Join for FREE
It only takes a minute!
Magnifying the passion for nature. Zeiss Victory Harpia 95. New!

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Species recognition between geographically isolated populations

Reply
 
Thread Tools Rate Thread
Old Saturday 21st October 2017, 06:43   #26
BenFreeman
Registered User

 
Join Date: Oct 2017
Location: Vancouve
Posts: 6
Hello all --

Was just pointed to this thread. Lots of interesting comments. I'm happy to address any questions or concerns.

A couple thoughts:

- All taxon pairs are allopatric (geographically isolated). Playback experiments simulate secondary contact - do the birds recognize each others' song? In some cases we conducted experiments in allopatry but the two taxa meet somewhere. In these cases, further work is needed at that place where they meet.

- We mention all this in the article, but there is some confusion here. The paper deals with less than half of the taxon pairs we have studied with playback experiments. The main project is to study how song evolves in geographic isolation in Neotropical birds; we have good data (good = lots of territories tested) for ~ 140 taxon pairs. The paper provides matched data for acoustic trait divergence & behavioral response to playback for 72 taxon pair comparisons. Quantifying acoustic trait divergence is very time consuming, thus the smaller sample. Of the 21 taxon pairs we highlight for species limits only ~ 8 come from the sample of 72.

- One key finding is that sometimes populations happily respond to song from an isolated population that is (to my ears) pretty different. And sometimes they consistently ignore song from an isolated population that is (to my ears) really similar. Of course song recordings are terrifically important. But we show that some birds care when differences are statistically minor and others do not. Remember that the job here is a tough one -- are two geographically isolated populations sufficiently different that they would not interbreed? So really we only care about differences that are relevant to reproductive isolation, and we argue that responses to playback are pretty good data in that regard.

- Another key thing is that we did not conduct these experiments to "prove" that a population deserves species status. We were instead interested in evolutionary patterns across many comparisons. It is noteworthy that we almost always had some responses even when songs are wildly different - responses could have been incidental, curious etc, but they are still a bird approaching the speaker.

- Someone mentioned that some birds like Henicorhina will respond to anything. Actually our previous paper showed that Henicorhina leucosticta in Costa Rica ignore song from NW Ecuador populations! And we had plenty of other wrens that ignored allopatric song. So playback experiments are even useful for wrens.

- Regarding the idea that someone could set up an online database where people could enter their own playback data. Yes yes yes! That would be amazing. I can imagine many folks could do an experiment here or there, and this data could be really useful! Please write to me or continue this thread if that is of interest to anyone.
BenFreeman is offline  
Reply With Quote
Old Monday 29th January 2018, 12:29   #27
thomasdonegan
Former amateur ornithologist

 
Join Date: Dec 2003
Location: United Kingdom
Posts: 322
With SACC voting starting to come in on this proposal, the authors may consider that they sold themselves short (and sold previous authors short) by not consulting and citing other literature supporting some of these proposals.

Most notably this one on Atlapetes crassus:
https://www.researchgate.net/publica..._brush-finches

And, for example, this short note on how Woodhaunters (then Hyloctistes, now Automolus) vocalizations differ, citing various other authors who split them already:
http://www.proaves.org/wp-content/up...on_Listado.pdf

Moreover, IOC and other authorities split a number of these "species", but that was not mentioned in the proposal. The proposal and related paper somewhat give the impression of original findings in instances when this is dubiously the case. Moreover, by omitting to reinforce their position on these splits with reference to other consistent works, their proposals on several of these taxa come across as weak, for the reasons discussed by Gary Stiles in the SACC proposal online...

My impression is that many of these splits are good ones, but prospects of progress seem a bit bleak, in part due to the above issues.

Last edited by thomasdonegan : Monday 29th January 2018 at 12:31.
thomasdonegan is offline  
Reply With Quote
Old Monday 29th January 2018, 18:36   #28
BenFreeman
Registered User

 
Join Date: Oct 2017
Location: Vancouve
Posts: 6
Hello Thomas --

Thanks for your message.

As you say, I did not submit comprehensive and detailed proposals to SACC. If that is cause for many of the proposals to be rejected, so be it. At least Graham and I have put out worthwhile data into the public sphere. I do expect that all of these proposals will eventually, one way or another, be adopted. Reasonable people can disagree with whether the playback evidence that I have presented is sufficient to split taxa at the moment, at least for some cases (other cases I think are beyond obvious, but of course I would say that). I do think it is worth pointing out that:

1) Because all taxa considered in my proposals are allopatric, genetic distances really don't mean much with respect to reproductive isolation. We expect populations that live in different places and do not interbreed to differ genetically. But what we want to know is whether allopatric populations are reproductively isolated (= different species) or not (= same species). The degree of genetic differentiation in allopatry doesn't help us make this assessment, unless it is absolutely huge (which would suggest that hybrid offspring would be likely to have defects).

2) So far all comparisons that we tested reciprocally (how does pop A respond to song from pop B? and also: how does pop B respond to song from pop A?) show symmetric responses. E.g. if pop A ignored song from pop B, pop B also ignored song from pop A, and vice versa. Thus I am very comfortable making recommendations based on comparisons that were only tested one direction.

3) We used many recordings in our playback experiments. Thus our results can be generalized to tell us how birds from one population respond to song from another population (if we had used only one recording we would be technically limited in our inference to how birds from one population respond to one particular song from another population).

4) Our metric of "discrimination" is rather severe -- we only call it discrimination when a territorial bird completely ignores song from a related population. Not that it shows a weak response, or a slow response, but completely ignores. I think this is the form of discrimination that is most relevant to trying to estimate premating reproductive isolation. (And note too that the territorial bird in question always responded strongly to local song).

5) I think playback data are a big step up from acoustic analysis of songs. Again, we expect populations that live in different places to sing a bit differently from one another. If these differences are huge and completely obvious, then it is pretty good inference to think that these two populations would ignore each other if they came into contact. But if the differences are more minor, it is really important to assess biological significance (behavioral response) rather than statistical significance. Acoustic analyses are extremely helpful and playback data are not always feasible to collect. But I do think playback data presented alone are more meaningful than acoustic data presented alone, and acoustic data presented alone are typically convincing enough for SACC to make decisions.

6) Last, I disagree with the viewpoint that "these species complexes are complex, let's wait until a thorough analysis deals with everything al at once." A "whole-complex" perspective is of course necessary to make taxonomic decisions in some cases, but this criticism is not fatal when we are only considering allopatric taxa. For example the chat-tyrants. Perhaps Venezuelan populations (which differ in plumage) ought to be considered distinct from other populations N of the Maranon. But whether that is true or not has no bearing on whether populations immediately N and S of the Maranon Gap are reproductively isolated from one another.

Whatever SACC decides, I think it is worthwhile to re-emphasize (again and again) that what we are trying to do is figure out which populations are reproductively isolated from one another and which are not. For allopatric taxa, this is, in the strict sense, impossible. But for taxa in which we think song plays an important role in mate choice, playback experiments are likely the best available method for helping us assess premating reproductive isolation.

Best,

Ben

Last edited by BenFreeman : Monday 29th January 2018 at 20:26.
BenFreeman is offline  
Reply With Quote
Old Tuesday 30th January 2018, 11:03   #29
andyadcock
Registered User
 
andyadcock's Avatar

 
Join Date: Dec 2005
Location: Nottingham UK and St Petersburg, Russia
Posts: 9,993
Interesting that in the OP, the species will be recognised on the basis of song, under the BSC. Surprising to me, does this mean that they're moving away from the emphasis on DNA?


A
andyadcock is offline  
Reply With Quote
Old Tuesday 30th January 2018, 14:25   #30
Kratter
Registered User

 
Join Date: Dec 2006
Location: Florida
Posts: 2,286
At least for the AOU/AOS Committees, results for DNA analyses on species level questions are often ambiguous,especially when trying to show that allopatric populations are reproductively isolated. They can be very useful in sympatry to show lack of gene flow (e.g, two populations are reproductively isolated and thus two species). They are also useful when they show a lack of a assortative mating, thus indicating extensive gene flow and the lack of reproductive isolation (the populations should be lumped as one species). There will never be an absolute metric for defining species (at least for those following the Biological Species Concept) using DNA.

Andy
Kratter is online now  
Reply With Quote
Old Tuesday 30th January 2018, 14:30   #31
andyadcock
Registered User
 
andyadcock's Avatar

 
Join Date: Dec 2005
Location: Nottingham UK and St Petersburg, Russia
Posts: 9,993
Quote:
Originally Posted by Kratter View Post
At least for the AOU/AOS Committees, results for DNA analyses on species level questions are often ambiguous,especially when trying to show that allopatric populations are reproductively isolated. They can be very useful in sympatry to show lack of gene flow (e.g, two populations are reproductively isolated and thus two species). They are also useful when they show a lack of a assortative mating, thus indicating extensive gene flow and the lack of reproductive isolation (the populations should be lumped as one species). There will never be an absolute metric for defining species (at least for those following the Biological Species Concept) using DNA.

Andy

I thought that the BSC had a benchmark differential for speciation, something like 2.7%?


A
andyadcock is offline  
Reply With Quote
Old Tuesday 30th January 2018, 14:49   #32
Kratter
Registered User

 
Join Date: Dec 2006
Location: Florida
Posts: 2,286
Quote:
Originally Posted by andyadcock View Post
I thought that the BSC had a benchmark differential for speciation, something like 2.7%?


A
Nope. Reproductive isolation could arise by theoretically a single base pair (e.g., changing the color of the throat from red to violet). Lack of assortative mating could occur between populations much greater than 5% different. For example, Common Ravens in California vs the rest of North America show no phenotypic/behavioral/vocal differences but are quite different in DNA (I think around 5%). The populations were isolated for a very long time, but never accrued differences that would lead to reproductive isolation.

Andy

Andy
Kratter is online now  
Reply With Quote
Old Tuesday 30th January 2018, 16:12   #33
andyadcock
Registered User
 
andyadcock's Avatar

 
Join Date: Dec 2005
Location: Nottingham UK and St Petersburg, Russia
Posts: 9,993
Quote:
Originally Posted by Kratter View Post
Nope. Reproductive isolation could arise by theoretically a single base pair (e.g., changing the color of the throat from red to violet). Lack of assortative mating could occur between populations much greater than 5% different. For example, Common Ravens in California vs the rest of North America show no phenotypic/behavioral/vocal differences but are quite different in DNA (I think around 5%). The populations were isolated for a very long time, but never accrued differences that would lead to reproductive isolation.

Andy

Andy
I know even less now than I did before!



A
andyadcock is offline  
Reply With Quote
Old Tuesday 30th January 2018, 16:45   #34
BenFreeman
Registered User

 
Join Date: Oct 2017
Location: Vancouve
Posts: 6
Andy Kratter said it perfectly --

Genetic data is of utmost importance when trying to determine whether species that are sympatric are reproductively isolated. Want to know how many species of Scytalopus there are in an Andean cloud forest? Then go out, sample thoroughly, sequence and see how many genetic groups are present. If they all interbreed (no reproductive isolation), then there will just be one genetic group. If two groups are reproductively isolated from one another and do not interbeed, then there will be two genetic groups.

But genetics is not especially useful when we are looking at allopatric populations. In the Andes, it is very common for related but allopatric populations to differ dramatically in mitochondrial DNA from one another (e.g. >5% sequence divergence, which is ~ 2.5 million years of evolving in isolation). It is *so* tempting to want to assign species limits based on sequence divergence. But what we really want to know is whether two groups are reproductively isolated or not. And we know from the ravens that Andy mentioned and other examples (e.g. Xanthomixis in Madagascar - (open access) http://onlinelibrary.wiley.com/doi/1...ece3.1639/full) that lineages can live in allopatry for millions of years but not evolve reproductive isolation (we know this because we infer that when they came back together they freely interbred).

Defining species status of allopatric populations is, has always been, and will always be a difficult task. But I think it is important to assemble data to try to define species limits as best as possible -- my personal bugaboo right now is that species are more narrowly defined in the temperate zone than the tropics, and this taxonomic bias may skew the results of comparative analyses that assume that taxonomy is applied consistently across Earth.

Best,

Ben

Last edited by BenFreeman : Wednesday 31st January 2018 at 02:19.
BenFreeman is offline  
Reply With Quote
Old Tuesday 30th January 2018, 17:16   #35
andyadcock
Registered User
 
andyadcock's Avatar

 
Join Date: Dec 2005
Location: Nottingham UK and St Petersburg, Russia
Posts: 9,993
Quote:
Originally Posted by BenFreeman View Post
Andy Kratter said it perfectly --

Genetic data is of utmost importance when trying to determine whether species that are sympatric are reproductively isolated. Want to know how many species of Scytalopus there are in an Andean cloud forest? Then go out, sample thoroughly, sequence and see how many genetic groups are present. If they all interbreed (no reproductive isolation), then there will just be one genetic group. If two groups are reproductively isolated from one another and do not interbeed, then there will be two genetic groups.

But genetics is not especially useful when we are looking at allopatric populations. In the Andes, it is very common for related but allopatric populations to differ dramatically in mitochondrial DNA from one another (e.g. >5% sequence divergence, which is ~ 2.5 million years of evolving in isolation). It is *so* tempting to want to assign species limits based on sequence divergence. But what we really want to know is whether two groups are reproductively isolated or not. And we know from the ravens that Andy mentioned and other examples (e.g. Xanthomixis in Madagascar - (open access) http://onlinelibrary.wiley.com/doi/1...ece3.1639/full) that lineages can live in allopatry for millions of years but not evolve reproductive isolation (we know this because we infer that when they came back together they freely interbred).

Defining species status of allopatric populations is, has always been, and will always be a difficult task. But I think it is important to do our best in all cases -- my personal bugaboo right now is that species are more narrowly defined in the temperate zone than the tropics, and this taxonomic bias may skew the results of comparative analyses that assume that taxonomy is applied consistently across Earth.

Best,

Ben
Thanks for this guys,
I can't pretend to be a scientist, I just always assumed that if two species had DNA that was different by a minimum of whatever, then under the BSC, they would be different.

Obviously I know even less than I thought I did and was surprised that the BSC would split a species based on vocalisations alone, that seems, to my very limited understanding, to be more like a PSC thing to do.

As Ben says though, uniformity is important and even with my scant knowledge, I can see that it's probably not being achieved.


A
andyadcock is offline  
Reply With Quote
Old Tuesday 30th January 2018, 17:21   #36
thomasdonegan
Former amateur ornithologist

 
Join Date: Dec 2003
Location: United Kingdom
Posts: 322
From bitter experience, Ben, I'm sorry to suggest that AOU/SACC has little to no interest in promoting rational taxonomies based on the latest research. Their main aim seems to be to promote "conservatism" which is a by-word for promoting irrationality over anything but detailed studies of a particular species group in the right kind of journals by the right kinds of authors using museum specimens, DNA and voice. That your study is more informative and based on more data or more relevant data than the efforts of past taxonomists is something I have tried before to little avail with SACC.

I would agree with all your proposed splits. It's a new approach using field data and provides a more rational and consistent basis for species limits for all groups treated compared to present treatments based on the hunches of 1910-1960s museum-based taxonomists. Many of them are a statement of the blindingly obvious. For those in "complexes", to me it is pretty obvious where other named subspecies fall. But SACC are not much interested in rationality in taxonomy. They may be interested in doing something with groups like Atlapetes given the other paper on this situation. They might even be interested in addressing cases where they are calling the earth flat in the face of all evidence and all other taxonomic authorities, like Automolus. I think you might struggle with the others, but surely there are other situations here where there is some "broadly consistent" molecular data or vocal study or field guide split or IOC treatment to point to, in terms of showing this study to be consistent with others and increasing the perceived cogency of your suggestions?
thomasdonegan is offline  
Reply With Quote
Old Wednesday 31st January 2018, 12:10   #37
Peter Boesman
Registered User

 
Join Date: Oct 2016
Location: Belgium
Posts: 15
It is a pity indeed that the SACC proposal did not include any other sources to support the statements. E.g., for about all cases a vocal analysis had already been executed (!) and these are referenced in HBW Alive. This would already have countered a number of arguments I am reading now in the comments of Gary Stiles. Obviously, the argument that these vocal analyses were not peer-reviewed can still be given but that's something else...

See the following direct links to the pdf's:
https://www.hbw.com/sites/default/fi...uftedcheek.pdf
https://www.hbw.com/sites/default/fi...oodhaunter.pdf
https://www.hbw.com/sites/default/fi...y_antpitta.pdf
https://www.hbw.com/sites/default/fi...hat-tyrant.pdf
https://www.hbw.com/sites/default/fi..._solitaire.pdf
https://www.hbw.com/sites/default/fi...ailed_wren.pdf
https://www.hbw.com/sites/default/fi...d_greenlet.pdf
https://www.hbw.com/sites/default/fi...ed_warbler.pdf
https://www.hbw.com/sites/default/fi...ed_warbler.pdf
https://www.hbw.com/sites/default/fi...ne_warbler.pdf
https://www.hbw.com/sites/default/fi...rush-finch.pdf
Peter Boesman is offline  
Reply With Quote
Old Wednesday 31st January 2018, 16:26   #38
DLane
Registered User

 
Join Date: Oct 2004
Location: USA
Posts: 75
Quote:
Originally Posted by Peter Boesman View Post
Obviously, the argument that these vocal analyses were not peer-reviewed can still be given but that's something else...
I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications. Furthermore, most do not provide the actual analyses or data other than a representative sonogram and the author's conclusion. Thus, as "gray literature," one mustn't be too upset if they are not cited by others.
DLane is offline  
Reply With Quote
Old Wednesday 31st January 2018, 18:35   #39
BenFreeman
Registered User

 
Join Date: Oct 2017
Location: Vancouve
Posts: 6
Thanks Peter and Dan for your messages --

Peter - Thanks for the links to the HBW vocal analyses you compiled. They are interesting to read. They do fall short of what would be necessary to convince a skeptic. I agree that ideally, playback experiments (to examine behavioral response) would be paired with detailed acoustic analyses (to examine acoustic geographic variation in song within and between populations).

Dan -- you are an active tour leader so are in a good position for me to ask the following question: Is it feasible to conduct occasional playback experiments while guiding tours? It's easy for me to get excited and imagine that it would indeed be feasible -- that you are often already using playback to lure in an interesting bird for the group to admire, and you are probably already telling your clients/friends about geographic variation in song that might be pertinent to species limits, perhaps even briefly playing allopatric song so everyone can hear how different songs are. But it may well be that my imagination is too rosy as I sit here at my desk -- in the field with a big group things may be way too busy and you have your hands full.

The broader idea is that I think it would be great if guides, ornithologists and birders could team up on playback experiments (each person doing a couple as they are able to) to compile data relevant to assessing species limits. Not sure if this would work in practice, but I do think it is a good idea. Playback experiments are easier to conduct then ever before (wireless speakers, lots of good quality recordings publicly available). One of the main goals of publishing this paper was simply to motivate others to try doing playback experiments themselves.

Best,

Ben
BenFreeman is offline  
Reply With Quote
Old Wednesday 31st January 2018, 20:45   #40
fugl
Registered User
BF Supporter 2018

 
Join Date: Feb 2003
Location: Reno, Nevada
Posts: 13,757
Quote:
Originally Posted by BenFreeman View Post
Thanks Peter and Dan for your messages --

Peter - Thanks for the links to the HBW vocal analyses you compiled. They are interesting to read. They do fall short of what would be necessary to convince a skeptic. I agree that ideally, playback experiments (to examine behavioral response) would be paired with detailed acoustic analyses (to examine acoustic geographic variation in song within and between populations).

Dan -- you are an active tour leader so are in a good position for me to ask the following question: Is it feasible to conduct occasional playback experiments while guiding tours? It's easy for me to get excited and imagine that it would indeed be feasible -- that you are often already using playback to lure in an interesting bird for the group to admire, and you are probably already telling your clients/friends about geographic variation in song that might be pertinent to species limits, perhaps even briefly playing allopatric song so everyone can hear how different songs are. But it may well be that my imagination is too rosy as I sit here at my desk -- in the field with a big group things may be way too busy and you have your hands full.

The broader idea is that I think it would be great if guides, ornithologists and birders could team up on playback experiments (each person doing a couple as they are able to) to compile data relevant to assessing species limits. Not sure if this would work in practice, but I do think it is a good idea. Playback experiments are easier to conduct then ever before (wireless speakers, lots of good quality recordings publicly available). One of the main goals of publishing this paper was simply to motivate others to try doing playback experiments themselves.
What an excellent idea! A way for we birders to make up for some of the environmental harm caused by our frivolous hobby.
__________________
Bird photos (Flickr): http://www.flickr.com/photos/fugl/
". . .Let them be left, O let them be left, wildness and wet;
Long live the weeds and the wilderness yet."

--Gerard Manley Hopkins

Last edited by fugl : Thursday 1st February 2018 at 00:46.
fugl is offline  
Reply With Quote

BF Supporter 2011 2012 2013 2014 2015 2016 2017 2018 Support BirdForum With A Donation

Old Thursday 1st February 2018, 00:05   #41
Murray Lord
Registered User

 
Join Date: Dec 2006
Location: Sydney, Australia
Posts: 248
Quote:
Originally Posted by BenFreeman View Post
Dan -- you are an active tour leader so are in a good position for me to ask the following question: Is it feasible to conduct occasional playback experiments while guiding tours? It's easy for me to get excited and imagine that it would indeed be feasible -- that you are often already using playback to lure in an interesting bird for the group to admire, and you are probably already telling your clients/friends about geographic variation in song that might be pertinent to species limits, perhaps even briefly playing allopatric song so everyone can hear how different songs are. But it may well be that my imagination is too rosy as I sit here at my desk -- in the field with a big group things may be way too busy and you have your hands full.

The broader idea is that I think it would be great if guides, ornithologists and birders could team up on playback experiments (each person doing a couple as they are able to) to compile data relevant to assessing species limits. Not sure if this would work in practice, but I do think it is a good idea. Playback experiments are easier to conduct then ever before (wireless speakers, lots of good quality recordings publicly available). One of the main goals of publishing this paper was simply to motivate others to try doing playback experiments themselves.
Ben, what would be the protocols for doing useful playback experiments in this way? If a bird has already been ‘taped in’ by a tour leader playing its call, I’d suggest it may not respond in the same way to a tape of an allopatric species as it would before it was provoked. So how useful would a playback experiment be in those circumstances? Just curious. Also I imagine there's a lot of room for different people to reach different conclusions on whether an individual bird has responded to a call. The idea sounds very interesting but my inner skeptic wonders whether the data produced would be robust enough to be useful?
Murray Lord is offline  
Reply With Quote
Old Thursday 1st February 2018, 01:26   #42
DLane
Registered User

 
Join Date: Oct 2004
Location: USA
Posts: 75
Quote:
Originally Posted by Murray Lord View Post
Ben, what would be the protocols for doing useful playback experiments in this way? If a bird has already been ‘taped in’ by a tour leader playing its call, I’d suggest it may not respond in the same way to a tape of an allopatric species as it would before it was provoked. So how useful would a playback experiment be in those circumstances? Just curious. Also I imagine there's a lot of room for different people to reach different conclusions on whether an individual bird has responded to a call. The idea sounds very interesting but my inner skeptic wonders whether the data produced would be robust enough to be useful?
Hello Ben,
I have to agree with Murray here. Between the goals of tours (to show birds to clients in a timely fashion, where the guide's most important concern is the clients' experience) and the protocols necessary to conduct scientifically viable playback experiments, I fear that the two would not mesh well. There are many tours where I hardly get to look at a bird because I can only look long enough to confirm it is our target, then must spend the next 20 minutes trying to get the clients on it (by which time, it usually loses interest and melts back into the habitat). It is a rare instance that I am able to study a bird in any detail while on tour, much less try to perform playback experiments on it (and again, as Murray points out, usually the bird is hyped up because of playback to begin with, so the time necessary for it to "cool off" to play alternative sounds using some experimental protocol would be prohibitive in a tour scenario). In addition, I foresee the concept of "citizen science" playback databases would provide in such uneven results that they couldn't be used for any sort of scientific purpose. It's a fine idea in theory, but the realities of the issues working against it would probably be insurmountable. To assure that a standardized protocol is followed and the proper source sounds and target birds are used, I think it best if the experiments be carried out by one or a small group of investigators who are thoroughly familiar with the project.
DLane is offline  
Reply With Quote
Old Thursday 1st February 2018, 15:33   #43
jurek
Registered User
 
jurek's Avatar

 
Join Date: Aug 2003
Location: Switzerland/Poland
Posts: 3,796
Quote:
Originally Posted by BenFreeman View Post
what we are trying to do is figure out which populations are reproductively isolated from one another and which are not.
Sorry, but you are not checking reproductive isolation. You are checking response of a male to a playback of another male. Two males will not make an egg.

Territorial defense from males and attractiveness to females are two distinct functions. In some birds and other animals, even different parts of the song are responsible for either. Response to playback is not equal to 'species recognition' either. Males can respond aggressively to other species, even dissimilar, which compete for resources. Males can also not respond to the song of its own species, for example because they are in a different time of breeding cycle, perceive playback as too dominant male, or respond by observation without approaching or calling back. Actually, I think your concept of 'species recognition' is rather artificial, because you lump different responses: mating and territory, with different signals.

To be sure, you are doing valuable and interesting study on bird communication. But it is not exactly reproductive isolation.
jurek is offline  
Reply With Quote
Old Thursday 1st February 2018, 17:25   #44
BenFreeman
Registered User

 
Join Date: Oct 2017
Location: Vancouve
Posts: 6
Thanks for the messages -- what Dan (and Murray) wrote makes sense. It won't be guides leading tours, but I do hope that more people (whether academics or not; such projects are often appropriate for sharp students as well) will conduct playback experiments along these lines.

Jurek -- you bring up a crucial point. What we really want to know is whether populations are reproductively isolated or not. Again the basic problem is that allopatric populations don't actually have the ability to interbreed (they don't interact in nature), so we can't directly measure the strength of barriers to reproduction. But clearly mate choice is what we really want to measure. The trick is that measuring mate choice (both female choice of males and also male choice of females) is really very difficult, while measuring territorial response is much easier. The assumption is that selection should be much stronger on mate choice (make a wrong mating decision and that is very bad for your fitness) vs. territorial response (respond when you didn't have to and that is more or less inconsequential in the scheme of things). So, in response to a given set of variable signals, birds should generally have broader territorial responses and narrower mating responses. Such that if a bird ignores a signal in a territorial context, we can infer that it would also ignore the signal in a mating context (but we can't confidently make the opposite assumption that a bird that responds to a signal in a territorial context also would respond to that signal in a mating context). That is the logic behind using territorial responses to infer reproductive barriers.

Also worth noting is that females defend territories in many/most tropical birds. So playback experiments often elicit an aggressive territorial response from females (and also males; often the pair respond together). This is why it is not in fact true that playback experiments in the tropics measure male responses alone -- they measure female responses too in many/most cases. It remains true that such experiments measure territorial responses (and not mate choice) in both sexes.
BenFreeman is offline  
Reply With Quote
Old Friday 2nd February 2018, 00:11   #45
Scelorchilus
Registered User

 
Join Date: Oct 2005
Location: California
Posts: 46
Quote:
Originally Posted by Kratter View Post
Nope. Reproductive isolation could arise by theoretically a single base pair (e.g., changing the color of the throat from red to violet). Lack of assortative mating could occur between populations much greater than 5% different. For example, Common Ravens in California vs the rest of North America show no phenotypic/behavioral/vocal differences but are quite different in DNA (I think around 5%). The populations were isolated for a very long time, but never accrued differences that would lead to reproductive isolation.

Andy

Andy
Andy. Actually "California" Common Ravens sound more like Chihuahuan Ravens, and they seem to rarely if ever give the complex clicks, pops, etc. that Holarctic Ravens give. As well, I think the extent of nasal bristles is different in the California birds. I think the real situation may be more complex than the papers on the ravens have made out. In fact, I wonder if the two are sympatric but separate. Very difficult to ascertain when specimens look so much alike, and no vocalizations are taken of the birds in the field before collection. But when I hear holarctic ravens, they sound noticeably different to my ear than the locals in CA. Confusingly, in SE Arizona when trying to separate ravens by call, everyone finds it difficult. Part of the reason is that over there, it is the CA Raven that appears to be present, not the Holarctic. Cheers! Alvaro.
Scelorchilus is offline  
Reply With Quote
Old Friday 2nd February 2018, 05:37   #46
McMadd
and the continuing battle to take *****cilious britbirders to task...

 
Join Date: Jan 2007
Location: Tampere
Posts: 2,304
Quote:
Originally Posted by DLane View Post
Hello Ben,
I have to agree with Murray here. Between the goals of tours (to show birds to clients in a timely fashion, where the guide's most important concern is the clients' experience) and the protocols necessary to conduct scientifically viable playback experiments, I fear that the two would not mesh well. There are many tours where I hardly get to look at a bird because I can only look long enough to confirm it is our target, then must spend the next 20 minutes trying to get the clients on it (by which time, it usually loses interest and melts back into the habitat). It is a rare instance that I am able to study a bird in any detail while on tour, much less try to perform playback experiments on it (and again, as Murray points out, usually the bird is hyped up because of playback to begin with, so the time necessary for it to "cool off" to play alternative sounds using some experimental protocol would be prohibitive in a tour scenario). In addition, I foresee the concept of "citizen science" playback databases would provide in such uneven results that they couldn't be used for any sort of scientific purpose. It's a fine idea in theory, but the realities of the issues working against it would probably be insurmountable. To assure that a standardized protocol is followed and the proper source sounds and target birds are used, I think it best if the experiments be carried out by one or a small group of investigators who are thoroughly familiar with the project.
Could the tour companies consider sponsoring researchers in any way (do they already?) Flights, permits, accommodation? It must be in the interests of a tour company to increase the number of species and to say that "this bird was 'discovered' because we made it possible" should have some attractions?

Having been a poor scientist in another life, I know the trials and tribulations of that career path!

Cheers, MCM
McMadd is offline  
Reply With Quote
Old Friday 2nd February 2018, 15:54   #47
Peter Boesman
Registered User

 
Join Date: Oct 2016
Location: Belgium
Posts: 15
Quote:
Originally Posted by DLane View Post
I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications. Furthermore, most do not provide the actual analyses or data other than a representative sonogram and the author's conclusion. Thus, as "gray literature," one mustn't be too upset if they are not cited by others.
Dan's comment is partially correct, but:
* I can cite quite a few SACC cases where the vocal evidence on top of other data/paper(s) was less well documented than in the above notes but seemingly allowed SACC to take a positive decision
* The few peer-reviewed papers that have been published since these ornithological notes and which tackled voice for the same species have fully or to a large extent confirmed the conclusions (and I am not aware of any contradictory cases)
* The reason for these brief ornithological notes lacking some of the criteria mentioned by Dan has been explained elsewhere (and I welcome anyone to find an author who single-handedly has published 400 papers meeting these standards in a single year...).

It thus boils down to the question whether the SACC members use their expertise to work with conclusions which have been published in a brief format (as they seemingly have done in the past) or not...
Peter Boesman is offline  
Reply With Quote
Old Friday 2nd February 2018, 16:33   #48
Peter Boesman
Registered User

 
Join Date: Oct 2016
Location: Belgium
Posts: 15
Quote:
Originally Posted by DLane View Post
I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications..... Thus, as "gray literature," one mustn't be too upset if they are not cited by others.
As a further comment, Dan seems to imply that "gray literature" should not be cited. In this case, I assume that the comment " the vast majority of these reports themselves don't cite previous publications" refers to "white publications"...

In this case I strongly disagree with his critic insinuating that in the vast majority of the notes existing in depth vocal analysis was not mentioned. On the contrary...
Peter Boesman is offline  
Reply With Quote
Old Friday 2nd February 2018, 19:58   #49
DLane
Registered User

 
Join Date: Oct 2004
Location: USA
Posts: 75
Quote:
Originally Posted by Peter Boesman View Post
As a further comment, Dan seems to imply that "gray literature" should not be cited. In this case, I assume that the comment " the vast majority of these reports themselves don't cite previous publications" refers to "white publications"...

In this case I strongly disagree with his critic insinuating that in the vast majority of the notes existing in depth vocal analysis was not mentioned. On the contrary...
Peter, I think you misunderstood my intent. "Gray literature" is that which has content, but is not published using "formal pathways" (i.e., peer-reviewed journals). Typically gray literature is not easily located unless the author already knows of its existence (environmental assement reports prepared for government agencies, for example), or is in field guides, or other published sources that have not passed through review and other processes to ensure the quality of the content. In this case, these reports do not present the recording numbers that were analyzed so that they can be reviewed by the reader, and therefore one has to take it on faith that the author's conclusions are well-based. I know that many recordings in XC and Macaulay are misidentified to taxon (species or subspecies), or the taxonomy used was flawed (our discussion on Herpsilochmus marginatus scapularis on the XC forum is one such situation), or vocalization type was misrepresented in the library (were homologous vocalizations compared?). If the reader can't know what recordings were used, then there is no way to know how the analyses were affected by these variables. If these data and analyses are not available to the reader (in some cases in these reports, results are available, but not what measurements were taken or how), then how is the reader to determine if the conclusions may be compromised?

I'm not saying that your reports are not valuable and should not be cited at all. However, I am saying that you should not consider it a personal slight if they are not. Viewed strictly from the point of view of the scientific process, they are not a standard publication and cannot be replicated by a third party if their samples and analyses are not provided; their citation would be anecdotal at best, the same way a field guide might be cited. Thus, if another author chooses not to cite them, or isn't aware of them, I don't think they can or should be blamed. Whether or not similar material has been cited previously in SACC proposals is immaterial.

Last edited by DLane : Friday 2nd February 2018 at 20:11. Reason: clarifying language
DLane is offline  
Reply With Quote
Old Friday 2nd February 2018, 20:04   #50
DLane
Registered User

 
Join Date: Oct 2004
Location: USA
Posts: 75
Quote:
Originally Posted by McMadd View Post
Could the tour companies consider sponsoring researchers in any way (do they already?) Flights, permits, accommodation? It must be in the interests of a tour company to increase the number of species and to say that "this bird was 'discovered' because we made it possible" should have some attractions?

Having been a poor scientist in another life, I know the trials and tribulations of that career path!

Cheers, MCM
Some do. Several companies have guides who actively publish such work, and they credit the company for helping to fund the fieldwork necessary. I don't know if it is reasonable to ask a tour company to fund extensive fieldwork by researchers with whom they have no relationship, however. Similarly, some tour companies also send funds to conservation organizations, both local and international, to help pay for conservation projects, as well as provide optics and other support for local guides who lack it. If you are curious, I encourage you to ask your favorite tour companies if they fund such work.
DLane is offline  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Climate change disrupts species’ populations worldwide (BTO) BF Newsroom Latest news from the BTO 0 Wednesday 4th November 2015 16:18
Best guess is Yellow-legged Gull but geographically not occurring Clibanarii Bird Identification Q&A 7 Tuesday 30th September 2014 18:42
Displaced Populations and Extreme Rarity (or Who cares if species become extinct?) birdman Birds & Birding 102 Tuesday 7th October 2003 22:42
Radio Alert: Isolated communities, 15 & 22 April pigsonthewing TV & Radio Alert For Birding, Nature and Other Wildlife 0 Wednesday 9th April 2003 21:29

{googleads}

Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.28653002 seconds with 37 queries
All times are GMT. The time now is 00:44.