Symbiosis

Symbioses - species living in close association Parasitism +,- parasite benefits, host harmed Commensalism +,0 or 0,0 can have positive effect for one species or for neither Mutualism +,+ both species benefit

Gopher Tortoise – Commensal Host

Gopher Tortoise Distribution

Epiphytes Bird’s Nest Fern

Nalini Nadkarni studying epiphytes

Epiphytes Figure 1: Hypothetical tree illustrating how vascular epiphytes in humid forests tend to partition substrates illustrating sensitivity to micro climate, particularly humidity, and associated development of the organic rooting media required by some populations.

Parasitism and Disease Lyme Disease Cycle in the UK

Parasitism Parasitism - intimate association between two species in which the parasite obtains its nutrients from a host - parasite usually causes some degree of harm to its host - either reduced growth or reproduction Pathogen – disease causing agent Disease – abnormal condition of host due to infection by a pathogen that impairs physiological functioning

Parasites on Plants

Insects are green, Fungi are brown, Worms are blue, Protozoa are yellow

Parasitism occurs on a continuum from: ectoparasites - live outside hosts body and experience same conditions as host - ticks, mites, fleas, aphids endoparasites - live inside host's body cavity - buffered from outside conditions - tapeworms, flukes intracellular parasites - live inside individual cells of the host - viruses, bacteria, protozoa - often called microparasites

Or another way to divide parasites: microparasites - viruses, bacteria, protozoa - small, often live intracellularly, main point is that they reproduce in host and will have very large numbers in host macroparasites - tiny to very large - nematodes, tapeworms, flukes - larger individuals that grow in host but multiply by producing infective stages that are shed by host to environment where they infect new hosts

Parasite Transmission Direct transmission – from one host to another of the same species via air, water, coughing, blood, feces, etc. Indirect transmission – from one host to another of the same species via another species called a vector Vector – species which transmits parasite or pathogen from one host to another

MicroparasitesMacroparasites Direct transmissionHIV virus, Amoebic dysentery, Mildews on plants Lice, fleas, ticks, aphids, hookworm, pinworm, mistletoe Indirect transmissionPlasmodium (mosquito), Plant viruses (aphids), Trypanosoma (tsetse fly) Tapeworms, Schistosomes (snails), Rust fungi

Powdery Mildew on Grape Leaf

Powdery Mildew Life Cycle

Head Lice and Life Cycle

Mistletoe

Mistletoe Life Cycle

Malaria disease cycle

Schistosomiasis - Life cycle of the schistosome worm

Worldwide incidence of schistosomiasis

Rust Fungus Canker

Rust Fungus Life Cycle

Two ways to study parasite numbers Prevalence – percent of host population that is infected – best for microparasites Intensity – number of parasite individuals per host – usually best for macroparasites

European rabbits as pests in Australia

Introduced pests in Australia – red fox, rabbit, cat, pig, & goat

Moose and White-tailed Deer

Deer – Moose brain worm interaction

Fungal parasites alter insect behavior Giant ant w/o and with fungus

Avian malaria occurs in areas below white line on Island of Hawaii

Hawaiian Crow – Extinct in Wild

I’iwi Honeycreeper – highly susceptible to avian malaria

Akiapolaau Honeycreeper – restricted to high elevation today

Amakihi Honeycreeper – shows evidence of evolving resistance