Mutualism & Commensalism Photo of hawk moth potentially pollinating Dianthus from Wikimedia Commons

Facilitation – in other words, “+” means benefits outweigh costs Commensalism = +/0 Mutualism = +/+ Positive Interactions Photo of hawk moth potentially pollinating Dianthus from Wikimedia Commons What might the benefits and costs be to each partner in a pollination mutualism?

Obligate – not optional, e.g., fig - fig wasp Facultative – optional, e.g., fig - seed disperser Obligate vs. Facultative Mutualisms Fig & its pollinating fig wasps Fig & one of its many seed-dispersers (in this case a frugivorous bat) Photo of fig & fig wasps from photo of bat & figs from

Types of Benefits to Mutualists Photo from Wikimedia Commons Service Mutualisms One partner receives an ecological service from the other – e.g., pollination, seed dispersal, or defense against herbivores, predators, or parasites E.g., ant - bullhorn acacia

Types of Benefits to Mutualists Photo from Wikimedia Commons Habitat Mutualisms One partner obtains shelter, a place to live, or favorable habitat from the other E.g., alpheid shrimp - goby symbiosis

Trophic Mutualisms One partner receives energy or nutrients from its partner E.g., mychorrizae – plant root - fungus symbiosis Types of Benefits to Mutualists Photomicrograph from Wikimedia Commons

Each mutualistic partner seeks to gain benefit from the other (just like a parasite seeks to gain benefit from a host); this can create conflicts Mutualists Are Not Altruists Photo of yucca moth from: Harms’s photo of yuccas in White Sands Nat’l. Park, NM; Cain, Bowman & Hacker (2014), Fig , after Pellmyr & Huth (1994) Nature Yuccas selectively abort flowers into which too many eggs are laid

Cheaters can be Penalized or Sanctioned A BC Plant can penalize fungus (for poor P delivery) with low C delivery Split-plate design: (A) plant roots labeled with 14 C; (B) mycorrhizal fungus without P; (C) mycorrhizal fungus with P (either 35  M or 700  M) Kiers et al. (2011) Science

Cheaters can be Penalized or Sanctioned Split-plate design: (A) fungal hyphae labeled with 33 P; (B) roots with no access to sucrose; (C) roots with access to sucrose (either 5 mM or 25 mM) A BC Fungus can penalize plant (for poor C delivery) with low P delivery Plant can penalize fungus (for poor P delivery) with low C delivery Split-plate design: (A) plant roots labeled with 14 C; (B) mycorrhizal fungus without P; (C) mycorrhizal fungus with P (either 35  M or 700  M) Title of the project: “Reciprocal rewards stabilize cooperation in the mycorrhizal symbiosis ” Kiers et al. (2011) Science

Notorious filamentous fungal pathogen, Colletotrichum magna, causes anthracnose disease in cucurbits Member of a large clade of pathogens capable of infecting the majority of agricultural crops worldwide Mutualisms Can Evolve From Other Types of Species Interactions Original research from Freeman & Rodriguez (1993) Science; photo of anthracnose on cucumber leaf from The heart-warming tale of a reformed parasite Infection occurs when spores adhere to host tissue, enter a cell, and subsequently grow through the host leaving a trail of necrotic tissue

Mutualisms Can Evolve From Other Types of Species Interactions The heart-warming tale of a reformed parasite “Path-1” = single-locus mutant of C. magna that spreads throughout the host (albeit more slowly) without necrosis & is a non-sporulating endophyte Plants infected with Path-1 were protected from the wild-type & were immune to an unrelated pathogenic fungus, Fusarium oxysporum Path-1 may induce host defenses against pathogens or may outcompete other fungi Considerable potential exists to tailor endophytes as biocontrol agents; an example of Darwinian Agriculture Original research from Freeman & Rodriguez (1993) Science; photo of cucurbits grown without (left) and with (right) Path-1 C. magna, both in the presence of Fusarium, from

Species Interactions Can Vary Geographically, Temporally, or in Other Context-Dependent Ways Cattail facilitated small- flowered forget-me-not at low soil temp. (possibly owing to soil aeration) Photo of cattail from Wikimedia Commons; Cain, Bowman & Hacker (2014), Fig. 15.9, after Callaway & King (1996) Ecology

Species Interactions Can Vary Geographically, Temporally, or in Other Context-Dependent Ways Cattail facilitated small- flowered forget-me-not at low soil temp. (possibly owing to soil aeration) Cattail competed with small- flowered forget-me-not at high soil temp. Photo of cattail from Wikimedia Commons; Cain, Bowman & Hacker (2014), Fig. 15.9, after Callaway & King (1996) Ecology

Daniel H. Janzen e.g., ant-acacia mutualism * When is it Coevolution? Reciprocal adaptive evolution in each of 2 interacting species in response to adaptations in the other species Photo of Janzen from premios/fronteras/galardonados/2011/ecologia.jsp; image of “Darwin’s hawk moth” pollinating its Malagasy orchid from *original idea from Janzen (1980) Evolution “Darwin’s hawk moth” potentially pollinating its Malagasy orchid

Positive interactions can influence individuals, populations, interactions between species, communities & ecosystems Photomicrograph from Wikimedia Commons Zoxanthellae = unicellular algal protist symbionts with corals A world without zoxanthellae would be a world without most shallow-water corals Imagine a world without corals

E.g., “Aprovechados” (parasites of mutualisms) sensu Mainero & Martinez del Rio 1985 Photo from ecosystem/1356/attachment/gal23/ Parasitic fig wasp Mutualism does not occur in isolation from other species interactions

Photo from E.g., Interactions among mutualists of semi-independent function E.g., Ants that act as defense mutualists against herbivores may influence pollinators’ activities & pollination success (see: Wagner 2000; Willmer & Stone 1997) Mutualism does not occur in isolation from other species interactions

2 Me Indirect Mutualisms “The enemy of my enemy is my friend” (e.g., plants whose defenses enlist the services of the “third trophic level”)

3 + + Me Indirect Mutualisms “The friend of my friend may be my friend too” (e.g., a seed-disperser may be an indirect mutualist of a pollinator of the same plant)