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

<p>The ability to subvert independent assortment of chromosomes is found in many meiotic drivers, such as the t haplotype in house mice <em>Mus musculu</em>s, in which the t-bearing chromosomal homolog is preferentially transmitted to offspring. This is explained by a poison-antidote system, in which developing + and <em>t</em> sperm in testes of + /<em>t</em> males are exposed to 'poison' coded by <em>t</em> loci, from which t sperm are protected, allowing <em>t</em> sperm an overwhelming fertilisation advantage in monogamous matings. This system is thought to result in poorly and normally motile sperm subpopulations within + /<em>t </em>sperm, leaving t sperm unharmed. Conversely, we found that the fastest quartile of sperm from + /<em>t</em> 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 + /<em>t</em> males had shorter tails and narrower heads than + / + sperm, and these morphological differences covaried with motility differences. Finally, + /<em>t</em> 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 <em>t</em> developing sperm, although previous studies indicate that + must be more harmed than <em>t</em> sperm. This damage to all sperm may explain the low success of + /<em>t</em> 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.</p>