#21 - CROSS-BREEDING & IN-BREEDING

INTRO

One topic that has been suggested I tackle is "cross-breeding" or hybridization. I was reluctant at first as I have no egregious examples of intentional hybridization and many of our hobby "species" have historically been unintentionally hybridized due to similarity and ignorance. I wasn't sure I had enough material for a full on rant and condemnation of the practice.

Don't get me wrong. I am completely agains hybridization. It is one of the reasons I am no longer involved in herpetoculture where people create freaks like the "carpondro" (carpet python x green tree (or "chondro") python) and cross genus aberrations like ratsnake/kingsnake combinations.

As for in-breeding, this is a subject that is equally controversial and even more common in herpetoculture. Line breeding for 200 flavors of sluggish little ball pythons means doing some incestuous breeding by mating siblings and child to parent. Cue the "Dueling Banjos". Out crossing is performed by the better breeders to strengthen the genetic lines, but the morph crazy world of snake breeding is full of cross-breeding and in-breeding. Most albino pythons in the hobby were the result of breeding an albino to a normal to produce "hets", babies that are heterozygous for amelanism ("albino"), which are then bred back to a parent to produce visible albinos. This is the shortcut, but it also is a necessity when there is only one albino of that species in the hobby.

But this Blog isn't called "Kiss My Big Scaly Snake", so let's focus on these two issues in arachnoculture and what damage they do.

CROSS-BREEDING

So exactly how does someone "unintentionally" or accidentally create tarantula hybrids. One example would be hobby forms that are already dubious. One of the best known of these clusterfucks is the Brachypelma vagans, B. sabulosum, B. epicuraneum group. Another Brachy example is the B. vagans and B. albopilosum hybrids. One American even proudly posted on his website that he did this deplorable deed in 2008. Rumor has it that he then mated the siblings with each other. Most hybrids are never marketed as hybrids, of course, so you may think what you have is "pure" and breed. Perhaps you even get a loan of a truly "pure" male. The resulting offspring are still not 100%. Some "accidental" hybrids occur when males look very similar and poor record keeping or labeling, or a dishonest seller or loaner provides you with the wrong species. This is easy with some tarantulas, for example the many Poecilotheria males that look similar to the inexperienced eye, or the case of P. cambridgei and P. irminia, which Ray Gabriel detailed in a recent Journal of the British Tarantula Society (Gabriel, R. & S. Jordan. 2013. Hybridisation of P. cambridgei & P. irminia. Journal of the British Tarantula Society 28(2): 82-84.)

It is unfortunate that some tarantulas are now known as possibly being "impure" and many responsible hobbyists are now avoiding these spiders. Of course, there are plenty of tarantula keepers who have no intention of breeding and these hairy spiders of questionable origin will still make interesting terrarium pets. But down the road these may be passed on to someone with the inclination to breed and lineages become diluted. Even remaining within the same species we run the risk of "clouding the heritage". For example, the majority of the Brachypelma albopilosum in the hobby are nothing like the gorgeous, hirsute spiders my team found in Costa Rica in 2006. They range north throughout Central America and many have been imported from Nicaragua. The same is the case with Aphonopelma seemanni across the same general range. In spiders we do not have subspecies. If these were, say, snakes they might be given subspecific names (races). But we only identify to the species level and if you mate a dull brown and cream Nicaraguan A. seemanni with a gorgeous dark brown, almost black, and vivid white striped A. seemanni from Costa Rica, perhaps a descendant of those that Al McKee was breeding twenty-some years ago and you may not have actual "hybrids", but you definitely have spiders that are less desirable than either. Therein lies the problem, most hobbyists have no way to know the origin of the spiders they get.

And, thus, much of the "cross-breeding" problem is unintentional. The intentional crosses are what we have to worry about. People who intentionally breed vagans with albopilosum such as linked above are the problem. Many Poecilotheria crosses have been produced in Europe over the years. P. regalis has been crossed with P. fasciata, P. striata and P. ornata. P. regalis is from India and in each of these cases it was hybridized with a Sri Lankan species! P. smithi has been hybridized with P. vittata. At least these two are from the same country as are the P. ornata and P. fasciata hybrids that were also made. Not that this fact makes the deliberate crossing of the species any less irresponsible. P. smithi is the most endangered species of Poecilotheria and now we have to question how much of the smithi stock we have in arachnoculture has been clouded by hybridization with vittata.

The species concept is a very complex zoological paradigm that would take a book, not a blog entry. When an old guy like me was studying zoology there were already debates and interpretations and philosophical skirmishes. But now, with modern DNA sequencing and all sorts of methodologies that far surpass the brain cells I have left, I cannot tackle it here for you. But the traditional or biological definition of species is members of populations that actually or potentially interbreed in nature. If there is, for example, a geographic barrier that does not allow two populations to interbreed speciation occurs over time. One good example is in Brachypelma. People have questioned the validity of B. baumgarteni, but my dear friend Andrew Smith has studied the Pacific Coast Brachypelma in the field along with Dr. Stuart Longhorn and reports that B. baumgarteni is separated by a river. It may be early on it its speciation and thus still somewhat similar to its neighbor. See Eddy Hijmensen's fine site for more info. You can also download Andrew Smith's lecture "In Search of Mexico's Brachypelma Red Leg Tarantulas" for about $3.50. I highly recommend doing so.

I don't have much more to say on cross-breeding. The examples I used are some of the best known and, thankfully, I don't feel it is a widespread problem. The intentional hybrids are troublesome and problematic. It is one scourge that taints our hobby. But it isn't a huge problem as we are fortunate that most breeders are more responsible. The unintentional hybrids are actually more worrisome. That is because the asshats who do it intentionally are in the minority. But neophyte breeders who don't realize that what they have isn't "pure" mean no harm, but may produce dubious offspring unwittingly. All of a sudden our hobby has been flooded with all these Genus sp. 'Locality' and it makes it even more difficult. One genus where this has become prevalent is Pamphobeteus. It's just a marketing scheme. A European travels to South America and (allegedly) smuggles out some Pamphobeteus. It may be a described species, but everyone wants to be the first to have something and it becomes Pamphobeteus sp. 'Santo Domingo' or Pamphobeteus sp. 'Costa' or whatever. As many of you know, I don't deal with big, itchy, New World terrestrials. I favor arboreals. I breed Iridopelma sp. 'Recife', but this is I. hirsutum! It just sounds cooler if you put a locality, which in this case is just a major port city along the coast of Brazil. Any slight difference in color is geographic variation, and since 'Recife' (the first "r" in Portuguese is pronounced like an "h" - this is heh-SEE-fay) is a huge city I doubt many of these spiders were actually collected in the city limits.

IN-BREEDING

As far as in-breeding goes, I am one of those who believes that this is a minor problem. There is an often quoted "fact" that is repeated ad nauseum in arachnoculture that only six P. rufilata have ever been collected. I suppose I find this hard to believe, but if it is true then the spiders I've been breeding for many generations over the past 12-15 years are seriously in-bred. I've never noticed a single problem. It stands to reason - in my very NON-SCIENTIFIC opinion - that a primitive animal like a very primitive "spider" is genetically simple. One might presume that in-breeding in arthropods would not have the negative effects that in-breeding in vertebrates has. By the same thinking, one might presume that in-breeding in snakes (a common practice) is less detrimental than in-breeding in mammals, and that in-breeding in squirrels doesn't have the serious negative results that in-breeding in humans does. Cue the "Dueling Banjos" again. I used to live in Nashville. I believe I saw many examples of what the latter can do.

You should strive for genetic diversity despite the preceding paragraph. Given the choice I believe that out-crossing will strengthen captive bred tarantula populations. I just don't believe that breeding siblings is a heinous act like hybridization is. I've bred males back to their mothers many times - out of necessity. The last phrase is the key. If I had access to an unrelated male I certainly would have used him first. As I mentioned in the beginning, reptile breeders often create morphs by in-breeding. However, most will also out-cross by breeding to completely unrelated animals given the opportunity. These more genetically diverse offspring will then be mixed into the breeding program to produce potentially more robust and healthy young. I advocate the same in tarantulas. But a tarantula is a far more simple organism than a snake. I won't condemn in-breeding in tarantulas. But try to avoid it if possible. In-breeding certainly is a problem in higher animals. The cheetah is at serious risk because the species has reached the point where almost all those left in Africa are related., that is, almost identical genetically. As habitat destruction makes some tarantulas gone from nature for good we will be forced to maintain the strongest (most diverse) lines of each species we can. That's why I love that my most recent Tapinauchenius sp. Colombia egg sac was fathered by a male I just got from Germany. I was raising the female's sons for future breeding out of necessity. Then again, who knows how many of this spider have ever been collected and how many sacs created the founder stock that the hobby now enjoys. The male I used may have been my female's brother. You just never know... And therein lies the dilemma.

Enjoy your weekend, MJ