no apologies necessary : victory:
regarding anecdotal in this case, i would agree and would prefer there was an alternative which there unfortunately isn't but retic breeding simply due to clutch size has an advantage, u get a large sample simply from siblings retained for recessive mutants for example, so though anecdotal it is not small in sample size and has the advantage of limited gene pool variation for mutations. the variation on the spectrum obviously is care, but retic keepers are somewhat unusual in that they are pretty uniform in this respect, due to the captive mechanics of maintaining an animal the size of a retic, ur choices and options are limited, and this has led to a uniformity in private captive care for this species. the same can be said for burms murinus and probably sebae.
re uv and females i would say no to it just possibly benefiting them, in captivity for boids if theres going to be issues with something like uv (or temps, or food, or heat) its before reproductive age, ie simply getting them to reproductive age is the issue not the sex of the specimen. if there was one species i would say deserves a caveat it would be boelens females of reproductive age, especially gravid females, given their unique habitat and evolution, if there was a need differential based on sex it would be them.
I am being lazy with my formatting at the moment so excuse the odd reading! My own particular issue with anedoctal evidence is the fact without exploring all the factors you cannot conclusively prove causation, correlation on the other hand is very easy and can be seen. I feel it is likely from the evidence that UV light isn't going to be a major factor in getting to the extreme sizes, however it could help produce healthier individuals? Isn't it commonly seen that most female boids show the last sentence?
actually in boids the opposite is the norm, the periods of fasting are periods of metabolic stability, boids though not unique in this ability have perfected the famine feast cycle better than virtually any other genus. a wild c.aspera may only eat 6-8 times per year but that is their evolutionary template, in captivity given the option they will eat more but not to the extent that they consume based on opportunity rather than need like many other species. another example would be bloods, they have a template like aspera but on a larger scale. if there is a failure in the captive cycle i would guess its in the way excess calories are stored as fat. the first thing u would notice in a retic during post mortem is the huge abundance of fat stores they carry, and i do wonder if these fats stores are simply under utilized, their job is to get thru lean times and produce clutches, only the latter happens in captivity, leading to an imbalance, a balance that could be critical, so instead of the evolutionary 100% utilization of these stores, they are continually topped up and continually under utilized, by lack of prey drought and increased feeding to make up for a recently laid clutch, so season after season the imbalance grows till critical mass and system failure.
I do wonder what causes boids to have these issues exactly, I would imagine it is something to do with the facts the if food is inconsistently coming in, therefore they have to extract everything they can from each meal (causing the heart issues you mentioned, and probably other issues), but when they are in extended periods of fasting, like probably not a few weeks, extending a month or more? Whether this fasting is causing additional stresses on each of the organs, which then if this happens regularly then can cause failures? To be honest your first comment is common sense and yet it often looked over...a bad diet going into your snake and lack of excerise isn't good!
i would say the difference is caused by the differing expectations of the sexes,
a male boid only has to reach reproductive age mate and his genes are passed on, so his number of prey to catch is x his number of hours of efficient heat is x, but the female not only has to reach a larger longer reproductive age, but she has to carry with that enough excess energy to fuel either a long gestation of embryos or the growth of a clutch of eggs. so in a male there is a point where evolutionary speaking he is disposable but that point is much much later on for the female in boids given the investment of a clutch or litter. you only have to look at kenyan sand boas to see that ratio in physical form, a male kenyan adult can be the size of a 12mth old female and successfully pass on his genes. a 6mth old male ball can reproduce, whereas females are usually 36mths. there are two main methods boids have chosen, large amounts of small babies or small amounts of large babies (proportionally), for egg laying species there is the retic with regular clutches not aberrant clutches on record of 50+ viable eggs, and there is perthensis with clutches as small as two, but the size of neonates in proportional comparison to the adult female is larger for perthensis. the livebearers have an equally diverse path, there are rosy boas with litters of around 4 and there are boa constrictors with as high as i *think* 90+ for pete kahls original img boa, but again the rosys boas are larger proportionally (not physically) given the size of the mother.
other species in which the differing evolutionary expectations of the sexes is obvious is paulsoni and carinata, the males are tiny in comparison, so much so that when first imported the animals where extremely female heavy, to the point it was thought that males were rare, possibly even TSD like leos etc, but what actually was happening was rather funny, the field collectors, thinking they would get paid more if they only caught larger specimens where leaving most of the smaller specimens alone, they were leaving all the males
This issue with saying parentage will determine the offspring size is there are a lot of in direct factors at play, a lot that aren't determined by genetics. As I said before there isn't one gene that will make a snake grow to a set length, however the exact way it works isn't actually known so I am going to try an infer to the best of my ability. However the best way to explain that a series of genes will allow the production of differing levels of growth hormones under optimal conditions, and thus meaning a pair of two larger snakes are more likely have the genetic code that produces more growth hormone, thus are more likely to grow more. A couple of things that should be noted, is that diseases/parasites/poor diet can actually stop or reduce the hormone production, meaning a reduced growth rate, but also if the genetic code doesn't produce the hormones for the full length of the main growth time that you can get stunted growth.
I wonder what exactly causes the difference between the two sexes in boids.
i do wonder if the different locales have differing reproductive ages, given their different minimum reproductive sizes, but do they take equal amounts of time to reach there, is the access to comparative prey size and amount the equalizing factor, do the smaller forms have a longer lifespan from a stretched out reproductive cycle due to the very pressures that dwarfed them in the first place...
The question of parasites and disease is a curious one on how much of an impact there is on the growth rates cause simply but there are more parasititc species then we can shake a stick at, and I think it would take a long time to study the major groups and how they react with each other. However you can imagine the parasites that life directly off the hosts food/body will cause some damage, however will it significantly cause a reduction in growth. It is very unlikely as Ed says, to be considered a "good" parasite that the parasite will not kill off the host before it has had a chance of spreading. If it kills off the host before it can spread the parasite could be considered a biological failure. I have a suspiscion that diseases would have a bigger impact then parasites (obviously some diseases can come from parasites) on growth rates of the snakes. It is probably very likely that you are correct with captive animals being likely to attain the wild giant sizes at a much younger age due to the fact keepers give more food then they would encounter in the wild.
I wonder if there are any studies on the wild diets of retics, and how different they are to their captive counterparts.
its been a pleasure chatting : victory:
rgds
ed