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Sexual Dimorphism and Population Differences in Structural Properties of Barn Swallow (Hirundo rustica) Wing and Tail Feathers.

Pap PL, Osváth G, Aparicio JM, Bărbos L, Matyjasiak P, Rubolini D, Saino N, Vágási CI, Vincze O, Møller AP - PLoS ONE (2015)

Bottom Line: Furthermore, we compared structural properties of Ta6 of barn swallows from six European populations.Ta6 elongation in males resulted in feathers with reduced resistance, as shown by the low barb density and reduced bending stiffness compared to females.Our results show that the material and structural properties of wing and tail feathers of barn swallows change as a result of aerodynamic forces and sexual selection, although the result of these changes can be contrasting.

View Article: PubMed Central - PubMed

Affiliation: Evolutionary Ecology Group, Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Cluj Napoca, Romania; MTA-DE "Lendület" Behavioural Ecology Research Group, Department of Evolutionary Zoology and Human Biology, University of Debrecen, Debrecen, Hungary.

ABSTRACT
Sexual selection and aerodynamic forces affecting structural properties of the flight feathers of birds are poorly understood. Here, we compared the structural features of the innermost primary wing feather (P1) and the sexually dimorphic outermost (Ta6) and monomorphic second outermost (Ta5) tail feathers of barn swallows (Hirundo rustica) from a Romanian population to investigate how sexual selection and resistance to aerodynamic forces affect structural differences among these feathers. Furthermore, we compared structural properties of Ta6 of barn swallows from six European populations. Finally, we determined the relationship between feather growth bars width (GBW) and the structural properties of tail feathers. The structure of P1 indicates strong resistance against aerodynamic forces, while the narrow rachis, low vane density and low bending stiffness of tail feathers suggest reduced resistance against airflow. The highly elongated Ta6 is characterized by structural modifications such as large rachis width and increased barbule density in relation to the less elongated Ta5, which can be explained by increased length and/or high aerodynamic forces acting at the leading tail edge. However, these changes in Ta6 structure do not allow for full compensation of elongation, as reflected by the reduced bending stiffness of Ta6. Ta6 elongation in males resulted in feathers with reduced resistance, as shown by the low barb density and reduced bending stiffness compared to females. The inconsistency in sexual dimorphism and in change in quality traits of Ta6 among six European populations shows that multiple factors may contribute to shaping population differences. In general, the difference in quality traits between tail feathers cannot be explained by the GBW of feathers. Our results show that the material and structural properties of wing and tail feathers of barn swallows change as a result of aerodynamic forces and sexual selection, although the result of these changes can be contrasting.

No MeSH data available.


Related in: MedlinePlus

Variation in GBW of Ta5 and Ta6 in male (black) and female (white) barn swallows originating from the Romanian population (mean + SE).Significance level for the difference between sexes for each feather type is shown above bars.
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pone.0130844.g003: Variation in GBW of Ta5 and Ta6 in male (black) and female (white) barn swallows originating from the Romanian population (mean + SE).Significance level for the difference between sexes for each feather type is shown above bars.

Mentions: We tested if the difference between sexes and feather types in feather quality is determined by variation in GBW. GBW was significantly larger for Ta6 than for Ta5 (Table 2, Fig 3). The significant sex × feather type interaction indicates that GBW of Ta5 was larger in females than in males, while the opposite was observed for Ta6 (Fig 3). None of the feather traits of Ta5 and Ta6 were predicted by GBW, as revealed by the non-significant effect of GBW in separate models where the effect of sex and feather type was controlled (Table 2).


Sexual Dimorphism and Population Differences in Structural Properties of Barn Swallow (Hirundo rustica) Wing and Tail Feathers.

Pap PL, Osváth G, Aparicio JM, Bărbos L, Matyjasiak P, Rubolini D, Saino N, Vágási CI, Vincze O, Møller AP - PLoS ONE (2015)

Variation in GBW of Ta5 and Ta6 in male (black) and female (white) barn swallows originating from the Romanian population (mean + SE).Significance level for the difference between sexes for each feather type is shown above bars.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482263&req=5

pone.0130844.g003: Variation in GBW of Ta5 and Ta6 in male (black) and female (white) barn swallows originating from the Romanian population (mean + SE).Significance level for the difference between sexes for each feather type is shown above bars.
Mentions: We tested if the difference between sexes and feather types in feather quality is determined by variation in GBW. GBW was significantly larger for Ta6 than for Ta5 (Table 2, Fig 3). The significant sex × feather type interaction indicates that GBW of Ta5 was larger in females than in males, while the opposite was observed for Ta6 (Fig 3). None of the feather traits of Ta5 and Ta6 were predicted by GBW, as revealed by the non-significant effect of GBW in separate models where the effect of sex and feather type was controlled (Table 2).

Bottom Line: Furthermore, we compared structural properties of Ta6 of barn swallows from six European populations.Ta6 elongation in males resulted in feathers with reduced resistance, as shown by the low barb density and reduced bending stiffness compared to females.Our results show that the material and structural properties of wing and tail feathers of barn swallows change as a result of aerodynamic forces and sexual selection, although the result of these changes can be contrasting.

View Article: PubMed Central - PubMed

Affiliation: Evolutionary Ecology Group, Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Cluj Napoca, Romania; MTA-DE "Lendület" Behavioural Ecology Research Group, Department of Evolutionary Zoology and Human Biology, University of Debrecen, Debrecen, Hungary.

ABSTRACT
Sexual selection and aerodynamic forces affecting structural properties of the flight feathers of birds are poorly understood. Here, we compared the structural features of the innermost primary wing feather (P1) and the sexually dimorphic outermost (Ta6) and monomorphic second outermost (Ta5) tail feathers of barn swallows (Hirundo rustica) from a Romanian population to investigate how sexual selection and resistance to aerodynamic forces affect structural differences among these feathers. Furthermore, we compared structural properties of Ta6 of barn swallows from six European populations. Finally, we determined the relationship between feather growth bars width (GBW) and the structural properties of tail feathers. The structure of P1 indicates strong resistance against aerodynamic forces, while the narrow rachis, low vane density and low bending stiffness of tail feathers suggest reduced resistance against airflow. The highly elongated Ta6 is characterized by structural modifications such as large rachis width and increased barbule density in relation to the less elongated Ta5, which can be explained by increased length and/or high aerodynamic forces acting at the leading tail edge. However, these changes in Ta6 structure do not allow for full compensation of elongation, as reflected by the reduced bending stiffness of Ta6. Ta6 elongation in males resulted in feathers with reduced resistance, as shown by the low barb density and reduced bending stiffness compared to females. The inconsistency in sexual dimorphism and in change in quality traits of Ta6 among six European populations shows that multiple factors may contribute to shaping population differences. In general, the difference in quality traits between tail feathers cannot be explained by the GBW of feathers. Our results show that the material and structural properties of wing and tail feathers of barn swallows change as a result of aerodynamic forces and sexual selection, although the result of these changes can be contrasting.

No MeSH data available.


Related in: MedlinePlus