Lithops hybrids

For the discussion of topics related to the conservation, cultivation, propagation and exhibition of cacti & other succulents.
Forum rules
For the discussion of topics related to the conservation, cultivation, propagation, exhibition & science of cacti & other succulents only.

Please respect all forum members opinions and if you can't make a civil reply, don't reply!
Terry S.
https://www.behance.net/kuchnie-warszawa

Re: Lithops hybrids

Post by Terry S. »

Ian, for the genetic work on Lithops, do you know of anything published after the 2010 Kellner et al article? I think that particular paper is decidedly dubious as a starting point for any revision of the genus. There are a few pairs of Lithops species that can be hybridised in cultivation, but there do not seem to be many. Below the level of species, many ecotypes can be crossed together as in a couple of the images above. These simple observations indicate that Cole's species concept is not far short of the mark.
User avatar
iann
BCSS Member
Posts: 14562
Joined: 11 Jan 2007
Branch: MACCLESFIELD & EAST CHESHIRE
Country: UK
Role within the BCSS: Member

Re: Lithops hybrids

Post by iann »

The best Lithops, in our narrow sense of the word, seem to come from selective crossing within species and even within particular forms, inbreeding rather than outbreeding.

Steven Hammer produced 'Blacktop' from L. lesliei var venteri, but they were more of a browntop for me, the windows being nice and open but the colour went to brown instead of grey/black.
blacktop-130612.jpg
I bred these from var rubrobrunnea, just a parent with nice open windows and a parent with very dark windows.
rubrobrunnea-0711.jpg
Cheshire, UK
Terry S.

Re: Lithops hybrids

Post by Terry S. »

I think that most of us tend to be rather selective when we produce seed from our own plants. Unless we have superhuman resolve, there is always a tendency to interpollinate the best looking plants of a particular taxon or ecotype. The cacti with the longest spines, the haworthias with most spotting on the leaves, the conophytums with the best colours and markings. In mercenary terms, these are the forms that many other collectors want to buy and is a good commercial technique.

The selection tendency even goes back to original wild collections where introductions of cuttings or a few seeds are likely to be made from the best-looking plants which are not representative of a population as a whole. These give rise to the "founder effect" whereby a breeding line developed in cultivation from a few individuals does not truly represent a wild population.
User avatar
iann
BCSS Member
Posts: 14562
Joined: 11 Jan 2007
Branch: MACCLESFIELD & EAST CHESHIRE
Country: UK
Role within the BCSS: Member

Re: Lithops hybrids

Post by iann »

Terry S. wrote:Ian, for the genetic work on Lithops, do you know of anything published after the 2010 Kellner et al article? I think that particular paper is decidedly dubious as a starting point for any revision of the genus. There are a few pairs of Lithops species that can be hybridised in cultivation, but there do not seem to be many. Below the level of species, many ecotypes can be crossed together as in a couple of the images above. These simple observations indicate that Cole's species concept is not far short of the mark.
There was supposed to be follow-up, but I haven't seen anything since then. I'd call the paper surprising rather than dubious, but either way it hasn't led to changes in the taxonomy and probably isn't going to without more research. Not least because it isn't obvious what the changes would need to be, short of lumping in Dinteranthus. The paper identified nine clades that don't always align with existing species boundaries but didn't really offer enough clarity on what different set of species would work better. In some cases (eg. L. julii, L. hallii, and L. salicola) the clades are entirely expected, in others (eg. L. dinteri, L. dorotheae, and L. karasmontana) definitely unexpected.
Cheshire, UK
User avatar
David1971
Registered Guest
Posts: 133
Joined: 30 Jan 2015
Branch: None
Country: Spain

Re: Lithops hybrids

Post by David1971 »

iann wrote: Mon Jul 09, 2018 10:30 pm There is certainly potential for lumping Lithops, but the reasons why it hasn't been done are well-known and widely-accepted. The very difficulty of crossing any particular pair of Lithops species speaks to their being well-differentiated.

Infra-specifically, Lithops subspecies are defined (following Cole) where the two forms are reliably distinct but close enough to be the same species. Varieties are used where two forms (or populations) are differentiable en mass but individuals are not reliably distinct. The species, subspecies, and varieties named by Cole are already a dramatic lumping of the previous situation.

Genetic studies have indicated that the traditional species groupings are partially the result of convergent evolution and apparently similar Lithops are not necessarily the most closely-related. Also, Lithops is not monophyletic with respect to Dinteranthus. No name changes have been made, partly because the DNA studies are quite tricky as Lithops show little divergence in the traditional markers used for such studies so relatively new techniques have to be used.

There are only a handful of Lithops hybrids in widespread cultivation, and perhaps widespread is being generous even to those. With the exception of the hybrids with Dinteranthus, I can't think of any that I'd recommend except to the most dedicated completionist.

Here is one more hybrid, deliberately made to produce a yellow flower on an apparent L. optica 'Rubra'. L. herrei and L. optica are likely to be very closely related and one of the top candidates for species lumping, despite having different coloured flowers which has traditionally been seen as a very strong dividing line among Lithops species (a dividing line that isn't supported by the DNA studies).
xrubra-1212.jpg
Very interesting Iann, thanks for commenting on this. Do you know if anyone is nowadays working on the philogeny of the genus with more refined molecular markers?
Last edited by David1971 on Mon Aug 13, 2018 11:49 am, edited 1 time in total.
Terry S.

Re: Lithops hybrids

Post by Terry S. »

I don't know of anyone who is currently working on the molecular systematics of Lithops. Cornelia Klak at UCT has resorted to using and analysing about 10 different DNA sequences in order to separate Mesembryanthemaceae species down to the genus level and can resolve at the species level for some of those genera that diverged early in chronological terms. The MSG has helped with a grant to Prof. Young at Liverpool in order to try and use modern techniques to identify more meaningful sequences in his work on Conophytum.

The problem with mesembs is that speciation has been relatively recent (around 5 million years) for a majority of them. Genes mutate at a fairly predictable rate and this length of time is too short for sufficient numbers of mutations to take place in order to make for easy genetic analysis.

I suggested that the 2010 Lithops article was unreliable because I was aware of how difficult it has been to develop meaningful molecular systematics in the family and insufficient sequences were used.
User avatar
David1971
Registered Guest
Posts: 133
Joined: 30 Jan 2015
Branch: None
Country: Spain

Re: Lithops hybrids

Post by David1971 »

Terry S. wrote: Mon Aug 13, 2018 8:17 am I don't know of anyone who is currently working on the molecular systematics of Lithops. Cornelia Klak at UCT has resorted to using and analysing about 10 different DNA sequences in order to separate Mesembryanthemaceae species down to the genus level and can resolve at the species level for some of those genera that diverged early in chronological terms. The MSG has helped with a grant to Prof. Young at Liverpool in order to try and use modern techniques to identify more meaningful sequences in his work on Conophytum.

The problem with mesembs is that speciation has been relatively recent (around 5 million years) for a majority of them. Genes mutate at a fairly predictable rate and this length of time is too short for sufficient numbers of mutations to take place in order to make for easy genetic analysis.

I suggested that the 2010 Lithops article was unreliable because I was aware of how difficult it has been to develop meaningful molecular systematics in the family and insufficient sequences were used.
Ok Terry, I undestand, thanks for the information. So it seems that we still have to wait some years to obtain a more detailed picture of Lithops systematics.
User avatar
D^L
BCSS Member
Posts: 341
Joined: 23 Sep 2010
Branch: BRISTOL
Country: UK

Re: Lithops hybrids

Post by D^L »

I was also true that much of the source material in the DNA paper was from "Atomic" nursery rather than having a good reliable link to the wild.
It was part of a PhD rather than a realistic study.
David Lambie
Post Reply