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

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] sci-biology/clustalw-2.1-r2:2::gentoo  343 KiB
[ebuild  N     ] virtual/fortran-0-r1::gentoo  USE="openmp" 0 KiB
[ebuild  N     ] sci-chemistry/tm-align-20150914-r1::gentoo  USE="-custom-cflags" 960 KiB
[ebuild  N     ] sci-biology/t-coffee-11.00-r3::gentoo  3421 KiB

Total: 4 packages (4 new), Size of downloads: 4723 KiB