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Males of a strongly polygynous species consume more poisonous food than females.

Bravo C, Bautista LM, García-París M, Blanco G, Alonso JC - PLoS ONE (2014)

Bottom Line: The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness.A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females.Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness.

View Article: PubMed Central - PubMed

Affiliation: Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Madrid, Spain.

ABSTRACT
We present evidence of a possible case of self-medication in a lekking bird, the great bustard Otis tarda. Great bustards consumed blister beetles (Meloidae), in spite of the fact that they contain cantharidin, a highly toxic compound that is lethal in moderate doses. In addition to anthelminthic properties, cantharidin was effective against gastrointestinal bacteria that cause sexually-transmitted diseases. Although both sexes consumed blister beetles during the mating season, only males selected them among all available insects, and ingested more and larger beetles than females. The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness. This plausibly explains the intense cloaca display males perform to approaching females, and the meticulous inspection females conduct of the male's cloaca, a behaviour only observed in this and another similar species of the bustard family. A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females. Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness.

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Blister beetle relative abundance (A) and biomass (B) in relation to all invertebrates sampled in field transects (column ‘available’), and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007).(C) Mean body size (± SD, g) of blister beetles sampled in field transects (column ‘available’) and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007). Differences in A and B were compared with the test of differences between percentages, and those in C with a Student's t-test, in all cases with data from both years pooled (horizontal lines; ns: P>0.05, *: P<0.05, **: P<0.01).
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pone-0111057-g004: Blister beetle relative abundance (A) and biomass (B) in relation to all invertebrates sampled in field transects (column ‘available’), and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007).(C) Mean body size (± SD, g) of blister beetles sampled in field transects (column ‘available’) and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007). Differences in A and B were compared with the test of differences between percentages, and those in C with a Student's t-test, in all cases with data from both years pooled (horizontal lines; ns: P>0.05, *: P<0.05, **: P<0.01).

Mentions: The frequency distribution of blister beetles in faeces did not differ between years (χ2 = 1.89, d.f. = 3, P = 0.595). At least one blister beetle was found in 34% of the samples (n = 72), with 62 faeces containing just one individual (29%), 6 faeces two individuals (3%) and 4 faeces three individuals (2%). Blister beetle consumption by great bustards was clearly male-biased. First, blister beetles were significantly more frequent in male than in female faeces (Table 2). Second, the biomass and abundance of blister beetles were significantly greater in male than in female faeces. Third, males selected blister beetles among other invertebrates, both in number of individuals and biomass, compared to their abundance in the field, whereas females did not (Fig. 4 A, B). And finally, males selected the largest blister beetles among those available, whereas females did not (Fig. 4 C). Moreover, among seven insect taxa consumed by great bustards (Acrididae, Formicidae, Hemiptera, Curculionidae, Meloidae, Scarabeidae and Tenebrionidae), there was only a selection of larger prey sizes by males compared to females in Tenebrionidae (F1,40 = 9.61 p = 0.003) and Meloidae (F1,22 = 4.37 p = 0.048), and the largest size differences were found in the latter (Meloidae: 1.6 times larger prey in great bustard males; 595.3 mg average size in males vs 370.7 mg in females; Tenebrionidae: 1.3 times larger prey in males; 144.8 mg average size in males vs 109.5 mg in females).


Males of a strongly polygynous species consume more poisonous food than females.

Bravo C, Bautista LM, García-París M, Blanco G, Alonso JC - PLoS ONE (2014)

Blister beetle relative abundance (A) and biomass (B) in relation to all invertebrates sampled in field transects (column ‘available’), and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007).(C) Mean body size (± SD, g) of blister beetles sampled in field transects (column ‘available’) and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007). Differences in A and B were compared with the test of differences between percentages, and those in C with a Student's t-test, in all cases with data from both years pooled (horizontal lines; ns: P>0.05, *: P<0.05, **: P<0.01).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206510&req=5

pone-0111057-g004: Blister beetle relative abundance (A) and biomass (B) in relation to all invertebrates sampled in field transects (column ‘available’), and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007).(C) Mean body size (± SD, g) of blister beetles sampled in field transects (column ‘available’) and found in faeces of females and males (columns ‘consumed’) in two springs (2006 and 2007). Differences in A and B were compared with the test of differences between percentages, and those in C with a Student's t-test, in all cases with data from both years pooled (horizontal lines; ns: P>0.05, *: P<0.05, **: P<0.01).
Mentions: The frequency distribution of blister beetles in faeces did not differ between years (χ2 = 1.89, d.f. = 3, P = 0.595). At least one blister beetle was found in 34% of the samples (n = 72), with 62 faeces containing just one individual (29%), 6 faeces two individuals (3%) and 4 faeces three individuals (2%). Blister beetle consumption by great bustards was clearly male-biased. First, blister beetles were significantly more frequent in male than in female faeces (Table 2). Second, the biomass and abundance of blister beetles were significantly greater in male than in female faeces. Third, males selected blister beetles among other invertebrates, both in number of individuals and biomass, compared to their abundance in the field, whereas females did not (Fig. 4 A, B). And finally, males selected the largest blister beetles among those available, whereas females did not (Fig. 4 C). Moreover, among seven insect taxa consumed by great bustards (Acrididae, Formicidae, Hemiptera, Curculionidae, Meloidae, Scarabeidae and Tenebrionidae), there was only a selection of larger prey sizes by males compared to females in Tenebrionidae (F1,40 = 9.61 p = 0.003) and Meloidae (F1,22 = 4.37 p = 0.048), and the largest size differences were found in the latter (Meloidae: 1.6 times larger prey in great bustard males; 595.3 mg average size in males vs 370.7 mg in females; Tenebrionidae: 1.3 times larger prey in males; 144.8 mg average size in males vs 109.5 mg in females).

Bottom Line: The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness.A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females.Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness.

View Article: PubMed Central - PubMed

Affiliation: Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Madrid, Spain.

ABSTRACT
We present evidence of a possible case of self-medication in a lekking bird, the great bustard Otis tarda. Great bustards consumed blister beetles (Meloidae), in spite of the fact that they contain cantharidin, a highly toxic compound that is lethal in moderate doses. In addition to anthelminthic properties, cantharidin was effective against gastrointestinal bacteria that cause sexually-transmitted diseases. Although both sexes consumed blister beetles during the mating season, only males selected them among all available insects, and ingested more and larger beetles than females. The male-biased consumption suggests that males could use cantharidin to reduce their parasite load and increase their sexual attractiveness. This plausibly explains the intense cloaca display males perform to approaching females, and the meticulous inspection females conduct of the male's cloaca, a behaviour only observed in this and another similar species of the bustard family. A white, clean cloaca with no infection symptoms (e.g., diarrhoea) is an honest signal of both, resistance to cantharidin and absence of parasites, and represents a reliable indicator of the male quality to the extremely choosy females. Our results do not definitely prove, but certainly strongly suggest that cantharidin, obtained by consumption of blister beetles, acts in great bustards as an oral anti-microbial and pathogen-limiting compound, and that males ingest these poisonous insects to increase their mating success, pointing out that self-medication might have been overlooked as a sexually-selected mechanism enhancing male fitness.

Show MeSH
Related in: MedlinePlus