Evolutionary Biology Online Journal Club

What is a “Novelty”?

5 Comments

Yesterday we discussed a paper by Hall & Kerney on “Levels of Biological Organization and the Origin of Novelty“. Although I initially didn’t really enjoy the paper, it ended up being quite interesting and it sparked some great discussion (see a video of our chat here).

Many people have shown an interest in continuing our discussion of “novelty”, so perhaps we can use this post to bounce ideas and share other papers on this topic. Some of the key themes/questions we were left wondering about were:

  1. What is a “novel” trait, and how can/should you define it?
  2. Is the classification of a trait as “novel” dependent on scale?
    1. If so, what kinds of scale (e.g., temporal, developmental)?
    2. How do you define scale in a useful way for studying macroevolution?
  3. Can a novel trait really only arise from horizontal gene transfer?
  4. Is there a disconnect between the fields of evo-devo and macroevolution in terms of defining “novelty”?

 

EBJClubber or not, anyone and everyone should feel free to join in this discussion. Leave your comments below!

Advertisements

Author: hossiet

PhD student at Carleton University. I study predator-prey interactions. My current project examines the ecology and evolution of caterpillar eyespots.

5 thoughts on “What is a “Novelty”?

  1. As an evolutionary palaeobiologist (yay fossils!) my first thought after looking through this paper was how do we distinguish a novel ‘occurrence’ from a novel ‘relic’, is it a recent specialization? is it the sole survivor of a diverse clade that that shared a novel adaptation? Does it even matter? Is this a source of incongruence between concepts of novelty re: macro and evo-devo as mentioned above? The questions are ENDLESS!

  2. (WARNING: thought dump.)

    Precisely. I for one suspect that it’s more useful just to consider everything that *isn’t* a “novelty” in the broadest sense of any definition, e.g. atavism, convergence, etc. Novelty is really just “everything else” as far as I’m concerned, and that’s too broad to be intellectually valuable on its own.

    A more charismatic and perhaps also more useful concept would be that of “innovation”–novelty causing accelerated speciation/diversification. Tetrapod limbs is obviously both a “novel” occurrence (they didn’t exist, and then later they did exist) and an “innovation” (there were no tetrapod species, then later there were lots and lots!), if you stretch out the temporal scale of your definition far enough. Which leads to what Rafael pointed out in the video, that the definition of novelty does not specify spatio-temporal bounds. I would go as far as to assume that most of us picture “innovations” when we think of novelty anyway. But a lot of our evidence for innovation is correlative, not causative, though the correlations are often particularly persuasive.

    Finally, on an abstract (and somewhat defeatist) level, we’ll never know for sure whether any particular multidimensional trait-space has been realized before, so an appropriate lower bound or acceptable level of approximation need be applied to a definition of novelty/innovation. But before I sound like I’m throwing the Hall & Kerns article under the bus… As they tried to do in their review, I think it is useful to work backwards toward a molecular/developmental mechanism behind the origin of novel traits. Perhaps the answer lies along the lines of molecular dynamics prediction. E.g. what mutations/pathways are more likely in a given scenario? We’ve seen many examples of repeated similar genetic changes in certain lineages, such as x-autosomal fusion in some jumping spiders. I also have a personal hunch that cytoplasmic inheritance and other such epigenetic modes of inheritance are behind a lot of key innovations in nature. One could argue that every endosymbiotic relationship is an innovation. So what innovations do we care about, and is there a useful set of criteria we can use to define the scale of an evolutionary innovation in a way that isn’t horribly arbitrary or (for lack of a better word) intellectually masturbatory?

    Hopefully this mind-dump of mine is at least marginally useful–or dare I say, “innovative”?

  3. Interesting thoughts Sam – I agree that epigenetic inheritance might turn out to be important for generating novelties in evolution, although I think there’s still much to be done both theoretically and empirically here. I’m not sure I agree as much about focusing on specific mechanisms though: it really depends on the aim of the review, but I think some readers might get left a bit cold if they want a broader perspective on the idea of novelty rather than delving into the details (which is maybe why I still haven’t quite read the paper in detail yet!).

    Here are my two cents (written a week ago but trouble uploading these at the time for some reason):
    I still haven’t read this paper in detail but one thing that wasn’t really discussed yesterday (maybe because the paper doesn’t go into this), which I think is an interesting angle, is the way in which development contributes to the generation of novel traits. So I think rather than development being an issue of scale (point 2), it’s more an issue about point 3 – how do novel traits arise. Recent work on phenotypic accommodation (West-Eberhard 2005, J Exp Biol) is relevant here. For a more general overview of ‘what is novelty’ – rather than the more mechanistic focus of the H&K paper (I think?) – this looks like a thought-provoking, but hefty read: ‘Novelty in Evolution: Restructuring the Concept’ (Muller & Wagner 1991, Ann Rev Ecol Syst).

  4. Pingback: EvoBio Journal Club: First season in review, and what to expect from next season « Evolutionary Biology Online Journal Club

  5. Just looked at that Muller & Wagner paper. It would definitely be an excellent paper to discuss–maybe we’ll use it for a future revisit of novelty. Thanks!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s