scholarly journals Greater sperm complexity in the Australasian old endemic rodents (Tribe: Hydromyini) is associated with increased levels of inter-male sperm competition

2017 ◽  
Vol 29 (5) ◽  
pp. 921 ◽  
Author(s):  
Hanna J. McLennan ◽  
Stefan Lüpold ◽  
Pete Smissen ◽  
Kevin C. Rowe ◽  
William G. Breed
Keyword(s):  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Sperm Tail ◽  
Apical Hook ◽  
Sexually Selected Traits ◽  
Male Sperm ◽  
Murid Rodents ◽  
Selected Traits

Spermatozoa exhibit considerable interspecies morphological variation across mammals, especially among murid rodents. In Australasia, most murids in the tribe Hydromyini have a spermatozoon with a highly complex head exhibiting an apical hook, characteristic of most murids, and two projections that extend from its upper concave surface, the ventral processes. In the present study we performed a phylogenetically controlled comparison of sperm morphology across 45 species of hydromyine rodents to test the hypothesis that the length and angle of both the apical hook and ventral processes, as well as the length of the sperm tail, increase with relative testes mass as a proxy for differences in levels of inter-male sperm competition. Although both sperm head protrusions exhibited considerable variation in their length and angle across species, only the angles increased significantly in relation to relative testes mass. Further, the length of the sperm flagellum was positively associated with relative testes mass. These results suggest that, in hydromyine rodents, the angle of the apical hook and ventral processes of the sperm head, as well as the sperm tail length, are likely to be sexually selected traits. The possible functional significance of these findings is briefly discussed.

Sperm morphology of the Rattini – are the interspecific differences due to variation in intensity of intermale sperm competition?

2018 ◽  
Vol 30 (11) ◽  
pp. 1434 ◽  
Author(s):  
Tessa Pahl ◽  
Hanna J. McLennan ◽  
Yun Wang ◽  
Anang S. Achmadi ◽  
Kevin C. Rowe ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murine Rodent ◽  
Murine Rodents ◽  
Sperm Size

It is widely accepted that in mammals a causal relationship exists between postcopulatory sexual selection and relative testes mass of the species concerned, but how much it determines sperm size and shape is debatable. Here we detailed for the largest murine rodent tribe, the Rattini, the interspecific differences in relative testes mass and sperm form. We found that residual testes mass correlates with sperm head apical hook length as well as its angle, together with tail length, and that within several lineages a few species have evolved highly divergent sperm morphology with a reduced or absent apical hook and shorter tail. Although most species have a relative testes mass of 1–4%, these derived sperm traits invariably co-occur in species with much smaller relative testes mass. We therefore suggest that high levels of intermale sperm competition maintain a sperm head with a long apical hook and long tail, whereas low levels of intermale sperm competition generally result in divergent sperm heads with a short or non-existent apical hook and shorter tail. We thus conclude that sexual selection is a major selective force in driving sperm head form and tail length in this large tribe of murine rodents.

Variation of sperm head shape and tail length in a species of Australian hydromyine rodent: the spinifex hopping mouse, Notomys alexis

2006 ◽  
Vol 18 (7) ◽  
pp. 797 ◽  
Author(s):  
M. Bauer ◽  
W. G. Breed
Keyword(s):  
Tail Length ◽  
Sperm Head ◽  
Filamentous Actin ◽  
Head Shape ◽  
Long Tail ◽  
Sperm Tail ◽  
Total Length ◽  
Murid Rodents ◽  
Species Specific ◽  
High Degree

In Australia, there are around 60 species of murid rodents that occur in the subfamily Hydromyinae, most of which produce highly complex, monomorphic, spermatozoa in which the head has an apical hook together with two ventral processes containing filamentous actin and a long tail of species-specific length. One of the few exceptions to this is the spinifex hopping mouse, Notomys alexis, whose spermatozoa have previously been shown to have pleiomorphic heads. In this study, the structural organisation of the sperm head has been investigated in more detail and the variability in length of the midpiece and total length of the sperm tail has been determined for this species. The findings confirm that pleiomorphic sperm heads are invariably present in these animals and that this variability is associated with that of the nucleus, although nuclear vacuoles were not evident. The total length of the sperm tail, as well as that of the midpiece, was also highly variable both within, as well as between, individual animals. The reason(s) for this high degree of variability in sperm morphology is not known but it may relate to a relaxation of the genetic control of sperm form owing to depressed levels of inter-male sperm competition.

scholarly journals The effects of inbreeding on sperm morphometry of captive-bred endangered mammals

2017 ◽  
Vol 95 (8) ◽  
pp. 599-606 ◽  
Author(s):  
M. Lawrence ◽  
G. Mastromonaco ◽  
K. Goodrowe ◽  
R.M. Santymire ◽  
W. Waddell ◽  
...  
Keyword(s):  
Captive Breeding ◽  
Negative Relationship ◽  
Tail Length ◽  
Poor Quality ◽  
Sperm Head ◽  
Head Width ◽  
Canis Rufus ◽  
Sperm Tail ◽  
Sperm Morphometry ◽  
Red Wolves

Captive breeding is used for the conservation of endangered species, but inbreeding can result when a small number of founders are used to establish populations. Inbreeding can reduce the proportion of normal sperm in an ejaculate, but may also have effects on sperm size and shape (morphometry). We investigated the effects of inbreeding on sperm morphometry of black-footed ferrets (Mustela nigripes (Audubon and Bachman, 1851)) and red wolves (Canis rufus Audubon and Bachman, 1851) from captive breeding programs to determine if more inbred males produced sperm of poor quality (bulky head, small midpiece, short tail). We measured sperm head length, head width, midpiece length, midpiece width, and tail length on 10 sperm from each male of both species. A negative relationship between variation in sperm tail length and inbreeding coefficient (f) was found in black-footed ferret, suggesting that more inbred individuals will have reduced genetic and phenotypic variation. Analyses indicated a negative relationship between sperm head width and f and a positive relationship between sperm tail length and f in red wolf, suggesting that more inbred male red wolves could have faster sperm. These results indicate that inbreeding affects functionally important aspects of sperm morphometry, but that these effects may not be entirely negative.

Sperm morphology, motility and fertilisation capacity in the myobatrachid frog Crinia georgiana

2010 ◽  
Vol 22 (3) ◽  
pp. 516 ◽  
Author(s):  
Martin A. Dziminski ◽  
J. D. Roberts ◽  
Leigh W. Simmons
Keyword(s):  
Male Fertility ◽  
Sperm Morphology ◽  
Negative Relationship ◽  
Tail Length ◽  
Aquatic Organisms ◽  
Sperm Head ◽  
Swimming Velocity ◽  
Male Body ◽  
Sperm Viability ◽  
Sperm Traits

Sperm traits have been found to vary between individuals within populations in a variety of taxa. Sperm motility, morphometry and viability may be expected to have important effects on male fertility, although previous studies have found varying patterns, especially in external fertilisers. In the present study, we examined the effects of sperm swimming velocity, the proportion of motile spermatozoa, sperm head and tail length and the proportion of live spermatozoa on fertilisation success in the externally fertilising myobatrachid frog Crinia georgiana using IVF techniques and by controlling sperm numbers. We found no effect of any of the sperm traits we measured on IVF success. Neither did we find any relationship between sperm morphology and sperm performance. There was a negative relationship between sperm viability and male body size, which could be a function of age or an alternative tactic of differential investment in spermatozoa by smaller-sized males using sneak tactics in multiple matings. In contrast with most externally fertilising aquatic organisms, high rates of fertilisation appear to be achieved in C. georgiana with relatively low sperm swimming speeds.

scholarly journals Intraspecific sperm competition genes enforce post-mating species barriers in Drosophila

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142050 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Sexual Isolation ◽  
Theoretical Models ◽  
Sexually Selected Traits ◽  
Genetic Mechanisms ◽  
Selected Traits ◽  
Additional Role

Sexual selection and sexual conflict are considered important drivers of speciation, based on both theoretical models and empirical correlations between sexually selected traits and diversification. However, whether reproductive isolation between species evolves directly as a consequence of intrapopulation sexual dynamics remains empirically unresolved, in part because knowledge of the genetic mechanisms (if any) connecting these processes is limited. Here, we provide evidence of a direct mechanistic link between intraspecies sexual selection and reproductive isolation. We examined genes with known roles in intraspecific sperm competition (ISC) in D. melanogaster and assayed their impact on conspecific sperm precedence (CSP). We found that two such genes ( Acp36DE and CG9997 ) contribute to both offensive sperm competition and CSP; null/knockdown lines both had lower competitive ability against D. melanogaster conspecifics and were no longer able to displace heterospecific D. simulans sperm in competitive matings. In comparison, Sex Peptide ( Acp70A )—another locus essential for ISC—does not contribute to CSP. These data indicate that two loci important for sperm competitive interactions have an additional role in similar interactions that enforce post-mating reproductive isolation between species, and show that sexual selection and sexual isolation can act on the same molecular targets in a gene-specific manner.

Interspecific diversity of testes mass and sperm morphology in the Philippine chrotomyine rodents: implications for differences in breeding systems across the species

2019 ◽  
Vol 31 (4) ◽  
pp. 705 ◽  
Author(s):  
William G. Breed ◽  
Hazirah Hassan ◽  
Macarena Gonzalez ◽  
Hanna J. McLennan ◽  
Chris M. Leigh ◽  
...  
Keyword(s):  
Sperm Morphology ◽  
Sister Group ◽  
Breeding Systems ◽  
Long Tail ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murid Rodents ◽  
Order Of Magnitude ◽  
High Diversity ◽  
Interspecific Diversity

The high diversity of native Philippine murid rodents includes an old endemic group, the chrotomyines, which are the sister group of the Australasian hydromyines. Herein we detail their interspecific diversity of relative testes mass (RTM) and sperm morphology. We find that in chrotomyines, as in the Australasian hydromyines, testes mass relative to body mass differs by an order of magnitude across the species and ranges from a large RTM in Soricomys and Chrotomys species to a small RTM in Apomys. Sperm morphology is associated with these findings, with individuals in species of Soricomys and Chrotomys producing relatively larger spermatozoa with a prominent apical hook and long tail, whereas, by contrast, the Apomys species have a sperm head that either has a very short or no apical hook and a shorter tail. These findings indicate coevolution of RTM with sperm morphological traits across the species, with the marked interspecific differences in RTM suggesting differences in the intensity of intermale sperm competition and hence breeding system. Thus, we hypothesise that species of Soricomys and Chrotomys that produce more streamlined spermatozoa with longer tails have a polyandrous or promiscuous mating system, whereas the Apomys species, which produce smaller and less streamlined spermatozoa, may exhibit monogamy.

scholarly journals FEMALE MATE PREFERENCE IS FOR MALE TOTAL LENGTH, NOT TAIL LENGTH IN FERAL GUPPIES

Behaviour ◽  
2002 ◽  
Vol 139 (11-12) ◽  
pp. 1491-1508 ◽  
Author(s):  
Kenji Karino ◽  
Jun Matsunaga
Keyword(s):  
Female Choice ◽  
Tail Length ◽  
Female Preference ◽  
Male Mating ◽  
Handicap Principle ◽  
Total Length ◽  
Sexually Selected Traits ◽  
Female Preferences ◽  
Trade Offs ◽  
Selected Traits

AbstractExaggerated male traits can evolve either directly by female choice of males with those traits or indirectly by female preferences for related traits. In this study, we tested whether female choice was based upon male tail length or total length in a feral guppy population in Okinawa, Japan. In this population, about 30% of the males had elongated sword-like tails, and even swordless males had longer tails than females. A series of dichotomous female choice experiments revealed that female guppies chose mates by total length, not by tail length itself. This is inconsistent with the handicap principle. Tail elongation of male guppies may have evolved as a male mating strategy to enhance their attraction to females, mediated by female preference for longer male total length. However, only one-third of the males developed pronounced sword-like tails. This suggests that there are some costs for tail elongation or trade-offs between multiple sexually selected traits. Alternatively, tail elongation may be a deceptive male strategy with frequency-dependent success.

Sperm Morphology of Murid Rodents From New-Guinea and the Solomon-Islands - Phylogenetic Implications

1995 ◽  
Vol 43 (1) ◽  
pp. 17 ◽  
Author(s):  
WG Breed ◽  
KP Aplin
Keyword(s):  
Sperm Morphology ◽  
Solomon Islands ◽  
New Guinea ◽  
Sperm Head ◽  
Lateral Face ◽  
Apical Process ◽  
Transmission Electron ◽  
Phylogenetic Implications ◽  
Murid Rodents ◽  
Head Morphology

Observations on sperm morphology from most species of murid rodents from New Guinea and the Solomon Islands, based on light microscopy, are presented. Transmission electron microscopy of spermatozoa for three species in two genera are also given. All Rattus species, Melomys lanosus, M. rattoides, Lorentzimys nouhuysi and Coccymys ruemmleri have sickle-shaped sperm heads and long sperm tails. In contrast, most of the other species have sperm with a broader lateral face and three ventral processes. These processes vary somewhat in size and shape, and in two Pogonomys and one Chiruromys species there is an extension of the nucleus into the most caudal of the three processes. Species of Anisomys and Hyomys have a sperm head with a broad lateral face but with only a single apical process. Abeomelomys sevia and Solomys salebrosus each have a distinct sperm head morphology unlike that of any other Australian murid; the latter species also has an extremely short sperm tail. Taxonomic and phylogenetic inferences are drawn from these data. Some of the phylogenetic conclusions are markedly divergent from traditional views, which are based on craniodental anatomy.

scholarly journals Unusual Sperm Morphology in the Eurasian Bullfinch (Pyrrhula Pyrrhula)

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 383-392 ◽  
Author(s):  
Timothy R. Birkhead ◽  
Simone Immler ◽  
E. Jayne Pellatt ◽  
Robert Freckleton
Keyword(s):  
Principal Component Analysis ◽  
Body Size ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Principal Component ◽  
Component Analysis ◽  
Sperm Head ◽  
The Other ◽  
Relaxed Selection ◽  
Pyrrhula Pyrrhula

Abstract The sperm of the Eurasian Bullfinch (Pyrrhula pyrrhula) differs markedly in gross morphology from that of all other passerines examined to date. In other passerines, the sperm head is pointed and helical, and the midpiece comprises a mitochondrial helix extending along the flagellum; whereas in the Eurasian Bullfinch, the sperm acrosome is rounded, not helical, and the midpiece is extremely short. In a pairwise study, using principal component analysis (PCA), we combined quantitative and qualitative sperm morphology traits and conducted a phylogenetic correlation to compare the sperm morphology of Eurasian Bullfinch and Beavan's Bullfinch (P. erythaca) with nine other pairs of congeneric passerines. The analysis revealed that Eurasian Bullfinch was a dramatic outlier in sperm morphology and that Eurasian and Beavan's bullfinches are more different than any other pair of species. Excluding Eurasian Bullfinch from the analysis showed that most variation in sperm morphology in the other species was attributable to phylogeny. The Eurasian Bullfinch also has extremely small testes for its body size, which indicates that sperm competition is infrequent in this species; we discuss the possibility that relaxed selection, via lack of sperm competition, may have contributed to the species' unusual sperm morphology. Morfología Espermática Inusual en Pyrrhula pyrrhula

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