Species Interactions:The Good, the Bad, and the Ugly

Types of species interactions

• Positive • Negative• Neutral

Positive species interactions

• Mutualism– Both species benefit by interacting with each

other

Ant-Acacia mutualism

Mutualism

http://www.australiangeographic.com.au/news/

Mutualism

http://coglab.hbcse.tifr.res.in/teacher-resources/

Mutualism

http://mathotter.wordpress.com

Mutualism

Negative species interactions

• One species benefits while the other species is harmed

http://www-rohan.sdsu.edu

Negative interactions (herbivory)

http://en.wikipedia.org/wiki/Herbivore

Negative interactions (competition)

Negative interactions

Strangler FigNectar Robbing

Neutral species interactions

• Commensalism– One species benefits while the other is unaffected

Plant-bacteria-herbivore experiment

• Do herbivores prefer plants with rhizobia or plants without rhizobia?

Materials

• 10 legume plants (such as beans, peas, clover), in 10 separate pots

• Rhizobia (bacteria) inoculant (purchase online)• 20 slugs or other insect herbivores (aphids,

beetles, caterpillars)• Old fish tank or large plastic bin, screen or

netting to put over top

Instructions

1. Plant legumes 3 weeks prior to conducting experiment. Inoculate half of the 10 plants with rhizobia bacteria.

+ rhizobia

- rhizobia

Instructions

2. Once plants are mature, put them all into anold fish tank or clear plastic bin and

put 2 herbivores on the soil surface in each pot. Make sure pots are close enough to touch.3. After 1-2 days, estimate the percent ofdamage to each leaf4. Record data and analyze results (graphing

activity)