Do we have any empirical evidence in favor of species (or lineage) selection? Do we know some cases that can only be explained (or seem to be only explained) by lineage selection? What are today the best study cases in favor of lineage selection?

If not, how could we find any evidence for lineage selection?

Note: I call lineage selection a differential in speciation and/or extinction rate that drive the proportion of lineage (species for example) displaying a given trait (emergent traits or not) to increase or decrease over time.


A commonly used empirical example of species selection (a.k.a clade selection, lineage selection) is pelagic larvae in sessile ocean species. See Maliska et al (2013) for a recent paper discussing this in Tunicata and Jablonski & Hunt (2006) for larval modes in gastropods. The idea is to some extent really intuitive - pelagic larvae means higher dispersal rates, so the species will be exposted to and can colonize new environments. This can lead to speciation through adaptive radiation. Larger ranges also means lower extinction rates (e.g. through less population synchrony). If the trait is fixed within a lineage, this lineage as a whole will, as compared to an sister lineage lacking the trait, contain more species (i.e. species selection).

However, you can also argue that pelagic larvae will lead to higher gene flow between populations, which could inhibit speciation. Therefore, the effect of pelagic larvae, and how these mechanisms are weighted in practice, is really an empirical question (see Duda & Palumbi, 1999 and Jablonski & Hunt, 2006 for discussions on this issue).

Jablonski (2008) provides a nice general review of species selection (concept, mechanisms, theoretical models and data), and Okasha (2006) (chap. 7) is good for a theoretical/philosophical treatment of levels of selection. Also remember that traits are selected for at the individual level, but can (especially if fixed) still act on a lineage level.


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