Biology subjects

Federici, P.

Publications and source records attributed to Federici, P..

5 recordsLinked to original sources

bioRxiv2025

Urbanisation and habitat fragmentation favour thermophilic and monogynous ant species

Environmental changes such as urbanisation and related habitat loss and fragmentation profoundly impact ecological communities by altering habitats, resources, and microclimates. Yet, the impacts of the resulting environmental conditions on metacommunity dynamics, ranging from species sorting to mass effects, remain a subject of debate. Ants, with diverse life histories and strong ecological effects, are ideal model species to study these pressures. We investigated the response of ant communities, including taxonomic and functional diversity, to urbanisation and habitat fragmentation in the Paris region, comparing wooded areas in 25 urban parks vs. 24 rural forests outside the city. We found a clear difference in species composition between urban and rural environments, with a higher prevalence of thermophilic species and a tendency for monogyny in the city. Forest communities were homogeneous across the size levels we studied, while park communities differed noticeably depending on park size, with larger parks harbouring more species. Our findings suggest that urbanisation selects specific ant traits and favours more thermophilic species, thereby increasing the mean thermal preference of urban communities. These selective effects influence which species can colonise and survive in different patches, shaping metacommunity structure and potentially affecting the resilience of ant communities under climate change.

ecology↗

bioRxiv2025

Lead exposure positively affects coccidia abundance in feral pigeons (Columba livia)

O_LIIn urban environments, organisms are exposed to high levels of pollutants, including trace metals, whose concentrations can be increased by anthropogenic activities. Numerous studies have shown the toxic effects of pollutants on exposed organisms. However, due to their life within the host, parasites can also be affected by exposure to these pollutants. Overall, previous correlative findings reveal that the effects of parasite exposure to pollutants through the host can vary, from positive to negative, highlighting the complexity of host-parasite-environment interactions in relation to pollution. C_LIO_LIIn this study, we experimentally tested whether lead exposure affects the abundance of ecto-, meso-, and endoparasites in wild pigeons (Columba livia), which host a wide variety of parasites and are naturally exposed to trace metals in urban environments. As we had previously reported the toxic effects of lead on the immune system of pigeons, we expected lead exposure to be indirectly beneficial for the parasites. C_LIO_LITo test this, we used a sample of wild pigeons captured in Paris, half of which were experimentally exposed to lead concentrations similar to those found in Paris. We then measured the abundance of several parasites: blood parasites (hemosporidian parasites), ectoparasites (Columbicola columbae and Campanulote compar), coccidia and helminths. Additionally, we measured the intensity of the pigeons antiparasitic behavioral response (grooming) through behavioral analyses. C_LIO_LIOur results did not reveal toxic effects of lead exposure on the parasites. On the contrary, we found positive effects of this exposure on coccidia abundance in male pigeons. This result could be explained by a toxic effect of lead on the hosts antiparasitic immune strategy, making the hosts less hostile to parasites. However, we found no effect of lead exposure on the abundance of lice, blood parasites and helminths. This could be explained by the lack of impact of lead exposure on grooming antiparasitic activity in our experiment, and by seasonal variations in the activity of blood parasite vectors, which may have masked potential effects of our treatment. C_LIO_LIIn conclusion, our study highlights the importance of considering the host environment, particularly pollutants, to understand parasite dynamics. C_LI

ecology↗

bioRxiv2025

Interactions between parasites within the host: helminth infection reduces lice abundance in feral pigeons (Columba livia)

O_LIWithin a host, parasites form a community and interact with each another. They can interact directly through competition for space or indirectly through competition for resources, or even via the hosts immune response. These interactions can influence infection patterns within the host. In particular, helminths are capable of facilitating the infection of other parasites through their immunosuppressive effects or hindering it by activating immune responses that reduce the ability of other species to infest the host. C_LIO_LIIn this study, we aimed to test the existence of parasite interactions in the wild pigeon host (Columba livia). More specifically, we experimentally tested whether helminth infestation influences the infestation dynamics of ecto- and endoparasites in pigeons. C_LIO_LIOur predictions were tested on a sample of pigeons captured in Paris, half of them were exposed to an anthelmintic treatment. We then assessed the effects of this deworming treatment on the abundance of blood parasites (hemosporidian parasites, Haemoproteus spp., Plasmodium spp., and Leucocytozoon spp.), lice (Columbicola columbae and Campanulote compar), as well as on the intensity of antiparasitic behavioral responses (preening). C_LIO_LIWe detected a negative relationship between helminth presence and lice abundance, with higher lice abundance when helminths were reduced (with anthelmintic treatment) and lower lice abundance when helminths were more abundant (without anthelmintic treatment), indicating inhibitory effects of helminths on ectoparasite abundance. However, these results were not supported by differences in preening activity between the two experimental groups, suggesting that other mechanisms are involved. Our results showed no effect of anthelmintic treatment on the abundance of blood parasites. The mechanism by which helminths induced ectoparasite repulsion remains to be demonstrated. C_LIO_LIOur study highlights the importance of considering interactions between different types of parasites in an eco-epidemiological approach when taking into account the factors affecting parasite prevalence and abundance. C_LI

ecology↗

bioRxiv2023

Group or solitary dispersal: worker presence and number favour the success of colony foundation in ants

Dispersal strategies are highly variable. Any strategy is associated to costs and benefits, and understanding which factors favour or disfavour a strategy is a key issue in ecology and evolution. Ants exhibit different dispersal and colony foundation strategies. Some species have winged queens that disperse solitarily and far by flight, and that found new colonies alone. Others have apterous queens that disperse with workers over short walking distances, and found new colonies as a group (colony fission). The putative benefits conferred by workers have been little studied and quantified, because comparing the costs and benefits of solitary vs. group dispersal and foundation is difficult when comparing different species. We did this using the ant Myrmecina graminicola, one of the few species that use both strategies. Young queens were mated and allowed to found new colonies in the laboratory, with either zero, two or four workers. We monitored the survival and growth of foundations over one year. The presence of workers increased both survival and growth, with more workers yielding higher growth. These results show the benefit of dispersing and founding in a group. The presence of few workers (as little as two workers) was sufficient to provide benefits, suggesting group foundation does not require a dramatic decrease in the number of propagules produced in M. graminicola. Our results support the hypothesis that the two strategies coexist along a competition-colonization trade-off, where solitary foundation offers a colonization advantage while group foundation has a competitive advantage.

ecology↗

bioRxiv2023

Habitat fragmentation selects for low dispersal in an ant species

Increased habitat fragmentation is one of the major global changes affecting biodiversity. It is characterised by a decrease in habitat availability and by an increase in the isolation of suitable habitat patches. The dispersal capacities of species may evolve in response to increased habitat fragmentation. Spatial heterogeneities and/or costs of dispersal, which are directly linked to habitat fragmentation, tend to select for lower dispersal abilities. We studied the effects of habitat fragmentation on dispersal using an ant species that exhibits a marked dispersal polymorphism. Myrmecina graminicola produces winged queens dispersing by flight over long distances, or apterous queens dispersing on foot over short distances. We sampled queens in 24 forests around Paris and 25 parks within Paris, representing varied levels of habitat fragmentation and habitat size. We identified the queen morphotypes in each environment and used it as a proxy of dispersal. Winged queens predominated in both environments. However, apterous queens were comparatively more common in parks than in forests, suggesting that high fragmentation counterselects dispersal in this species. We argue that this is because dispersing within urban environments is very costly and discuss the factors favouring each queen morph or resulting in their co-occurrence (maintenance of polymorphism).

evolutionary biology↗