Why do we keep our phasmid cultures pure ?

  • not too long ago, phasmid breeders considered it a great idea to mix "new blood" with an existing culture. Meaning that they were mixing their specimens of a long-established culture with specimens of a newly imported, "fresh out-of-nature" culture. Without considering whether both populations are actually conspecific (= the same species) and "biologically fully compatible"
  • but things are a bit more complex than this simplistic approach ....
  • first there is the age-old controversy amongst biologists - "what is a species after all?"
    • one might think that taxonomists have a clear idea about what a species is, but as John Wilson puts it "there are n+1 species concepts in a room with n biologists"
    • for example there is the biological species concept, which defines a species as "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups" (Mayr, 1942). Yet no phasmid taxonomist is testing this concept when describing a new species (due to practical reasons). Thus this concept has no significance in phasmid taxonomy
    • then there is the morphological species concept, which groups individuals into different taxon based on their outer appearance (morphology). This concept is widely applied by phasmid taxonomists. This concept leaves much room for personal interpretation and choice, which inevitably leads to differences of opinion amongst taxonomists (which might sometimes even be fueled by personal animosities). Furthermore our increasing knowledge about cryptic species, siblings species, species groups and convergent evolution strongly indicate that defining a species based mainly on it's morphology can be tricky
    • a "very similar" morphology is a hint but no proof that two populations are conspecific. And there is good cause for circumspection when comparing geographically well seperated populations - e.g. morphologically similar populations from different islands, or even populations seperated by a long distance with geographical barriers (mountain ranges, rivers, arid areas)
    • to add to the confusion, there are even more species concepts
    • and even though DNA sequenzing seems to offer a preciser way to distinguish species, the species problem is far from being solved. The age-old question has just reappeared with a new livery ... Which DNA difference indicates that two populations are different species ? Humans and chimpanzees are phenotypically very different, yet their DNA is 98.8% the same. So where to draw the line between species when it comes to DNA? Different taxonomists will have different ideas about that - so the quarrels will go on
    • what about sub-species? Is this more than a last resort for unassertive taxonomists?
    • so no wonder that defining / describing a species is a controversial subject, as no species concepts can claim to be universally and absolutely true nor is there any concept which is absolutely wrong
    • taxonomy is the attempt to categorize the world around us, driven by the basic human desire to unterstand. It is like sieving through some stuff, to get order and control. Some biologists (lumpers) will use a rather coarse sieve, and obviously end with a lower number of distinctly seperated groups than those biologists (splitters) who apply a finer sieve. But neither approach is better nor worse than the other 
    • here are some videos, which give some basic infos on this subject and it's controversy:
  • and secondly, even if two well seperated populations are biologically and genetically fully compatible and thus conspecific (= the same species), it is very likely that they show consistent minor differences. The worldwide human society is good proof for that. And why would it be different in the world of phasmids? 
  • thirdly, there are indications that geographically well seperated populations might not be fully "biologically compatible" anymore. An example for this are Ensatina eschscholtzii (a salamander in California) or the Greenish Warbler (Phylloscopus trochiloides)
  • all this shows that there is good cause for serious phasmid breederes to keep cultures from well seperated locations strictly seperat and pure, at all stages of their developement. Keeping cultures pure is a way to preserve nature's astounding diversity and it's scientific value. Who knows what future taxonomical in-depth studies will come up with ...
  • finally, let's have a look at the E. tiaratum cultures in Europe. They thrived for 50 - 60 years in Europe and this species was considerate a very easy "beginners species". Yet some years ago, breeders across Europe "suddenly" reported problems with Extatosoma tiaratum. Interestingly these problems arose just during the time when "new" E. tiaratum cultures from Australia became available. And many breeders frantically mixed their old cultures with these newly imported cultures. Is it just a coincidence, or could it be that these newly imported cultures were not fully "biologically compatible" with the old culture, which lead to weak hybrid cultures? Just a thought ...

How to keep phasmid cultures pure ?

  • always use the full scientific name of a culture, and make sure that have the full scientific name correctly for your own personal use
  • never use common names (like "prickly stick insect" ect.), 
  • for all cultures with known and confirmed exact geographical origin / provenance, use the full scientific name always with the provenance as affix. For example Phyllium rubrum "Tapah", which is the Phyllium rubrum culture originating from the hills around Tapah (Peninsular Malaysia)
  • if you import or collect a new culture yourself, make it a point to add the provenance to the species name when you distribute your new culture to other breeders. Be as specific as possible when choosing the provenance. Just the country name is not good enough!
  • if there are several closely related yet significantly different cultures from the same provenance, then one can add an additional morphological feature to the affix. For example Phyllium rubrum "Tapah" has first been named as Phyllium sp. "Tapah, red coxae". So this was the Phyllium culture from the area of Tapah which has red coxae
  • if you do not know the exact geographical origin / provenance of your culture, please be honest about it. Only crooks label their culture of unknown origin with a specific location
  • never ever keep two species of the same genus in the same cage! We just don't know how easily different species hybridize
  • keep cultures with different geographical orgins strictly seperate at all stages - eggs, nymphs and adults
  • it is the best anyway to keep no more than one phasmid species per cage. The population density even in the biggest cage is still much higher than it is out in nature 
  • make sure that your cages are escape-proof, this is not only important for cages but also for the hatching boxes
  • only use physically seperated incubation boxes, so that there is no possibility to mix-up nymphs of related species
  • nymphs which escape and roam outside the cage can not be put back into a cage, especially if we have similar species in breeding. It is not unlikely that even from eggs which lay in a dark and dusty corner of your phasmid room nymphs will hatch!