Complex sentence: Males can be distinguished from females by the presence of a jagged crest, which is more prominent during the breeding season, that runs along their backs, dipping at the rear of the abdomen to a smoother-edged crest above and below the tail.
Split into simpler sentences: Males can be distinguished from females by the presence of a jagged crest during the breeding season. This runs along their backs, then a separate smoother-edged crest runs above and below the tail.