Mutualism Commensalism Photo of hawk moth potentially pollinating

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

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

Obligate vs. Facultative Mutualisms Obligate – not optional, e. g. , fig - fig wasp Facultative – optional, e. g. , fig - seed disperser Fig & its pollinating fig wasps Fig & one of its many seed-dispersers (in this case a frugivorous bat) Photo of fig & fig wasps from http: //www. zoology. ubc. ca; photo of bat & figs from http: //www. sserc. org. uk/wwwroot 2/members/Photos/Plants/seed%20 dispersal/Menu. htm

Types of Benefits to Mutualists 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 symbiosis Photo from Wikimedia Commons

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

Types of Benefits to Mutualists Trophic Mutualisms One partner receives energy or nutrients from its partner E. g. , mychorrizae – plant root - fungus symbiosis (this type of mutualism probably characterized the very first land plants ~500 mya) Photomicrograph from Wikimedia Commons

Types of Benefits to Mutualists Trophic Mutualisms One partner receives energy or nutrients from its partner E. g. , E. coli is part of the human microbiome Humans require various essential organic compounds that the organism itself cannot synthesize, including various: purines & pyrimidines amino acids vitamins Photomicrograph from Wikimedia Commons

Mutualists Are Not Altruists Each mutualistic partner seeks to gain net benefit from the other (just like a parasite seeks to gain net benefit from a host); this can create conflicts Yuccas selectively abort flowers into which too many eggs are laid Photo of yucca moth from: http: //www. cals. ncsu. edu/course/ent 425/images/pollinators_gallery/pages/06_yucca_moth_jpg. htm; Harms’s photo of yuccas in White Sands Nat’l. Park, NM; Bowman, Hacker & Cain (2017), Fig. 15 after Pellmyr & Huth (1994) Nature

Cheaters can be Penalized or Sanctioned 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) Plant can penalize fungus (for poor P delivery) with low C delivery A B Kiers et al. (2011) Science C

Cheaters can be Penalized or Sanctioned 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: Plant can penalize fungus (for poor P delivery) with low C delivery A B Fungus can penalize plant (for poor C delivery) with low P delivery C 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 m. M or 25 m. M) Kiers et al. (2011) Science “Reciprocal rewards stabilize cooperation in the mycorrhizal symbiosis”

Mutualisms Can Evolve From Other Types of Species Interactions The heart-warming tale of a reformed parasite 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 Infection occurs when spores adhere to host tissue, enter a cell, and subsequently grow through the host leaving a trail of necrotic tissue Original research from Freeman & Rodriguez (1993) Science; photo of anthracnose on cucumber leaf from http: //urbanext. illinois. edu/hortanswers/detailproblem. cfm? Pathogen. ID=128

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 http: //wfrc. usgs. gov/research/contaminants/STRodriguez 4. htm

Species Interactions Can Vary Geographically, Temporally, or in Other Context-Dependent Ways Cattail facilitated smallflowered forget-me-not at low soil temp. (possibly owing to soil aeration) Photo of cattail from Wikimedia Commons; Bowman, Hacker & Cain (2017), Fig. 15. 8, after Callaway & King (1996) Ecology

Species Interactions Can Vary Geographically, Temporally, or in Other Context-Dependent Ways Cattail facilitated smallflowered forget-me-not at low soil temp. (possibly owing to soil aeration) Cattail competed with smallflowered forget-me-not at high soil temp. Photo of cattail from Wikimedia Commons; Bowman, Hacker & Cain (2017), Fig. 15. 8, after Callaway & King (1996) Ecology

*When is it Coevolution? Reciprocal adaptive evolution in each of 2 interacting species in response to adaptations in the other species Daniel H. Janzen e. g. , ant-acacia mutualism “Darwin’s hawk moth” potentially pollinating its Malagasy orchid Photo of Janzen from http: //www. fbbva. es/TLFU/tlfu/ing/microsites/ premios/fronteras/galardonados/2011/ecologia. jsp; image of “Darwin’s hawk moth” pollinating its Malagasy orchid from http: //botany. si. edu/events/sbsarchives/sbs 2008; *original idea from Janzen (1980) Evolution

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

Mutualism does not occur in isolation from other species interactions E. g. , “Aprovechados” (parasites of mutualisms) sensu Mainero & Martinez del Rio 1985 Parasitic fig wasp Photo from http: //www. pbs. org/wnet/nature/episodes/the-queen-of-trees/photo-essay-an-extraordinaryecosystem/1356/attachment/gal 23/

Mutualism does not occur in isolation from other species interactions 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) Photo from http: //coronadetucson. blogspot. com/2009_03_01_archive. html

Indirect Mutualisms “The enemy of my enemy is my friend” (e. g. , plants whose defenses enlist the services of the “third trophic level”) 3 - + + 2 - Me + +

Indirect Mutualisms Cartoon and examples from Degenhardt (2009)

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) Me +/+ + 2 + + + 1

Indirect Mutualisms +/+ + + K. Harms’s photo of strangler fig, Queensland, Australia; photo of fig & fig wasps from http: //www. zoology. ubc. ca; photo of bat & figs from http: //www. sserc. org. uk/wwwroot 2/members/Photos/Plants/seed%20 dispersal/Menu. htm