With the widespread using of barcoding or metabacording and genomic sequencing, many cryptic species, which morphological similar butgenetic difference largly, were frequently reported in many groups and ecosystems. Especially for Tropical insect.
It seems cryptic species should be very common, In a recent work, Janzen et al.(2017 PNAS) said maybe 10-20% traditional morphologically single species may turn out to be two or more. If that is ture. It will definitely increase the absolute species diversity. Meanwhile, cryptic species may be a common phase in speciation.
What other means of cryptic species to speciation process, food web, plant-animal network and ecological serves? Whether crypitic species will changge some parts of our understanding fundermentaly on above concepts?
Furthermore, what kind of groups have a relatively higher ratio of cryptic species, whether some different pattern between generalist species or specialist species in ecology network?
I study the coevolution between fig tree and fig wasp, in which many cryptic fig wasps were reported. That is also the pattern in many other systems. So I interest How cryptic species arose and what it means in ecology and evolution.
Thanks in advance for anyone suggestions and comments!
Gang
Hi Gang. This is a very interesting topic. The great difficulty is the definition of what is a species. There is a nice paper by de Queiroz in Systematic Biology summarizing the current species concepts and the difficulties dealing with them. https://academic.oup.com/sysbio/article/56/6/879/1653163/Species-Concepts-and-Species-Delimitation. I guess the best thing you can do is to be very clear about what criteria you are using in order to define species and cryptic species.
Cryptic species are often viewed as cryptic as they detect conspecifics through non visual cues; therefore when it comes to classification we often miss those traits. In bats these partially come down to acoustics, but in other taxa may be chemical (hormones, or olfactory).
I think we have to be very careful with using cryptic species concepts, and should use other measures (divergence time, niche overlap) instead as so many species we view as cryptic may be in large part be because of how we typically delineate and identify species-using traits which may be largely insignificant to them, rather than those that are either evolutionarily significant or form pre-mating barriers
Hi Andreas and Alice, Thanks very much for your interesting and nice comments.
Yes. as there are many species concepts, choosing some stabel criteria or one concept before any discussion related to species and speciation is important.
For cryptic species, in most time, people may use morphological specie concept combing with (Phylogenetic) lineage species concept. As Alice said, cryptic species based on morphological similarity and genetic different may suggested the importance of other no-morphological traits on species identification, speciation process and/or ecological function, such as acoustics, chemical cues and behaviours traits, which require more attention.
If we accept the commen pattern of many genetic lineages under one morphological type (taxon), what kind of challenge to traditional knowledge of ecological servers function, species interaction/network and speciation process? Those may be more complicated and important. Yes?
Hello Gang. Your question is very intersting and I also came across similar questions. I work with Lasioglossum (Dialictus) spp. that are 3 mm size and morphological extremely similar. However with barcode (COI) and microsat (nuclear DNA) they appear as something very different. They are many points here. First, as the bee is too small and there is almost nobody interested to study them, the use of "traditional" tools and keys give to the conclusion that they were morphological similar, but recently a researcher in Canada, found many microscopic morphological characteristics that help to differentiate. I am sure that something like that could be the case for your fig wasps.
In the last years, there are a new tools or aproach that is used for this taxa that are difficult to differentiate morphologically; one is the integrative taxonomy; that is the use of many sources of information together and the use of new and alternative concept of species. I find it very robust because you base the identification of a species in the confirmation of different source (nuclear, mitochondrial DNA, behaviour, ecology, morphology) and therefore when there is something different you could have an idea of the posible evolutionary process. Here is one paper about integrative taxonomy: http://www.annualreviews.org/doi/pdf/10.1146/annurev-ento-112408-085432
other tool, is the development of species delimitation statistical methods for analysis of DNA data, as ABGD, GMYC, bPTP. But I imagine that since you talk about barcode you know them.
Now with respect to the question of which challenge to traditional knowledge on network and speciation process bring the cryptic species and if they are complicate and important. I think the answer is yes. In particular for our species that are key pollinators. Different species with the same morphology means in some form that there are some force of the environment choosing the morphology. In my case we consider, that the cryptic lasioglossum have a tendency to be generalist but some of them have some specialization in a different niche.
In the case of Bombus spp. for example, there are species of european Bombus that have a very similar patter of colour and that is because there are a pollinator and the species of bombus that parasite the same (in this case is more an opportunistic relationship). But there are some papers that discuss that cryptic species in sympatry can be due to specialization of the niche in the same type or source. Here is one paper on Bombus again.
http://onlinelibrary.wiley.com/doi/10.1002/ece3.1965/abstract
I think that your case is very interesting because it was always consider that fig tree and fig wasp were a clear and very strong example of coevolution. However, other species as the bee rediviva and the plant Diascia, since to show that are not really coevolution but maybe some kind of shift between pollinator species and populations. So, if happens that exist many cryptic species of fig was, this could help to understand if really coevolution exist or again is another kind of specialization in different variables of the niche with shifts in the species and populations. I will be very interested to discuss with you more of your data over this small pollinator.
It is depends on the species. But in general its one of two or more morphologically indistinguishable biological groups that are incapable of interbreeding
Actually, this question may miss the main point! Taxonomists used traditionally morphological diagnostic characters to determine species but it is obvious that speciation and establishment of morphological diagnostic characteristics are not correlated directly with some notable exceptions. In turn, morphological diagnostic characters have usually little correlation with ecological characteristics of species. In summary, we need to accept that taxonomy based on morphological diagnostic characters is very limited in its value for evolution and ecology. Thus, the lack of detecting inconsistencies between the number of species recognized using morphological diagnostic characters and the true number of species is a major source of error that is often ignored in biodiversity research.
Hi Patricia,Salwan and Harald,
Thanks so much for your informative answer.
I agree with you that, in most cases, cryptic species suggested the limitation of morphological diagnostic characters on species delimitation. Meanwhile, it also suggest the role of other factor, such as behaviour, chemical, habitat preference and other ecological factors on species delimitation, which should be pay more attention for further classification, and will also supply more directly view on speciation process and selection driver. That may the be one of the most important roles of the concept of cryptic species to our knowledge development.
As general niche theory of species coexisting, there are usually some niche divergence between (cryptic) species. That may be related or non-related to morphological traits. Just as Bombus case Patricia supplied.
In my study system, fig wasp, untill now, that seems very common to find the so-called "cryptic species", which in most cases may because limiting researching work on taxonomy of this very tiny size wasp group(>1-2mm). Another reason may relate to the evolutionary convergence as all fig wasp have to adaptive to live within fig inflorescence (we call syconia or just figs).
Yes,，the detection of cryptic species in one fig species did challenge the classical view of the obligate pollination or parasite relationship between fig and fig wasp. Multi-pollinator in one fig species enhance the chance of pollinator sharing among sympatric fig species.
One of my work also found that a lower level of pollinator sharing is common among closely related sympatric fig species, specific floral volatiles of each fig species could attract more than one pollinator species, some adult hybrid trees were also found, pleas see this link if you interesting (https://www.researchgate.net/publication/301233967_Pollinator_sharing_and_gene_flow_among_closely_related_sympatric_dioecious_fig_taxa).
There is also some report on functional divergence between cryptic fig wasps, such as one is legal pollinator. Another cryptic species has lost the pollination function and behaviors. In other cases, cryptic species may host different sympatric fig species or the same fig species allopatrically. I think the more we study, the more difference detection among those cryptic species.
Thanks again for all your wonderful answer and wonderful paper suggested.
Gang
Article Pollinator sharing and gene flow among closely related sympa...
Of course, traditionally taxonomy is limited by the assumption of 100% barriers excluding the possibility of gene flow among species. Of course, this assumption is incorrect. However, it is not always easy to show gene flow among related species because of several factors, most famously incomplete lineage sorting. Technical issues are also important to be considered especially in the context of markers like micro-satellites. In short, we need to move forward to a taxonomy that is based on realistic evolutionary scenarios. Of course, it is expected that fig-wasps are not as exclusive than some early hypotheses assumed. Thus, no surprised if you find gene flow - because this should be assumed as the null-model. Instead we need to give attention to quantification of these events although this is a bit of a challenge.
Hi Harald.
You mentioned two points that interesting me very much.
The first is "Taxonomy based on realistic evolutionary scenarios". That does be very interesting idea!
Maybe we can call it as Ecolutionary Taxonomy for short. Can you go on supplying some definition sketch and description on how to do taxonomy under this concept? Thought that should be a very difficult thing as the species concept is still a problem until now. But I will be very happy to learn more about this idea.
Second, How to quantify the inter-taxa gene flow in many organism groups and evaluate the effect of inter-taxa gene flow to taxonomy, species delimitation, speciation process, species adaptation and coexisting. Many people had did some hybrid and introgression detection work in each of their research group(usually in species complex or within genus level),while very few case on local community scale or in larger taxonomy level, such as family,order level or in plant or animal group level, may limited with molecular marks can be used. Any other methods may avoid those problems?
Gene flow among species should be a genuine evolutionary scenarios, how to evaluate their role speciation and local diversification is a challenge.
Thanks
Dear Colleagues,
I would like to add that cryptic species often remain unnoticed despite considerable morphological differences, not to mention genetic ones. A good example of the situation of that kind can be found here: http://onlinelibrary.wiley.com/doi/10.1111/syen.12081/full. In this paper, we were able to describe a new cosmopolitan parasitoid species, Anisopteromalus quinarius, that lives in people's homes and similar habitats. However, this species remained unrecognized for many decades, partly because it was difficult to distinguish between inherited morphological traits and those imposed by the environment. Nevertheless, as soon as the presence of two reproductively isolated species under the same name "A. calandrae" was established (using chromosomal analysis in that particular case), many differences between these taxa in terms of morphology, life-history strategies, nuclear and mitochondrial DNA, etc. etc. were immediately recognized. I have recently published a corresponding review in Zhurnal Obshchei Biologii (= Journal of General Biology): http://elementy.ru/genbio/abstracts/532/Dimensions_and_borderlines_of_parasitoid_Hymenoptera_species_A_paradigm_shift. Although the review is in Russian, an English language version of the paper is going to be published in Biology Bulletin Reviews in a few months.
Best regards,
Vladimir
Kindly see the following RG links and PDF attachment.
Article Cryptic speciation associated with geographic and ecological...
Article Cryptic species as a window on diversity and conservation
I think this is a very interesting question. In the interest of clarity, I think that we should consider debating two questions when talking about cryptic species:
1. Are cryptic species 'mere' taxonomic artefacts?
2. What cryptic species mean in ecology, conservation, biogeography and evolution? (the question considered here).
1. Are cryptic species 'mere' taxonomic artefacts?
Not all of them. A problem that we encountered in a literature survey (available here Article Finding Evolutionary Processes Hidden in Cryptic Species
). Is that many cryptic species complexes are diagnosed with very few evidence. For instance, most papers using DNA provided only mitochondrial data is considered (despite its limitations), and most papers do not focus on morphology. As such, many cryptic species complexes are diagnosed poorly and the term became somehow a 'buzz word'.The other problem is that the most cited paper in the cryptic species literature ( Article Cryptic species as a window on diversity and conservation
) focuses on the "taxonomic history" of the species complex, rather than on biological phenomena. We have analysed this issue providing evidence that focusing on the taxonomic history leads to the diagnosis of cryptic species even when morphological differences occur ... or does not permit the diagnosis of cryptic species even when there are no morphological differences in the complex (Chapter Cryptic Species and Their Evolutionary Significance
). In that online book chapter we provide two cases where that occurs.Considering this, in my opinion, while many cryptic species complexes are not well diagnosed, there is still evidence that "morphologically identical or quasi-identical species" (as suggested by Article Delimitation of cryptic species drastically reduces the geog...
) occur and these should be considered cryptic species. An important aspect in this diagnosis is the time of divergence. For instance, 2 quasi-identical species that have diverged 10 millions of years ago would be considered cryptic species as one would expect more morphological divergence to have occurred. A good example of cryptic species complex is the Stygocapitella species complex which is >100 million years old (Article Deceleration of morphological evolution in a cryptic species...
), or the Cavercnamella species complex (Article Long-term stasis and short-term divergence in the phenotypes...
) or the Mastigias species complex (Article Three routes to crypsis: Stasis, convergence, and parallelis...
).2. What cryptic species mean in ecology, conservation, biogeography and evolution? (the question considered here).
Considering that cryptic species complexes are biological entities, the decceleration of morphological evolution is an interesting phenomena. Bickford et al, and Bernardo make a very interesting case for conservation biology suggesting we're overlooking much diversity and potentially need to conserve different areas ( Article Cryptic species as a window on diversity and conservation
;Article A critical appraisal of the meaning and diagnosability of cr...
). For biogeography, we found that the discovery of cryptic species leads to the diminuishing of species-distributions. This is important for, for instance, marine organisms which distribution is largely unknown or paradoxical (Article Marine connectivity dynamics: clarifying cosmopolitan distri...
;Article Delimitation of cryptic species drastically reduces the geog...
). Also, as part of my thesis, I have been arguing that cryptic species can impact ecology (niche partitioning theory), evolution (deceleration/acceleration of morphological evolution) and paleontology (is there a link between cryptic species stasis?)Article Incomplete lineage sorting and ancient admixture, and specia...
Article Deceleration of morphological evolution in a cryptic species...
) . I personally think that understanding the underlying factors leading to the deceleration of morphological divergence (as seen in cryptic species complexes) is a very pertinent and interesting question.PS: I provide many links to my research as this has been the main topic of my dissertation. Apologies for the shameless self promotion, but I wanted to contribute meaningfully to this debate
Hello Jose; To the extent that we are unable to recognize how many species there are in a "single" cryptic species we badly misinterpret the biology of the "taxon". As an example of how dramatic this confusion might be I take note of this citation.
Smith, MA, DM Wood, DH Janzen, W Hallwachs, PDN Hebert 2007. DNA barcodes affirm that 16 species of apparently generalist tropical parasitoid flies (Diptera: Tachinidae) are not all generalists. PNAS 104(12): 4967-4972.
What appears, on morphological grounds, to be a single generalist parasitoid turns out to be a number of host-specific parasitoids. Understanding the dynamics of a host/parasite community depends on being able to recognize the interacting participants in the system. That's a big deal. Best regards, Jim Des Lauriers.
Hi, everyone.
Every time that someone says "cryptic species" I try to understand which feature that "cryptic" means. Some colleagues already said about biochemical and behavior traces, that are some aspects that would be cryptic too. I think that the first point is to establish the "why that species is cryptic". Every signal on nature has a target organism and often we are evaluating it by our human perception and not by the perception of the target organism. I'm currently working with praying mantises, which are very known for their camouflage capacity. There is a lot of problems in their taxonomy due to a high morphology convergence and many times only internal structures or genetic analysis can separate them.
I think that is very difficult to find an ecological meaning for crypticity studying organism looking at the species level. I'm trying to understand Mantodea's importance by their functionality and importance on the community. Maybe discard "species name" and look only for the behavior, physiology, and morphology, without look for a "label" help us to better understanding the ecological meanings of an organism inside a network. Species' identification will always be important. However, nature does not work in "boxes", as we do, and some times we spend large amounts of effort trying to fit our "artificial classification" on the natural process.
Gang Wang Hi ,
Before understanding the meaning of cryptic ,we should know the what is 'SPECIES',i.e. how to define a species.
Hundreds of years, traditional morphological, behavior and new genetic technologies are applied to define the speciation.What we talk about CRYPTIC is based on the genetic distances between other similar species, namely without siginificantly morphologiccal or behavior differences.According to the phylogenetic tree, these species appears on the different branch on the BIG TREE.
See the articles, Hope it helps.
Article Cryptic Species or Inadequate Taxonomy? Implementation of 2D...
Article Hebert PDN, Penton EH, Burns JM, Janzen DH, Hallwachs W. Ten...
The key in this scenario is assessement of gene flow among specis ???
This, maybe can sketch a concept of cryptic species in the speciation process.
Hi Chen Xiao Fish,
I totally agree with your describtion. The new concepts of genetics allowing us to discuss new definition of species.
C. Linné proposed the morphological creteria and G. Mendel gave to 20 century scientists and geneticist this new classification according to the phylogenetic tree.
What do you think ?
Cryptic species could represent a substantial fraction of biodiversity. However, inconsistent definitions and taxonomic treatment of cryptic species prevent informed estimates of their contribution to biodiversity and impede our understanding of their evolutionary and ecological significance. Hopeful, the article attached underneath helped.
Best wishes
Ht. Decemson
- Badges
- Science method
- Similar topics
- Biological Science
- Histology
- Staining