Monday, May 2, 2011

Reinventing species selection with molecular phylogenies

When I was a PhD-student in Sweden in the nineties, one of the most ugly words you could say was "group selection", and the so-called "selfish-gene paradigm" of Richard Dawkins was taken as almost a religious truth. These were the days when behavioural ecology ruled much of of the scentific activities in biology in Scandinavia and Britain. Lower-level selection of selfish genes was assumed to be either the only or at least the major evolutionary force that would explain all adaptation and biological diversity. Higher-level selection, on goups, demes, populations or species, was either deemed impossible or dismissed as unimportant.

This remarkable dogmatic reductionism in Scandinavian behavioural ecology seems, in the aftermath, as both dogmatic and not very well supported by either theory or empirical evidence. Even the great population geneticist R. A. Fisher did actually believe in group selection, and for him it was mainly an empirical issue how strong it was, compared to lower-level selection of individuals and genes.

However, one thing is certain: scientific paradigms change, and clearly group-selection (or rather multi-level selection) is on the rise again. This week's lab-meeting (Wednesday May 4), we will discuss a relatively recent TREE-paper on how molecular phylogenies might be used to study the process of species selection in a statistically rigorous and empirical way. Increasing evidence suggest that macroevolutionary trends, such as increases or decreases in diversity, speciation and extinction can simply not be extrapolated from lower-level selection processes, challenging the selfish-gene paradigm. Below, you will find an abstract and a link to the paper.

Time as usual: 13.30 on Wednesday (May 4) afternoon. Place: Probably "Argumentet".

Rabovsky, M. L. & MacCune, A. R.

Trends Ecol. Evol. 25: 68-74

Abstract: Species selection as a potential driver of macroevolutionary trends has been relegated to a largely philosophical position in modern evolutionary biology. Fundamentally, species selection is the outcome of heritable differences in speciation and extinction rates among lineages when the causal basis of those rate differences can be decoupled from genotypic (within-population) fitnesses. Here, we discuss the rapidly growing literature on variation in species diversification rates as inferred from molecular phylogenies. We argue that modern studies of diversification rates demonstrate that speciesselection is an important process influencing both the evolution of biological diversity and distributions of phenotypic traits within higher taxa. Explicit recognition of multi-level selection refocuses our attention on the mechanisms by which traits influence speciation and extinction rates.




1 comment:

  1. for those interested in the matter, I highly recommend this recent paper from evolution:
    Omar Tonsi Eldakar, David Sloan Wilson.
    There is a summary of the paper on Wilson's blog which I recommend as well:

    Have a nice discussion.