1. FLOWER HEATING
FOLLOWING ANTHESIS
&
THE EVOLUTION OF GALL MIDGE
POLLINATION IN SCHISANDRACEAE
AMERICAN JOURNAL OF BOTANY
-JULY 2010-
2. Shi Xiao Luo & Dianxiang Zhan
South China Botanical Garden,
Guangzhou, China
Shu-Miaw Chaw
Biodiversity Research Center
Taipei, Taiwan
Susanne S. Renner
Department of Biology,
University of Munich
Munich, Germany
3. KEY TERMS
• Agamospermy -the asexual formation of
embryos and seeds without the occurrence of
fertilization.
• Anthesis - the period during which a flower is
fully open and functional.
• Oviposition - to deposit or lay eggs.
• Saprophytic - organisms that feed on dead or
decaying matter.
6. STAR VINE FAMILY
~90 SPECIES
Schisandraceae
Kadsura (22 species) - Endemic to Tropical Asia
Schisandra (25 species) - Tropical Asia- (Exception - S. glabra)
Illicium (42 species) - SE Asia, SE U.S., Mexico, Greater Antilles
7. WHY IS THIS PAPER INTERESTING?
• First Data Ever Published On
Thermogenesis & Pollination
In Any Asian Illicium Species
• TR-71U THERMO RECORDER
8. PREVIOUS STUDIES
POLLINATION BIOLOGY
(5 of 90 Species)
North American Schisandraceae
&
Asian Schisandraceae
Thien et al., 1983;
White and Thien, 1985;
Deringer et al.,1999;
Liu et al., 2007;
Yuan et al., 2007, 2008
9. PREVIOUS EXPERIMENTS SUPPORT:
FLOWER HEATING:
1.) is a direct energy reward for ectothermic pollinators
2.) increases the volatilization of chemicals directed at pollinators
3.) helps the plant mimic mammalian feces or carrion attracting saprophytic pollinators
4.) enhances the respiratory release of CO₂, which in combination with other volatile
chemicals may stimulate fly oviposition
10. NORTH AMERICAN
SPECIES
(New World Illicium & Schisandra)
-Pollinated predominantly by flies with beetles as co-
pollinators
Thien et al., 1983;
White and Thien, 1985;
Deringer et al.,1999;
Liu et al., 2007
18. FLOWER HEATING
FOLLOWING ANTHESIS
&
THE EVOLUTION OF GALL MIDGE
POLLINATION IN SCHISANDRACEAE
19. POST ANTHESIS FLOWER HEATING
Schisandraceae Old World Illicium
EVOLUTION OF GALL MIDGE POLLINATION
20. OBJECTIVES
QUESTIONS AUTHORS ARE TRYING TO ANSWER
1.) Given that some Schisandraceae exhibit flower heating, do Asian
Illicium species also possess this trait?
2.) Does any flower heating continue after a flower’s sexual function
is over, and if so, what is the adaptive significance of postanthetic
flower heating?
3.) Are Asian Illicium species pollinated by gall midges, or do they
show “generalized” fly and/or beetle pollination similar to New World
Illicium?
4.) Are flower heating and midge pollination functionally correlated?
22. STUDY SPECIES 1: Illicium dunnianum
DESCRIPTION: Small shrub (0.5 – 2m high)
HABITAT: Riverbanks in wooded ravines (Elevations 300-750m)
LOCATION: Shiheqiguan - Nan Kun Shan National Forest Park, China
OBSERVED: Mid March to late April – 2008 & 2009
# OBSERVED: 53 individuals total: (38 at site A, 8 at site B, 5 at site C)
STUDY SPECIES 2: Illicium tsangii
DESCRIPTION: Shrub or small tree (up to 10m)
HABITAT: Mixed forests or thickets (Elevations 500-800m)
LOCATION: Along road - Nan Kun Shan National Forest Park,
China
OBSERVED: April to late May – 2008 & 2009
# OBSERVED: 56 individuals total
24. FLORAL DEVELOPMENT, FUNCTION, & TEMPERATURE
Open Pollinated, Male Phase,
Cross Pollinated, Nursing Phase,
Bagged Pre-Anthesis Female Phase
•
Relative position & color of tepals, stamens, and styles.
•
Presence or absence of secretion.
•
Timing of; style movements, anther dehiscence, and floral organ
wilting/abscission.
•
Ambient and floral temperatures in open-pollinated flowers
recorded for 50 h) using TR-71U thermo recorder (AWESOME!)
Readings taken every 5 sec. (male phase, nursing phase, female phase)
•
One-way ANOVA F-tests and t-tests – using statistical package SPSS
•
G-test- using Microsoft Excel Poptools 3.0
25. Plant Reproductive Biology
-Mating Systems-
1.) Randomly selected flowers and marked as controls
2.) Flowers self pollinated from male-phase flower then bagged
3.) Flowers bagged to test for agamospermy
4.) Flowers cross pollinated then bagged
26. VISITORS & POLLINATORS
Diurnal & nocturnal observations made over 150
hours:
-Recorded Kinds & Numbers of Visitors
-Duration of Visits
-Insect Behavior
To investigate flowers functional phases
•
Visitor behavior was monitored inside flowers
•
Flowers were bagged at end of female phase
•
Flowers were bagged at end of male phase
•
Tepal tips were trimmed in male phase flowers
•
Tepal tips were trimmed at beginning of nursing phase
27. Molecular Phylogenetics
&
Ancestral Trait Reconstruction
•
Sequenced complete internal transcribed spacer (ITS) of ribosomal DNA
•
Sequenced part of the chloroplast trnL region
•
Data set comprised 43 species – 2197 aligned nucleotides
•
Performed Maximum Likelihood analysis under GTR + G model of
substitution
•
Bootstrap support values were estimated w/ 100 replicate heuristic searches
28. RESULTS
♦ 1st night = Female flowers w/ fully receptive stigmas
♦ 1st day = interim phase (female to male)
♦ 2nd night = flowers entered male phase –last 2-3 nights (anther dehiscence)
♦ Day 3-7= Nursing phase begins
Inner tepals close, forming a chamber,
Adaxial filament surfaces and inner tepal bases produce a secretion,
Filaments increased in diameter in control from female to nursing
phase
Filaments thickened from female to male and then wilted by nursing.
29. FEMALE PHASE
(Illicium dunnianum)
Pollination occurred mostly at night
Single midges entered same flower numerous times
Only one midge at a time – if occupied other midges would fly away
Midge eggs became visible & pollen grains appeared on stigmas after visits
Single midges deposited 26 (+/- 3) pollen grains
Captured midges carried numerous pollen grains on body
New species of Clinodiplosis was likely discovered
30. MALE PHASE
(Illicium dunnianum)
When anthers dehisced midges again visited to oviposit
20 eggs were found per flower in the male phase, but flowers with trimmed tepals
caused eggs to die
The highest number of larvae/ flower were found in the bagged male-phase.
Highest number of eggs was found in male phase flowers
High temperatures beginning of female phase then dropped to ambient during male
Produced little heat during day and throughout male stages
31. NURSING PHASE
(Illicium dunnianum)
Onset of nursing phase chamber temp. increased to higher than in female phase
Midges did not try to enter nursing phase flowers
Larvae in nursing phase flowers were seen feeding on filament and tepal secre=on.
32. OBJECTIVES
1. Asian Illicium species do possess postanthe:c flower hea:ng.
2. The key stage of thermal warming was well aEer the sexual func:on was over in the two
studied species. The only observable & supported benefit of post‐anthe:c hea:ng is
exclusive to the larvae of the pollinator. The increase in temperature provides warm enough
temperatures for larvae to survive and the heat also causes filament and tepal secre:on
which the larvae feed on. The hea:ng seems to be a reward for the pollinator in a plant‐
pollinator mutualis:c rela:onship.
3. In contrast to the New World Illicium, the two study species Illicium dunnianum and I. tsangii
were pollinated only by Clinodiplosis gall midges.
4. Despite these findings, comparison of the ancestral state reconstruc:ons for two traits
showed that flower hea:ng and gall midge pollina:on are not strictly correlated.
