Triploid ZZZ Zebra Finches Taeniopygia guttata exhibit abnormal sperm heads and poor reproductive performance

Here we report the first discovery of two viable triploid male Zebra Finches Taeniopygia guttata. We compared the morphology of their sperm with that of normal diploid Zebra Finches and examined eggs resulting from a triploid male and diploid female pairing to investigate whether triploid Zebra Finches can reproduce. The majority (78%) of the triploids' spermatozoa had malformed sperm heads, which were 60% larger, and all examined eggs (n = 42) were infertile. Our results tentatively suggest that triploid ZZZ Zebra Finches cannot reproduce, and thus represent a rare evolutionary dead‐end.