Exploitation (Ch. 14) -drpViV5LSw&feature=related

They Infect You! …and the animals and plants you depend on!

Microparasite Example (Malaria) Plasmodium spp. (5 human) Complex Life History (2 hosts) –Intermediate- required for life cycle but no sexual reproduction occurs (humans) –Definitive- where parasite is sexually mature (mosquito) 40% population at risk million infected, 1-3 million dead

Location on/in the Host Matters Ectoparasite: outside host –Ex. parasitic plants, mites, ticks Endoparasite: inside host –Ex. tapeworms, bacteria, protists

Cost/Benefit of Host Habitat EctoparasiteEndoparasite Feeding (acquire food) Harder EASIER Vulnerability to Predation Higher LOWER Environmental Stability Lower HIGHER Exposure to host immune system LOWER Higher Dispersal EASIER Harder

Parasites Influence Other Interactions Can influence host reaction to other species! Tribolium castaneumTribolium confusum Adelina tribolii (Protozoan)

Can You Tell the Difference? T. castaneumT. confusum

Effects of Parasite Greater on the Better Competitor, T. castaneum! Percent Winning (Park, 1948)

Widespread Interactions Many interactions in food webs are exploitations Provide many links: 500 aquatic species in a lake may be linked by 25,000 exploitative interactions! Evolutionary effects……

Red Queen Hypothesis "Now, here, you see, it takes all the running you can do, to keep in the same place.” –Lewis Carroll (Through the Looking Glass)

Red Queen Hypothesis 1)Hosts constantly evolve to fight off parasites. 2)Parasites evolve to exploit host 3)Failure to “keep up:” extinction!

Red Queen Hypothesis Coevolution: Evolution caused by the other species and vice versa. Evolutionary “Arms Race” Nuclear weapons…

Australian Problem Who am I? Native range Spain, Portugal, NW Africa

Australian Problem "The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting.” Australian rancher Thomas Austin (1859) Biocontrol??

Australian Rabbit Problem 1950 Myxoma virus introduced to naïve (no previous exposure) rabbits: Lethality decreased (transmission max. for level III) Coevolution between rabbits and virus

What about us? “Sweaty T-Shirt Experiment” (1995) 44 males wore t-shirt for 2 nights Women ranked smells of 7 t-shirts (3 Similar, 3 different, and 1 unused) Red = Dissimilar, Orange = Similar

Adaptive Immunity Major histocompatibility complex (MHC): Hundreds of alleles U want to be different! Why? Mates choose most different mate (due to smell) in mice, birds, fish and lizards

Parasites That Alter Host Behavior Enslaver parasites: alter host behavior to increase reproduction Often causes host death Increases parasite dispersal

Nematomorpha Adult worms live/mate in water Larvae encyst on vegetation near water Japan: 60% of annual calories to trout from suicidal crickets! b, c, d, show worm escaping after predator eats host! Supplemental 1

Parasites That Alter Host Behavior Acanthocephalan, terrestrial isopod, starling Detritivore!

Parasites That Alter Host Behavior Isopod behavior suicidal... 1% Armadillidium infected, but 40% starlings!

Plants affected too! Rust fungus Puccinia manipulates mustard (Arabis spp.). –Puccinia infects Arabis rosettes –Rosettes elongate, topped by cluster bright yellow leaves. “Pseudoflowers” Rosette of leaves

Parasites That Alter Host Behavior Pseudoflowers: sugary fungal reproductive fluids Pollinators move reproductive cells to other pseudoflowers Mmmmm, fungal fluids….

Final Example…Zombie Snails! B_COSUXMw&feature=relatedhttp:// B_COSUXMw&feature=related Take parasitology with Dr. Sundermann (BIOL 5110)

Mutualism (Ch. 15)

5 main types of interactions among species: Effect on Type of interaction species A species B Competition - - Predation + - Parasitism + - Commensalism + 0 Mutualism + +

Mutualism Mutualism: Interaction benefits both (+,+) interaction. –Facultative Mutualism: can live w/o mutualist –Obligate Mutualism: dependent on mutualist

Mutualism Margulis and Fester. Endosymbiotic theory: eukaryotes mutualism between prokaryotes and eukaryotes Margulis “Life did not take over the globe by combat, but by networking”

Mutualism

Mutualisms Classified based on benefit –Trophic: provide food, water, etc. –Dispersive: help organism move –Defensive: protect against enemy Ex: moth pollination of flowers Moth: ___________ (nectar) Plant: _________ (pollen moved)

Pollination Interesting story: nectar spur of orchids (long tube at bottom of which is nectar) Fringed orchid

Pollination Long spurred flowers reproduce better Leads to longer tongues…. Which leads to longer tubes......

Pollination Angraecum orchid (Madagascar). Darwin predicted moth. Found after 40 years searching! Nectar spur almost 1 foot long!

Plants + Mycorrhizal Fungi Mycorrhiza: root and fungus (mycorrhizae is plural) Plant trophic: increases uptake P and other immobile (don’t move well from soil to root) nutrients Fungi get sugars (trophic)

Plants + Mycorrhizal Fungi Common types mycorrhizae : –Arbuscular mycorrhizal fungi (AMF) Produces arbuscules (site of exchange between plants and fungi), hyphae (fungal filaments) –Ectomycorrhizae (ECM) Forms mantle around roots

Mycorrhizae and Plant Water Balance Ex: water relations Agropyron smithii (western wheatgrass)

Mycorrhizae and Plant Water Balance With mycorrhizae - higher leaf water potentials 90% plant species have mycorrhizae!

Ants and Bullshorn Acacia Acacia: trees/shrubs (legume family). Hollow spines (spine=modified leaf pointy thing)

Ants and Bullshorn Acacia Leaves: extrafloral nectary (makes nectar but not flower) Leaflets: Beltian Bodies (protein rich) Ant benefit? Plant benefit??

Experimental Evidence For Mutualism

Acacia mutualism Benefits to plant (defensive): –Ants predators –Ants territorial –Ants clear below shrub: removes competitors, protects shrub (and ants!) from fire