![Dr. Patricia Ornelas-García seated.](https://thenode.biologists.com/wp-content/uploads/2024/03/865175-1-500x332.jpg)
Lately, Brent Foster and I printed an article on non-model organism (NMO) analysis, the place we interviewed a number of researchers working throughout the globe on the challenges, rewards, and the actual questions they examine whereas engaged on (comparatively) little-studied organisms. Though we aimed to supply a chook’s-eye view of NMO analysis in a pot pourri-style article, we discovered that they every of our interviewees had many fascinating issues to say that we thought it was a disgrace to not share with a wider viewers. Because of this, we determined to publish the total interviews as nicely, which we can be doing over the subsequent a number of weeks.
This interview is with Dr. Claudia Patricia Ornelas-García, investigator on the Nationwide Autonomous College of Mexico (Universidad Nacional Autónoma de México, UNAM), who works on the Mexican cavefish (Astyanax mexicanus) and different freshwater fish, taking a look at their systematics and speciation. The total transcript of the interview is under:
Are you able to summarise your work in just a few sentences?
I work primarily with the systematics and speciation mechanisms in freshwater fish species. Since my PhD, I’ve labored with Astyanax, a really fascinating genus as a result of it’s distributed from Argentina [all the way] to the Mexico-US border. Throughout my PhD we reconstructed the evolutionary historical past of the genus in a selected area recognized as Mesoamerica. However generally phrases, what we have been doing in that venture was to analyse 4 molecular markers, three mitochondrial and one nuclear, to get well the systematics of the group. Throughout the growth of the venture, I used to be very within the lacustrine methods of Central American Lakes in Nicaragua and Mexico. In these lacustrine methods there are a pair of morpho-species that have been sympatric and we have been very within the correlation between the morphology and the genetic differentiation, as a result of after we have been doing this systematic group, they at the very least appeared to be sharing some haplotypes within the mitochondria. We continued engaged on the ecological divergence, ecomorphological divergence, and a few morphometrics on this pair of species, and extra just lately with RadSeq Knowledge.
Years later, after I got here to Mexico and established my very own lab, we began working with cavefish. Truly, after I began, my first job was in Querétaro, very near the caves in San Luis Potosí. I began engaged on the caves and I fell in love instantly as a result of the atmosphere is so superb. It’s very specific. And the system can be very fascinating. As you understand, there are a number of genomic assets out there these days. At first, after I began working with this group, there have been perhaps 10 or 11 cave populations already analysed from [a] phylogenetic perspective, however not from an evolutionary or developmental perspective. So to start with, I simply wished to incorporate as many caves as we might, so we might take a look at these hypotheses of what number of instances the fish has been capable of adapt to the caves. There have been a number of hypotheses, a few of them say that it occurred solely as soon as and there was a number of drift. The opposite says that there’s two unbiased lineages. I’m in that group that might counsel that there are two unbiased lineages that got here to the caves and tailored to them. Truly, in our most up-to-date paper, by a grasp’s scholar of mine, we assess this query, utilizing not solely the entire genomes which might be already out there, but in addition together with some caves that have been by no means analysed earlier than. So we now have a really, very exhaustive sampling. And in our outcomes, we now have at the very least three unbiased colonisation occasions of the caves, which for some is loopy, it’s not attainable. However from our standpoint, we’re actually counting on exhaustive sampling of the caves, and that’s what we’re suggesting.
These days, we’re beginning to transfer to some developmental analyses, as a result of we have been capable of seize some fish from the caves, and we’re reproducing them right here within the lab. To this point, we now have been capable of reproduce 5 totally different populations, totally different from the widespread ones like Pachón or Tinaja. We’re reproducing Escondido, Arroyo, Tigre, Chica, and Pichijumo. Sabinos is widespread, nevertheless it’s much less widespread than others. To this point, we try to characterise some developmental options.
Certainly one of my college students is engaged on the Rad-seq, and we’re beginning to work with RNA-seq, and we’re a making an attempt to check the genetic convergences throughout totally different cavefish lineages, notably together with some much less studied populations similar to Escondido, which is from the [second] linage within the Guatemala area. We try to check the variations throughout early growth as a result of we now have realised that they’ve a really specific mutant in some visible pigments, so we try to match that variation with the phenotype. We’re additionally exploring the phenotypic convergence with different cavefish in Mexico, like Prietella phreatophila, a catfish within the northern a part of Mexico, and likewise with different households of cavefishes from the southern a part of Mexico. We try to research them for convergences in phenotype, notably in some processes associated with asymmetry that has been reported in Astyanax and in P. phreatophila, and we try to take a look at if it’s constant throughout cavefish residing in Mexico or solely in these two cavefish.
What sorts of asymmetry is that this?
Astyanax could be very fascinating as a result of in Pachón there was described a directional asymmetry, in addition to in Ictalurids [such as Prietella], and truly it’s in the identical facet, left flip of the pinnacle. Significantly in a cave referred to as Chica there may be one very nicely characterised Astyanax hybrid inhabitants (between the floor [fish] and the cavefish). In that inhabitants there may be fluctuation asymmetry, [toward the] left or proper, [similar to] chiclids, [that have] fluctuating asymmetry within the mouth of a scales-eating species. It’s fascinating that whenever you analyse it within the hybrid inhabitants, the asymmetry is totally different compared to the opposite caves.
I perceive that there are much more assets so that you can research most of these species now. However clearly, it’s typically a bunch of species that isn’t studied by an unlimited variety of individuals around the globe. Are there specific challenges related to that?
Yeah, I believe one of many challenges is that there are a really restricted variety of individuals working with these [species]. And in a manner, it’s fascinating, as a result of you will see that one thing new for positive. However [from another point of view], in analysis teams [studying established organisms] it’s simpler.
We have been making an attempt to characterise the microbiome of the fish, we now have a paper on that. And it was a little bit difficult, as a result of there was not a number of info already printed on protocols or deal with the info. Or after we try to arrange [experiments], for instance, for physiology or for one more type of ecological evaluation, it’s generally troublesome. However in a manner, I believe it’s very, very fascinating. Throughout my Bachelor’s, I used to be working with mice, the everyday mannequin within the lab, and by some means I believe that the variety of questions generally will be very restricted as a result of there’s already so many research in these animals, that it’s troublesome to give you one thing new.
You probably did contact upon this whenever you’re describing your work, however was there a selected factor that satisfied you that these fish are what you need to work on?
I believe the principle cause was a as a result of I’ve all the time been keen on mechanisms driving the evolution of morphology. Once I began engaged on the lacustrine varieties, it was like “Why have they got these totally different tooth, or totally different heads, or totally different physique shapes?” and within the caves it’s dramatic, the change is spectacular. Are these vital morphological modifications? Once I began investigating the atmosphere, it’s fascinating that they will survive below these situations. That was one of many causes.
One other vital factor to focus on in Astyanax is that we now have the Annual Assembly. It is rather fascinating as a result of there are a number of younger individuals, along with senior researchers, and the neighborhood could be very open. As a result of it’s not a mannequin organism, [everyone is] actually [willing] to speak concerning the system in a really open manner, and embrace new researchers. Significantly for me, after I was ending my PhD, this was a really dramatic level, as a result of I noticed a possible within the system that I will be included. And I’ve a number of issues in my favour, I’m from Mexico, I can work within the discipline, I can do a number of in situ experiments. Even these days, there are only a few Mexicans working with Astyanax. It simply occurred that there have been a number of issues that made me realise that there was a number of potential within the [Astyanax] system for me.
Would you say there’s a selected query in your discipline that you simply discover actually fascinating? Or a discovering or a outcome that you simply actually weren’t anticipating?
Yeah, as a scientific biologist, I’ve a really, crucial query for me, which is what number of species [the cavefish are]. This is a vital query from two totally different views. One is conservation. The opposite is from an evolutionary standpoint, as a result of for positive, they will hybridise, even lineages between the 2 branches can hybridise. So in a manner, it’s very troublesome to check for the organic idea of a species. Typically it’s troublesome even for the developmental biologists, as a result of they’re actually making an attempt to grasp the hyperlink between the gene and the morphology. We try to grasp the mechanisms giving rise to this sort of methods, and the way straightforward it’s to speciate on this context. So the implicit query relating to these ecomorphs or ecotypes is, are they totally different species? And the way vital is that this for the evolutionary historical past of the mannequin?
So in a manner, it was very fascinating for me firstly, as a result of after I began going to those conferences on Astyanax, it was very straightforward for me to all the time take into consideration the systematics, concerning the phylogeny. And generally [other groups] have been decoding some variation within the morphology via native adaptation. However really, it’s associated to the [evolutionary] historical past of the system, just like the variety of vertebrae, or varied traits, really, they have been shared by ancestry, not by native adaptation. So I believe that’s very, crucial in these sorts of research, making an attempt to hyperlink between the genetics and the morphology. That’s one of many causes I need to have an excellent notion of what number of instances this [cave dwelling] mannequin has developed, as a result of if it [evolved] solely as soon as, the interpretation of repeated evolution, or no matter we’re asking, is totally different. The opposite query that could be very fascinating for me is how their morphology will be so divergent, even below gene circulate circumstances. How is that this attainable with none limitations [between the putative species]? That’s the explanation we work with Astyanax.
How does knowledge evaluation and sharing between labs that use Astyanax and associated species differ, in your opinion, in comparison with research that use extra established mannequin organisms? You mentioned, it’s a reasonably open neighborhood. However you understand, are there any main variations?
I have to admit that I don’t know if I’ve sufficient expertise on this query. All of my expertise is with Astyanax. Although throughout my Bachelor’s I used to be working with mice, I’m not acquainted with different teams. Within the lab the place I used to be working, they have been very particular within the questions that they have been [asking], and it was not very straightforward to share info with different labs.
For my part, one of many issues that the Astyanax mannequin has is that [researchers working on it] are very open. For instance, after we have been making an attempt to breed a fish, we have been acquiring a number of info [from other groups].
From what I learn about Astyanax, that there are labs that work on it within the context of coronary heart regeneration, as a result of some have a non-regenerative coronary heart, in distinction to the regenerative zebrafish coronary heart. How massive is the neighborhood that works on the extra phylogenetic side of the species in comparison with these engaged on developmental or regenerative questions and is there any crosstalk?
These days, lots of people try to [investigate] this mannequin [from] the eco-evo-devo perspective. They’ve realised [that it is important to distinguish between the different Astyanax lineages], as a result of a number of the outcomes that they get are associated with the lineage, and never with notably with the atmosphere. In these phrases, there’s a rising variety of labs desirous to work within the discipline, know extra concerning the ecology in situ, study extra concerning the behaviour, the physiological variations. Some are is making an attempt to [replicate] experiments within the discipline, examine if the identical factor occurs within the lab versus in pure situations. For my part, the species offers a really specific alternative, as a result of it’s not like in different places the place it’s very troublesome to get entry to the cave methods within the within the discipline. So these days, though laws are growing, they’re attainable. [Researchers] can [request] permits and get them in a yr, which an inexpensive time. So it’s extra a query of what the pursuits of the researchers are, as a result of they will actually put their questions in numerous contexts, and navigate between eco, evo, and devo.
Is there anything that you simply wish to add?
The issue with non-model organisms is the conservation scenario. For positive, no person will catch Mus musculus from the sector, they have already got so many reproductive strains in captivity that they don’t must. The non-model organisms are within the reverse scenario. Many of the labs [working on them] need to have extra wild strains, extra associated with what is actually occurring within the discipline. And in case you have 200 labs working [on cavefish], think about the affect that we are able to have on the pure inhabitants. These cavefish should not actually massive [populations]. We printed, simply firstly of 2023, a paper [on] measurement estimation of the fish inhabitants within the caves, and it’s perhaps round 1000 fish, or [a few thousands] of fish. It’s probably not that enormous [a] quantity. And picture, within the final 10 years, roughly, there have been round 200 fish extracted from the caves. So when you think about a system that has to get well from 20% of the inhabitants being misplaced solely due to scientific sampling, it’s a problematic scenario.
Once you attempt to make researchers conscious of the scenario, [they] actually consider that the principle extinction drivers of this sort of inhabitants should not associated with our sampling. Most of us actually consider that it’s all world warming, or native individuals extracting water for drink. I’m very shocked, as a result of usually you need to battle this sort of angle exterior the scientific [world]. So in my place, I’m making an attempt to make individuals conscious of this, nevertheless it’s not straightforward. However not one of the above is fake. International warming, and folks extracting water for drink, are a part of the issue. Thus, it’s vital to be a part of the answer, and perhaps we must always take into account what we are able to do to resolve the conservation scenario.
A few of the most iconic populations, like Pachón, you could find hundreds of papers printed on it. And it’s in a little bit little bit of a vital conservation scenario proper now. Many labs have been capable of reproduce it. And most [subpopulations] will be simply [obtained] from [other] labs. However even these days, to keep away from inbreeding, some labs might require to gather wild fish. The Guatemala area has conservation points, as a result of though they don’t seem to be easily-accessible caves, most populations are very small, and never well-connected between them, due to the phreatic stage of the water, which may result in extinction extra resulting from their demography than to different causes. So its conservation scenario could be very totally different. However in a manner, we now have the identical scenario in different places.
And it’s not solely in Astyanax, it might occur in different non-model organisms too. For instance, Axolotl can be an incredible mannequin system. If 50 labs on the planet begin working with one specific inhabitants, there can actually be an affect within the native inhabitants. That’s the reason I believe we must be extra conscious of the affect and do our greatest to ensure the prevalence of this mannequin for future generations. [Because] what makes these organisms superb additionally makes them weak, in a manner.