Birds have not evolved as much as evolutionary theories about them have.
Among the vast diversity of birds alive today, from ostriches to hummingbirds, only a few have been given detailed analysis by evolutionists. Those are Darwin’s finches. Is this indeed the case? Look what Cooney et al. say in Nature this week:
Small clades such as Darwin’s finches demonstrate that natural selection is the driving force of adaptive radiations, but how microevolutionary processes scale up to shape the expansion of phenotypic diversity over much longer evolutionary timescales is unclear.
While Darwin’s finches are the best-studied example (2/12/15), the only other “small clades” they refer to are Hawaiian honeycreepers and Malagasy vangas. Even if they had more examples, though, their statement is problematic at several points. For one, natural selection is not a “driving force” (see 10/03/15). For another, “adaptive radiation” presupposes Darwinian evolution rather than demonstrating it (i.e., evolutionists typically find the tips of branches of phylogenetic trees, but not the nodes or branching points of ancestral lines). Third, the authors assume that microevolution can scale up to macroevolution, but they freely admit it is “unclear” how. That’s why they went to work to address the problem.
Here we address this problem on a global scale by analysing a crowdsourced dataset of three-dimensional scanned bill morphology from more than 2,000 species. We find that bill diversity expanded early in extant avian evolutionary history, before transitioning to a phase dominated by packing of morphological space. However, this early phenotypic diversification is decoupled from temporal variation in evolutionary rate: rates of bill evolution vary among lineages but are comparatively stable through time. We find that rare, but major, discontinuities in phenotype emerge from rapid increases in rate along single branches, sometimes leading to depauperate clades with unusual bill morphologies. Despite these jumps between groups, the major axes of within-group bill-shape evolution are remarkably consistent across birds. We reveal that macroevolutionary processes underlying global-scale adaptive radiations support Darwinian and Simpsonian ideas of microevolution within adaptive zones and accelerated evolution between distinct adaptive peaks.
Read more at CREV