Given this difference in timing of the divergence between the two species and the formation of the Isthmus, the fact that their ranges are currently separated by the Isthmus suggests that caution must be used when inferring a causal role for geographic barriers based solely on overlap with genetic breaks.
It is possible that representations of duration, encoded in the brain in a particular pattern of neural activity, can be rooted in distinct context-specific brain areas, thus accounting for divergence in different timing behaviours.
Despite the recent convergence in the quantum of fertility (Kreyenfeld 2003), significant divergences in the timing and forms of family formation persist and characterize the two regions.
In general, the input species tree can be undated, partially dated, or fully dated depending on whether the divergence timing information associated with the nodes of the species tree is absent, partial, or complete, respectively.
We also found weak evidence for genetically based population divergence in return migration timing, with natives returning earlier than non-natives and hybrids intermediate.
There, Unwin et al. (2000) documented a divergence in juvenile migratory timing associated with differences in water temperatures that had affected juvenile growth, an association similar to that observed in Snake River fall Chinook salmon.
Although it is unclear how this relates to our results, it is important to acknowledge the uncertainty that exists in our results, in the 1 6 poplar: Arabidopsis ratio and in timing divergence, even when relaxed molecular clocks are used.
Molecular clock estimates showed that the timing of divergence in Joshua tree was substantially earlier than in the moths, rejecting the hypothesis that a common vicariant event caused the divisions within these species.
Here we present analyses of sequences of mitochondrial and nuclear loci from across the distribution of the three taxa to assess lineage diversity, relationships, and relative timing of divergence in amphiumid salamanders.
This low degree of validation reflected the divergence in the stage-specificity and timing of transcriptional programming.
