Niche Partitioning of Feather Mites within a Seabird Host,
Calonectris borealis
|
| |
Authors: | Laura M Stefan Elena Gómez-Díaz Eric Elguero Heather C Proctor Karen D McCoy Jacob González-Solís |
| |
Institution: | 1. Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia
Animal, Universitat de Barcelona, Barcelona, Spain.; 2. Estación Biológica de Doñana, Consejo Superior de
Investigaciones Cientificas (CSIC), Isla de La Cartuja, Sevilla,
Spain.; 3. MIVEGEC Research Unit, UMR 5290, CNRS-IRD-UM, Centre IRD, Montpellier,
France.; 4. Department of Biological Sciences, University of Alberta, Edmonton, Alberta,
Canada.; Universidad de Granada, SPAIN, |
| |
Abstract: | According to classic niche theory, species can coexist in heterogeneous environments
by reducing interspecific competition via niche partitioning, e.g. trophic or spatial
partitioning. However, support for the role of competition on niche partitioning
remains controversial. Here, we tested for spatial and trophic partitioning in
feather mites, a diverse and abundant group of arthropods. We focused on the two
dominant mite species, Microspalax brevipes and Zachvatkinia
ovata, inhabiting flight feathers of the Cory’s shearwater,
Calonectris borealis. We performed mite counts across and within
primary and tail feathers on free-living shearwaters breeding on an oceanic island
(Gran Canaria, Canary Islands). We then investigated trophic relationships between
the two mite species and the host using stable isotope analyses of carbon and
nitrogen on mite tissues and potential host food sources. The distribution of the two
mite species showed clear spatial segregation among feathers; M.
brevipes showed high preference for the central wing primary
feathers, whereas Z. ovata was restricted to the
two outermost primaries. Morphological differences between M.
brevipes and Z. ovata support
an adaptive basis for the spatial segregation of the two mite species. However, the
two mites overlap in some central primaries and statistical modeling showed that
Z. ovata tends to outcompete M.
brevipes. Isotopic analyses indicated similar isotopic values for
the two mite species and a strong correlation in carbon signatures between mites
inhabiting the same individual host suggesting that diet is mainly based on shared
host-associated resources. Among the four candidate tissues examined (blood, feather
remains, skin remains and preen gland oil), we conclude that the diet is most likely
dominated by preen gland oil, while the contribution of exogenous material to mite
diets is less marked. Our results indicate that ongoing competition for space and
resources plays a central role in structuring feather mite communities. They also
illustrate that symbiotic infracommunities are excellent model systems to study
trophic ecology, and can improve our understanding of mechanisms of niche
differentiation and species coexistence. |
| |
Keywords: | |
|
|