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Transcript of MONOTOCA SCOPARIA TWO FRUITS Betsy R. Jackes James Cook University Peter G. Kevan University of...
MONOTOCA SCOPARIA TWO FRUITS
Betsy R. Jackes
James Cook University
Peter G. Kevan
University of Guelph
MONOTOCA SCOPARIA
• Subfamily Styphelioideae, family Ericaceae• Shrubs to 1.3 m tall, lignotuber present• Inflorescence axillary, few-flowered spikes
often clustered• Functionally dioecious or ?• Ovary 1-locular• Fruit a drupe, yellow to orange
OBSERVATION
ALL REPRODUCTIVE PLANTS NEAR PALUMA PRODUCED FRUITS.
MAIN QUESTION
IS MONOTOCA SCOPARIA GYNODIOECIOUS, FUNCTIONALLY DIOECIOUS OR?
Townsville
Wet Tropics bioregion
Where are we?
BRISBANE
Queensland
STUDY SITES
• THREE POPULATIONS ALONG A DECREASING RAINFALL GRADIENT
• QUADRAT 30 X 18 M
• ALL PLANTS AT EACH SITE SEXED AND TAGGED AND CO-ORDINATES RECORDED
• ARE SEXES RANDOMLY DISTRIBUTED OR NOT?
Site 1 19o 00’ 27.8”S 146o 05’ 31.3”E
Distribution Site 1
Site 2 19o 00’ 08.1”S 146o 04’ 48.7”E
Distribution Site 2
Site 3 18o 59’ 59.5”S 146o 04’ 29.5”E
FEMALE PLANTS (WITH STAMINODES)MALE PLANTS (WITH FERTILE STAMENS)
WERE RANDOMLY DISTRIBUTED AT ALL SITES DESPITE VARIATIONS IN TOPOGRAPHY AND MOISTURE LEVELS
IS THERE A DIFFERENCE IN THE NUMBER OF FLOWERS PRODUCED PER SEX?
For each sex, 10 plants tagged, 10 sprigs per plant tagged, each sprig 10 cm long, all flowers counted
Female mean 1381, SD 196Male mean 1295, SD 240No significant difference
No significant difference
Female sprigs Male sprigs
♀
Male flower, c. 2.1 mm long
Female flower c. 1.5 mm long
DO MALE AND FEMALE PRODUCE EQUAL QUANTITIES OF NECTAR?
Sprigs cut and placed in water, covered with a plastic bag, left overnight
Then checked under a dissecting microscope and scored for the amount of nectar present.
1 = brim full
2 = well above ovary but not overtopping the style
3 = visible sparkle at base of corolla tube4 = no visible nectar
NECTAR RESULTS
Female n=150 Male, n= 192
1 (none visible) 56 02 49 23 32 724 (brim full) 13 96
Female flowers produced significantly more nectar than male flowers
POLLEN
Pollen from 10 plants, 4 flowers per plantStained with Alexander’s Stain – grains
unstained or partially stained and irregular in shape recorded as aborted.
Pollen grains per flower ranged from 2437 to 13375 mean 8762
% fertility or non-aborted grains = 81.9%
TWO FRUITS
• Fruit from female plantfirmly attached to parentglobular to pear-shaped2.4-2.7 mm long, 2.1-2.4 mm wide
• Fruit from male plantweakly attached to parentcylindrical2.5-3 mm long, 1.25-1.5 mm wide
Female plant
Female, mature and maturing
Male, mature and maturing
FRUIT SET
• All fruit present on the tagged plants were collected after 2 months.
• Percentage fruit set based on the number of buds and flowers recorded for each plant.
• Combined data for sites 1 and 2Female 27.11%Male 11.41%
‘female’ ‘male’
Presence or absence of a well-developed embryo
• Fruits collected from both sites 1 and 2
• Method 1: Fruits cut in half and nature of the embryo noted microscopically, n=20
• Method 2: Fruits cleared with methyl salicylate (modified from Stelly et al. and Scriballo & Barrett). All questionable results confirmed by sectioning
• Method 3: squishing
• Sex Site # examined #well-developed embryos
female 1 154 872 296 142
450 229
male 1 327 02 216 0 (2 partial)
543 0
Note: No females without partially developed embryos
‘female’ seeds with endocarp
2.1-2.5 mm long, 1.2-1.5 mm wide
FLORAL VISITORS
• 20 plants, 10 of each sex, 4 sweeps per plant• All insects captured and examined for pollen
load• Only Trigona ?carbonaria carried Monotoca
pollen.• Male plants, 21 bees captured
• 10 with pollen, 11 lacking pollen• Female plants, 23 bees captured
• 7 with pollen, 16 lacking pollen
CONCLUSIONS
• Monotoca scoparia is functionally dioecious, sexes are randomly distributed
• Two fruits develop but no viable embryos in ‘male’ fruit
• Flowers differ in size and shape with sex• Female flowers produce considerably more nectar
than male flowers• Trigona ? carbonaria is the pollinator