: you may be helping baby birds give parasites the boot.

How other primates self-medicate – and what they could teach us

Despite our advances in technology and medicine, we seem to be fighting a never-ending battle against a number of diseases and ailments. As viruses become more complex and bacteria become resistant to antibiotics, it seems ...

Stash of stem cells found in a human parasite

(Phys.org)—The parasites that cause schistosomiasis, one of the most common parasitic infections in the world, are notoriously long-lived. Researchers have now found stem cells inside the parasite that can regenerate worn-down ...

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Parasitism

Parasitism is a type of symbiotic relationship between two different organisms where one organism, the parasite, takes favor from the host, sometimes for a prolonged time. In general, parasites are much smaller than their hosts, show a high degree of specialization for their mode of life, and reproduce more quickly and in greater numbers than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and diverse animals such as tapeworms, flukes, the Plasmodium species, and scabs. Parasitism is differentiated from parasitoidism, a relationship in which the host is always killed by the parasite such as moths, butterflies, ants, flies and others.

The harm and benefit in parasitic interactions concern the biological fitness of the organisms involved. Parasites reduce host fitness in many ways, ranging from general or specialized pathology (such as castration), impairment of secondary sex characteristics, to the modification of host behaviour. Parasites increase their fitness by exploiting hosts for food, habitat and dispersal.

Although the concept of parasitism applies unambiguously to many cases in nature, it is best considered part of a continuum of types of interactions between species, rather than an exclusive category. Particular interactions between species may satisfy some but not all parts of the definition. In many cases, it is difficult to demonstrate that the host is harmed. In others, there may be no apparent specialization on the part of the parasite, or the interaction between the organisms may be short-lived. In medicine, only eukaryotic organisms are considered parasites, with the exclusion of bacteria and viruses. Some branches of biology, however, regard members of these groups as parasitic.[citation needed]

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