1. Pollination BiologyPollination Biology
of Orchidsof Orchids
Mark Whitten
Florida Museum of
Natural History
University of Florida
Ernst Haeckel, 1904
Kunstformen der Natur
2. Orchid DiversityOrchid Diversity
Orchids are the largest family of flowering plantsOrchids are the largest family of flowering plants----~~
10% of angiosperms10% of angiosperms
~25,000 species described so far (Kew Checklist of~25,000 species described so far (Kew Checklist of
Orchids, RBG Kew)Orchids, RBG Kew)
New species being described weeklyNew species being described weekly
Highest diversity in poorlyHighest diversity in poorly--explored tropicsexplored tropics
3. Number of NewOrchid Species
Described Each Year
0
100
200
300
400
500
600
1978
1980
1982
1984
1986
1989
1991
1993
1995
1997
1999
2001
Source: Cribb, P. 2005. Just how many orchids are there? Proceedings of the 18th WOC
4. Orchids are HYPERDIVERSE inOrchids are HYPERDIVERSE in
montane tropicsmontane tropics
Telipogon spp. Of Ecuador: C.H. Dodson
5. Why are orchids so diverse?Why are orchids so diverse?
Inhabit all continents except poles;Inhabit all continents except poles;
geologically old family (90geologically old family (90--100 MY ?)100 MY ?)
Orchids exploit many different animals asOrchids exploit many different animals as
pollinatorspollinators
Pollination relationships often highly speciesPollination relationships often highly species--
specificspecific----reproductive isolationreproductive isolation
Have obligateHave obligate mycorrhizalmycorrhizal associationsassociations
Predominately epiphytic (new niches?)Predominately epiphytic (new niches?)
6. Habitat diversity fosters biologicalHabitat diversity fosters biological
diversitydiversity
Teagueia spp. : Lou Jost
21 new species in 2 years in 80 sq. miles
Ecuador: Pastaza valley
8. Reproductive IsolationReproductive Isolation
How can sympatric,How can sympatric,
interfertileinterfertile speciesspecies
live together withoutlive together without
hybridizing?hybridizing?
Highly specificHighly specific
pollinators preventpollinators prevent
hybridization, andhybridization, and
avoid wasting pollenavoid wasting pollen
Precise pollenPrecise pollen
placement mightplacement might
preventprevent
hybridizationhybridization
12. Pollination rewardsPollination rewards
Nectar (insects, birds)Nectar (insects, birds)
PollenPollen----No!No!
Floral fragrances (maleFloral fragrances (male euglossineeuglossine
bees)bees)
Resins (used by bees for nest building)Resins (used by bees for nest building)
Oils (used byOils (used by anthophoridanthophorid bees to feedbees to feed
larvae)larvae)
13. Pollination syndromesPollination syndromes
A bit simplistic, but useful and oftenA bit simplistic, but useful and often
predictivepredictive
Based upon reward offered and uponBased upon reward offered and upon
the behavior and morphology ofthe behavior and morphology of
pollinatorspollinators
Floral morphology, color, fragrance mayFloral morphology, color, fragrance may
allow prediction of probable pollinatorsallow prediction of probable pollinators
14. Dendrobium
cuthbertii Bird pollination
-Nectar reward present or absent
-Present in Neotropical and
Paleotropical orchids
Masdevallia rosea Fernandezia subbiflora Maxillaria sophronitis
18. Pollination of Disa
chrysostachya by
Sunbirds in South
Africa
S.D. Johnson and M. Brown. 2004.
Transfer of pollinaria on bird’s feet:
A new pollination system in orchids.
Plant Systematics and Evolution
Pollinaria are
attached to bird’s
feet!
28. Disa draconis and
tanglewing fly
Johnson, S.D. and K. E. Steiner. 1997. Long tongued fly
pollination and the evolution of spur length in Disa
draconis. Evolution 51:45-53.
31. MaleMale EuglossineEuglossine beebee
pollinationpollination
Ca. 250 species inCa. 250 species in NeotropicsNeotropics
OnlyOnly malesmales collect floral fragrancecollect floral fragrance
chemicals and store them in specialchemicals and store them in special
hindhind tibialtibial organsorgans
Probably use compounds in matingProbably use compounds in mating
behavior (sexual selection)behavior (sexual selection)
64. Oil reward flowersOil reward flowers
Oils (Oils (triacyltriacyl glyceridesglycerides) produced on) produced on
surface of flowers, often in specializedsurface of flowers, often in specialized
glandsglands---- elaiophoreselaiophores..
Oils are collected by femaleOils are collected by female anthophoridanthophorid
bees; used to provision nest (food forbees; used to provision nest (food for
larvae)larvae)
Many orchids mimicMany orchids mimic MalpighiaceaeMalpighiaceae
69. Wax or resin rewardWax or resin reward
Collected and used by female bees forCollected and used by female bees for
nest constructionnest construction
Found inFound in MaxillariaMaxillaria andand CymbidiumCymbidium;;
poorly studiedpoorly studied
70. Resin reward: collected by female bees for nest construction
Maxillaria notylioglossa
Waxy resin
crystals
72. Resin deceit?Resin deceit?
Many Maxillaria species
appear to produce resin,
but “resin” is simply a
shiny callus on lip.
Deceit of resin-collecting
female bees?
73. Sexual deceptionSexual deception
Based on floral fragrance mimicry ofBased on floral fragrance mimicry of
sexual pheromones of pollinatorssexual pheromones of pollinators
Usually visual, tactile mimicry, tooUsually visual, tactile mimicry, too
Has evolved repeatedly in severalHas evolved repeatedly in several
different orchid groupsdifferent orchid groups
86. Food or Brood site deceptionFood or Brood site deception
Not well studied, but probably not rareNot well studied, but probably not rare
Possible examples:Possible examples:
DraculaDracula ---- pollinated bypollinated by DrosophilidDrosophilid
flies; mimicry of yeast?flies; mimicry of yeast?
PaphiopediumPaphiopedium ---- some pollinated bysome pollinated by
syrphidsyrphid flies; mimicry of aphids (prey forflies; mimicry of aphids (prey for
larvae)?larvae)?
92. Fly pollination inFly pollination in PaleotropicalPaleotropical
BulbophyllumBulbophyllum andand CirrhopetalumCirrhopetalum
93. ““Motel 6Motel 6”” syndromesyndrome
Bees seek out flowers to sleep inBees seek out flowers to sleep in
overnightovernight
No obvious food rewardNo obvious food reward
Chemical attractants?Chemical attractants?
Confirmed only for European genusConfirmed only for European genus
SerapiasSerapias
95. Trap mechanismsTrap mechanisms
Found in association with variousFound in association with various
reward/attractant syndromesreward/attractant syndromes
Pollinators are lured into an area theyPollinators are lured into an area they
cancan’’t escape, then forced to exit pastt escape, then forced to exit past
the columnthe column
Or, the pollinator may be forcibly thrownOr, the pollinator may be forcibly thrown
against the columnagainst the column
97. Porroglossum eduardii
Lip open
Lip closed
Active trap mechanisms
Some pleurothallid flowers
have sensitive, motile lips
(similar to Venus Fly Trap)
Insect landing on lip
triggers lip to close, lifting
insect into contact with
column.
102. Nectar DeceitNectar Deceit
Relatively few orchids actually produceRelatively few orchids actually produce
a nectar reward (energeticallya nectar reward (energetically
expensive? Longexpensive? Long--distance pollendistance pollen
movement?)movement?)
Most have emptyMost have empty nectariesnectaries; deceive; deceive
pollinatorspollinators
Might be mimics of other nectarMight be mimics of other nectar--
producing nonproducing non--orchids in same habitatorchids in same habitat
104. Oil deceitOil deceit
Many species ofMany species of OncidiumOncidium do not offerdo not offer
an oil reward, but are thought to mimican oil reward, but are thought to mimic
flowers of the nonflowers of the non--orchidaceousorchidaceous
MalpighiaMalpighia (an oil(an oil--rewardreward eudicoteudicot) or) or
CalceolariaCalceolaria..
Typical yellow/brownTypical yellow/brown ““oncidioidoncidioid”” flowersflowers
occur in many unrelatedoccur in many unrelated cladesclades ofof
subtribesubtribe OncidiinaeOncidiinae
Taxonomic confusion!Taxonomic confusion!
106. OTHER MODELS ???
CALCEOLARIA & OTOGLOSSUM HARLINGII
Calceolaria is an oil reward flower; sympatric with
“Oncidiums” at higher elevations in the Andes
110. PlatantheraPlatanthera: Using Molecular Phylogenetics to: Using Molecular Phylogenetics to
Study Adaptation to Different PollinatorsStudy Adaptation to Different Pollinators
Work ofWork of HapemanHapeman and Inoue (1997)and Inoue (1997)
Used DNA sequencing to produce aUsed DNA sequencing to produce a
phylogenetic tree; usedphylogenetic tree; used characterscharacters
independent of floral traitsindependent of floral traits
Then, mapped floral characters ontoThen, mapped floral characters onto
tree, allowing evolution of traits to betree, allowing evolution of traits to be
tracedtraced
115. PlatantheraPlatanthera: Take: Take--home messageshome messages
PollinationPollination--related floral traits (color,related floral traits (color,
size, spur length, etc.) undergo rapidsize, spur length, etc.) undergo rapid
and frequent evolutionary changeand frequent evolutionary change
Floral traits areFloral traits are
““homoplasioushomoplasious””=evolutionarily labile=evolutionarily labile
Orchid classifications shouldOrchid classifications should NOTNOT bebe
based primarily on floral characters!based primarily on floral characters!
116. Emphasis on gross floral
characters can result in
incorrect classifications!
Dendrophylax fawcetti
“Campylocentrum” filiformis
Dendrophylax filiformis
117. CoevolutionCoevolution??
Orchids are highly adapted to utilizeOrchids are highly adapted to utilize
specific pollinators, butspecific pollinators, but……..
Do orchids affect the evolution of theirDo orchids affect the evolution of their
animal pollinators?animal pollinators?
““Orchid and bee marching petal inOrchid and bee marching petal in
tarsus down the aisle oftarsus down the aisle of coevolutioncoevolution””??
118. CoevolutionCoevolution??
NoNo---- no evidence that orchids affect theno evidence that orchids affect the
evolution of morphology or behavior ofevolution of morphology or behavior of
their pollinatorstheir pollinators
Most orchids are rareMost orchids are rare----not the primarynot the primary
source of nectar or other rewards forsource of nectar or other rewards for
their pollinatorstheir pollinators
ProbablyProbably ““parasitesparasites”” on otheron other
plant/pollinator systemsplant/pollinator systems
119. Is Pollinator SpecificityIs Pollinator Specificity
OverOver--estimated?estimated?
How many observations are needed toHow many observations are needed to
document pollinator set for an orchid?document pollinator set for an orchid?
What about seasonal, geographicWhat about seasonal, geographic
variation?variation?
For most species, we donFor most species, we don’’t havet have
enough observations to adequatelyenough observations to adequately
measure pollinator specificitymeasure pollinator specificity
120.
121. How many species?
How many
polllinators,
fungal partners?
Conservation—
Ex situ, in situ?
122.
123.
124.
125. What can you do to conserveWhat can you do to conserve
orchids?orchids?
$45 buys 1 acre of montane
rainforest– makes a great
birthday or holiday gift
Ecominga Foundation: purchasing land to
conserve Ecuador’s orchid-rich habitats:
www.loujost.com
126. AcknowledgementsAcknowledgements
National Science FoundationNational Science Foundation
American Orchid SocietyAmerican Orchid Society
Marie Selby Botanical GardenMarie Selby Botanical Garden
Atlanta Botanical GardenAtlanta Botanical Garden
Many commercial & private growersMany commercial & private growers
