Has the Etheostoma spectabile group had any new descriptions since the last edition of Peterson's Field guide? Mike Berg and I collected some Etheostoma spectabile darters from a tributary of the Wabash in Battle Ground Indiana. Are they still spectabile? Thanks!
Etheostoma spectabile group in Indiana, any new species?
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, Nov 20 2012 05:26 PM
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#5
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Posted 21 November 2012 - 01:29 PM
I haven't made a careful comparison, but the ones here in Ohio seem to have more variability in color. These Wabash ones are very consistent. Nearly identical to one another. But the reason I asked about anything in the works is because Blake said "still E. spectabile proper -- at least for now...." Also, I knew that there had been several new ones described over the last several years and I wanted to be sure I have the right name on these Wabash ones.
#6
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Posted 21 November 2012 - 04:10 PM
The Wabash populations of E. spectabile do look a bit different than those that occur in Mississippi drainages (Illinois River, etc), but then again, these differences are only apparent in nuptial males. There is also so much intraspecific variation in a single drainage that it would be hard to make a case either way.
And no, I don't know of anyone working on Wabash or Ohio drainage populations of E. spectabile. I was just merely poking fun at the current rate that species are split, especially on grounds of nuptial male apomorphies (non-history based). When folks actually start looking at a lot of these splits with molecular characters (history based), they find that a lot of these 'species' still share a lot of genes, and that is with genes that change very fast at a constant rate....
Now if the drainages have been separated for a long period of time, and these species will remain allopatric, then you have a pretty solid case, but if you're talking about drainages that were inundated by glaciers and had their drainge routes remodeled less than ~50,000 ya, then you're on shaky ground at best.
And no, I don't know of anyone working on Wabash or Ohio drainage populations of E. spectabile. I was just merely poking fun at the current rate that species are split, especially on grounds of nuptial male apomorphies (non-history based). When folks actually start looking at a lot of these splits with molecular characters (history based), they find that a lot of these 'species' still share a lot of genes, and that is with genes that change very fast at a constant rate....
Now if the drainages have been separated for a long period of time, and these species will remain allopatric, then you have a pretty solid case, but if you're talking about drainages that were inundated by glaciers and had their drainge routes remodeled less than ~50,000 ya, then you're on shaky ground at best.
Edited by blakemarkwell, 21 November 2012 - 04:10 PM.
#7
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Posted 21 November 2012 - 05:18 PM
One person who was working with the Eth. spectabile complex some years ago was Patrick Ceas, who I don't think has ever been on the Forum although he's been a NANFA member (I think). If someone is really motivated you could look him up and ask if he's up to anything.
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Posted 21 November 2012 - 05:42 PM
Etheostoma lawrencei from 2002 is the latest member of the spectabile complex to be described, I believe. The Ihiyo Darter, Mamequit Darter, Ozark Darter and Sheltowee Darter remain undescribed/unnamed.
Chris
Chris
Edited by kalawatseti, 21 November 2012 - 05:42 PM.
#10
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Posted 22 November 2012 - 12:02 PM
Matt, I do not want to argue here, but I do want to understand, We do not make other things (birds, people, just to name a few) as different species just because they are a different color. There are color morphs right? I have always tried to understand this. Why are not different races of people different species (or is that just too emotionally charged to ask when I am a white male)? Why are some macaws different species when they readily interbreed? Or color morphs of Australian Gouldian finches with black or red faces that both appear in the wild. It seems that fish are more often given a species status because they are more isolated (you cant just fly over a drainage and mate with the next fish).
This may be too much of a thread highjack... sorry, but I am not going to delete it now that I got it all typed up... maybe move it later
This may be too much of a thread highjack... sorry, but I am not going to delete it now that I got it all typed up... maybe move it later
Either write something worth reading or do something worth writing. - Benjamin Franklin
#11
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Posted 22 November 2012 - 02:16 PM
I'm not arguing for or against those characteristics as THE delineating factor of a species either and for these in particular (I want to see and participate in a decent discussion here since they have all but disappeared). But you do note the isolation of genes from one population to another, which is a delineating factor. I'm not sure these are color morphs either. The coloring is associated with a behavior that is directly tied to reproduction, i.e., the passing of inherited traits that were undoubtedly related to the fitness of a common ancestor that had some pigments which may have mutated.
Edited by ashtonmj, 22 November 2012 - 02:17 PM.
#12
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Posted 22 November 2012 - 05:11 PM
Matt,
It is my understanding that morphological apomorphies are chosen simply if they’re diagnostic, and nothing else. The only ‘goal’ of taxonomy is to understand evolutionary relationships, and choosing a diagnostic morphological character willy-nilly (not the best word choice!) may have absolutely nothing to do with the evolutionary history of that lineage.
I will agree with you that morphological characters, such as pigmentation of nuptial males has a genetic basis, but these probably evolved from changes in promoters that control the degree of expression of these pigments. Like you noted, these characters would be female-driven (via sexual selection), but this would be an example of directional selection. Since these genes would contribute to the fitness of the individual, their mutation rate would not be clock-like (= constant) such as those that occur in junk DNA (neutral evolution), as they would instead be subject to purifying selection.
Therefore, I believe that when phylogeneticists choose characters for analysis, they often choose nucleotide sequences that are junk (those sequences not actively in use of the organism, such as introns, microsatellites, etc) in all taxa analyzed, and thus expect all of them to be equally free of purifying selection and evolve at a constant rate which is useful in constructing relationships. Of course, mtDNA in general evolves at a fast and constant rate due to its much smaller effective population size, but when studying species groups very closely related, the gene trees seem to be riddled with evidence of introgression. I’ve now heard that a new focus is searching for regions in the nuclear genome that evolve at a fast, constant rate, which can take more time and money, but seem to be continually getting cheaper.
I should note that I don’t see any problems with choosing nuptial male apomorphies with species that have poor dispersal capabilities (such as Etheostoma), especially if they occur in drainages that geologists have shown to be separated for long periods of time, such as E. maydeni in the Cumberland, and E. cinereum in the Tennessee. I’m sure all the E. spectabile and E. stigmaeum splits are legit too, given they all occur south of the extent of Quaternary glaciation and occur in disjunct river drainages (well, most of them I presume -- I don't know the drainage history of all these). It seems you could get monophyletic gene trees with any species distributed in both the Cumberland and the Tennessee, so long as it isn’t a big river disperser. However, when positing a three species scenario in a single river drainage (such as the Cumberland) from a single species group (such as that of E. simoterum = E. atripinne, E. occidentale, E. orientale), I think it makes sense to consult some gene trees to see the degree of concurrent or past gene sharing at the distribution overlaps, and if the morphological characters are clinal or not.
Just like you may want to check the Kankakee River for specimens if you are proposing a two species scenario in the Great Lakes and Illinois (= Mississippi) drainages, such as N. percobromus and N. rubellus, when the species can do some swimming and dispersing, and when a French fur trapper could float from the Great Lakes to the Mississippi without portaging in just the 1700 and 1800s….
I’d be nice to hear from some of the actual taxonomists on the forum, such as Ben, Dave, Tom, Mike Sandel, Peter, etc, etc, as they actually deal with the business end of this stuff! I’m just some who reads a lot of evolutionary biology, and the new papers surfacing. I’m FAR from an expert, just someone trying to learn one paper, or forum post at a time. In fact, I typically skip the ‘Materials and Methods’ sections entirely, as the data analyses are usually too esoteric for my understanding; I'll save that for the drudgery of graduate school, and for now stick to the more interesting 'Introduction' and 'Discussion'! I agree with you that this forum has been missing some good content that was more frequent in the past.
It is my understanding that morphological apomorphies are chosen simply if they’re diagnostic, and nothing else. The only ‘goal’ of taxonomy is to understand evolutionary relationships, and choosing a diagnostic morphological character willy-nilly (not the best word choice!) may have absolutely nothing to do with the evolutionary history of that lineage.
I will agree with you that morphological characters, such as pigmentation of nuptial males has a genetic basis, but these probably evolved from changes in promoters that control the degree of expression of these pigments. Like you noted, these characters would be female-driven (via sexual selection), but this would be an example of directional selection. Since these genes would contribute to the fitness of the individual, their mutation rate would not be clock-like (= constant) such as those that occur in junk DNA (neutral evolution), as they would instead be subject to purifying selection.
Therefore, I believe that when phylogeneticists choose characters for analysis, they often choose nucleotide sequences that are junk (those sequences not actively in use of the organism, such as introns, microsatellites, etc) in all taxa analyzed, and thus expect all of them to be equally free of purifying selection and evolve at a constant rate which is useful in constructing relationships. Of course, mtDNA in general evolves at a fast and constant rate due to its much smaller effective population size, but when studying species groups very closely related, the gene trees seem to be riddled with evidence of introgression. I’ve now heard that a new focus is searching for regions in the nuclear genome that evolve at a fast, constant rate, which can take more time and money, but seem to be continually getting cheaper.
I should note that I don’t see any problems with choosing nuptial male apomorphies with species that have poor dispersal capabilities (such as Etheostoma), especially if they occur in drainages that geologists have shown to be separated for long periods of time, such as E. maydeni in the Cumberland, and E. cinereum in the Tennessee. I’m sure all the E. spectabile and E. stigmaeum splits are legit too, given they all occur south of the extent of Quaternary glaciation and occur in disjunct river drainages (well, most of them I presume -- I don't know the drainage history of all these). It seems you could get monophyletic gene trees with any species distributed in both the Cumberland and the Tennessee, so long as it isn’t a big river disperser. However, when positing a three species scenario in a single river drainage (such as the Cumberland) from a single species group (such as that of E. simoterum = E. atripinne, E. occidentale, E. orientale), I think it makes sense to consult some gene trees to see the degree of concurrent or past gene sharing at the distribution overlaps, and if the morphological characters are clinal or not.
Just like you may want to check the Kankakee River for specimens if you are proposing a two species scenario in the Great Lakes and Illinois (= Mississippi) drainages, such as N. percobromus and N. rubellus, when the species can do some swimming and dispersing, and when a French fur trapper could float from the Great Lakes to the Mississippi without portaging in just the 1700 and 1800s….
I’d be nice to hear from some of the actual taxonomists on the forum, such as Ben, Dave, Tom, Mike Sandel, Peter, etc, etc, as they actually deal with the business end of this stuff! I’m just some who reads a lot of evolutionary biology, and the new papers surfacing. I’m FAR from an expert, just someone trying to learn one paper, or forum post at a time. In fact, I typically skip the ‘Materials and Methods’ sections entirely, as the data analyses are usually too esoteric for my understanding; I'll save that for the drudgery of graduate school, and for now stick to the more interesting 'Introduction' and 'Discussion'! I agree with you that this forum has been missing some good content that was more frequent in the past.
#14
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Posted 22 November 2012 - 10:23 PM
Whew! Blake
Oh c'mon -- I'm just posting about the 'pillars' of molecular evolution. Trust me, if I can understand it (or more like think I do!), anyone can!
Actually, I should probably keep my mouth shut on a lot of these issues, and just let the authorities and actually taxonomist deal with the issues, but I've never been good at letting others do the thinking for me.... It gets really nerdy and over my head when they start talking about reconstructing character states, homologies, etc. After reading that stuff, I just want to go photograph a darter and drool around the campfire...
#16
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Posted 27 November 2012 - 12:09 AM
Etheostoma lawrencei from 2002 is the latest member of the spectabile complex to be described, I believe. The Ihiyo Darter, Mamequit Darter, Ozark Darter and Sheltowee Darter remain undescribed/unnamed.
Chris
Hey Chris, where do these puppies live (Ihiyo Darter, Mamequit Darter, Ozark Darter and Sheltowee Darter)?
#17
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Posted 27 November 2012 - 01:35 AM
Hey Mark,
The Ihiyo Darter occurs in the western tribs of Caney Fork River downstream from Mountain Creek (of Collins River), and Cumberland River tribs from Bledsoe Creek to Dixon Creek in Tennessee.
Mamequit Darter occurs in Cumberland River tribs from Marrowbone Creek of Cheatham Co. Tennessee downstream to Cumberland River tribs of Lyon Co. Kentucky.
Ozark Darter occurs in the White River of Arkansas and Missouri.
Sheltowee Darter occurs in the Dix River system of Kentucky.
This info is all in Chris' AC Volume 34(4)/Fall 2008 edition. I figured I at least owed you that for derailing your thread!
The Ihiyo Darter occurs in the western tribs of Caney Fork River downstream from Mountain Creek (of Collins River), and Cumberland River tribs from Bledsoe Creek to Dixon Creek in Tennessee.
Mamequit Darter occurs in Cumberland River tribs from Marrowbone Creek of Cheatham Co. Tennessee downstream to Cumberland River tribs of Lyon Co. Kentucky.
Ozark Darter occurs in the White River of Arkansas and Missouri.
Sheltowee Darter occurs in the Dix River system of Kentucky.
This info is all in Chris' AC Volume 34(4)/Fall 2008 edition. I figured I at least owed you that for derailing your thread!
#18
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Posted 27 November 2012 - 12:22 PM
Thank you Blake for cluing me in. Guess I should be paying closer attention. Thank you Chris for publishing this. We can always count on you to keep us well informed! I got what I needed from this thread, so feel free to take it to whatever netherworld you like! ...though I imagine our faithful moderators will have something to say/do about it. 
#20
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Posted 30 November 2012 - 12:17 PM
Hmmm, well, there are lots of species concepts (or definitions) out there and taxonomists tend to adopt which ever one fits the situation in their current organism of interest. Etnier's species concept is perhaps the best, if only that it avoids definitions; "A species is whatever a competent taxonomist says it is." The definition of a competent taxonomist is basically to wait a few decades to see if their described species stand up to subsequent analyses. I can't speak to the methods of all taxonomist or even most ichthyologists, but it's nice to see concordance among several lines of evidence. For the species I'm describing my process went kinda like: 1) seeing differences in color or body shape in the field, very subjective but a start, 2) doing a literature search to find any previously reported differences, 3) expanding genetic sampling to provide a comprehensive estimate of population structure, 4) if there is genetic structure I've gone back and counted scales and taken color notes to see if we can find a 'good' morphological character that varies along the same boundaries as the genetic structure. I've found morphological characters that allow discrimination between the genetic lineages identified and for those I am working on descriptions. Where I didn't find concordant morphological differences, I have decided to wait until I have more robust estimates of relationships among lineages.
I primarily use genetic methods to study evolutionary questions, so I put a lot of stock in genes and the appropriate interpretation of patterns in gene trees and gene flow. However, I have no problem with species descriptions that are based on deep genetic divergence with no morphological correlate, as in Noturus maydeni, or when there is little genetic divergence but morphological characters galore as in most African Rift Lake cichlids. For darters, male nuptial coloration/pigmentation is highly variable both within and among populations. For instance, in the Nothonotus sanguifluus species group males develop bright red ocelli on the anterior, proximal inter-radial membranes. When I first started looking at these guys I thought the Caney Fork population (about to be described as a new species) did not exhibit these ocelli. After going back at various times during the breeding season I found that they did have them and expression was variable. Not all males would have them, usually only one out of every 8 to 10 would have well developed ocelli. I started to observe similar ratios in other populations, and now I have a feeling that these ocelli could be exhibited only by the buck spawning males that are in full reproduction mode, while the ones with out ocelli are the subordinate males. I don't have any evidence from observations to back this up, so take it as a story until someone spends some time horizontal in the creek.
As for the choice of genetic loci, it all depends on the question and the study organisms. It's getting even more interesting with some of the new Next Generation Sequencing technologies. These can produce nearly absurd amounts of data, measured in terabytes, ranging from hundreds of thousands of small 100 base pair fragments to hundreds or thousands of 2000 or more base pair lengths. The age old problem is that when some people get a hammer, everything suddenly becomes a nail.
I primarily use genetic methods to study evolutionary questions, so I put a lot of stock in genes and the appropriate interpretation of patterns in gene trees and gene flow. However, I have no problem with species descriptions that are based on deep genetic divergence with no morphological correlate, as in Noturus maydeni, or when there is little genetic divergence but morphological characters galore as in most African Rift Lake cichlids. For darters, male nuptial coloration/pigmentation is highly variable both within and among populations. For instance, in the Nothonotus sanguifluus species group males develop bright red ocelli on the anterior, proximal inter-radial membranes. When I first started looking at these guys I thought the Caney Fork population (about to be described as a new species) did not exhibit these ocelli. After going back at various times during the breeding season I found that they did have them and expression was variable. Not all males would have them, usually only one out of every 8 to 10 would have well developed ocelli. I started to observe similar ratios in other populations, and now I have a feeling that these ocelli could be exhibited only by the buck spawning males that are in full reproduction mode, while the ones with out ocelli are the subordinate males. I don't have any evidence from observations to back this up, so take it as a story until someone spends some time horizontal in the creek.
As for the choice of genetic loci, it all depends on the question and the study organisms. It's getting even more interesting with some of the new Next Generation Sequencing technologies. These can produce nearly absurd amounts of data, measured in terabytes, ranging from hundreds of thousands of small 100 base pair fragments to hundreds or thousands of 2000 or more base pair lengths. The age old problem is that when some people get a hammer, everything suddenly becomes a nail.
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