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<WRAP center round todo 60%> Option 1 below. Other options (ordered by difficulty) :
Plant defences limit herbivore population growth by changing predator–prey interactions. Kersch-Becker et al 2017. Proceedings of the Royal Society B: Biological Sciences. 284: 20171120. http://rspb.royalsocietypublishing.org/content/royprsb/284/1862/20171120.full.pdf
Exposure to the leaf litter microbiome of healthy adults protects seedlings from pathogen damage. Christian et al 2017. Proceedings of the Royal Society B: Biological Sciences. 284: 20170641. http://rspb.royalsocietypublishing.org/content/royprsb/284/1858/20170641.full.pdf
Zika virus activates de novo and cross-reactive memory B cell responses in dengue-experienced donors Rogers et al. 2017. Science Immunology. 2: eaan6809. http://immunology.sciencemag.org/content/2/14/eaan6809 </WRAP>
Competition between apex predators? Brown bears decrease wolf kill rate on two continents. Tallian et al. 2017. Proceedings of the Royal Society B: Biological Sciences. 284: 20162368.http://rspb.royalsocietypublishing.org/content/royprsb/284/1848/20162368.full.pdf
Abstract: Trophic interactions are a fundamental topic in ecology, but we know little about how competition between apex predators affects predation, the mechanism driving top-down forcing in ecosystems. We used long-term datasets from Scandinavia (Europe) and Yellowstone National Park (North America) to evaluate how grey wolf (Canis lupus) kill rate was affected by a sympatric apex predator, the brown bear (Ursus arctos). We used kill interval (i.e. the number of days between consecutive ungulate kills) as a proxy of kill rate. Although brown bears can monopolize wolf kills, we found no support in either study system for the common assumption that they cause wolves to kill more often. On the contrary, our results showed the opposite effect. In Scandinavia, wolf packs sympatric with brown bears killed less often than allopatric packs during both spring (after bear den emergence) and summer. Similarly, the presence of bears at wolf-killed ungulates was associated with wolves killing less often during summer in Yellowstone. The consistency in results between the two systems suggests that brown bear presence actually reduces wolf kill rate. Our results suggest that the influence of predation on lower trophic levels may depend on the composition of predator communities.
Description: Different apex predators may share the same resources in a giving environment. The grey wolf and the brown bear are predators of ungulates in North America and Europe. The authors evaluated a long dataset to understand how the presence of bears affects the kill rate of wolves. Wolves increased the time between consecutive kills in bears’ presence in both sites. The authors suggest some mechanisms to explain this:
- bears reduce densities of neonate ungulates (i.e. exploitative competition)
- wolves delay by killing larger preys or feeding on usurped kills under bears' presence (i.e. interference competition + kleptoparasitism)
Proposed task: Think about the balance of exploitative and interfere nce competition between bears and wolves. What are the negative and positive effects of bears to wolves’ kills? How bears can enhance the feeding of wolves? Think about considering the handling time differences in the absence and presence of bears.
Challenge: The authors suggest that the presence of both predators possibly impact prey less than the sum of their individual impacts. Include prey’s population dynamic on the model considering the effect of the predators in sympatry and allopatry.