Sex, Evolution and Form: Clarifying the Relationship Between Dandelion and the European Honey Bee

With the artist’s, Sue Abonyi’s, permission.

The European Honeybee, EHB, and the Common Dandelion, are both ubiquitous in our modern urban lives though the one is portrayed as being both essential to our lives while its future is threatened and dependent upon our constant support. The Dandelion in contrast is a product of our disruption of the natural world and our very way of life and continues on as a pest species despite our efforts to ‘control’ it. They viability of the EHB is often linked to the continuation of a large population of Dandelion individuals. The EHB certainly benefits from the Common Dandelion finding ready individuals across our lawns and gardens, but the dandelion isn’t particularly dependent upon the EHB. The common dandelion, Taraxacum officinalis, is apomictic and doesn’t require pollinators at all. Apomixis isn’t a fancy word for ‘selfing’ or wind pollination either…what it means is that it, in lieu of an available pollinator, possess the capacity to skip over meiosis, the entire part of sexual reproduction in which an organism’s typical double, pair of chromosomes, which exist normally in all cells, and are known as diploid, ‘di’ for two sets of chromosomes, are reduced by half, to one set in ‘sexual’ cells, known as gametes, the sperm and egg cells, their chromosomes now ‘haploid’. Then, after pollination, the two haploid chromosomes are reunited uniquely through the process of fertilization. This is is the process skipped over in an apomictic plant. While it possess all of the ‘accoutrements’ of all flowering plants, stamen with their filaments and anthers, pistils with their stigma, style and fused carpels or ovaries, Dandelions are able to ‘short-circuit’ the process and produce viable seed on their own from their undivided, diploid, cells. Ever noticed how Dandelion seed heads always tend to be filled out? Perfectly spherical?
Dandelions are a member of the Asteraceae, one of the more recent plant families to evolve on Earth and, as such, are within the massive group of flowering plants, the Angiosperms. Prior to their arrival/evolution over 100-150 million years ago, the landscape was populated by Gymnosperms, Ferns and their now extinct predecessors, plants whose sexual structures did not include ovaries of more modern plants with their carpels fused together into protective structures, aiding and shielding the development, internally, of the embryo and seed, seed which if you went back to even earlier ages, was not produced at all. Earth’s plant palette was very different. Species of Asteraceae possess the outwardly most complex flower structures of all Angiosperms, and some argue, the most efficient of all in terms of sexual reproduction. Plants which evolved earlier tend to show greater variability of fine structure within their families, genera and species and more primitive structure which modern plants do not. Over time details within these patterns have in a sense ‘tightened up’. There are more species today which more closely resemble each other than there were in ages past. By protecting more of their reproductive process within the flowers Angiosperms are slightly less effected by the varying conditions of life on an Earth which is much more arid today. Less is left to chance, the ‘mother’ plant providing more ideal conditions for the early stages of a seed’s development. So, with apomixis, are Dandelions, taking this alternate reproductive path compromising themselves over the longer term, or does this confer on it some kind of an advantage? Evolution, according to Darwinian thinking, moves ahead through time utilizing the processes of natural selection, those individuals and species possessing advantages being more successful at survival and reproduction, over time, supplanting the less ‘fit’ individuals without those advantages.
Why, one could ask, have Dandelions and the several hundred other species which appear to possess this capacity, developed this particular survival strategy, ‘apomixis’, which makes them capable of producing viable seed, on their own, without the processes of meiosis, or unzipping their paired chromosomes, pollination and fertilization? This unzipping and mixing appears to be essential for the progression of evolution. Have these plants become more ‘perfect’ and no longer need to evolve? Are they taking a rest and will at sometime return to their sexual mixing of chromosomes or simply perish over time as the rest of the world continues to change? Is Apomixis an error? A doomed pathway? Do their genes today give them all of the capacity they need to produce their constituent parts? Are their other ‘epigenetic’ forces and patterns in effect which are somehow ‘outside’ of the individual that work to shape/control them? Such as the several ‘fields’ physicists have begun to consider and study? Like the gravitational, electro-magnetic and various quantum fields that move elementary particles into the particular conformations of matter at such tiny scales? These plants have the ability to bypass the first stages of the reproduction ‘game’, foregoing the production of haploid, single chromosome, gametes within their pollen and ova. Instead they proceed directly to producing an embryo, using their somatic, normal, diploid or double chromosomes of their adult selves, not bothering to mix the genetic material with those of another individual Dandelion or even those of another flower on the same plant.
The embryos within their apomicticly produced seed, are genetically identical to the mother plant. Clones. These seedlings develop normally from germination onward. Their progeny are normal other than their genetically identical genomes. Dandelions retain the ability to go through sexual reproduction the old fashioned way. It is not clearly understood what the mechanism may be that causes an individual to switch to its apomictic process or why it may do this.

The above diagram illustrates the normal process within the flower of a typical Angiosperm.  Apomixis essential eliminates the need for the entire male process shown on the right.  It also eliminates the female process shown in light blue. as well as the act of fertilization at the bottom in gray. The ovum or egg forms directly within the flower’s ovary which through mitosis, simply splits duplicating itself with its chromosomes intact, moving horizontally in the illustration where it begins to form the embryo, endosperm and seed-coat.

In ‘normal’ flowers undergoing sexual reproduction haploid pollen and ova are produced before the arrival of a pollinator in order to be ‘ready’ so the process can’t be triggered by an absence of pollinator activity, or can it? If an individual has gone to all of the trouble of producing haploid gametes for its pollen and ova, why it give them up and short circuit the process or is this decision made earlier? It would seem to be a waste of the plant’s energy to develop these haploid gametes if they aren’t to be used. Is this more common in particular populations than others? Is it related to the age of the plant? is it tied to day length or some seasonal variable? Some other stressor or something else? Is it somehow a response within a local population that once it has passed a particular ‘threshold’ number of individuals, plants begin to switch because there is already so much seed developing that little advantage is being gained by expending the energy to complete the entire process? or, is it triggered in individuals in a widely scattered population with lower probability of successful pollination? Also, how common is this across the floral world? If sexual reproduction and the mixing of parental genetic material provides an advantage long term to the progeny, essential to the process of evolution, as science has long claimed, is this some kind of down grading of the process? leading to extinction as entire Dandelion populations become genetically stagnant, contributing the same ‘limited’ gene set to natural selection? This wouldn’t seem to be the case today as local populations are entirely capable of rapidly dominating landscapes, especially those which we have ‘disturbed’. Is this somehow a result of our own continuing massive distrubance? Or, is sexual reproduction less important than we thought and there are other ‘forces’ in play here, in addition to genetics, driving the appearance and development of new ‘forms’ as more scientists are beginning to suggest, ‘forces’ ‘propelling species along pathways and patterns of self-organization toward complexity, playing out unseen, all along, within all species? So many questions?

So the Dandelion doesn’t ‘need’ the European Honey Bee nearly as much as the bee may need it, though it too has many better choices. Dandelions are a great nectar source for them, necessary as a supply of carbohydrate to ‘power’ the EHB, but we have found that Dandelion’s pollen is a poor source of several essential amino acids the EHB require to maintain a high level of health. Feeding on a diet of Dandelion nectar and pollen leaves EHB’s malnourished. The health of hives dependent upon Dandelions is thus compromised. They must have other food sources which contain these essential amino acids, but because of the EHB’s ‘habit’ of becoming ‘attached’ to a nectar source once they begin to feed on it, ignoring other nectar/pollen sources nearby, this can put the EHB in a more precarious state of health. This habit is an asset to commercial beekeepers who rent out their EHB’s services to farmers. It would do farmers little good if the bees ‘wandered’ about choosing to service other flowers than their crops. While this pattern may not be an exclusive one it certainly does provide limitations on their roaming and feeding This habit is also an asset to honey producers who can move their hives around to particular sources the EHBs than producing different honey’s with distinctive flavors. Last year a neighbor’s bees found my flowering Echium wildpretii plants early and visited them heavily while ignoring other nearby sources such as ‘Monte’, my flowering Agave montana, which is a heavy producer of both nectar and protein rich pollen. It took a couple weeks of flowering before the EHBs ‘discovered’ it though they were only 50’ apart.
As western civilization spread across the globe, we brought the Dandelion with us. We brought the European Honey Bee as well, a species whose value lies to a large part in its adaptability to the floral world around the globe. Our own native bees, of which there are an estimated 500 species in Oregon alone, estimated because there has never been a complete census taken of the state (the Oregon Bee Atlas project is addressing this in a four year citizen supported project, the fieldwork to be completed this year, 2021) tend to have much more limited adaptability, sometimes even to a single flowering species, and are often restricted to the floral species they evolved with. This relationship sometimes goes both ways the native bees requiring the native plants in order to survive and the native plants dependent upon the native pollinators for their survival. We ourselves have ‘evolved’ with the EHB’s, where we go they go. Our forms of agriculture, the plants we cultivate, being supported by the EHB, and the natural habitat of native bees, destroyed and developed as farm and urban lands which are largely devoid of the native plant species so many native bees are dependent upon. At the same time we go to great lengths to assure the survival of EHB providing them hives, tending them and delivering them to crop sites where they can work crops they’ve worked with for hundreds if not thousands of years. The other plants, not as highly valued by our culture, decline and with them their pollinators. Dandelions, a plant associated with our culture for several hundred generations may be evolving in a way that will preserve it should its pollinator decline into obscurity. It is very difficult to know exactly what is going on today immersed in the world as we are at this moment in time. We have no long term perspective to the consequences of our own actions which take several of our own generations to play out. It is highly doubtful that these things are happening independently, randomly. Because we do not see the pattern does not mean that it is not there.

One could be tempted to draw parallels between the process of apomixis and that of parthenogenesis in insects like the aphid, where several consecutive generations may produce already ‘pregnant’ females in exclusion of males, producing males once annually over the course of multiple other generations as if to help maintain the genetic viability of a population. This is a more familiar pattern probably because the aphid is a much studied insect as a serious pest species and vector of several significant plant diseases. Dandelions, with their longer life cycles have been less studied. It is in the definition of patterns themselves, that things repeat in related though not identical ways, even when there is little to no shared genetic history.
This raises the question of what is responsible for pattern, how does that tiny embryo in a seed form from the merger of two haploid cells, or in this case, from a single diploid cell and from the embryo, upon germination, into a mature adult? Why this particular form shared so closely by all of the individuals in a species? What governs this process of morphogenesis? The exquisite timing necessary for this? Not to mention the countless diverse chemical reactions which must proceed in a highly coordinated manner just to remain alive? Geneticists argue that the genes that comprise an organism’s chromosomes rule all, how they might do this remains a mystery especially given the complexity of multi-celled organisms with various tissues and organs. Some are beginning to follow the lead of physicists who have recognized that as ‘parts’ assemble into ‘wholes’ each added layer of complexity, molecule to cell to tissue, to organ to individual to local population, follow particular and consistent patterns which can evolve over time. Physicists, who have explored so deeply into the quantum world, a nearly unimaginable world at the core of matter and energy, have now been exploring/considering this world of ‘wholes’ and patterning…while biology and geneticists have remained largely in the molecular world insisting that all of the answers are there….In physics some write of ‘formative causation’ of how what was and what is influences form, how those forms can evolve over time, while remaining true and viable. This is a huge topic I’m exploring elsewhere and will continue to do so.
Apomixis is not clearly understood. It is a process that we only became aware of less than a 100 years ago. It requires the analysis of an individuals genetic material to determine which genes were carried on, shared between generations, to understand whether a haploid gamete was produced first or not. Botanists aren’t sure how long this strategy has been around. Whether it is some kind of aberration or a strategy that is just developing and will become more common over the next several thousands of years. Or, whether it has been around all along. This is due to the relatively recent capacity and affordability of science and technology to relatively quickly analyze an organisms genome. Apomixis gives an isolated individual options that it would otherwise not have, but at least in the case of the common Dandelion, isolation is not generally a problem. Whether a particular Dandelion is an apomictic clone or the product of pollination and fertilization, is not readily observable. The species appears to be under little survival pressure as both the shear numbers of plants around us and their seed would seem to attest. Any puff of wind on a dry spring or summer day sends untold millions of seed on their journeys to their new soil homes. If the physicists and those studying patterns in ‘wholes’ rather than just genetic bits, are on the right path, apomixis will not be a dead end. Genes play a core role, but do not tell the entire story. Patterns themselves evolve, individuals following/influenced by them while they are in turn effected by individuals. Just as species, including Dandelion, are relatively new arrivals to life on Earth, science is beginning to understand that matter itself, its constituent parts, the elements, molecules and compounds are themselves continuing to emerge and evolve, the patterns evolving over time. DNA does play an essential role in determining the constituent parts of an organism, it contain the ‘codes’ for our proteins, but there appear to be patterns playing larger, organizational roles in the complex forms of proteins, the details of an individual’s form and function. Theoretically the ‘behavior’ of matter and by extension organisms, can be explained via mathematical formula…that is still the view of much of mainstream physics, but with the exception of the most simple of all elements, hydrogen, this has not be done, because to do these calculations are beyond the capacity of the world’s most powerful computers. Even if we could do such calculations, how would this forming process occur? Again science is beginning to turn toward the idea of formative causation and the power of morphic resonance, that nature has a kind of memory, that fields have a determining factor in the forms of all things, much as they do for elements and their particles.
Do not worry over the fate of the Dandelion, Taraxacum officianale, it will endure along with the patterns that support and sustain it…as will the EHB, our survival’s dependence assures that we will act to secure them. We should not confuse what we might believe with the actual world. Over time our understanding of the world within which we live has changed. The history of science and knowledge shows an evolution in thinking…is it straight and continuous, no. It exhibits the breaks and cycles characteristic of evolutions of all types. What we do know is that species and individuals which become mired or stuck in the past, resistant to change and evolution, reduce the chance of their own survival and that of their line, just as those who follow unsupportable trends and fads may. Evolution is a long game and, in our own case, will require the awareness and wisdom to determine which path we should take. Because something is known and familiar doesn’t mean that it is correct. In this we too are like the EHB who can become committed


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s