The genetic basis and fitness consequences of sperm midpiece size in deer mice

Abstract

An extensive array of reproductive traits varies among species, yet the genetic mechanisms that enable divergence, often over short evolutionary timescales, remain elusive. Here we examine two sister-species of Peromyscus mice with divergent mating systems. We find that the promiscuous species produces sperm with longer midpiece than the monogamous species, and midpiece size correlates positively with competitive ability and swimming performance. Using forward genetics, we identify a gene associated with midpiece length: Prkar1a, which encodes the R1α regulatory subunit of PKA. R1α localizes to midpiece in Peromyscus and is differentially expressed in mature sperm of the two species yet is similarly abundant in the testis. We also show that genetic variation at this locus accurately predicts male reproductive success. Our findings suggest that rapid evolution of reproductive traits can occur through cell type-specific changes to ubiquitously expressed genes and have an important effect on fitness.

Essential role for SUN5 in anchoring sperm head to the tail

“…After careful examination, we found some separated but morphologically normal sperm heads, most of them had an intact acrosome and a nucleus, and only a small amount of them had defective acrosomes ( Figure 2A , Figure 2—figure supplement 1B ). We then measured the width and length of WT and Sun5 -null sperm heads ( Fisher et al, 2016 ), finding that the Sun5 -null sperm heads were wider and shorter than those of the WT ones ( Figure 2—figure supplement 1C–E ). This promoted us to investigate what exactly happened inside the so-called round-headed Sun5 -null spermatozoa, so we performed transmission electron microscopy (TEM) analysis of the epididymis from both WT and Sun5 −/− mice.…”

Relationship between the Length of Sperm Tail Mitochondrial Sheath and Fertility Traits in Boars Used for Artificial Insemination

“…Mitochondria contained within the MS generate ATP for dynein motor-driven movement of the sperm flagellum, which is vital for spermatozoa transport to the oocyte, but also produce reactive oxygen species (ROS) and perform other cellular functions. Length of sperm tail midpiece, occupied by the MS has been shown to correlate with reproductive traits in deer mice [ 1 ], as well as in domestic mice [ 2 ], salmon fish [ 3 ] and passerine birds [ 4 ]. However, it is not known whether this could be the case in domestic animals positioned higher on phylogenetic tree such as boars and bulls, and if so, whether such a parameter could be used as a fertility marker.…”

Correlates of evolutionary rates in the murine sperm proteome

“…For instance, sperm competition, the competition between sperm from several males for fertilization of a female’s ova [ 1 ], is considered to increase sperm viability in Drosophila [ 2 ] and numbers of sperm produced in mice [ 3 , 4 ]. In primates, sperm midpiece volume varies depending on mating systems and thus presumably in response to different levels of sexual selection [ 5 ] (for rodents, see [ 6 ]). Furthermore, sperm competition and other types of sexual selection, such as cryptic female choice (see, e.g., [ 7 ]) and sexual conflict (reviewed in [ 8 ]), may exert selective pressures not only on sperm form or production, but also on the proteins constituting these cells.…”