76 research outputs found
Unintended Consequences of Conservation Actions: Managing Disease in Complex Ecosystems
Infectious diseases are increasingly recognised to be a major threat to biodiversity. Disease management tools such as control of animal movements and vaccination can be used to mitigate the impact and spread of diseases in targeted species. They can reduce the risk of epidemics and in turn the risks of population decline and extinction. However, all species are embedded in communities and interactions between species can be complex, hence increasing the chance of survival of one species can have repercussions on the whole community structure. In this study, we use an example from the Serengeti ecosystem in Tanzania to explore how a vaccination campaign against Canine Distemper Virus (CDV) targeted at conserving the African lion (Panthera leo), could affect the viability of a coexisting threatened species, the cheetah (Acinonyx jubatus). Assuming that CDV plays a role in lion regulation, our results suggest that a vaccination programme, if successful, risks destabilising the simple two-species system considered, as simulations show that vaccination interventions could almost double the probability of extinction of an isolated cheetah population over the next 60 years. This work uses a simple example to illustrate how predictive modelling can be a useful tool in examining the consequence of vaccination interventions on non-target species. It also highlights the importance of carefully considering linkages between human-intervention, species viability and community structure when planning species-based conservation actions
The Effect of Wind Exposure on the Web Characteristics of a Tetragnathid Orb Spider
Studies on spiders in their natural habitats are necessary for determining the full range of plasticity in
their web-building behaviour. Plasticity in web design is hypothesised to be important for spiders building
in habitats where environmental conditions cause considerable web damage. Here we compared web
characteristics of the orb spider Metellina mengei (Araneae, Tetragnathidae) in two different forest
habitats differing in their wind exposure. We found a notable lack of differences in web geometry,
orientation and inclination between webs built along an exposed forest edge and those built inside the
forest, despite marked differences in wind speed. This suggests that M. mengei did not exhibit web-
building plasticity in response to wind in the field, contrasting with the findings of laboratory studies on
other species of orb spiders. Instead, differences in prey capture and wind damage trade-offs between
habitats may provide an explanation for our results, indicating that different species employ different
strategies to cope with environmental constraints
- …