These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.01 s (backtrack: 0/20).

[ebuild  N     ] sci-biology/clustalw-2.1-r2:2::gentoo  343 KiB
[ebuild  N     ] sci-libs/gsl-2.7.1-r3:0/27::gentoo  USE="deprecated -cblas-external -static-libs" 7346 KiB
[ebuild  N     ] sci-chemistry/theseus-3.3.0-r1::gentoo  USE="-examples" 22020 KiB

Total: 3 packages (3 new), Size of downloads: 29708 KiB