What are the Current Debates in Evolutionary Science?

[kosovo dave]

I'm curious about what debates are currently going on within the scientific community. Are there still things about evolution that scientists don't understand or agree upon? Links/sources would be greatly appreciated!

 

[D H]

Current trends in evolutionary biology -- that certainly is a good discussion topic. Discussions of evolution vs creationism is not. Creationism is pure nonsense.

To those who wish to post a reply, please keep the above in mind.

 

[Greg Bernhardt]

Here are a few questions that are being worked on1. Does evolution tend to proceed slowly and steadily or in quick jumps?

2. Why are some clades very diverse and some unusually sparse?

3. How does evolution produce new and complex features?

4. Are there trends in evolution, and if so, what processes generate them?

http://evolution.berkeley.edu/evolibrary/article/evo_50

 

[Ygggdrasil]

Here are some more interesting questions in evolutionary biology, along with some scientific articles on the subjects:

1) To what extent is evolution deterministic? If we were to "replay the tape of life" (i.e. go back in the evolutionary history of an organism and let it evolve again under the same or similar circumstances), would you get the same result? To what extent can we predict how a system will evolve and use that knowledge to fight disease (e.g. pathogens or cancer)?

Lobkovsky and Koonin. 2012. Replaying the Tape of Life: Quantification of the Predictability of Evolution. Front Genet 3: 246. doi:10.3389/fgene.2012.00246 PMCID:3509945

Łuksza & Lässig. 2014. A predictive fitness model for influenza. Nature, 507: 57. http://dx.doi.org/10.1038/nature13087

2. How did eukaryotes evolve? What gave rise to the unique features of eukaryotes such as the nucleus and innermembrane system, the widespread use of introns and gene splicing, the spatial separation of transcription and translation, the ability to form complex, multicelular organisms, etc.?

Williams et al. 2013. An archaeal origin of eukaryotes supports only two primary domains of life. Nature 504: 231. http://dx.doi.org/10.1038/nature12779

The Birth of the Nucleus (non-peer-reviewed news article from Science) http://www.sciencemag.org/content/305/5685/766.full

 

[phinds]

I cannot give you sources but I read recently that there have been some very surprising discoveries about the fact that evolution can in some circumstances proceed much more rapidly than was previously believed, even by those who are firmly in the "jumps and starts" camp. Since this is a relatively new discovery, there is debate about how widely it might apply. That is, were the instances discovered one-offs or something more systemic?

 

[atyy]

I found this hilarious. Nowak et al attacked the concept of "inclusive fitness" for explaining eusociality. Many disagreed.

http://www.ncbi.nlm.nih.gov/pubmed/20740005 (free link at top right)
The evolution of eusociality.
Nowak MA, Tarnita CE, Wilson EO.
Nature. 2010 Aug 26;466(7310):1057-62.
Eusociality, in which some individuals reduce their own lifetime reproductive potential to raise the offspring of others, underlies the most advanced forms of social organization and the ecologically dominant role of social insects and humans. For the past four decades kin selection theory, based on the concept of inclusive fitness, has been the major theoretical attempt to explain the evolution of eusociality. Here we show the limitations of this approach. We argue that standard natural selection theory in the context of precise models of population structure represents a simpler and superior approach, allows the evaluation of multiple competing hypotheses, and provides an exact framework for interpreting empirical observations.

http://rspb.royalsocietypublishing.org/content/278/1723/3313.full
The validity and value of inclusive fitness theory.
Bourke AF.
Proc Biol Sci. 2011 Nov 22;278(1723):3313-20. doi: 10.1098/rspb.2011.1465.
"If the analysis of these authors is correct, then inclusive fitness theory has been a decades-long distraction in the field that is theoretically unsound, unnecessarily focused on genetic relatedness and poorly supported by the empirical evidence. If it is not correct, then the theory has been on the right lines all along and it is the critiques that are shaky. The critique by Nowak et al. [38] has met with both support [39–41] and rebuttal [42–50]. In a response, Nowak et al. [51] maintained their view that ‘Inclusive fitness theory is neither useful nor necessary to explain the evolution of eusociality or other phenomena’."

By googling "The evolution of eusociality", I see that Jerry Coyne disliked the paper. The following commentary is not peer-reviewed, but I think we can make an exception for Jerry Coyne.

http://whyevolutionistrue.wordpress.com/2010/08/30/a-misguided-attack-on-kin-selection/
A misguided attack on kin selection
Jerry A. Coyne

 

[willbell]

I found this hilarious. Nowak et al attacked the concept of "inclusive fitness" for explaining eusociality. Many disagreed.

This is probably the most major debate in evolution nowadays, kin selection is being brought into the spotlight, even being questioned by the person who proposed it E.O. Wilson. However it seems to be still on fairly firm ground.

Another common issue is adaptationism (the belief that everything is the way it is because it serves a purpose) vs neutral theory (the belief that some alleles are fixed due to genetic drift), and to what extent each applies.

 

[Cal King]

There is a debate raging on as to whether birds evolved from an advanced theropod dinosaur, or whether they evolved from a thecodont like Longisquama insignis. On one side are most of the paleontologists and their employers, the museums that spend millions constructing exhibits. They are firmly on the side of the dinosaurian origin of birds. On the other side are a few knowledgeable paleontologists who point out that flight from the ground up is extremely unlikely, that there is no known tree climbing dinosaur and that if a theropod dinosaur tries to launch itself into the air, it would end up as a grease spot on the ground. Many paleontologists do not like the debate and they want us to stop arguing and accept as fact that birds evolved from a dinosaur. Others disagree, and claim that there is a mountain of evidence opposing the dinosaurian origin of birds.

http://www.aou.org/auk/content/130/1/0001-0013.pdf

 

[willbell]

There is a debate raging on as to whether birds evolved from an advanced theropod dinosaur, or whether they evolved from a thecodont like Longisquama insignis. On one side are most of the paleontologists and their employers, the museums that spend millions constructing exhibits. They are firmly on the side of the dinosaurian origin of birds. On the other side are a few knowledgeable paleontologists who point out that flight from the ground up is extremely unlikely, that there is no known tree climbing dinosaur and that if a theropod dinosaur tries to launch itself into the air, it would end up as a grease spot on the ground. Many paleontologists do not like the debate and they want us to stop arguing and accept as fact that birds evolved from a dinosaur. Others disagree, and claim that there is a mountain of evidence opposing the dinosaurian origin of birds.

http://www.aou.org/auk/content/130/1/0001-0013.pdf

For some reason I think I can guess which side you're on. ;)

 

[Pythagorean]

The existence of "master genes". (edit: Actually, existence is probably the wrong term. It's more about the interpretation of what such genes imply about the process of evolution).

More formally, from John Kaas Evolutionary Neuroscience:
Ch 1.1, "Common plan vs. diversity"

many biologists proceeded to search for molecular genetic
homologies that could reveal previously unimagined
morphological homologies (Janies and DeSalle, 1999).
Geoffroy would have been thrilled. There are, however,
problems with the view that animals are all alike.
The most serious problem, in my view, is that
homologous genes may sometimes be involved in
the development of adult structures that are clearly
not homologous (Striedter and Northcutt, 1991).
For example, insect wings and vertebrate nervous
systems both depend on hedgehog function for normal
development, but this does not make neural
tubes and insect wings homologous (Bagun˜a and
Garcia-Fernandez, 2003). Instead, findings such as
this suggest that evolution tends to work with highly
conserved ‘master genes’ (Gehring, 1996) or, more
accurately, tightly knit assemblies of crucial genes
(Nilsson, 2004), which it occasionally reshuffles by
altering their upstream regulatory elements and/or
downstream targets.

 

[willbell]

The existence of "master genes".

More formally, from John Kaas Evolutionary Neuroscience:
Ch 1.1, "Common plan vs. diversity"

I am confused, what are these in relation to hox genes?

 

[Pythagorean]

I am confused, what are these in relation to hox genes?

My understanding is that hox genes would be an example of master genes. They control more large scale morphology. Gehring's master genes were particular to eye morphology.

 

[willbell]

My understanding is that hox genes would be an example of master genes. They control more large scale morphology. Gehring's master genes were particular to eye morphology.

Okay, before your edit I was confused because it seemed to be describing hox genes but said their existence was debated.

 

[Pythagorean]

Okay, before your edit I was confused because it seemed to be describing hox genes but said their existence was debated.

Yes, the genes themselves definitely exist; my impression from my first reading of Kaas was that the concept of "master genes" is what's disputed... but I thought "master genes" implied some kind of universal homology. Now that I've looked a little closer, the term just more loosely describes the direct observation that these genes are at the top of the hierarchy of a series of coordinated processes.

 

[willbell]

Yes, the genes themselves definitely exist; my impression from my first reading of Kaas was that the concept of "master genes" is what's disputed... but I thought "master genes" implied some kind of universal homology. Now that I've looked a little closer, the term just more loosely describes the direct observation that these genes are at the top of the hierarchy of a series of coordinated processes.

Okay, that makes more sense. The only universal gene is DNA+RNA polymerase AFAIK, the central dogma is the only thing that life accepts... dogmatically. ;)

 

[Pythagorean]

Hrmm.. I wonder what the chance of the same gene showing up independently in two different species is? (Not the aforemention polymerases, just in genera). I know there's morphological examples of convergent evolution, but are there precise genetic examples?

 

[willbell]

Hrmm.. I wonder what the chance of the same gene showing up independently in two different species is? (Not the aforemention polymerases, just in genera). I know there's morphological examples of convergent evolution, but are there precise genetic examples?

Very very small, most traits have many ways to the same result (bee's and bird's wings for example), especially because the biochemical environment in which the traits are evolving are different (as they would be in unrelated species).

 

[Cal King]

This is probably the most major debate in evolution nowadays, kin selection is being brought into the spotlight, even being questioned by the person who proposed it E.O. Wilson. However it seems to be still on fairly firm ground...

There is a problem with kin selection theory, identified early by social scientists who rebutted E.O. Wilson's book "Sociobiology: The New Synthesis." They point out that kin selection theory is a tautology, meaning it can explain everything. For example, selfish behavior can be explained by individual fitness, but seemingly altruistic behavior can also be explained, by "inclusive fitness." A tautology can never be falsified. Therefore a kin selectionist can invent all sorts of stories and never have to be subjected to falsification.

 

[Ygggdrasil]

Hrmm.. I wonder what the chance of the same gene showing up independently in two different species is? (Not the aforemention polymerases, just in genera). I know there's morphological examples of convergent evolution, but are there precise genetic examples?

Horizontal gene transfer is one example which produces this phenomena at the genetic level.

 

[willbell]

There is a problem with kin selection theory, identified early by social scientists who rebutted E.O. Wilson's book "Sociobiology: The New Synthesis." They point out that kin selection theory is a tautology, meaning it can explain everything. For example, selfish behavior can be explained by individual fitness, but seemingly altruistic behavior can also be explained, by "inclusive fitness." A tautology can never be falsified. Therefore a kin selectionist can invent all sorts of stories and never have to be subjected to falsification.

It could be falsified, by altruism that is geared specifically towards non-kin or even different species. I'm curious, if you'd still consider that tautology, what exactly would you want out of a theory of altruism? After all, any theory that explains altruism would fit into "selfish behaviour can be explained by individual fitness, but seemingly altruistic behaviour can be explained by <insert theory of altruism here>".

 

[jk22]

It's sometimes said that evolution cannot be falsified, but what about if we consider this experiment : we take a black person and put for some years in a world region with less sun. Then analyzing the genes for reproduction we could maybe see a diminution in the probability for the genes coding for melatonine ? (or the reverse way, a white in africa), thus proving an adaptation of the genome to the environnement...

 

[Pythagorean]

It's sometimes said that evolution cannot be falsified, but what about if we consider this experiment : we take a black person and put for some years in a world region with less sun. Then analyzing the genes for reproduction we could maybe see a diminution in the probability for the genes coding for melatonine ? (or the reverse way, a white in africa), thus proving an adaptation of the genome to the environnement...

That wouldn't falsify evolution and it's not a contested point that adaptation depends on environment. Genetics is only half of evolution.

 

[willbell]

It's sometimes said that evolution cannot be falsified, but what about if we consider this experiment : we take a black person and put for some years in a world region with less sun. Then analyzing the genes for reproduction we could maybe see a diminution in the probability for the genes coding for melatonine ? (or the reverse way, a white in africa), thus proving an adaptation of the genome to the environnement...

Evolution requires several generations to act, mutations don't just happen like that (the only ones that have a chance of getting passed on happen in your reproductive organs). Plus, we've already seen changes in species to suit their environment, so it would hardly be something new.

 

[willbell]

Horizontal gene transfer is one example which produces this phenomena at the genetic level.

Pythagorean seems to be trying to talk about it happening through evolutionary means (two separate genes evolving to be the same), rather than Horizontal Gene Transfer, in which the gene only evolves once.

 

[jk22]

That wouldn't falsify evolution and it's not a contested point that adaptation depends on environment. Genetics is only half of evolution.

But how would evolution act on a lot of generation if it's not transferred in the genes ?

 

[Ryan_m_b]

But how would evolution act on a lot of generation if it's not transferred in the genes ?

An individuals genome doesn't change, you have the same genome through out your life. When reproduction occurs the offspring gets half its genetic material from one parent and half for another but when that DNA is made it is not copied perfectly. There will be errors such as changes in the sequence, duplicated segments, deleted segments etc. This means the organism will be ever so slightly different. Going back to your example of a population of black people moved to higher latitudes: some children will randomly be born with mutations causing slightly less melanin to be produced. These children will have a slight advantage in terms of vitamin D synthesis and be more likely to stay healthy and have kids of their own, thus spreading the genes for lighter skin. This process repeats itself over and over until an optimum level is reached.

 

[Pythagorean]

Pythagorean seems to be trying to talk about it happening through evolutionary means (two separate genes evolving to be the same), rather than Horizontal Gene Transfer, in which the gene only evolves once.

Yeah, I was thinking convergent evolution, where the same thing evolves in two separate lines. Morphological convergence is quite common, but molecular convergence is rare:

http://www.ncbi.nlm.nih.gov/pubmed/20539788

 

[Torbjorn_L]

There is a debate raging on as to whether birds evolved from an advanced theropod dinosaur, or whether they evolved from a thecodont like Longisquama insignis. On one side are most of the paleontologists ...

"Based on fossil and biological evidence, most scientists accept that birds are a specialized subgroup of theropod dinosaurs. ... A small minority of researchers, such as paleornithologist Alan Feduccia of the University of North Carolina, oppose the majority view ..." [ http://en.wikipedia.org/wiki/Birds#Dinosaurs_and_the_origin_of_birds ]

I don't think that is much of a debate or raging, or a useful idea which is imperative in science. It has the telltale signs of a rejected minority opinion that awaits its defenders to die the usual extinction death of failed differential reproduction.

In the context, I don't think thecodonts are recognized anymore. "Thecodontia (meaning "socket-teeth"), now considered an obsolete taxonomic grouping,". [ http://en.wikipedia.org/wiki/Thecodontia ]

 

[DiracPool]

More formally, from John Kaas

There's no "h" in Jon's name Pythagorean, just for the record. I must say, though, I am impressed with your reference here. In my mind, Jon Kaas is the premier evolutionary neuroscientist we have. Northcutt is great as well. A lot of my research is based off Kaas' work. Here's a cool article if you're interested: http://www.ncbi.nlm.nih.gov/pubmed/?term=kaas+mice+men

He had a graduate student, Leah Krubitzer, who's work I also love. I don't know either of them personally, but I do know Georg Striedter (just going through your reference list there). He is of hyperstriatum bird fame and gave me kind reviews on several publications of mine. Of course, a couple years back I sent him a major review article I published that he never got around to reading because he was too busy with his new job as the editor of Brain, Behavior, and Evolution. I'm sure that's a tough gig, but he could have at least pretended that he was interested in my paper. That still miffs me.

 

[atyy]

Hrmm.. I wonder what the chance of the same gene showing up independently in two different species is? (Not the aforemention polymerases, just in genera). I know there's morphological examples of convergent evolution, but are there precise genetic examples?

Yeah, I was thinking convergent evolution, where the same thing evolves in two separate lines. Morphological convergence is quite common, but molecular convergence is rare:

http://www.ncbi.nlm.nih.gov/pubmed/20539788

Another example: http://phys.org/news/2014-06-truth-electric-fish.html?