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Article
Taiwo C. Omotoriogun, Auteur ; Terje Laskemoen, Auteur ; Melissah Rowe, Auteur ; Tomáš Albrecht, Auteur ; Rauri C. K. Bowie, Auteur ; Ondřej Sedláček, Auteur ; David Hořák, Auteur ; Ulf Ottosson, Auteur ; Jan T. Lifjeld, AuteurBirds show considerable variation in sperm morphology. Closely related species and subspecies can show diagnostic differences in sperm size. There is also variation in sperm size among males within a population, and recent evidence from passerin[...]
Article
Terje Laskemoen, Auteur ; Frode Fossoy, Auteur ; Geir Rudolfsen, Auteur ; Jan T. Lifjeld, AuteurIn passerine species with frequent extrapair mating, young (second calendar year) males often have a lower fertilization success than older (after second calendar year) males. This pattern might be explained by male- or female-driven mechanisms,[...]
Article
Jan T. Lifjeld, Auteur ; Terje Laskemoen, Auteur ; Frode Fossoy, Auteur ; Arild Johnsen, Auteur ; Oddmund Kleven, AuteurInformation about male infertility in free-living birds is scarce, but anecdotal and circumstantial evidence suggests that it does occur regularly at a low frequency. In this paper we document three cases of azoospermia in two passerine species,[...]
Article
Terje Laskemoen, Auteur ; Oddmund Kleven, Auteur ; Frode Fossoy, Auteur ; Jan T. Lifjeld, AuteurSperm cells are highly diversified in birds and considerable research effort has focused on variation in sperm morphology between species. However, surprisingly little is known about intraspecific variation in sperm morphology in birds. We analy[...]
Article
Eduardo Garcia-Del-Rey, Auteur ; Gunnhild Marthinsen, Auteur ; Pascual Calabuig, Auteur ; Loly Estevez, Auteur ; Lars Erik Johannessen, Auteur ; Arild Johnsen, Auteur ; Terje Laskemoen, Auteur ; Jan T. Lifjeld, AuteurThe Blue Chaffinch (Fringilla teydea) is endemic to the Canary Islands and restricted to the pine forests on Tenerife (ssp. teydea) and Gran Canaria (ssp. polatzeki). While the teydea population is large and stable, the polatzeki population unde[...]
Article
Terje Laskemoen, Auteur ; Oddmund Kleven, Auteur ; Lars Erik Johannessen, Auteur ; Frode Fossoy, Auteur ; Raleigh J. Robertson, Auteur ; Jan T. Lifjeld, AuteurSperm morphometry and motility are important male traits affecting fertility and post-copulatory competitive ability. However, studies examining consistency in sperm traits over time for individual males are rather scarce, particularly in free-l[...]
Article
Oddmund Kleven, Auteur ; Terje Laskemoen, Auteur ; Jan T. Lifjeld, AuteurHow long is a sand martin Riparia riparia spermatozoon? In a recent study, Helfenstein et al. (2008) presented data on the intraspecific variation in sperm length, swimming speed and longevity in this species and some interesting correlations be[...]
Article
Emily R. A. Cramer, Auteur ; Terje Laskemoen, Auteur ; Oddmund Kleven, Auteur ; Jan T. Lifjeld, AuteurIt is well documented that sperm size and structure varies considerably among avian species, but we know much less about the extent of intraspecific variation in sperm morphometry and its possible co-variation with somatic traits like body size [...]
Article
Hanna N. Stostad, Auteur ; Silje L. Rekdal, Auteur ; Oddmund Kleven, Auteur ; Terje Laskemoen, Auteur ; Gunnhild Marthinsen, Auteur ; Arild Johnsen, Auteur ; Jan T. Lifjeld, AuteurSperm morphology is highly diversified among species and at higher taxonomic levels. In birds, there is also increasing evidence of geographical differentiation in sperm traits within species, especially in those with strong sperm competition. G[...]
