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Journal of Evolutionary Biology Apr 2016Sperm morphological traits are highly variable among species and are commonly thought to evolve by post-copulatory sexual selection. However, little is known about the...
Sperm morphological traits are highly variable among species and are commonly thought to evolve by post-copulatory sexual selection. However, little is known about the evolutionary dynamics of sperm morphology, and whether rates of evolutionary change are variable over time and among taxonomic groups. Here, we examine sperm morphology from 21 species of Old World leaf warblers (Phylloscopidae), a group of generally dull, sexually monochromatic birds, which are known to have high levels of extra-pair paternity. We found that sperm length differs markedly across species, spanning about 40% of the range observed across a larger selection of passerine birds. Furthermore, we found strong support for an 'early-burst' model of trait evolution, implying that the majority of divergence in sperm length has occurred early in the evolutionary history of this clade with subsequent evolutionary stasis. This large early divergence matches the early divergence reported in ecological traits (i.e. body size and feeding behaviour). Our findings demonstrate that rates of evolution in sperm morphology can change over time in passerine taxa, and that evolutionary stasis in sperm traits can occur even in species exhibiting characteristics consistent with moderate-to-high levels of sperm competition. It remains a major challenge to identify the selection mechanisms and possible constraints responsible for these variable rates of sperm evolution.
Topics: Animals; Body Size; Male; Organ Size; Passeriformes; Phylogeny; Spermatozoa; Testis
PubMed: 26781541
DOI: 10.1111/jeb.12826 -
PLoS Genetics 2013Sperm and egg proteins constitute a remarkable paradigm in evolutionary biology: despite their fundamental role in mediating fertilization (suggesting stasis), some of...
Sperm and egg proteins constitute a remarkable paradigm in evolutionary biology: despite their fundamental role in mediating fertilization (suggesting stasis), some of these molecules are among the most rapidly evolving ones known, and their divergence can lead to reproductive isolation. Because of strong selection to maintain function among interbreeding individuals, interacting fertilization proteins should also exhibit a strong signal of correlated divergence among closely related species. We use evidence of such molecular co-evolution to target biochemical studies of fertilization in North Pacific abalone (Haliotis spp.), a model system of reproductive protein evolution. We test the evolutionary rates (d(N)/d(S)) of abalone sperm lysin and two duplicated egg coat proteins (VERL and VEZP14), and find a signal of co-evolution specific to ZP-N, a putative sperm binding motif previously identified by homology modeling. Positively selected residues in VERL and VEZP14 occur on the same face of the structural model, suggesting a common mode of interaction with sperm lysin. We test this computational prediction biochemically, confirming that the ZP-N motif is sufficient to bind lysin and that the affinities of VERL and VEZP14 are comparable. However, we also find that on phylogenetic lineages where lysin and VERL evolve rapidly, VEZP14 evolves slowly, and vice versa. We describe a model of sexual conflict that can recreate this pattern of anti-correlated evolution by assuming that VEZP14 acts as a VERL mimic, reducing the intensity of sexual conflict and slowing the co-evolution of lysin and VERL.
Topics: Animals; Egg Proteins; Evolution, Molecular; Female; Fertilization; Gastropoda; Male; Molecular Mimicry; Mucoproteins; Phylogeny; Reproductive Isolation; Selection, Genetic; Spermatozoa
PubMed: 23408913
DOI: 10.1371/journal.pgen.1003287 -
Molecular and Cellular Biology Oct 2004Human epididymal protein 6 (HE6; also known as GPR64) is an orphan member of the LNB-7TM (B(2)) subfamily of G-protein-coupled receptors. Family members are...
Human epididymal protein 6 (HE6; also known as GPR64) is an orphan member of the LNB-7TM (B(2)) subfamily of G-protein-coupled receptors. Family members are characterized by the dual presence of a secretin-like (type II) seven-transmembrane (7TM) domain and a long cell adhesion-like extracellular domain. HE6 is specifically expressed within the efferent ductules and the initial segment of the epididymis, ductal systems involved in spermatozoon maturation. Here, we report that targeted deletion of the 7TM domain of the murine HE6 gene results in male infertility. Mutant mice reveal a dysregulation of fluid reabsorbtion within the efferent ductules, leading to a backup of fluid accumulation in the testis and a subsequent stasis of spermatozoa within the efferent ducts. The fertility phenotype of HE6 knockout mice identifies this receptor as a potential nonsteroidal, nontesticular target for future male contraceptives and identifies an in vivo function for a member of this unusual gene family.
Topics: Animals; Blotting, Northern; Epididymis; Gene Deletion; Infertility, Male; Male; Mice; Mice, Knockout; RNA, Messenger; Receptors, G-Protein-Coupled; Testis
PubMed: 15367682
DOI: 10.1128/MCB.24.19.8642-8648.2004 -
Fertility and Sterility Sep 1979It is known that progestins can induce in the secretory cells of the cervix the excretion of a mucus that is highly viscuos, scanty, and impenetrable to spermatozoa....
It is known that progestins can induce in the secretory cells of the cervix the excretion of a mucus that is highly viscuos, scanty, and impenetrable to spermatozoa. Mucus of this type is similar to that excreted during the luteal phase of the normal human menstrual cycle and the cow estrous cycle. It is a natural sequence to ask the question, do progestins also have a direct effect on sperm motility? With dynamic laser light-scattering we measured the motility of freshly washed human spermatozoa and of spermatozoa in the presence of a progesterone, both in terms of their swimming speed distribution as expressed in the spectrum of scattered light. The swimming speed was significantly reduced when the concentration of progesterone was three orders of magnitude greater than that of the physiologic level. This finding confirms the finding in earlier biochemical studies that progesterone has a distinct spermiostatic effect. We suggest this answer to the above question: progestin-releasing contraceptive devices may act on spermatozoa directly as well as in the secretory cells of the cervix.
Topics: Animals; Cattle; Cervix Mucus; Dose-Response Relationship, Drug; Ethanol; Humans; Intrauterine Devices; Lasers; Light; Male; Progesterone; Scattering, Radiation; Sperm Motility
PubMed: 488413
DOI: No ID Found -
Fertility and Sterility Aug 1988The purpose of this study is to compare the effectiveness of varicocelectomy for improving the spermogram in treating varicoceles diagnosed by physical examination and... (Comparative Study)
Comparative Study
The purpose of this study is to compare the effectiveness of varicocelectomy for improving the spermogram in treating varicoceles diagnosed by physical examination and those diagnosed by Doppler but with a negative physical examination. The charts of 112 patients were retrospectively analyzed and the patients divided in two groups: group A, where the varicocele was detected by physical examination, and group B, where physical examination was negative but Doppler studies revealed the presence of stasis or backflow in the pampiniform plexus of the spermatic veins. In subjects complaining of infertility, the two groups were similar with regard to age distribution and duration of infertility. After varicocelectomy, 85% of patients in group A had improved spermogram, compared with only 27% in group B. This difference was statistically significant (P less than 0.0001).
Topics: Adult; Humans; Infertility, Male; Male; Physical Examination; Retrospective Studies; Sperm Count; Sperm Motility; Ultrasonography; Varicocele
PubMed: 3294046
DOI: 10.1016/s0015-0282(16)60080-8