Figure 7
Survival and development of backcrosses. a, c to e, g: tadpoles, one week after spawning. a: female B. siculus × male F1 (B. balearicus × B. siculus) - note dead embryos and malformations; b: postmetamorphic toadlets exhibited size differences among siblings and low survival; c: F2 from among hybrid crosses, female F1 (B. balearicus × B. siculus) × male F1 (B. balearicus × B. siculus) - all tadpoles malformed; d: female F1 (B. balearicus × B. siculus) × male B. balearicus - most tadpoles malformed; e, f: female B. balearicus × male F1 (B. balearicus × B. siculus) - note enormous size differences among siblings in the age of one month after spawning (f); g: female F1 (B. balearicus × B. siculus) × male B. siculus - note most tadpoles show malformations; h: F1-hybrid from crossing female B. siculus × male B. balearicus (as shown in Figure 6b) in the age of one year. Photographs: M. Stöck.