University of Granada
Spanish Introduction
La abubilla (Upupa epops) por su hermoso aspecto ha interesado al hombre desde el tiempo de los faraones.
Su dieta y su fetidez deben haber sido de las razones por las que la abubilla se incluye en el Antiguo Testamento en la lista de aves no limpias (ver Levítico 11:19 y Deuteronomio 14:18).
Hueles peor que un nido de abubillas" aparece en El Quijote de Cervantes (1605).
La abubilla es una especie de ave coraciforme de la familia Upupidae;pertenece al mismo orden que los martines pescadores, los abejarucos, y las carracas No obstante, en la taxonomía de Sibley-Ahlquist, Upupa es separado en un orden propio, los Upupiformes, diferente de los Coraciiformes. Especie diurna, solitaria, territorial y migratoria.
Las abubillas son propias de Europa, Asia y África, excepto Madagascar, donde existe una especie propia, Upupa marginata (considerada por algunos autores solo una subespecie más de U. epops).Es una especie migratoria en las regiones septentrionales de su área de distribución y residente o parcialmente migratoria en las otras regiones. La mayor parte de las que migran de Europa probablemente invernan en África al sur del Sahara, en cambio las poblaciones del centro y este de Siberia migran a Asia meridional.Habitan en regiones secas, encontrándose en bosques claros, zonas de frutales, viñedos y campos cultivados con arboledas
Summary:
Hoophoes cover
their eggs with a secretion produced by themselves, loaded with mutualistic
bacteria, which is then retained by a specialized structure in the eggshell
that increases successful hatching. So far this sort of behavior has only been
detected in this species of birds, and it is a mechanism to protect their eggs
from infections by pathogens.
Researchers from the
University of Granada and the Higher Council of Scientific Research (CSIC) have
found that hoophoes cover their eggs with a secretion produced by themselves,
loaded with mutualistic bacteria, which is then retained by a specialized
structure in the eggshell and which increases successful hatching. So far this
sort of behaviour has only been detected in this species of birds, and it is a
mechanism to protect their eggs from infections by pathogens.
Through an experiment
published in the Journal of Animal Ecology, scientists from several
research groups precluded several female hoophoes from impregnating their eggs
with this substance, which they produce themselves inside the so-called
uropygial gland. The research groups involved in this project were the
following: Animal Behaviour and Ecology, Microorganism-Produced Antagonistic
Substances, both from the UGR, and Evolutive Ecology and the Behaviour and
Conservation groups from the Dry Areas Experimental Station (Almería, CSIC).
By doing so they confirmed
that the amount of pathogen bacteria that could be found inside the eggs which
failed to hatch was higher in those nests in which they had experimentally
precluded the females from using their secretion than in those where they were
allowed to use this substance. They concluded that this secretion provides a
barrier for the entry of pathogens towards the interior of the egg.
Presence of enterococci
On the other hand, not just
the secretion as a whole, but particularly the bacteria that did produce
bacteriocins (small antimicrobial proteins) in that secretion, the enterococci,
are beneficial for the developing embryos, since successful hatches were
directly related to the amount of these enterococci in the egg shells and in
the secretions of the females. The more enterococci they had, the higher the
rate in their successful hatching.
As UGR zoology professor,
Manuel Martín-Vivaldi, one of the authors of this research underlines, during
the last few years the field of evolutive ecology has acknowledged "the
important role played by bacteria, not just as infectious agents capable of
producing diseases, but also as allies of animals and other living creatures in
their struggle against disease, due to their extraordinary capacity to
synthesise compounds with antimicrobial properties".
In the case of the hoophoe's
uropygical gland, scientists have confirmed that its components are very
different from those of other birds. This is to a large extent due to the
action of the bacteria present in this particular gland.
This research has also
revealed that hoophoes have developed an exceptional property in their eggs --
which has not so far been found in any other species of bird. This consists in
the presence in the surface of many small depressions that do not completely
penetrate the shell, and whose function appears to be the retention of this
bacteria-carrying secretion that covers the egg.
Bacteria in the eggshell
"With this experiment, we
have been able to establish that if the females can use their secretion,
towards the end of the incubation period, those tiny craters are full of a
substance saturated with bacteria. If we preclude the use of this secretion,
these tiny craters appear empty towards the end of the hatching process,"
said professors Martín-Vivaldi.
These results prove that in
this particular species of bird, "its reproductive strategy has evolved
hand in hand with the use of bacteria which may be beneficial for the
production of antimicrobial substances, which they cultivate in their gland and
then apply upon eggs which are particularly endowed to retain them".
These scientists are currently
working to determine the specific composition of the bacterial community within
the gland, how these symbionts are acquired, and the types of antimicrobial
compounds which synthesize these bacteria, capable of protecting the embryos
which are undergoing development.
Further research along these
lines will facilitate a better understanding of the way in which mutualistic
interactions function between animals and beneficial bacteria, and also to
detect new antimicrobial substances with a potential to be used in medicine of
for food preservation.
This study is the result of
the following two projects: "Nests, parasites and bacteria: a
multidisciplinary approach to the study of adaptation for breeding in high
parasitism risk environments," funded by the Ministry of Science and
Innovation, and "Biodiversity and acquisition mechanisms in the bacterial
community within the uropygial gland of hoophoes (Upupa epops), funded
by the Department of Innovation, Science and Business of the Junta de Andalucía
(within the Programme of Incentives for Excellence in Research).
Story Source:
The above story is based on materials provided by
University of Granada. Note: Materials may be edited for
content and length.
Journal Reference:
- Manuel Martín-Vivaldi, Juan J. Soler, Juan M. Peralta-Sánchez, Laura Arco, Antonio M. Martín-Platero, Manuel Martínez-Bueno, Magdalena Ruiz-Rodríguez, Eva Valdivia. Special structures of hoopoe eggshells enhance the adhesion of symbiont-carrying uropygial secretion that increase hatching success. Journal of Animal Ecology, 2014; 83 (6): 1289 DOI: 10.1111/1365-2656.12243
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