Continuing last week’s blog, here is the completion of Rudie Kuiter’s Introducion, Orchid Pollinators of Victoria. In this section he discusses some factors of hybridisation and the value of regular observation by local people interested in orchids.
Lissopimpla excelsa is the pollinator of all members of Cryptostylis, but hybrids are not known, even when sympatric, thus a molecular mechanism is in place that prevents cross-fertilisation. Hybrids in other orchid genera do occur and these usually are amongst closely related species. Several congeneric orchids attract the same male pollinator species, thus would be emitting the same kairomones, the scent that is a mimic of the female’s sex-pheromones, but normally these orchids are allopatric or have different habitat preferences. The land clearing, frequent fires, changes of watercourses, gold-diggings are amongst many unnatural human habitat interference of recent times. Historically in undisturbed natural habitats sibling orchid species that attracted the same male insect were not sympatric, not flowering at the same time or were in close vicinity to each other. In disturbed sites the situation has changed, as closely related species may have become sympatric and hybridisation take place. Spider-orchids that attract thyniid wasps with kairomones normally target a certain local species, but many allopatric species are know to share the same pollinator and readily hybridise where they became sympatric. In Pterostylis greenhoods the known hybrids are also caused when different species attract the same pollinators.
We still have much to learn to fully understand how adaptable the orchids are, the role insects play and how to interpret what we see. Orchids are finely tuned to their world and can change and adapt in ways that most people seem to underestimate. I requires observations of the same plants over many seasons to get a good understanding of their variability and adaptability. Unusual forms often show after a drought or fire may look like a new species, but soon change back to typical or normal within a few good seasons or after regeneration. It is usually the local people taking an interest that see the changes in the same plants over time that dispute what the ‘on-the-fly’ taxonomist come up with.
Creatures evolved as part of an endless combination of life-forms, ranging from microscopic to the tallest tree, that together form an ecosystem in which all organisms depend on each other. The climate, weather and other factors changes the environment constantly that influence the members differently, dome doing better than others, but it collectively maintains a balance. Natural events such as a major fire or flood may benefit environments in areas as part of seemingly long cycles, but they are very short in evolutionary terms. Unnatural man-made fires are very destructive as these are conducted much too frequently, wrong time of the year, and in the wrong place. Not obvious, but also very detrimental is the use of insecticides that seems to effect the Diptera members the most. Many of the important pollinators such as the fungus-gnats have gone locally extinct and most of the Pterostylis depend on them. To work with the pollinators it is essential to have a good understand of the life-cycles of the insects involved and watch the flowers in the wild. After witnessing Pollinator behaviours of the fungus-gnat on Pterostylis nutans countless times, the principal pollinator is easily recognised with other species. Unfortunately few good areas to find orchids and learn about their pollinators are left. Many are now rare and measures taken to protect them usually focuses on just a species. To be effective their habitat area and surrounding needs to be cared for, letting the natives grow and have the natural canopy reform. At least, habitats should be protected from further disturbances, especially by badly informed governmental environment departments with their fires.
Note This book is solely based on first-hand observations on the orchid-pollinators in the wild. Descriptions and comments are from many hours of watching each species over multiple seasons.
Apart from Orchid Pollinators of Victoria, Rudie Kuiter has produced several Victorian orchid books. If you are interested in purchasing any please contact us.