Mutualism By Latoya Tousant
What is Mutualism? • Mutualism is defined as: interactions between individuals of different species, one where participating partners benefit.
Some Examples of Mutualism • Plant Mutualisms: Plant; bacteria, fungi, and animals. -Example with animals: -Ants (Pseudomyrmex supp.) and the Bullshorn Acacia(Acacia cornigera). These ants exhibit a close relationship with the swollen thorn Acadia plant. - Normally, the ants have larger colony sizes, are aggressive, fast and agile.
Some Examples of Mutualism • Swollen thorn acacia have enlarged thorns: soft, easily usable pits. • Year round leaf production and enlarged foliar nectaries that contain Beltian bodies providing a source of sugar, liquid, oils, and protein.
Benefits of Ant and Bullshorn Acacia • How does the Plant benefit? • Protection from attack by herbivores • Protection from competition of other plants • Plant has better access to light and soil nutrients are increased • How does the Ant benefit? • Shelter • Food
Some Examples of Mutualism • Coral Mutualisms: • Zooxanthellae- unicellular algae that live within the coral reefs receive nutrients. In return, the corals receive organic compounds. • Coral anemone • Shrimp and crab receive shelter and food while protecting the coral from predators.
Evolution of Mutualism • The theory of the evolution of mutualism predicts: Mutualism will evolve where benefits exceed the costs.
Some examples of Mutualism • Small animals and larger mammals: -Oxpeckers (Buphagus) and Cattle: • Oxpeckers are Pan-African birds: 2 species: -Red-billed oxpecker (Buphaguserythrorhynchus) and yellow-billed Oxpecker (Buphagusafricanus). • Specializes in feeding on ticks. • Cattle: host 5 species of ticks • Ticks 3 life stages: 1) Larval 2) Nymph 3) Adult
Mutualism between oxpeckers and large Mammals • Oxpeckers are able to consume a convenient meal from the cattle and a safe place to eat them. • Cattle receive a free cleaning of ticks and their wound injuries. • Traditionally a mutual relationship but a closer suggests otherwise
Study • In 1999, Paul Weeks traveled to a ranch in Zimbabwe studying the relationship between red-billed oxpeckers and their partner; domestic cattle. • He observed the effect oxpeckers had on the cattle and whether were actually reducing tick loads off cattle. • Previous studies suggests oxpeckers also prefer eating dead skin, mucous, saliva, blood, sweat, and tears of cattle.
S • Oxpecker Exclusion Experiment: • 2 Groups: • Experimental treatment-oxpeckers excluded • Control treatment- oxpeckers present Predictions: If the birds do provided tick reduction benefits, Weeks expected to find a significant decrease in the number of ticks on control animals. If blood is the oxpeckers favored food, Weeks would expect to find the controls have significantly more wounds than the experimental animals.
Results Figure 1: Figure 2: The magnitude and direction of change in mean total tick load (±SE) for Control and experimental oxen for each replicated experiment (Mann-Whitney test throughout). The magnitude and direction of change in mean tick load (±SE) for red-legged ticks between control and experimental oxen in the third experiment (Mann-Whitney test, z = -3.09, p =.002).
Figure 3: Figure 4: The mean number (±SE) of individual wounds per animal in all three treatments. In each case, control oxen had significantly more wounds than experimental ones (Mann-Whitney test throughout). The mean changes (±SE) in earwax scores for control and experimental for each treatment (Mann-Whitney test throughout).
Results • In the absence of oxpeckers: -no significant effect on the changes in tick load (in all 3 treatments) -The open wound load (on cattle) decreased -The earwax score increased • In the presence of oxpeckers:-The open wounds (on cattle) increased -The earwax score decreased
Conclusion • Oxpeckers are blood suckers and earwax eaters. • They spend most of their time feeding on blood, eating earwax or scissoring their bills through the animals hair. • Oxpeckers deepen existing wounds and delay the healing process.
Study • Flaw: -domestic cattle are not oxpeckers native hosts. Two species did not co-evolve. • Another study by Alan McElligott and colleagues (2004) observed oxpeckers feeding on black rhinoceros (Diceros bicornis). • They examined the amount of time oxpeckers spent on their hosts, removal attempts by rhino. • Found: the oxpeckers spent 45% of the time feeding on open wounds, creating new ones. • The rhinos removal attempts were low and unsuccessful.
New Studies • The impact oxpeckers have on tick loads may vary with varying densities of different species of ticks, test which ticks they would prefer in this example. • Oxpeckers eating earwax are neither helpful nor harmful to the cattle (not known) • Whether oxpeckers benefit or not from eating earwax • Conduct the same experiment during different time of temperature and levels precipitation (was never a factor in any of the experiments)
Refrences • Buskirk, William H. 1975. Substrate Choices of Oxpeckers. The Auk. Vol. 92. P. 604-606. • McElligott, Alan G., Maggini, Ivan, Hunziker, Lorenz. 2004. Interactions Between Red-billed Oxpeckers and Black Rhinos in Captivity. Wiley and Sons. Vol. 23. P. 347-354. • Milius, Susan. 2000. Do Oxpeckers Help or Mostly Just Freeload? Science News. Vol. 157. P. 278. • Ostfeld, Richard S., Price, Amber, Hombostel, Victoria L. 2006. Controlling Ticks and Tick-Borne Zoonoses with Biological and Chemical Agents. BioScience. Vol. 56. P. 383-394. • Robertson, Anthony, Jarvis, Alice. M. 2000. Oxpeckers in North-eastern Nambia. Recent Populations Trends and the Possible Negative Impacts of Drought and Fire. Biological Conservation. Vol. 92. P. 241-247. • Weeks, Paul. 2000. Red-billed Oxpeckers: Vampires or Tickbirds? Behavioral Ecology. Vol. 11. P. 154-160.