Browsing by Author "Lifjeld, Jan T."
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Item Evolution of female promiscuity in Passerides songbirds(BMC Ecology and Evolution, 2019-08-14) Lifjeld, Jan T.; Gohli, Jostein; Albrecht, Tomáš; Garcia-del-Rey, Eduardo; Johannessen, Lars Erik; Kleven, Oddmund; Mark, Petter Z.; Omotoriogun, Taiwo C.; Rowe, Melissah; Johnsen, ArildBackground: Female promiscuity is highly variable among birds, and particularly among songbirds. Comparative work has identified several patterns of covariation with social, sexual, ecological and life history traits. However, it is unclear whether these patterns reflect causes or consequences of female promiscuity, or if they are byproducts of some unknown evolutionary drivers. Moreover, factors that explain promiscuity at the deep nodes in the phylogenetic tree may be different from those important at the tips, i.e. among closely related species. Here we examine the relationships between female promiscuity and a broad set of predictor variables in a comprehensive data set (N = 202 species) of Passerides songbirds, which is a highly diversified infraorder of the Passeriformes exhibiting significant variation in female promiscuity. Results: Female promiscuity was highly variable in all major clades of the Passerides phylogeny and also among closely related species. We found several significant associations with female promiscuity, albeit with fairly small effect sizes (all R2 ≤ 0.08). More promiscuous species had: 1) less male parental care, particularly during the early stages of the nesting cycle (nest building and incubation), 2) more short-term pair bonds, 3) greater degree of sexual dichromatism, primarily because females were drabber, 4) more migratory behaviour, and 5) stronger premating sexual selection. In a multivariate model, however, the effect of sexual selection disappeared, while the other four variables showed additive effects and together explained about 16% of the total variance in female promiscuity. Female promiscuity showed no relationship with body size, life history variation, latitude or cooperative breeding. Conclusions: We found that multiple traits were associated with female promiscuity, but these associations were generally weak. Some traits, such as reduced parental care in males and more cryptic plumage in females, might even be responses to, rather than causes of, variation in female promiscuity. Hence, the high variation in female promiscuity among Passerides species remains enigmatic. Female promiscuity seems to be a rapidly evolving trait that often diverges between species with similar ecologies and breeding systems. A future challenge is therefore to understand what drives within-lineage variation in female promiscuity over microevolutionary time scales.Item First photographs of Grey Ground Thrush Zoothera princei for Nigeria, from Omo Forest Reserve(ABC Bulletin, 2018) Omotoriogun, Taiwo C.; Temidayo, Omogbemi; Adeyanjub, Taiye A.; Ottosson, U.; Lifjeld, Jan T.Item Sperm competition in tropical versus temperate zone birds(Royal Society Publishing, 2012-11-21) Albrecht, Toma´sˇ; Kleven, Oddmund; Kreisinger, Jakub; Laskemoen, Terje; Omotoriogun, Taiwo C.; Ottosson, Ulf; Reif, Jirˇı´; Sedla´cˇek, Ondrˇej; Horˇa´k, David; Robertson, Raleigh J.; Lifjeld, Jan T.Sperm competition represents an important component of post-copulatory sexual selection. It has been argued that the level of sperm competition declines in birds towards the equator. However, to date, sperm competition estimates have been available mainly for avian species inhabiting the northern temperate zone. Here we apply a novel approach, using the coefficient of between-male variation (CVbm) in sperm size as an index for sperm competition risk, in a comparative analysis of 31 Afrotropical and 99 northern temperate zone passerine species. We found no difference in sperm competition risk between the two groups, nor any relationship with migration distance. However, a multivariate model indicated that sperm competition risk was highest in species with a combination of low body mass and few eggs per clutch. The effect of clutch size was most pronounced in tropical species, which indicates that sperm competition risk in tropical and temperate species is differently associated with particular life-history traits. Although tropical species had lower sperm competition risk than temperate zone species for overlapping clutch sizes, the idea of a generally reduced risk of sperm competition in tropical birds was not supported by our analysis.