Susan Martinez
Mohamed Jama
Biology Lab
November 1, 2011
Comparative Analysis of the Reproductive Ecology of Monotropa and Monotropsis: two
Mycoheterotrophic Genera in the Monotropioideae (Ericacea)
Mycoheterotrophy is a symbiotic relationship between a plant and a fungus that manages to
produce all or parts of its food without photosynthesis. This study defines that plants containing and
providing carbon resources associated with mycorrhizal fungi (fungus inhabits the primary plant's roots) are
still reliant to some ecological interactions.
In this study the two subjects being examined are Monotropa and Monotropsis, these plant
species are found in the Monotropaceae mycoheterotrophic ericaceae family. These plants thrive in acidic
soils. The purpose of this experiment was to observe and test the hypothesis of the possible traits such as
generalist pollination syndrome, and automatous self-pollination. The plant species were manipulated and
observed for their flower phenology (studies done on natural phenomena), pollution ecology, breeding
system, floral herbivory,(organisms that feed off themselves) and reproductive effort and output.
Experimenting the hypothesis made by Bidartondo; that these plant species would be sustainable to
produce offspring due to their autogamy. Autogamy is self-fertilization, and self-pollination of a flower.
Each species differ in their breeding systems, timing and duration of reproductive development,
fluctuations in reproductive effort and outcome. This study is the first investigation of the reproductive
ecology of mycoheterotrophic plant species and provides insight into possible limitations in reproductive
traits imposed by a mycoheterotrophic life history.
Mycoheterotrophy has been have remained understudied, this experiment plays a key role in
mutualisms and interdependences that are important within ecological interactions. Driving the function of
the ecosystem, and most importantly the evolutionary ecosystem of non-photosynthetic plant biology.
These plant species containing carbon resources are diverse group of organisms that have evolved from
photosynthetic ancestors, which are now free from the limitations of “green plants”. Though these plants
come with requirements for survival such as carbon influx. However the mycorrhizal symbioses taxa
accounts for most the traits produced from each organism. Yet even though the reproductive ecology of
these organisms remain understudied.
Bidartondo predictions give insight to the possible reproductive traits of Mycoheterotrophy
predicting that they would be evolutionarily unstable. When already in stationary symbiotic reproduction
mode, affecting the most genera distinctive traits such as color, size of reproductive stems, flower per stem,
floral fragrance, seed shape, and fruit type. Taxa (group) varies in is a major effect on the flowering
fluctuations in yearly fecundity (production of offspring).
In this study there were varies method and materials included some of which were: site
description, pollinator diversity, and visitation rates. The main focus was on the Monotropa uniflora and
Monotropsist the control and experimental group. The plants were observed and compared to one another
through their physical characteristics produced upon fertilization and without natural ecological factors to
contribute.
The site description was used as the compare and contrast method to identify populations of each
taxon (group of species). Each taxa is identified to their natural habitat where they’re typically grown.
With each species accustom to diverse ecological factors, some are considered be isolated clumps of
reproduction underestimating the actual population size. Human pollinators each had significant roles when
visiting and addressing the hypothesis. Observations were conducted within largest population of each
taxon in daylight hours, for two consecutive years. One of the most vital materials used was the nylon
pollinator exclusion tent. This is where plants of each taxon were examined, excluding flying and crawling
insects. While still allowing light, moister and airflow. There they had placed video cameras to better
observe the peak of the bloom. Video footage was one of the other materials used, to view and later to
determine the average number of stems for each flower. The voucher specimens from pollinators were
collected during visitations assessing pollen loads; this was their main method reproduction evaluation.
Foraging behavior was observed by video to better reinforce comportments of the plants breeding. The
differences in worthwhile observations were set between self-compatibility and autogamy treatment groups
determined by fruit studies done under a dissecting microscope observing the development. As you can tell
there were a variety of materials used in this study to carefully follow the reproduction of these plants.
Populations were monitored for three years to determine when plants became reproductive and to assess the
duration of flowering phenology which is the study of cyclic and seasonal natural phenomena.
Towards the end of the blooming season flower numbers were recorded, and fruits were collected
to determine the plants potential reproductively. Fecundity (offspring) was highly variable across each
population of taxon. Rates considered on behalf of their mature fruits, flower per stem, and floral
fragrance. Although the drought that happened in the 2007 summer was a significant factor because it
caused fixed ratios to take place for statistical outcomes. Which was the reason for decline in reproductive
growth, and increasing the odds herbivory; which is the own consumption of living plants.
The final conclusions plants were analyzed into one of three categories: Mature, Aborted, and
Damaged by Herbivory (fed of its self). Mature fruit was one of the ratios used to determine the measure of
reproductively. There was a significant difference with each taxon, for example some produced more
flowers then others. Plants considered to be aborted were plants that just died from no apparent reason.
There were different levels of herbivory and were further classified into different types of herbivory that
most frequently affected each taxon: floral herbivory (consumption of flower sex parts), stem herbivory
(consumption of part of the stem and or roots), nectar robbing (small chew holes of petals), or seed
predation (digging into fruit into fruit to consume developing or mature seeds). Results mainly illustrated
quantify differences in the reproductive output among the Monotropaceae mycoheterotrophic populations
of each taxa.
This research has helped the understanding of the dynamics and complexity of non-photosynthetic
mycoheterotrophic Monotropoideae plant-fungal and their ecological interactions. The tented treatments
also demonstrated the dependency of natural pollinators, because it declined the productivity of autogamy
in the plants. Considering all the associations that went on in this experiment there were some significant
factors that contributed to the final consequences of each taxa. Each taxa had different blooming periods,
and unique breeding systems. Ultimately it failed to prove Birdartandi prediction of that autogamy would
be favored in this experiment. Therefore concluding that pollinator abundance and fidelity are vital for
successful reproduction.
This experiment defines that interaction of pollinator’s behaviors, breeding systems, and
environment all are important factors that are needed for reproduction. One of the most significant factors
was weather; it has the maximum control on reproductive fluctuations. The drought that happened in 2007
drastically decreased the fecundity in each Mycoheterrophic taxa, each were sensitive to the environmental
fluctuations. Considering the outcome of this experiment it obvious that plants will better reproduce when
all ecosystem contributors are present on a day-to-day basis. Maybe with all necessary contributors
herbivory of flowers and stems wouldn’t have been the outcome, there might have been more herbivory
defense. All in all this experiment mainly represents the limitations associated with Mycoheterophic life,
creating a good foundation for future examinations of the evolution of these non-photosynthetic plants. As
result it is safe to say the results document of reproductive traits from the Mycoheterophic species
demonstrate that each taxa possesses a complex reproductive strategy.