Data from: A meiotic driver alters sperm form and function in house mice: a possible example of spite

The ability to subvert independent assortment of chromosomes is found in
many meiotic drivers, such as the t haplotype in house mice Mus musculus,
in which the t-bearing chromosomal homolog is preferentially transmitted
to offspring. This is explained by a poison-antidote system, in which
developing + and t sperm in testes of + /t males are exposed to
‘poison’ coded by t loci, from which t sperm are
protected, allowing t sperm an overwhelming fertilisation
advantage in monogamous matings. This system is thought to result in
poorly and normally motile sperm subpopulations within + /t sperm, leaving
t sperm unharmed. Conversely, we found that the fastest quartile of sperm
from + /t males swam more slowly, both forwards and along their
travel path, and had reduced straightness and linearity, compared to the
fastest quartile of + / + sperm. Moreover, sperm from + /t males
had shorter tails and narrower heads than + / + sperm, and these
morphological differences covaried with motility differences.
Finally, + /t traits did not show evidence of bimodal
distributions. We conclude that the t haplotype drive results in lasting
damage to the motility of both + and t developing sperm,
although previous studies indicate that + must be more harmed
than t sperm. This damage to all sperm may explain the
low success of + /t males in sperm competition with + / + males,
seen in earlier studies. We propose that the harm the t causes to itself
could be termed ‘spiteful’, which may also be common to other
gamete-harming meiotic drive systems.