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Challenges facing Parasites, hosts as islands, how to infect new ones? High specificity, high fecundities, exploitation of vectors (mosquitoes) Intermediate.

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Presentation on theme: "Challenges facing Parasites, hosts as islands, how to infect new ones? High specificity, high fecundities, exploitation of vectors (mosquitoes) Intermediate."— Presentation transcript:

1 Challenges facing Parasites, hosts as islands, how to infect new ones? High specificity, high fecundities, exploitation of vectors (mosquitoes) Intermediate and final hosts, host altered behavior (rabies, etc.) Assassin bugs (Triatoma) Malaria, protists (Plasmodium) Tapeworms (Cestodes), Nematodes (roundworms) Cholera (Shigella) transmission via dysentery Toilet seats, elevator buttons, door knobs, shopping carts...etc. Molecular mimicry: “eclipsed antigens” resemble host antigens hence do not elicit formation of host antibodies Major Histocompatibility Complex (MHC) Trypanosoma (protozoans) shed coats, change antigens Filariasis Elephantiasis (lymph nodes blocked by nematodes carried by mosquitoes) Botflies Dracunculus medinensis, caduceus symbol of medicine

2 Dar winian Medicine: don ’ t treat symptoms, distinguish between host defenses and parasite manipulation. Evolution of Virulence (benign parasites allow hosts to live) Host altered behavior Rabies virus — rabid animals bite, passes on virus to new host Lancet fluke Trematode Dicrocoelium dentriticum Cercaria —> Metacercariae encyst on ant’s brain Sheep ingest an ant and get infected Starlings, Pill bugs, and Acanthocephalans Ducks, Amphipods, and Acanthocephalans STDs —> increased sexual activity? Ectoparasites (fleas, ticks, lice), endoparasites Social parasites (thievery, brood parasitism) Parasitoids: Ichneumonid wasps Microparasites—> macroparasties—>parasitoids—>predator spectrum and many correlates thereof, such as relative sizes, rates of increase, number of parasites per host, virulence, stability, and ability to regulate lower trophic level

3 Coevolution Joint evolution of two (or more) taxa that have close ecological relationships but do not exchange genes, and in which reciprocal selective pressures operate to make the evolution of either taxon partially dependent on the evolution of the other

4 Enterobius Pinworms (Parasites on Primates)

5 Parallel phylogenies Primate hosts Enterobius species

6 Drosophila pachea and senita cactus. Danaid butterflies use polyuridine alkaloids as chemical precursors for synthesis of pheromones used in attracting mates. An arginine mimic, l-canavanine, present in many legumes, ruins protein structure in most insects. However, a bruchid beetle has evolved metabolic machinery that enable it to use plants containing canavanine.

7 Wild ginger, Asarum caudatum, in western Washington are polymorphic for growth rate, seed production, and palatabililty to a native slug, Ariolimax columbianus (Cates 1975). Where slugs are uncommon, plants allocate more energy to growth and seed production and less to production of antiherbivore chemicals. In habitats with lots of slugs, less palatable plants have a fitness advantage — even though they grow more slowly, they lose less photosynthetic tissue to slug herbivory.

8 Some of the Suggested Correlates of Plant Apparency _____________________________________________________________________________ Apparent Plants Unapparent Plants _____________________________________________________________________________ Common or conspicuousRare or ephemeral Woody perennialsHerbaceous annuals Long leaf life spanShort-lived leaves Slow growing, competitive speciesFaster growing, often fugitive species Late stages of succession, climaxEarly stages of succession, second growth Bound to be found by herbivoresProtected from herbivores by escape in (cannot escape in time and space)time and space (but still encountered by wide-ranging generalized herbivores) Produce more expensive quantitativeProduce inexpensive qualitative chemical (broad-based) antiherbivore defensesdefenses (poisons or toxins) to discourage (tough leaves, thorns, tannins)generalized herbivores Quantitative defenses constituteQualitative defenses may be broken down effective ecological barriers to her-over evolutionary time by coevolution of bivores, although perhaps only a weakappropriate detoxification mechanisms in evolutionary barrier unless supple-herbivores (host plant-specific herbivore mented with qualitative defensesspecies result) _____________________________________________________________________________

9 Coevolution: Joint evolution of two (or more) taxa that have close ecological relationships but do not exchange genes, and in which reciprocal selective pressures operate to make the evolution of either taxon partially dependent on the evolution of the other. Parallel phylogenies: coevolution of pinworms and primate hosts Drosophila pachea and senita cactus. Danaid butterflies use polyuridine alkaloids to synthesize pheromones l-canavanine, present in many legumes ruins protein structure However, a bruchid beetle has evolved metabolic machinery that enable it to use plants containing canavanine. Correlates of plant apparency: quantitative versus qualitative defenses Coevolution of wild ginger and slug

10 Antibiotics first discovered in fungi, but also occur in many plants. Plant secondary chemicals have proven to be a vast reservoir for useful pharmaceuticals — these include analgesics, diuretics, laxatives, tranquilizers, contraceptive agents, and cough drops. Clinically proven drugs derived from higher plants include morphine, codeine, atropine, quinine, digitalis, and many others. Bark of Pacific yew trees contains taxol, an effective agent for treating certain ovarian Cancers (yew genes have been transplanted into bacteria which produce commercial quantities of taxol in chemostats) Scientists have only examined about 1 percent of existing plant species for such useful pharmaceuticals.

11 Dan Janzen Scheelea Palm Bruchid Beetles

12 Pine squirrels (Tamiasciurus) and coniferous food trees (Smith 1970) Squirrels are very effective seed predators, stockpile cones Trees reduce squirrel effectiveness in many different ways: 1.Cones difficult for squirrels to reach, open, or carry 2.Putting fewer seeds in each cone (fake cones without any seeds) 3.Increasing thickness of seed coats (seeds harder to harvest) 4.Putting less energy into each seed (smaller seeds) 5.Shedding seeds from cones early, before young squirrels forage 6.Periodic cone crop failures decimate squirrel populations Individual trees out of synchrony would set fewer seeds and thus be selected against. Christopher Smith

13 Pharmaceuticals analgesics antibiotics diuretics laxatives tranquilizers contraceptives taxol (bark of Pacific Yew trees) Janzen ’ s seedling ring hypothesis Coevolution of pine squirrels (Tamiasciurus) and coniferous food trees

14 Phylogenetics in Ecology Phylogenetic Systematics = Cladistics Importance of shared derived characteristics (synapomorphies) Monophyletic groups = Clades (Polyphyletic, Paraphyletic) Sister groups, outgroups Identify ancestral states — polarize character state changes

15 Phrynosoma Moloch Page 343 Evolutionary Ecomorphology Convergent Evolution Ecological Equivalents

16 Monophyletic Paraphyletic Polyphyletic

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18 Phylogenetics in Ecology Phylogenetic Systematics = Cladistics Shared derived characteristics (synapomorphies) Monophyletic vs. Polyphyletic groups Sister groups, outgroups, rooting trees Identify ancestral states — polarize character state changes Minimum Evolution (maximum parsimony) shortest trees Vicariance Biogeography and Area Cladograms Phylogeny and the Modern Comparative Method Phylogenetically Independent Contrasts Evolutionary Ecomorphology Convergence (homoplasy) Willi Hennig

19 Inferring probable ancestral states

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21 Estimation of ancestral states from those of extant descendents Ray Huey Al Bennet

22 Mike Ryan Physolemus Frogs

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25 Phylogenetics in Ecology Phylogenetic Systematics = Cladistics Shared derived characteristics (synapomorphies) Monophyletic groups = Clades Monophyletic, Polyphyletic, Paraphyletic Sister groups, outgroups, rooting trees Identify ancestral states — polarize character state changes Vicariance Biogeography, Area Cladograms Phylogeny and the Modern Comparative Method Phylogenetically Independent Contrasts Evolutionary Ecomorphology Convergence (homoplasy)

26 Vicariance Biogeography Area Cladograms

27 Area cladogram for Eublepharid Geckos

28 Aeluroscalabotes felinus Borneo Aluroascalabotes (Borneo)

29 Goniurosaurus hainanensis, Hainan Island, China

30 Coleonyx brevis Coleonyx mitratus Coleonyx switaki Coleonyx variegatus

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32 Heloderma suspectum Heloderma, North America

33 Lanthanotus borneensis Lanthanotus, Borneo

34 VaVaranus giganteus Varanus giganteus, Australia

35 Independent Contrasts Joe Felsenstein

36 Independent Contrasts Joe Felsenstein

37 Independent Contrasts

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39 Independent Contrasts Pairs

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