Table 2.

Gene diversity across developmental stages

Libraries	No. of sequences	No. of distinct genes	Gene discovery rate, %	No. of singletons	Percentage of singletons
Embryonic	2,920	1,929	66.1	1,056	36.2
Developmental I	3,566	2,593	72.7	1,581	44.3
Developmental II	1,873	1,611	86.0	989	52.8
Developmental III	1,486	1,158	77.9	555	37.4
Total	9,845	5,866	59.6	4,181	42.5

Within each library, distinct genes refer to clones that represent different sequences. Gene discovery rate = (number of distinct genes)/(number of sequenced clones in a library). Singletons refer to the clones that appear as a single copy and do not match any other clones in any of the libraries. Percentage of singletons = (number of singletons)/(number of sequenced clones in that library). The gene discovery rate is significantly higher in Developmental Library II than in each of the other libraries (Fisher's exact test; P < 10⁻⁸ in all cases). The comparison between Developmental Libraries II and III, which contain similar numbers of sequences, is significant, P < 1.2 × 10⁻⁹.