Rough analysis

June 23, 2017

After another full week of dedicated attention to leaves in the lab, I’ve managed to record the size and shape of about a third of the target leaves (10 leaves each from the 36 Latin American Viburnum species). This week, I added a few especially large-leafed species: V. jucundum, V. disjuntum, and V. microcarpum. These three, keeping with the replicated radiation hypothesis, also have thick hair on the bottom of the leaf lamina and quite a few teeth on the leaf margins.

jucundum1
On the left, Viburnum juncundum leaves (above) and margins (below) showing hair and teeth. On the right, Viburnum microcarpum leaves (above) and tips (below)

With all the data collected so far, Professor Donoghue was interested in taking a look at some of the preliminary leaf shape and size comparisons. After coming up with a simple plot of leaf blade length over leaf blade width, we were able to see the divergence of leaves in a couple of clades of Viburnum—one in Chiapas, Mexico and the other in Bolivia. We were also able to see convergence in these blade measurements between V. lautum and V. acutifolium—two smaller leafed species, whose leaves are also nearly hairless and toothless.

For me, this perspective was quite fascinating. As Professor Donoghue explained, we could then start combining data from other factors, such as weather, to place the leaf morphometries within a wider context. For example, the divergence between V. seemenii and V. ayavacense in the Bolivia clade corresponded, respectively, to the drier and wetter areas these plants grown in. Even though much more thorough analysis remains, being able to intersperse leaf data collection with an analytical view of the progress so far was certainly rewarding.

bolivia clade leaf size
Blade dimensions for measured leaves, parsed by species. Annotation shows divergence between V. ayavacense and V. seemenii, two plant species found in Bolivia.
chiapas clade leaf size
Annotation here highlights Viburnums found in Chiapas, Mexico. V. lautum and V. acutifolium show convergence in blade length and width, while V. Jucundum diverges from both.

 

Another highlight for the week includes lab presentations in preparation for this year’s Evolution meeting in Portland, Oregon. Postdoc Michael Landis presented on modeling evolution in vertebrates using Lévy processes (as opposed to the traditionally used Gaussian processes such as Brownian motion and the Ornstein-Uhlenbeck process), and Beth Spriggs presented on resolving a North American lineage of Viburnum found across the Eastern seaboard of the US. Watching these, I gained a little more insight into the other work going on in the Donoghue Lab.

Leave a comment