mutualism & commensalism photo of hawk moth potentially pollinating dianthus from wikimedia...
TRANSCRIPT
Mutualism & Commensalism
Photo of hawk moth potentially pollinating Dianthus from Wikimedia Commons
Facilitation – in other words, “+” means benefits outweigh costs
Commensalism = +/0Mutualism = +/+
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 waspFacultative – optional, e.g., fig - seed disperser
Obligate vs. Facultative Mutualisms
Fig & its pollinating fig waspsFig & 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/wwwroot2/members/Photos/Plants/seed%20dispersal/Menu.htm
Types of Benefits to Mutualists
Photo from Wikimedia Commons
Service MutualismsOne 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 MutualismsOne partner obtains shelter, a place to live, or favorable habitat from the other
E.g., alpheid shrimp - goby symbiosis
Trophic MutualismsOne 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: http://www.cals.ncsu.edu/course/ent425/images/pollinators_gallery/pages/06_yucca_moth_jpg.htm; Harms’s photo of yuccas in White Sands Nat’l. Park, NM; Cain, Bowman & Hacker (2014), Fig. 15.16, after Pellmyr & Huth (1994) Nature
Yuccas selectively
abort flowers into which too many eggs are
laid
Cheaters can be Penalized or Sanctioned
A
B C
Plant can penalize fungus (for poor P delivery) with low C delivery
Split-plate design: (A) plant roots labeled with 14C; (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 33P; (B) roots with no access to sucrose;
(C) roots with access to sucrose (either 5 mM or 25 mM)
A
B CFungus 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 14C; (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 fromhttp://urbanext.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=128
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, fromhttp://wfrc.usgs.gov/research/contaminants/STRodriguez4.htm
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 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/sbs2008;*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