Defensive Mutualisms – Trade protection for food Acacia and Acacia ants

Induced and Constitutive Defenses in Acacia. The species in the right-hand column have mutualistic relationships with ant species - the ants nest in the thorns. Those on the left can attract ants with extra-floral nectary secretions, but the ants do not nest. The Acacia species on the left increase their nectar secretions after damage, inducing wandering ants to come visit and stay a while. The species on the right have to support the ant colonies all the time, and nectar production is uniformly high and unaffected by damage.

Induced and Constitutive Defenses in Acacia. The species in the right-hand column have mutualistic relationships with ant species - the ants nest in the thorns. Those on the left can attract ants with extra-floral nectary secretions, but the ants do not nest. The Acacia species on the left increase their nectar secretions after damage, inducing wandering ants to come visit and stay a while. The species on the right have to support the ant colonies all the time, and nectar production is uniformly high and unaffected by damage. WHICH CAME FIRST??

Induced and Constitutive Defenses in Acacia. Induced defenses first, then the obligate relationship evolved…

Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M. Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss of Large Herbivores from an African Savanna. Science 319:192-195. Fig. 1. Rewards produced in the presence (white bars) and absence (gray bars) of large herbivores by A. drepanolobium occupied by different species of Acacia ants. Ant species' abbreviations are indicated as: Cs, C. sjostedti; Cm, C. mimosae; Cn, C. nigriceps; Tp, T. penzigi. Plants produce fewer rewards and fewer thorns when large herbivores are absent and herbivory rates are LOWER. Bribing ants to stay and protect them is less important.

Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M. Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss of Large Herbivores from an African Savanna. Science 319:192-195. Fig. 2. The proportion of host trees occupied by the four Acacia-ant species in the presence of large herbivores (white bars) and in plots from which large herbivores had been excluded (gray bars) for 10 years. And if large herbivores are excluded and plants produce less nectar, then some ants abandon the trees (the mutualist).

“Our results indicate that the large herbivores typical of African savannas have driven the evolution and maintenance of a widespread ant-Acacia mutualism and that their experimentally simulated extinction rapidly tips the scales away from mutualism and toward a suite of antagonistic behaviors by the interacting species. Browsing by large herbivores induces greater production of nectary and domatia rewards by trees, and these rewards in turn influence both the behavior of a specialized, mutualistic ant symbiont and the outcome of competition between this mutualist and a non-obligate host-plant parasite. Where herbivores are present, the carbohydrate subsidy provided by host trees plays a key role in the dominance of the strongly mutualistic C. mimosae, which is consistent with the hypothesis that plant exudates fuel dominance of canopy ant species that are specialized users of these abundant resources (28). In the absence of large herbivores, reduction in host-tree rewards to ant associates results in a breakdown in this mutualism, which has strong negative consequences for Acacia growth and survival. Ongoing anthropogenic loss of large herbivores throughout Africa (29, 30) may therefore have strong and unanticipated consequences for the broader communities in which these herbivores occur.” Todd M. Palmer, Maureen L. Stanton, Truman P. Young, Jacob R. Goheen, Robert M. Pringle, Richard Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss of Large Herbivores from an African Savanna. Science 319:192-195.

Defensive Mutualisms – Trade protection for food Ants ‘farm’ aphids and drink their ‘honeydew’

Cleaning Mutualisms – Trade cleaning for food

Cleaning Mutualisms – Trade cleaning for food

Cleaning Mutualisms – Trade cleaning for food Fish visit non-cheating cleaners more And watched cleaners cheat less.

Dispersive Mutualisms – Trade dispersal for food

Dispersive Mutualisms – Trade dispersal for food

Dispersive Mutualisms – Trade dispersal for food Not mutualism (commensal or parasitic)

Mutualisms in Mimicry: “Mullerian” mimicry – toxic species resemble one another

Population Ecology   I. Attributes II.Distribution III. Population Growth – changes in size through time IV. Species Interactions V. Dynamics of Consumer-Resource Interactions VI. Competition VII. Mutualisms VIII. Evolutionary Responses to Species Interactions Why won’t this population unit end?

Population Ecology   I. Attributes II.Distribution III. Population Growth – changes in size through time IV. Species Interactions V. Dynamics of Consumer-Resource Interactions VI. Competition VII. Mutualisms VIII. Evolutionary Responses to Species Interactions The abiotic environment is often stable, or at least predictable. Other species in the environment are always changing, sometimes as a direct result of changes in other species.

“Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!”

A. Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection Predation

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - crypsis and detection

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - poisons and detoxification

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - poisons and detoxification

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - poisons and detoxification

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - poisons and detoxification

Coevolution in Consumer-Resource Relationships: One species is evolving to ‘escape’ the relationship, the other to enhance it. “Arms Race” - Mimicry “Batesian” mimicry – palatable mimic looks like a toxic/dangerous model

Plant “crypsis” and “mimicry” Heliconius and Passiflora

Plant “crypsis” and “mimicry” Heliconia and Passiflora

Host-pathogen “arms races”

B. Evolution of Competitors - competitive ability can evolve - can result in character displacement Competition No positive feedback

A. Coevolution in Consumer-Resource Relationships: B. Evolution of Competitors C. Coevolution of Mutualists Mutualism Positive, coevolutionary feedback.

A. Competition Facilitation A. Coevolution in Consumer-Resource Relationships: B. Evolution of Competitors C. Coevolution of Mutualists D. Relationships Change A. Competition Facilitation Initially facultative (commensal) relationships, like one plant shading another in the desert) can become competitive when they are large.

A. Competition Facilitation Trees may compete for light aboveground, but share nutrients via mycorrhizal fungi belowground – even between species

A. Competition Facilitation Old dieing trees shunt nutrients to younger trees – even between species- through mycorrhizal networks. May be change in relationships with the fungus, whereby ‘old tree’ is being parasitized while young tree is being facilitated. Net result is shunting of carbon.

Mutualism Parasitism Orchids, Euglossine Bees, and Wasps.

B. Mutualism Parasitism