Friday, April 5, 2013

Updated information about lab-meeting on April 9: ERC, phylogenies and tropical diversification

This is an update about the coming lab-meeting on Tuesday April (10.30), as there was some mis-communication, and it turns out Lesley will not be able to attend the meeting due to a course in landscape genetics, and this is probably also the case for Rachel and Maren. The lab-meeting on Tuesday will start with  Jessica presenting her ERC-talk for the coming interview in Brussels, and she can then get final feedback from the lab-members that attend. Our new student Anais from Cataluna has also promised to bring some catalunian "fika", and we can try out the red wine she brought last week.

Then, we should discuss this paper that I originally suggested which deals with how the use of multiple phylogenies can be used to answer basic ecological and evolutionary questions about the niche conservatism and range expansions and test the classical "tropical conservatism" hypothesis. This paper is in press in Evolution, and is quite long, but in case you have time you can also read the shorter paper Lesley suggested that was published in Ecology Letters

Both these papers are thematically similar and demonstrate the power of a phylogenetic perspective and modern comparative methods to address fundamental problems and general processes in ecology and evolution. The titles and abstracts of both papers are posted below. Enjoy!


We reviewed published phylogenies and selected 111 phylogenetic studies representing mammals, birds, insects, and flowering plants. We then mapped the latitudinal range of all taxa to test the relative importance of the tropical conservatism, out of the tropics, and diversification rate hypotheses in generating latitudinal diversity gradients. Most clades originated in the tropics, with diversity peaking in the zone of origin. Transitions of lineages between latitudinal zones occurred at 16–22% of the tree nodes. The most common type of transition was range expansions of tropical lineages to encompass also temperate latitudes. Thus, adaptation to new climatic conditions may not represent a major obstacle for many clades. These results contradict predictions of the tropical conservatism hypothesis (i.e., few clades colonizing extratropical latitudes), but support the out-of-the-tropics model (i.e., tropical originations and subsequent latitudinal range expansions). Our results suggest no difference in diversification between tropical and temperate sister lineages; thus, diversity of tropical clades was not explained by higher diversification rates in this zone. Moreover, lineages with latitudinal stasis diversified more compared to sister lineages entering a new latitudinal zone. This preserved preexisting diversity differences between latitudinal zones and can be considered a new mechanism for why diversity tends to peak in the zone of origin.

  • Alex L. Pigot*
  • Joseph A. Tobias

  • Whether biotic interactions limit geographic ranges has long been controversial, and traditional analyses of static distribution patterns have made little progress towards resolving this debate. Here, we use a novel phylogenetic approach to test whether biotic interactions constrain the transition to secondary sympatry following speciation. Applying this temporal framework to a diverse clade of passerine birds (Furnariidae), we reject models of geographic range overlap limited purely by dispersal or environmental constraints, and instead show that rates of secondary sympatry are positively associated with both the phylogenetic and morphological distance between species. Thus, transition rates to sympatry increase with time since divergence and accelerate as the ecological differences between species accumulate. Taken together, these results provide strong empirical evidence that biotic interactions – and primarily ecological competition – limit species distributions across large spatial and temporal scales. They also offer phylogenetic and trait-based metrics by which these interactions can be incorporated into ecological forecasting models.

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