subadult?

[Berislav Horvatic]

In our reports we often declare animals as "subadult" rather loosely,
and usually nobody objects...

Perhaps the best definition of "subadult" can be found at "Biology online":

subadult - stage in which an organism has developed many but not all
adult characteristics and is not sexually mature.

The second defining condition is unambiguous, but the first one leaves
some free space for rather liberal estimates....

However, regarding the second, strict condition, if you catch an animal in nature,
on what grounds can you decide/determine whether it is sexually mature or not?
If it's obviously old enough or too young, than it's easy, but that just REVERSES
the original question - you DECLARE it to be sexually mature/immature on the
grounds that it obviously IS an adult or a juvenile.

My raising this "theoretical" issue was prompted by a question from a colleague who
was lucky enough to catch and measure 40 (!) individuals of Elaphe quatuorlineata
on the island of Olib (in addition to 10 M. insignitus and 4 D.caspius!) last week.
Three of the E. q. were obviously juvenile, but some of the others, with total body
lengts reaching 110 to 120 cm still showed the transverse dorsal coloration pattern.
Should they be classified as "subadult" solely on that grounds?

[Jeroen Speybroeck]

Hmmm... I think I myself might rather (unknowingly) use "juvenile" for 1 or 2 years old animals, relying on my guestimation about body size. It's true this type of classification is usually bases on these grounds alone (being size and pattern). It goes without saying that adulthood means sexual maturity. Other than that, I don't care an awful lot whether someone talks about subadult or juvenile.

To be honest, I've always assumed sexual maturity in this species (Elapquat) to go hand in hand with pattern evolution, but I have no reference to back that up. Finding animals of over 1m with (remnants of) spotted pattern is not that unusual, I would say.

Sounds wonderful to find that many snakes on such a small island, although I hope this won't turn in to too much of an advertisement.

[Berislav Horvatic]

Other than that, I don't care an awful lot whether someone talks about subadult or juvenile.

That's fine as long as you don't have to write an official report on your finds or,
even worse, a scientific paper... Then it suddenly starts to matter very much.

[Jeroen Speybroeck]

Other than that, I don't care an awful lot whether someone talks about subadult or juvenile.

That's fine as long as you don't have to write an official report on your finds or,
even worse, a scientific paper... Then it suddenly starts to matter very much.

No, because the term has little or no scientific bearing.

[Jeroen Speybroeck]

Neither juveniles nor subadults contribute to the reproductive population. I don't know what kind of paper you are thinking of but imho for most cases your "very much" is exaggerated, especially for ecological studies. It's nothing more than a refinement of the non-reproductive portion of a population.

[Berislav Horvatic]

Neither juveniles nor subadults contribute to the reproductive population. I don't know what kind of paper you are thinking of but imho for most cases your "very much" is exaggerated, especially for ecological studies. It's nothing more than a refinement of the non-reproductive portion of a population.

OK, so does a 120 cm long Elaphe quatuorlineata with a transverse dorsal coloration pattern
belong to the reproductive or non-reproductive portion of a population?

[Sandra Panienka]

I do a lot of field work and am usually asked to give minimum numbers for juveniles, subadults and adults in reports. The people I usually work for define an amphibian or a reptile to be subadult after its first winter - before that it is a juvenile. It's an adult when it is ready to reproduce. You have to come to some terms of aggreement when you work in a group of several people that all have to hand in their reports. The stuff needs to be comparable.
I think the same definition for subadult is also quoted in Ulrich Schulte's book about Podarcis muralis. But I would have to look that up again. Or maybe he wants to contribute to this.

I actually find it hard to call an animal "subadult" after its first winter when it still has all the juvenile traits, which goes especially for indivudals that for example metamorphosed very late in a year. I tend to still call them juveniles after the first winter but usually give them the number of the year, like juvenile of '11 when they are still really small.
Juveniles and subadults may not represent the reproductive part of a population but they for sure tell you something about how many indivudals metamorphosed and what is still there from the year before.

[Mario Schweiger]

In (most) reptiles is a question of length (% of normally full grown adults, no giants) and not of age!
For example, many Podarcis reproduce successful in their 2nd year.
Ammodytes males will be able to reproduce in their 3rd or 4th year, females in their 4th or 5th year under normal conditions.
But I know keepers, getting the first fertle eggs from Corn snakes (Pantherophis guttatus) from raisen hatchlings within 6 month - the snakes have length then between 80 and 90 cms.
Diesener G. published in the eighties, he got babies from ammodytes only 10 month old.
I would say, a 4lineata with 90 - 100 cm (females) and a bit larger for males is mature and able to breed for sure. May still have a fade youth pattern.

Mario

[Berislav Horvatic]

I would say, a 4lineata with 90 - 100 cm (females) and a bit larger for males is mature
and able to breed for sure. May still have a fade youth pattern.
Mario

Thanks, Mario, that's a straight answer that solves the particular practical problem my friend has.
Much obliged, in his name as well.

Now we can theorize further, if anyone feels like it, of course.

[Jeroen Speybroeck]

Neither juveniles nor subadults contribute to the reproductive population. I don't know what kind of paper you are thinking of but imho for most cases your "very much" is exaggerated, especially for ecological studies. It's nothing more than a refinement of the non-reproductive portion of a population.

OK, so does a 120 cm long Elaphe quatuorlineata with a transverse dorsal coloration pattern
belong to the reproductive or non-reproductive portion of a population?

I already told you I don't know.