19 minutes ago, sethoflagos said:

Is there really such a thing as a 'norm' in mate selection? Doesn't it depend where you look? The whydahs and widowbirds typify one norm, yet Ploceidae proper selects via male nest weaving skils - and that is a huge family that includes some of the most populous undomesticated bird species on the planet

Index signaling doesn't mean a behavioral or strategic norm, nor was I speaking of one. Index simply means any signal which harmonizes with the animal's morphology and physiology and requires no burdensome costs that can't be sustained over time. They can vary immensely as you note.

Of course I agree there's a vast landscape of signaling behaviors and traits. Just leaning towards the majority of them being index signals that are not costly. The nest weaving skills you mention would be such, no? Being able to select and transport materials and weave them would seem to be almost all upside and not costly to the bird - such skills rest in cognitive traits and lifting energy that generalize across the bird's life as fitness. My guess is selective pressures lead to more of that and less of dragging giant arseloads of plumage.

56 minutes ago, TheVat said:

The nest weaving skills you mention would be such, no? Being able to select and transport materials and weave them would seem to be almost all upside and not costly to the bird - such skills rest in cognitive traits and lifting energy that generalize across the bird's life as fitness. My guess is selective pressures lead to more of that and less of dragging giant arseloads of plumage.

I get this. And also @CharonY 's clarifications on the criticality of marginal returns as opposed to absolute costs. However, I still have a nagging doubt here. It is the females who chose which index is important to them, and where to set performance benchmarks. The exquisitely woven nests or 'arseloads of plumage' actually cost them nothing but the time taken to make an inspection. The selection driver would therefore appear to be not the metabolic cost of the index parameter but the relevance of the index as an honest measure of genetic suitability.

5 hours ago, sethoflagos said:

The selection driver would therefore appear to be not the metabolic cost of the index parameter but the relevance of the index as an honest measure of genetic suitability

Well, the index signal is by definition an honest signal. So anything that's pertinent to a signal of adaptive fitness, not just metabolism, right. Female "choice" in most species is steered by selection, hence I place quote marks. Selective advantage would steer towards maximum signal for that least cost (cost: in hazard, metabolism, predation, immunity, social effects) which will still manage to exceed the costs weak individuals can handle. To be an honest signal, it must cost something, but arrive at an equilibrium where the strong individual doesn't "overinvest." That's what I think is meant by "evolutionarily stable"? Or part of the meaning, anyway.

🐓🐡🦔🦔🐩🐩🐩

1 hour ago, sethoflagos said:

The selection driver would therefore appear to be not the metabolic cost of the index parameter but the relevance of the index as an honest measure of genetic suitability.

This is a bit the crux of the matter and the question is moving now a bit more from sexual selection to more complex behavioural sciences. There, the discussion is actually even more complex as behaviours might not be as deterministic as many evolutionary models suggest (or require).

I think what that posted as well as some other papers are debating is whether the cost itself is necessary as a signal of genetic suitability and this is where the models fall a bit flat. What some papers focusing e.g. on mating behaviour in birds of paradise describe is closer to what is argued in the paper, i.e. elaborate courting is contingent on design features (e.g. is the signal visible and effective in courtship) and constraints (e.g. mechanical limits and resource optimization). I.e. having a high cost is not a signal per se and the trait does not e.g. converge to maximum waste that still does not reduce net survival (at least not prior procreation).

The second part, whether the display is perceived as honest (i.e. an accurate display of mate quality) then requires a different model to explain evaluation. Two recent ones are the balance and trade-off model. The former argues that individuals need to allocate resources between mating signalling and viability. Fitness is ultimately determined by taken these factors together. Hence, fitness is determined by mating success as well as viability and individuals finding the optimal balance are ultimately successful. Here honesty is not determined by waste.

I.e. imagine a low-quality individual who wastes already limited resources towards signaling to imitate a high-quality individual. The net allocation would be unbalanced and net fitness will drop. In some ways it is extension of the handicap model, but not looking from waste, but from a resource allocation perspective.

The trade-off model is more generalized and states that individuals in different conditions face different fitness trade-offs. As the respective optima vary, the signals have to adaptive to these conditions. Under these parameters, deception becomes net unprofitable. I.e. we are looking essentially at a condition-dependent trade-off between marginal benefits and costs. As TheVat pointed out, the optimization of these parameters are honest by by pushing the trade-off to the individual optimum.

7 hours ago, TheVat said:

Well, the index signal is by definition an honest signal. So anything that's pertinent to a signal of adaptive fitness, not just metabolism, right. Female "choice" in most species is steered by selection, hence I place quote marks. Selective advantage would steer towards maximum signal for that least cost (cost: in hazard, metabolism, predation, immunity, social effects) which will still manage to exceed the costs weak individuals can handle. To be an honest signal, it must cost something, but arrive at an equilibrium where the strong individual doesn't "overinvest." That's what I think is meant by "evolutionarily stable"? Or part of the meaning, anyway.

🐓🐡🦔🦔🐩🐩🐩

And yet Euplectes is so deeply embedded in the weaver clade Ploceidae. It's ancestors were clearly obligate male nest builders, and they still retain the habit with varying reduced degrees of commitment, down to the token efforts of the male red-collared widowbird, Euplectes ardens.

Typical of polygynous species, male red-collared widowbirds do not provide parental care. In fact, the only resources males provide are potential nest sites in their territories. They are different from other Euplectes species in that the males use only a simple nest ring in courtship and the females build and position the actual nests.

In addition, Euplectes males also invest heavily in producing brilliant carotenoid-based red or yellow patches of plumage as an honest agonistic signal to other males in establishing a breeding territory. The substantial energy costs of producing these intense pigments (from their diet), if not fully mitigated by the avoidance of physical violence, is going to compete with their investment in their tail growth, display, and nest building. As @CharonY points out, things can get complicated quite rapidly. It does appear that in finding the evolutionary balance between these competing forces, it is (in Euplectes at least) the male nest building activity that tends to decline.

And not apparently for the first time in superfamily Ploceoidea.

If current taxonomy is correct, the earliest divergent extant member of Viduidae is the cuckoo-finch (Anomalospiza imberbis) which to my eye is morphologically indistinguishable from some generic Ploceus weaver. Now this doesn't actually prove that the mid-Miocene last common ancestor of Viduidae and Ploceidae was a weaver, it may well have been some archetypal Estrildid finch, but it's extant descendants split cleanly into two distinct clades: weavers on one side; obligate brood parasites on the other. For the latter, nest building behaviour simply vanished.

10 hours ago, CharonY said:

The trade-off model is more generalized and states that individuals in different conditions face different fitness trade-offs. As the respective optima vary, the signals have to adaptive to these conditions. Under these parameters, deception becomes net unprofitable. I.e. we are looking essentially at a condition-dependent trade-off between marginal benefits and costs. As TheVat pointed out, the optimization of these parameters are honest by by pushing the trade-off to the individual optimum.

This may well have a lot of truth in it. The paper certainly seems to be pushing in this direction. But having slogged my way through it, my immediate response to the literature collectively is 'what a #@$!! shambles'. And 'where's the field data?'

Edited September 14Sep 14 by sethoflagos
missing link

2 hours ago, sethoflagos said:

This may well have a lot of truth in it. The paper certainly seems to be pushing in this direction. But having slogged my way through it, my immediate response to the literature collectively is 'what a #@$!! shambles'. And 'where's the field data?'

That is absolutely a weakness of most of these hypotheses. They tend to be modeling approaches to see if that would work in principle, but they are often based on very little biological data (if any). Most publications aim to build hypotheses so that other groups would to the actual work (and the former get most of the glory...;P). But I think this is generally true in biological sciences, modelling is important, but it always lags behind the experimental or observational data to support or refute them. This is why at least for now AI is making limited inroads into biology, as we have still a dearth of information and understanding of these systems. There are a few papers including on birds of paradise in my memory who have tried to measured some parameters. I don't recall them offhand, however as I believe the data set provided only limited conclusions. But maybe it is just my recollection- I have only skimmed those (outside my field of expertise).

Edit: just saw a paper still in my files:

Proc Biol Sci. 2022 Jun 1;289(1976):20220444

https://doi.org/10.1098/rspb.2022.0444

This is not exactly what we were discussing, but it is a meta-analysis of studies where the effect of sexual signals on predation are studied (though I cannot comment on the quality of those papers). They did find wide variation which they interpreted that the cost of sexual signalling is very context-dependent and might in some cases carry no cost or even reduce predation chance.

There is also a follow-up discussion on predatory eaves-dropping by olfactory and acoustic signals, whereas visual signals showed no higher risk.

But in summary, cost appeared to be highly context-dependent, making the cost (handicap) as the primary principle to assess honesty rather unlikely.

The framework at the intersection of ethology and evo biology, laid out by Tinbergen (his famous 4 questions), is one that demands mindnumbing quantities of field data. Where this intersects with ornithology, there is the benefit of the popularity of birding, so a large army of passionate amateurs can potentially be recruited. Does that lead to quality data? Maybe serious birders can answer that.

Citizen scientists seem to be more interested in birds than, say, hedgehogs. Not hard to understand. 🔭🦅

Honestly, pretty much anything in biology requires a mind numbing amount of data. Looking at more recent paper specifically in behavioral sciences seems to add yet another slightly dimensions, which is basically learning. It touches on two of his questions, but they focus necessarily on population level effects in order to focus on the evolutionary context.

As such, in most areas of biology we tend to look at general principles that can be extended over populations or species as the organizing unit. However, in my read, behavioural sciences have become more granular, and while they still deduce general principles, they increasingly acknowledge individuality in animals that are dependent on unique experiences. While close, they are in my mind not fully embedded within Tinbergen's framework and are probably most closely to what is considered to be ontogeny.

It is a bit of an expansion of the more classic, reductionist view and opens up even more complexity. I am not yet sure where the field is going but I think it helps to a large agree to explain some phenomena that are often simply not measured in traditional ethological studies.

4 hours ago, TheVat said:

The framework at the intersection of ethology and evo biology, laid out by Tinbergen (his famous 4 questions), is one that demands mindnumbing quantities of field data. Where this intersects with ornithology, there is the benefit of the popularity of birding, so a large army of passionate amateurs can potentially be recruited. Does that lead to quality data? Maybe serious birders can answer that.

In lieu of a 'serious birder', perhaps I'll do for now. 😝

Where's the payback in amassing say 5 years worth of personal observation of a particular taxon only to have it generally dismissed by the better qualified receivers as 'an exceptional case' simply because it jars a little with their pet statistical model. Maybe doesn't quite mesh with someone's projection of idealised human gender norms, or rational economic behaviour patterns (which seems to get excessive attention in creating these models).

I'm only being a tad ironic here.

Also, here's my entire life records for the male white morph African Paradise Flycatcher (Terpsiphone viridis ferreti). (not many folk have knowingly seen one of these)

Where would one even start to get fine-grained population dynamics data on a subject whose behaviour was clearly significantly influenced by th observer's proximity.

18 hours ago, sethoflagos said:

Where would one even start to get fine-grained population dynamics data on a subject whose behaviour was clearly significantly influenced by th observer's proximity.

That is why, unfortunately, a lot of quantitative data is collected in artificial and controllable environments. However, it is well-known that those are prone to artifacts and in many cases do not represent what is happening in nature. I am sure the discussion is fairly old, but at least in the last decade or so it seems that the warnings are a bit more prominent than they used to be (certainly compared to when I was studying ethology as an undergrad).

I’ve been thinking now, that perhaps the Handicap Principle isn't actually so counter-intuitive as it can look like. A question for those familiar with Grafen’s experiment: am I right that the "handicaps" (inherently disadvantageous traits that help a male attract females precisely because they are disadvantageous) are exclusively male traits that aren't passed on to female offspring?

In humans, for instance, these would be traits encoded on the Y chromosome, which women lack. That makes the whole subject seem more or less clear. Suppose a man has a huge ..., so large that it actually harms him and hinders his survival. A woman considering him as a potential father for her future children knows that if they have daughters, those daughters won't inherit this disadvantaguos trait; instead, they’ll inherit other genes of this man (i.e. the ones that allowed him to survive despite this problem). It’s trickier with sons, but there’s another factor at play: if conditions for the population turn bad and 90% of the males die, nobody really cares, because the remaining 10% will be still able fertilize all the females and pass them their good genes. I think I understand it a bit better now.

But that implies that Dawkins was talking nonsense in the final sentence of the last quote above (signal of an animal to a lion) that’s not exactly how it works.

1 hour ago, Linkey said:

In humans, for instance, these would be traits encoded on the Y chromosome, which women lack. That makes the whole subject seem more or less clear. Suppose a man has a huge ..., so large that it actually harms him and hinders his survival. A woman considering him as a potential father for her future children knows that if they have daughters, those daughters won't inherit this disadvantaguos trait; instead, they’ll inherit other genes of this man (i.e. the ones that allowed him to survive despite this problem).

It's worth noting that the Y-chromosome is a very small chromosome containing very little genetic information. It is my understanding that the Y-chromosome contains the trigger gene for producing male characteristics, but not the genes for actually producing male characteristics. I recall an episode of "House" in which a rather beautiful young woman had a Y-chromosome that contained a defective trigger gene, and therefore failed to develop any male characteristics, being physically female by default.

5 hours ago, KJW said:

It's worth noting that the Y-chromosome is a very small chromosome containing very little genetic information. It is my understanding that the Y-chromosome contains the trigger gene for producing male characteristics, but not the genes for actually producing male characteristics.

It's worth noting that a lack of understanding has never stopped @Linkey from making an unsupported argument ...

7 hours ago, Linkey said:

A question for those familiar with Grafen’s experiment: am I right that the "handicaps" (inherently disadvantageous traits that help a male attract females precisely because they are disadvantageous) are exclusively male traits that aren't passed on to female offspring?

No. And most genes do not express as simple specific phenotypic traits. For example, male baldness is mediated by over 250 gene loci and most of them are autosomal.

The Y chromosome only has a regulatory transcription factor, SOX9, which gets gonadal tissues to differentiate into testes and gets other tissues to be androgen receptive, i.e. it turns a vast array of other genes off, or on, to foster male development. Again, most of these other genes are autosomal, since a transcription factor can migrate all over the DNA.

For those wishing to further explore the teenage supermodel episode which @KJW mentions (which I warn also involves a disturbing theme of parental incest, as well as House's usual levels of insensitivity and bluntness):

https://youtu.be/ZFWMIZsxIhs?si=29gHfbv175Gv1Z6f

If you want to skip to the topic relevant (sort of) part, it's around minute 9:00.

7 hours ago, MigL said:

It's worth noting that a lack of understanding has never stopped @Linkey from making an unsupported argument ...

Such as birds being subject to ZW sex determination, for example?

1 hour ago, sethoflagos said:

Such as birds being subject to ZW sex determination, for example?

Or, for that matter XY chromosomal functions in humans, based on this framing:

16 hours ago, Linkey said:

In humans, for instance, these would be traits encoded on the Y chromosome, which women lack.

There is a reason why in men X-linked traits are dominant (and not it is not because of feminism). Women have two functional X chromosomes, whereas in men one is a reduced version, as KJW mentioned, which is why it looks more like a Y in a karyogram. I.e. men are lacking bits of a whole X-chromosome is a slightly more accurate framing.

8 hours ago, TheVat said:

The Y chromosome only has a regulatory transcription factor, SOX9, which gets gonadal tissues to differentiate into testes and gets other tissues to be androgen receptive, i.e. it turns a vast array of other genes off, or on, to foster male development.

Slight clarification, the Y chromosome does have more genes (though estimates vary). Beyond encoding the SOX-9 protein, it also encodes the SRY protein, that activates the expression of the Sox9 gene, for example. IIRC a full X chromosome has over 1k genes, whereas estimate of the Y chromosome are around 100-ish.