Are you splitter or lumper?

[Willem Heijns]

Researching my Australoheros article I was astonished by the fact that some 24 species have been described in this genus. And more on the way. Surely there must be "splitters" at work here. For a splitter, every minor difference (be it in morphology or in DNA) is a reason to describe a new species. Lumpers on the other hand simply state that this variation in nature does not necessarily have to be given names as taxa (species). They would probably say: All Australoheros are facetus to me.

I believe that not every river or stream should by definition hold its own different species even if one might say that the populations in these rivers are (genetically?) isolated from each other. Which raises the question: what would happen if this isolation were to disappear and populations would come together?

To be more specific: Are there any Australoheros-species that occur together (syntopic) with a congener?

Any ideas?

[Dan Woodland]

By your definition Willem I'm a lumper. I think variations in species are inevitable as they evolve which does not make them a new animal. This being said I'm also a firm believer in keeping "like species" from different rivers separated as a precaution because there is potential for them to be defined as different species. Keeping them separated also benefits us/me in keeping things in order.

What defines a species as you pointed out is up for debate and evidenced by the "splitting" of Cichlids like Cichla and "Discus".

[Bas Pels]

To be more specific: Are there any Australoheros-species that occur together (syntopic) with a congener?

I once asked precisely this question to Felipe Cantera - the expert on Uruguayan fish. He answered yes, but did not name any place

I have bred 3 species / varieties of Australoheros, and some take their fry to the bottom of the tank, as most cichlids do, but others take them to the surface.

Thus, regardless whether you are a lumber or splitter, there are more than one species of Australoheros - in Uruguay.

Still 24 species in total does seam a bit over the top. I do think that if one would apply this criterium to the Central American cichlides (the closest relatives of Australoheros are found in central America, thus this thought exercition does make sens) we would end up with a few hundred new species - species which would, I think, for quite a large proportion not pass the musterd

And thus the spliting criteria are to firm - I think

[Rico Morgenstern]

Thank you, Willem, for bringing up this topic. It has the potential to get a really interesting discussion.

With regard to Australoheros, I would say that even an extreme lumper would have difficulties to explain how a 'form' as distinctive as A. forquilha would fit into a pattern of intraspecific variation. A. scitulus and some others also clearly distinguished by morphology. Additionally, this species overlaps in distribution with A. facetus in Southern Uruguay and with A. minuano in the middle Uruguay drainage.

To be more specific: Are there any Australoheros-species that occur together (syntopic) with a congener?

There is at least one report of a syntopic occurence of A. scitulus and one of the other two species (which were not distinguished than) in the Argentinan Uruguay drainage: Körber, S. & R. Stawikowski (1999): "'Cichlasoma' sp. 'Palmar' = 'Cichlasoma' sp. 'Quarai'" (DCG-Informationen 30, no. 7).

In general, I think (or at least hope) that there could be a sound middle course between splitting and lumping. Certainly a single diagnostic feature may be sufficient to distinguish a species (although it is certainly better to have at least two independent characters), howewer, the difficulty is to decide if the character in question is really diagnostic for the species or only for the available sample of specimens. An example: The Lake Malawi cichlid Nimbochromis linni is distinguished from N. polystigma only by its peculiar mouth and jaw morphology. In all other respects, the two species are identical. Nevertheless, the validity of N. linnii is unquestioned. The status of N. maculimanus, on the other hand, rested on the higher number of jaw teeth. When a greater variation of of this feature in N. polystigma was discovered, the two taxa had to be synonymized.

[Paulo José Alves]

Hi

This a basic question that plagues fish breeders with constant name changes and with "new" species that would merit the rank of subespecies at best. Of course taxonomy is made by human beings and "finding" a new species is something that brings something to the taxonomist that nothing less does. The matter is reaching a ridiculous point, the proliferation of Australoherus species is just an example, there are many other genus bred by aquarium lovers that are growing in numbers of species in a manner without any justification than an obvious desire to take the slightest pretext to describe something remotely different as a new species. Some describers of new species seem to have a machine gun in their hands when it reports to this matter, the velocity and quantity of new designations pertaining to look a like species is staggering.
At the actual stage of cientific knowledge in the area of description of species there is nothing that allows anyone to say with absolute certainty that this species is or is not a valid species. In the end it is a matter of opinion. I think that only when the knowledge of this matter takes a big leap with a diferent perspective based on facts that we are not aware today then things will be clearer. For the time being if someone says that this a new species even if it is the spitting image or near so of something else nobody can really have the authority or the certainty to say that it is not. We just have for now we just the comon sense to see some obvious similarities and think that there is something wrong even if we are not ichthiologists.

All The Best
Paulo José

[Darrell Ullisch]

Having been involved with Cyprinodonts for much of my time in the hobby, I've always tried to follow more of a middle of the road belief in species level taxonomy. Many of the taxonomists working with Killifish tended towards lumping, while livebearer students seemed to like splitting. I tend to lean slightly toward lumping, probably due to my association with a lot of old school taxonomists such as Dr. Jim Thomerson and Dr. Stan Weitzman. However, I have also followed the DNA work of folks like Glen Collier and Tomas Hrbek (he started with New World Killifish) since the late 1980s. I see the DNA data as more useful for genus classification than for species. The problem with using it for the latter is that, in the end, an individual has to decide where to draw the line at species separation, and minor differences can easily be misconstrued and overweighted.

Bas noted differences in behavior between 'species' of Australoheros, citing them as reason to believe in different species. While gross differences in behavior (mouthbrooding vs. standard substrate) might be useful, simply taking fry toward the surface or the bottom can be dependent on the environment, and really does not qualify (in my mind, at least) as a trait for separating species. This is especially true of Cichlids, a group that is well known for behavioral and even physiological elasticity. The fact that a behavior persists in a specific line in the hobby would have to be tested to make sure it's not learned/imprinted behavior.

[Bas Pels]

Bas noted differences in behavior between 'species' of Australoheros, citing them as reason to believe in different species. While gross differences in behavior (mouthbrooding vs. standard substrate) might be useful, simply taking fry toward the surface or the bottom can be dependent on the environment, and really does not qualify (in my mind, at least) as a trait for separating species. This is especially true of Cichlids, a group that is well known for behavioral and even physiological elasticity. The fact that a behavior persists in a specific line in the hobby would have to be tested to make sure it's not learned/imprinted behavior.

basically, I do agree with you - cichlids are, indeed, well known for their adapatbility

However, the fish I referred to are all wild-caught and kept under quite similar circumstances: a similar tank (112 * 92 cm footprint) with 5 cm water, standing outdoors next to each other, and both without any other species

And the behaviour has persisted for over 4 years now.

Australoheros scitulum from the Rio Santa Maria, near Paso Pache, go to the bottom, while Australoheros sp local (collected near Valentinas, in the far west of the region Treinta y Tres go to the surface just as A sp red cerbail (I don't have their collection locality) do.

However, I started with this observation

I once asked precisely this question to Felipe Cantera - the expert on Uruguayan fish. He answered yes, but did not name any place

and, obviously, this is also part of what drew me to the conclusion that Uruguay has more than 1 species of Australoheros

But obviously, their ancesters were adapting themselves to their habitat -and whether this specific adaptation is easy or not, that is something I can't answer, obviously

[cichla]

Dear Willem, dear all,
Splitter vs lumper:
A friend of mine like to say: „I am neither a splitter nor a lumper, I know how to do it right“

A drastically increased number of descriptions of new species is observed worldwide and in almost all systematic groups of living nature. The rapid accumulation of scientific names which is forced by processes that are not based on the classic “discovery” of new forms, but on 'artificial reasons' (e.g. splitting) is labelled as “taxonomical inflation”. A possible way to detect 'taxonomic inflation' is to calculate the relation between species richness (number of species taxa) and the functional diversity. Theory (in short): If the number of species increase than the functional diversity should increase too. The figure (see below) shows that two regions possess a higher number of species taxa than it is explained by the functional diversity. These hydro-geographical areas are: Rio Uruguay (mainly forced by the number of species of genus Crenicichla) and lower Atlantic Coast (mainly forced by the number of specie of genus Australoheros). This might be an indication that there is something what someone may recognize as ''splitter at work''.

Reproductive behaviour: Well, I agree with Darrell that there is a kind of 'functional plasticity' and that the behaviour also depends on the environmental conditions. However, I think the behaviour may be also an indication for phylogenetic relationship and/or taxonomic separateness. Members of the genus Mesonauta (for example) take their fry near to the surface. This behaviour is surely an diagnostic character state for the genus. This is why I think that it is not unlikely that there are species of Australoheros which are separated by different reproductive behaviour (as suggested by Bas) or by using different micro-habitats.

Australoheros: There are at least two different species groups in Australoheros... viz. the facetus- and the forquilha-group . Both are well separated by morphological and molecular characters. An analysis of phenetic characteristics of the species of Australoheros shows that within the facetus-group both A. scitulus and A. facetus are the most distinguished ones.

Greetings, Ingo

[Willem Heijns]

In the meantime my question on the syntopic Australoheros species has been answered by Rico as well as by Felipe Cantera. Thanks guys. Now we can concentrate on the title of this topic.

I must say your diagram is intriguing Ingo. It triggered me to reread your articles in DCG Info and Makropoda. It is plain to see that there's a correlation between diversity and number of species. My guess would be that it is a positive correlation, so I don't really understand the diagram, especially its upper limits (confidence level). This may be caused by the fact that it is not really clear to me what you mean by functional diversity (Taxonomic Diversity Index in your original publication). Could you elaborate on this?

On a side note: I'd be interested in a PDF of Riehl 1991 and Sites & Marshall 2004. Any chance?

[cichla]

Dear Willem, dear all,

yes, the index used is actually called 'Taxonomic Distinctness Index'. It measured the ''taxonomic diversity'' and not right away (what I call here) the ''functional diversity''. However, (smart enough) the index was calculated by taxonomical characters which based on functional traits. This is why, I label it here as the ''functional diversity''. It is – if you like - a kind of shortcoming for the discussed case. Nevertheless I am still convinced that this statistic (summarized in the figure above) is a good start to detect ''taxonomic inflation'' (or as it called here ''splitters at work).

Yes, Willem, I agree with you. There is (should be; if the hypothesis is correct) a positive correlation between ''functional diversity'' and the number of recognized species. The statistic method used is, however (fortunately) a bit more sophisticated than just to reproduce a linear correlation line. The upper limit is there to ''detect'' taxonomic lumper (to keep the terms of this topic). Currently we are not in danger to see such cases (because it is en vogue to describe every single variation as new species), but to give reader an example here: it might be that different species are treated just as ecomorphs or that the morphological differences are treated as variation within a sole genus instead of recognizing a new genus. In such cases a hydro-geographical area would place above the upper ''confidence limit''.

Anyway, I am working on a static analysis which include functional, evolutionary traits. This paper will appear in about six month. However, first results are showing that it differs from the here depicted one only slightly.

Greetings, Ingo

PS: Willem, you wote that Felipe Cantera answered your question too. But I can not find a post by him here. Do you like to share this information with the forum?

[Willem Heijns]

Thanks for the papers, Ingo. I hope your beer is/was cold enough.

I'm still puzzled by the graph. I understand that if splitting puts a region below the limit (too many species than would be expected from the diversity index), lumping would put a region above the limit, following the same reasoning. But how is the taxonomic distinctness index defined to result in the graph you presented? What does the mean mean?

As for Felipe's reply: he gave it to me in an e-mail, but there's no secret here. His statement was that he saw more than one Australoheros species together in the Río Uruguay, the Río Cuareim and the Río Negro. Strange enough on his map at http://www.aqvaterra.com only the Río Cuareim has different species. It does not show any species in the Río Uruguay proper and only one in the Río Negro.

[Darrell Ullisch]

Nothing personal, Bas, but unless you tried to separate the fish from the behavior, that history is purely anecdotal. I would expect wild fish to continue any learned behavior, and their young would also continue the behavior with which they were imprinted. How many different wild lines of each species did you observe? Did you correlate observations with others breeding the same species?

I believe that some of the fry care of various species is learned, and imprinted onto the fry by the parents' care. Also anecdotally, I've pbserved and theorized that it is one of the reasons that domestic angels often have a hard time caring for their own young when they themselves were raised artificially. Again, we are talking about the "intelligence" factor of these fish, and their adaptability. I've also seen surface/bottom preference displayed in newborn livebearer fry, which obviously are not learned behaviors, so yes, it could be genetic.

Did you ever pull a spawn of eggs and hatch them artificially? If you did, THEN how did the grown fish from that spawn behave? Without that control data, theories based on those observations are little more than conjecture. I'm not saying those differences aren't part of the species' profile, I'm saying it needs to be tested before that can be declared as fact.

I understand that behavioral differences can and do separate species within a given environment. It is worth note, however, that those species you've spawned were already identifiable as distinct before the behavioral observations, and not from the same systems. Connecting the behavior to the species is a theory based on observation, but it still needs to be tested to become fact. These days there are a lot of theories being accepted as fact without properly testing them first.

[cichla]

Thank you Willem for sharing the information about Felipe's reply.

Well, I hope the discussion about the particular statistic is not only of some interest for the two of us, but for other readers too.
The confidence limits (95%) are calculated by a randomization test and the mean over these simulated resamplings. This procedure has the advantage that the confidence limits (and the mean) are based only on the data for the particular area and the focussed taxonomic group (here the South-American Cichlidae), instead of being arbitrarily assigned. In simple words: the mean express the average of 'how many' hierarchical (taxonomic) levels are found in a particular hydro-geographic area.

[Darrell Ullisch]

Ingo, sorry if we were interrupting your discussion.

When calculating these diversity numbers, is this limited to the single genus, or does it incorporate and compare other genera? Obviously there are a lot of Gymnogeophagus populations coming out of the same area in the recent past, but how many of those are actually new species, or more likely to simply be variant populations? And how would this influence the probabilities for Australoheros?

[Bas Pels]

@ Darrell

While discussing a topic, I think one should not take arguments personally. So no offence intended and none taken

Still, you state breeding behaviour is learned from the parents. This might be the result of many an experiment, but to me, I would need some more support before I can go along with your statements. After all, fry are cared for for a month, or so, and not more. For Australoheros it might take even several years before they start breeding (they grow slowly and as they live a long time, when 5 year olds are around, 3 year olds will not breed), and no parent is around to teach them anyting by then.

I think imprinting is what happens, and impinting relates to instinctive behaviour - not much individuality there.

Obviously, my observatioons are anecdotical, but I get the feeling you apply a theory which is not generally accepted (that beeding behaviour is more or less a matter of choise) in dealing with the observations.

As I wrote, I don't know how easy breeding behaviour can change/adapt. But if it is hard to adapt, then the observations might be arguments.

@ artificial breeding, I will not do that, as I condider artificial breeding immoral. On a sidenote, Australoheros grow very slowly, and therefore it would take 2 years at least before one could start breeding them.

[Willem Heijns]

Can we please stay on topic here?

I'm not sure I understand what you are saying Ingo. Could you try and explain the meaning of the Y-axis? Is there a formula to calculate the "diversity index"?

[cichla]

When calculating these diversity numbers, is this limited to the single genus, or does it incorporate and compare other genera?

The diversity index consider all genera. It is based on presence/absence data. I just mention these two genera to give an idea of what might be the reason for the position below of the lower confidence limit of some hydro-geographic areas.

Obviously there are a lot of Gymnogeophagus populations coming out of the same area in the recent past, but how many of those are actually new species, or more likely to simply be variant populations?

If the number of Gymnogeophagus species taxa increase in a particular area (say from rio Uruguay region) only, then the 'outlying position' of this region (e.g. rio Uruguay) would be more apparent.

Could you try and explain the meaning of the Y-axis? Is there a formula to calculate the "diversity index"?

Well, first of all allow me to correct myself ... the mean on the y-axis is not the average of 'how many' hierarchical levels are found in an area, but it is the overall average of taxonomic distinctness (it its not always that easy to explain complex things ''in simple words'' )

The y-axis explains the taxonomic distinctness. And yes there is a formula to calculate this "diversity index". However, I think it is a bit to technical to print it here (a lot of mathematical characters) and you need to know the procedure for the resampling test. So, take a look on google books and search for 'Measuring biological diversity' by Magurran, pages: 121-128.

There is a huge number of indices to measure the biodiversity. The 'taxonomic distinctness index' is a sophisticated method to measure it (here the diversity of South-American Cichlidae). As a side effect it might be possible to detect areas where ''splitter or lumper are at work''. But we need to be aware, that it is just a statistic value, which is based on the data used (and it may happen that the data used are not appropriate for the procedure). For sure the measurement (as depicted in the figure above) is just an indication that there might be ''something''. To understand why a particular hydro-geographic region is placed outside of the confidence limits needs always more data and research.

So, to stay on the topic ... I think there are manifold reasons why are so many new species taxa are described nowadays. Just to mention few: typological thinking, discoveries, desire to name something, commerce ...

[Willem Heijns]

So, if i understand correctly, the taxonomic distinctness measures the hierarchy of all studied taxa where, given a number of species, the higher taxa (genera, families, etc) are decisive. If 10 species are all assigned to one genus the distinctness is less than it they were assigned to two, three or more (maybe even ten) different genera. Am I correct here?
One thing that still puzzles me is the presence/absence information. How does that come into play?

Sites & Marshall (2004) was a good read too. They present 12 different empirical methods of delimiting species. I particularly like the genetic distance and the Templeton test. But then, maybe that is because I understand those two slightly better than the others
And in the end even Sites & Marshall state that: "virtually all methods require researchers to make qualitative judgments". Where have I seen that before?

[cichla]

So, if i understand correctly, the taxonomic distinctness measures the hierarchy of all studied taxa where, given a number of species, the higher taxa (genera, families, etc) are decisive. If 10 species are all assigned to one genus the distinctness is less than it they were assigned to two, three or more (maybe even ten) different genera. Am I correct here?

Yes, more or less.

One thing that still puzzles me is the presence/absence information. How does that come into play?

A data matrix with 1 = species present and 0 = species absent is needed to calculate this kind of diversity index.

Sites & Marshall (2004) was a good read too. They present 12 different empirical methods of delimiting species. I particularly like the genetic distance and the Templeton test. But then, maybe that is because I understand those two slightly better than the others

Yes, the paper by Sites & Marshall is a good review of the possible methods how to do species delimitation. To keep the topic... I think the use and comparison of 'character based' and 'tree based' species delimitation as described by Rican et al. in their Australoheros papers is at least a bit more sophisticated than the 'classic' approach.

[cichla]

There is an increasing number of new species taxa in South-American Cichlidae (see figure 1). However, a comparison of the taxonomic exploration of South-American Cichlids with other fish families (see figure 2) shows that the rates of descriptions per year are similar. Interesting is that the rocketed number of species taxa per year is correlated with an increasing number of authors (indicated by the size of the quadrates in fig 2). One might say that the naming of new species is just proportional to the number of people at work in the field.