Reproductive consequences of an extra long-term sperm storage organ

Abstract

Background Sperm storage plays a key role in the reproductive success of many sexually-reproducing organisms, and the capacity of long-term sperm storage varies across species. While there are theoretical explanations for why such variation exists, to date there are no controlled empirical tests of the reproductive consequences of additional long-term sperm storage. While Dipterans ancestrally have three long-term sperm organs, known as the spermathecae, Drosophila contain only two. Results We identified a candidate gene, which we call spermathreecae (sp3), in which a disruption cause the development of three functional spermathecae rather than the usual two in Drosophila. We used this disruption to test the reproductive consequences of having an additional long-term sperm storage organ. Compared to females with two spermathecae, females with three spermathecae store a greater total number of sperm and can produce offspring a greater length of time. However, they did not produce a greater total number of offspring. Conclusions Thus, additional long-term sperm storage in insects may increase female fitness through extending the range of conditions where she produces offspring, or through increasing the quality of offspring via enhanced local sperm competition at fertilization.

A new allele of <i>engrailed</i>, <i>en^NK14</i>, causes supernumerary spermathecae in <i>Drosophila melanogaster</i>

“…Development of the spermathecal duct requires expression of dac (dachshund) (Keisman et al, 2001) and may be influenced by invected (inv), which is located close to en and functions similarly to en (Poole et al, 1985;Coleman et al, 1987;Tabata et al, 1995). Recently, females having three spermathecae were found in a P element-induced mutation line, in which the P element is inserted in CG7956 (now renamed sp3) on III chromosome (Dhillon et al, 2020). In another lacW insertion line, FBst10175, females had three spermathecae, although the P element insertion was not the direct cause of the mutation (Bangham et al, 2003).…”

“…CK2 is expressed ubiquitously and phosphorylates Ser/Thr and Tyr of various substrates related to growth and development in many animals, and thus is suggested to be one of the essential kinases in kinomes (reviewed by Franchin et al, 2017;Götz and Montenarh, 2017). Furthermore, sp3, the gene responsible for a recently identified supernumerary spermathecal mutation, encodes a phosphatase that is thought to hydrolyze phosphate from inositol, although the substrate is not yet identified (Dhillon et al, 2020). It is therefore conceivable that En plays an important role via phosphorylation in the development of spermathecae and that Ser325 and Ser340 of En are the targets of kinases.…”

“…By a series of complementation tests, spt was shown to be an allele of engrailed (en), en spt (Chase and Baker, 1995). Recently, females having three spermathecae were also found in some P elementinduced mutation lines (Bangham et al, 2003;Dhillon et al, 2020). En is well known as a homeodomaincontaining transcription factor that plays important roles in boundary formation (Kornberg, 1981;Kornberg et al, 1985).…”

Long‐term sperm storage in eusocial Hymenoptera

“…The box covers the interval between the lower and the higher quartile; the vertical line in the box represents the median; the whisker reaches the value that is the furthest from the centre while still being within 1.5 times the interquartile range from the lower or upper quartile; data points that are outside this interval are considered as potential outliers; N, number of species. References for FSS duration: birds, mammals and Testudines: ; non-eusocial insects: McCauley & Reilly (1984), Ridley (1993), L opez-Le on et al (1994), Qazi et al (1996), Ribou & Reinhardt (2012), Reinhardt (2004), Twig & Yuval (2005), Degner & Harrington (2016), Allen et al (2018), Dhillon et al (2020); Rhynchocephalia and Crocodilia: , Sever & Hamlett (2002); amphibians: Brizzi et al (1995), Sever et al (1995Sever et al ( , 1999Sever et al ( , 2001, Sever (2002), Baylis (2009); fishes: Warner & Harlan (1982), Pratt (1993) (1996), Gardner & Howel (2002); eusocial Hymenoptera: Keller & Genoud (1997).…”

“…(2018), Dhillon et al . (2020); Rhynchocephalia and Crocodilia: Birkhead & Møller (1993), Sever & Hamlett (2002); amphibians: Brizzi et al . (1995), Sever et al .…”