Exploitation (Ch. 14)http://www.youtube.com/watch?v=-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

• 300-500 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

Ectoparasite Endoparasite

Feeding (acquire food)Harder EASIER

Vulnerability to PredationHigher LOWER

Environmental StabilityLower HIGHER

Exposure to host immune systemLOWER Higher

DispersalEASIER Harder

Parasites Influence Other Interactions

• Can influence host reaction to other species!

Tribolium castaneum Tribolium confusum

Adelina tribolii (Protozoan)

Can You Tell the Difference?

T. castaneum T. confusum

Effects of Parasite Greater on the Better Competitor, T. castaneum!

Per

cent

Win

ning

(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)

http://www.youtube.com/watch?v=-drpViV5LSw&feature=related

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• http://www.nature.com/nature/journal/v440/n7085/suppinfo/440756a.html

Adult worms live/mate in waterLarvae encyst on vegetation near water

Japan: 60% of annual calories totrout from suicidal crickets!

b, c, d, show wormescaping after predatoreats 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!• http://www.youtube.com/watch?v=EW

B_COSUXMw&feature=related

• Take parasitology with Dr. Sundermann (BIOL 5110)

Mutualism(Ch. 15)

5 main types of interactions among species:

Effect on Effect onType 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 almost1 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