Male mate preferences have been demonstrated across a range of species, including the Malaysian stalk-eyed fly, Teleopsis dalmanni. This species is subject to SR, an X-linked male meiotic driver, that causes the dysfunction of Y-sperm and the production all female broods. SR is associated with a low frequency inversion spanning most of the X chromosome that causes reduced organismal fitness. While there has been work considering female avoidance of meiotic drive males, the mating decisions of drive-bearing males have not been considered previously. As drive males are of lower genetic quality they may be less able to bear the cost of choice or may experience weaker selection for its maintenance if they are avoided by females. We investigated preference of drive males using binary choice trials. We confirmed that males prefer to mate with large females (indicative of greater fecundity) but found no evidence that the strength of male mate preference differs between drive and standard males. This suggests that the cost of choice does not restrict male reference among drive males. In a further experiment, we found that large eyespan males showed strong preference whereas small eyespan males showed no preference. This is likely to weaken mate preference in drive males, as on average they have reduced eyespan compared to standard males. In this respect, drive males are subject to and exert weak sexual selection.Lay summaryWe studied male mate preference in stalk-eyed flies. This species suffers from meiotic drive, a selfish genetic element that causes a reduction in sperm production and organismal fitness. We predicted that males with meiotic drive would show weak mate preference. Males preferred to mate with large females, but there was no difference in the strength of preference between drive and non-drive males. Males with larger eyespan showed stronger mate preference. Meiotic drive males usually have reduced eyespan so on average they exert weaker sexual selection on females, but this is mediated by eyespan, not genotype per se.

Hematopoietic stem cells (HSCs) are of major clinical importance, and finding methods for their in vitro generation is a prime research focus. We demonstrate here that the cell cycle inhibitor p57Kip2/Cdkn1c limits the number of emerging HSCs by restricting the size of the sympathetic nervous system (SNS) and the amount of HSC-supportive catecholamines secreted by these cells. This regulation occurs at the SNS progenitor level and is in contrast to the cell-intrinsic function of p57Kip2 in maintaining adult HSCs, highlighting profound differences in cell cycle requirements of adult HSCs compared with their embryonic counterparts. Furthermore, this effect is specific to the aorta-gonads-mesonephros (AGM) region and shows that the AGM is the main contributor to early fetal liver colonization, as early fetal liver HSC numbers are equally affected. Using a range of antagonists in vivo, we demonstrate a requirement for intact b2-adrenergic signaling for SNS-dependent HSC expansion. To gain further molecular insights, we have generated a single-cell RNA-Seq dataset of all Ngfr+ sympathoadrenal cells around the dorsal aorta to dissect their differentiation pathway. Importantly, this not only defined the relevant p57Kip2-expressing SNS progenitor stage, but also revealed that some neural crest cells, upon arrival at the aorta, are able to take an alternative differentiation pathway, giving rise to a subset of ventrally restricted mesenchymal cells that express important HSC-supportive factors. Neural crest cells thus appear to contribute to the AGM HSC niche via two different mechanisms: SNS-mediated catecholamine secretion and HSC-supportive mesenchymal cell production.

Male mate preferences have been demonstrated across a range of species, including the Malaysian stalk-eyed fly, Teleopsis dalmanni. This species is subject to sex-ratio (SR), an X-linked male meiotic driver, which causes the dysfunction of Y-sperm and the production of all-female broods. While there has been work considering female avoidance of meiotic drive males, the mating decisions of drive-bearing males have not been considered previously. Drive males may be less able to bear the cost of choice as SR is associated with a low-frequency inversion that causes reduced organismal fitness. Drive males may also experience weaker selection for preference maintenance if they are avoided by females. Using binary choice trials, across two experiments, we confirmed male preference for large (fecund) females but found no evidence that the strength of male preference differs between drive and standard males. We showed that large eyespan males displayed strong preference for large females, whereas small eyespan males showed no preference. Taken together, these results suggest that, even though meiotic drive is associated with lower genetic quality, it does not directly interfere with male mate preference among available females. However, as drive males tend to have smaller eyespan (albeit only ~5% on average), this will to a minor extent weaken their strength of preference.