The Red Queen hypothesis: organisms must constantly adapt, evolve, and proliferate not only to gain reproductive advantage, but also simply to survive pitted against ever-evolving opposing organisms in changing environments-intends to explain two different phenomena: constant extinction rates observed in the paleontological record caused by co-evolution between competing species and advantage of sexual reproduction at level of individuals.Antibiotic resistance-Common features: Genetic resistance occurs through random mutation[s] that are then selected in the presence of the drug or defense-Resistance appears not long after new drug or defense is introduced-degree of resistance and number ofresistant species increases over time-eventually multi-resistant species appear.-Examples: Bacteria resistant to antibiotics-mosquitoes resistant to DDT and other pesticides-Malaria parasites resistant to anti-malaria drugs (we get the situation that pesticide-resistant mosquitoes carry drug-resistant malaria parasites)-Targets for antibiotics: Inhibition of bacterial cell wall synthesis-damaging plasma membrane-Inhibition DNA, RNA, or protein synthesis-must target processes specific to bacterial metabolism to avoid side effects to human-drugs like penicillin target bacteria-specific structures that eukaryotes don’t have (especially side effect-free)-Mechanisms antibiotic resistance in bacteria: Enzymatic inactivation or destruction of the drug-Reduced permeability of bacterial cell to drug-Mechanisms for drug efflux from the cell - special “pumps” to remove antibiotics-Development of tolerance to a drug (bacteria can turn down metabolism; then the non-growing bacteria are not killed by the drug)Predator-prey arms races: adaptation in a population of one species (predators, parasites) changes selection pressure on a population of another species (prey, host), giving rise to an antagonistic coevolution.Cooperation between more than one species to parasitize another-symbiosis and parasitism-Parasitoid wasps and polydnaviruses combine forces to manipulate the caterpillar-co-evolution of species: wasp and virus-Braconid wasps and associated bracoviruses-wasp and virus each requires the other to complete its life cycle-Both are pathogens for the caterpillar -Braconid wasps (17,500 species - each with own bracovirus)-wasp has venom that paralyzes prey, deposits eggs into caterpillar along with virus particles-ovaries of wasp have special tissue where virus particles form-caterpillar’s immune system inactivated by viral proteins: wasp larva can live and grow, consuming the caterpillar (not organ systems required for caterpillar to move eat and grow-continuing source of nutrition for wasp larvae)-wasp larvae emerge from consumed host to pupate and continue free-living part of wasp life cycle – carrying the viral genome with them-The virus: a polydnavirus-“poly dna” because of a large size genome synthesized in multiple pieces of DNA that contain only partial sets of viral genes-total viral genome inserted into genome of host-virus cannot make viral particles containing entire viral genome-gets passed on only because it is integrated into genome of wasp-each virus particle carries circle of DNA with one or two genes that encode viral proteins that act to silence the caterpillar’s immune system-without the wasp=no future for virus-association seems to have originated with single event in ancestral wasp species ca 100 million years ago-association maintained because of the contribution of the virus to success of the wasp host.Behavioral modification of hosts by their pathogens-wasps recruit lady beetles as food for developing larva-service as “zombie” guard for pupa case of developing wasp-wasp injects egg into body of lady beetle- egg hatches and larva consumes insides of Lady beetle as it grows- when larva is ready to pupate, emerges from “zombie” lady beetle and pupates in protection of lady beetle’s legs-lady beetle not quitedead and remains as shelter for the pupa-cost to host is death, but also a cost for the wasp: wasps with body guards had lower fecundity than wasps without body guards (BUT, more wasps survived with body guards than without them)-since the “body guard” serves to protect from predators, overall the trait is selected - but with a trade off in terms of decreased potential for number of progeny.-Toxoplasmosis-Toxoplasma gondii:protist parasite can live in several intermediate hosts, including humans-must complete life cycle in cats (where it completes sexual stages of lifecycle-prey animals of cats (such as mice, rats) preferred for remainder of the lifecycle)-human infection rate depends on eating style (20% of US adults; 80% in France=higher consumption of undercooked meat)-parasite encysts in brain, liver, and muscle-pathogenic only if primary infection occurs in immune-compromised person or developing fetus-pregnant women who have not been previously exposed to T.gondii if infected, fetus can also become infected, resulting in birth defects such as vision problems, mental retardation or learning problems, cerebral palsey-like problems, or even early death-symptoms come not from toxins produced by parasite, but from damage caused by proliferation of parasite encysting in tissues of host-rats infected with Toxoplasma gondii lose fear of cats-willingness of rats infected with Toxoplasma gondii to enter areas bearing the scent ofcat urine, which they usually avoid-infected rats exhibited preferential visits to cat-parasite subtly alters the brain of its intermediate host to enhance predation rate whilst leaving other behavioral categories and general health intactMalaria-species of Plasmodium, protists similar to Toxoplasma gondii -infect many animals, including humans, nonhuman primates, reptiles, birds, and rodents- Human malaria caused by four Plasmodium species (P. falciparum most virulent)-carried by mosquitoes of several Anopheles species-most prevalent carrier of human malaria Anopheles gambiae: carriesP. falciparum-over 200 million cases annually, causing over half a million deaths – leading cause of death among children in tropical regions-now Chloroquin-resistant Plasmodium strains; DDT-resistant mosquito strains-inexorable rise of malariain Africa as resistant strains spread-part of life cycle spent in human host and part in vector mosquito; several stages of development occur in each-transferred from infected to uninfected persons when