Genus vs. Specie

[SkeletalFrog]

Anybody in need of, or know an individual in need of a topic for their biology dissertation? (hey- possible paper-publication here...)

Pacman's seem to be a great candidate for reclassification (original Genus was described in 1824).

Ceratophrys Cranwelli (Genus/specie) by definition would only be able to breed with (and have viable young) other Ceratophrys Cranwelli (and sub-species of).
If, as I understand it, a "samurai blue" is a cross between Ceratophrys Cranwelli and Ceratophrys Ornata, then they should be grouped as sub-species in a new species category (Ornwelli ?)- whereas Ceratophrys Cornuta- wich is unable to produce viable offspring when crossed with another variant (resulting in "fantasys") would be correctly placed in it's current taxonomical position.

I always found this topic intriguing when I bred Lichanura Trivirgata and Labeotropheus Trewavasae/Fuelleborni.

Technically, it's always "species", both singular and plural, like "sheep" or "moose".

Also, the definition of "species" doesn't necessarily hinge on total incompatability. Generally speaking, species do not interbreed, but there are numerous exceptions, including species which do interbreed to form "hybrid zones" in certain areas. If they are isolated, this can be through numerous mechanisms, including incompatibilities that don't show up in captivity, such as slightly different breeding seasons, as well as infertile hybrids or even just hybrids that aren't as capable of survival in the wild as the parents.

An extreme example is actually a side-project I have with one of more genetics-oriented evolution faculty here, involving cross-genus hybrids (Lampropeltis getula californiae X Elaphe obsoleta obsoleta) which not only do just fine in captivity, but are fertile as well. The two lineages have been separated for ~18 million years, yet still form fertile hybrids.

[GrifTheGreat]

Technically, it's always "species", both singular and plural, like "sheep" or "moose".

Also, the definition of "species" doesn't necessarily hinge on total incompatability. Generally speaking, species do not interbreed, but there are numerous exceptions, including species which do interbreed to form "hybrid zones" in certain areas. If they are isolated, this can be through numerous mechanisms, including incompatibilities that don't show up in captivity, such as slightly different breeding seasons, as well as infertile hybrids or even just hybrids that aren't as capable of survival in the wild as the parents.

An extreme example is actually a side-project I have with one of more genetics-oriented evolution faculty here, involving cross-genus hybrids (Lampropeltis getula californiae X Elaphe obsoleta obsoleta) which not only do just fine in captivity, but are fertile as well. The two lineages have been separated for ~18 million years, yet still form fertile hybrids.

That's very interesting.

[cali]

Technically, it's always "species"...

Ya, that quip was hit-or-miss at work too.



The Pantherophis/ Lampropeltis/ Elaphe debate is an excellent example. They have been shuffled and re-shuffled since discovery- there are multiple arguments being played out as we speak to re-classify their current nomenclature.

Given that the native range of Ornates and Cranwells overlap- if young are viable, then they would be geographical subs.
DNA from local-specific specimens would be great, but I'm not trying to burn up a grant here- simply asking for a general consensus.

[SkeletalFrog]

Given that the native range of Ornates and Cranwells overlap- if young are viable, then they would be geographical subs.
DNA from local-specific specimens would be great, but I'm not trying to burn up a grant here- simply asking for a general consensus.

Not necessarily. The are plenty of clearly morphologically divergent species with overlapping ranges and intermittent hybridization, including the very icons of evolution, Darwin's finches. Hybridization is not a disqualifier for species status.

So far, we only have evidence that they can sometimes hybridize under captive conditions (potentially with mixed success). They may not hybridize in the wild at all due to slightly different breeding times or preferred congregation areas or call preferences, etc. Even if they do, if the hybrids are strongly weeded out of the gene pool, gene flow will be minimal. Heck, even if the hybrids are just as strong, they could be infertile or just never manage to mate because their call has the wrong frequency for either parent (frog mating responses are *strongly* tuned to specific call frequencies).


However, a bit of googling turned up a conclusive answer, in this paper: 1320 Cranial morphology and karyotypic analysis of Ceratophrys joazeirensis (Anura: Ceratophryidae, Ceratophrynae): taxonomic considerations | Mendeley (full version here: http://ecoevo.com.br/alunos/ana_paul...otaxa_2006.pdf)

Basically, ornata is octoploid, while cranwelli is diploid. Any hybrid's cells would therefore have unpaired chromosomes, preventing meiosis and rendering the hybrids totally infertile.

[GrifTheGreat]

Not necessarily. The are plenty of clearly morphologically divergent species with overlapping ranges and intermittent hybridization, including the very icons of evolution, Darwin's finches. Hybridization is not a disqualifier for species status.

So far, we only have evidence that they can sometimes hybridize under captive conditions (potentially with mixed success). They may not hybridize in the wild at all due to slightly different breeding times or preferred congregation areas or call preferences, etc. Even if they do, if the hybrids are strongly weeded out of the gene pool, gene flow will be minimal. Heck, even if the hybrids are just as strong, they could be infertile or just never manage to mate because their call has the wrong frequency for either parent (frog mating responses are *strongly* tuned to specific call frequencies).


However, a bit of googling turned up a conclusive answer, in this paper: 1320 Cranial morphology and karyotypic analysis of Ceratophrys joazeirensis (Anura: Ceratophryidae, Ceratophrynae): taxonomic considerations | Mendeley (full version here: http://ecoevo.com.br/alunos/ana_paul...otaxa_2006.pdf)

Basically, ornata is octoploid, while cranwelli is diploid. Any hybrid's cells would therefore have unpaired chromosomes, preventing meiosis and rendering the hybrids totally infertile.

So basically its saying that Cranwells can only breed with their own kind to produce offspring that are fertile and if they breed with a any other Ceratophrys. The young are to be infertile? So that would conclued that all Fantacy Frogs are mules? Ornates can reproduce with othe Ceratophrys and still produce fertile young?

[SkeletalFrog]

I don't know about *any* other Ceratophrys - they don't mention the chromosome numbers for cornuta, testudo or calcarata. But they at least have the same chromosome numbers as aurita and joazeirensis.

But there's a lot more to hybridization than fertility, and there could be other genetic incompatabilities even between species with the same number of chromosomes.

[GrifTheGreat]

I don't know about *any* other Ceratophrys - they don't mention the chromosome numbers for cornuta, testudo or calcarata. But they at least have the same chromosome numbers as aurita and joazeirensis.

But there's a lot more to hybridization than fertility, and there could be other genetic incompatabilities even between species with the same number of chromosomes.

Aurita and Joazeirensis look like types of Cranwellies with different color patterns. That and the Aurita is supposed to be the largest of the Horned Frogs. I guess one day a breeder will attempt to interbreed the different species and see whether of not the offsoring are fertile. Only time will tell.

[cali]

Interesting read.


Abstract-
"...morphology between C. joazeirensis (8n)..."

Introduction-
"...The greatest difference between the two species is found at the ploidy level, since C. cranwelli is a 2n species and C. joazeirensis PROBABLY an 8n species..."

Discussion-
"...Barrio and De Chieri (1970) registered diploid populations of C. ornata in soggy central areas of Argentina..."

This one alone hints that ornates and cranwells may interbreed where their populations overlap, and that the genus may need multiple new categorys.

As in most papers, the last couple paragraphs are the most interesting.
Looks to me as though it only reinforces the idea that the genus is in need of a massive amount of research, verification and reclassification.

[cali]

This discussion may give birth to a new postulate (for purely hypothetical debate of course)

If "a" breeder (not going to point fingers here) came across a 2n ornate- the hybridization results with a cranwell might be interesting...

[Namio]

Technically, it's always "species", both singular and plural, like "sheep" or "moose".

Also, the definition of "species" doesn't necessarily hinge on total incompatability. Generally speaking, species do not interbreed, but there are numerous exceptions, including species which do interbreed to form "hybrid zones" in certain areas. If they are isolated, this can be through numerous mechanisms, including incompatibilities that don't show up in captivity, such as slightly different breeding seasons, as well as infertile hybrids or even just hybrids that aren't as capable of survival in the wild as the parents.

An extreme example is actually a side-project I have with one of more genetics-oriented evolution faculty here, involving cross-genus hybrids (Lampropeltis getula californiae X Elaphe obsoleta obsoleta) which not only do just fine in captivity, but are fertile as well. The two lineages have been separated for ~18 million years, yet still form fertile hybrids.

Just because two species are capable of interbreeding does not make them the same species. Reproduction compatibility or capability are not the only deciding factors in terms of species definition. There are 500 species of cichlid fishes living in the (same) African Great Lake, all of which are capable of producing viable offspring and yet they don't do it in nature. In coastal northern California (where I live), we have northern red-legged frog (Rana aurora) and California red-legged frog (Rana aurora) who were once considered as one single species but two subspecies until 2004 when Shaffer et al. did a phylogenetic study to show that they are in fact of separate lineages, despite in the overlap zone in Medocino County where the two species meet they do hybridize.

There are many definitions of "species" in the science world and most scientists cannot agree upon on one. That is because evolution is a continuous and dynamic process. What we call a "species" is quite arbitrary.