Indirect effects of primary prey population dynamics on alternative prey

We develop a theory of generalist predation showing how alternative prey species are affected by changes in both mean abundance and variability (coefficient of variation) of their predator's primary prey. The theory is motivated by the indirect effects of cyclic rodent populations on ground-breeding birds, and developed through progressive analytic simplifications of an empirically-based model. It applies nonetheless to many other systems where primary prey have fast life-histories and can become locally superabundant, which facilitates impact on alternative prey species. In contrast to classic apparent competition theory based on symmetric interactions, our results suggest that predator effects on alternative prey should generally decrease with mean primary prey abundance, and increase with primary prey variability (low to high CV) - unless predators have strong aggregative responses, in which case these results can be reversed. Approximations of models including predator dynamics (general numerical response with possible delays) confirm these results but further suggest that negative temporal correlation between predator and primary prey is harmful to alternative prey. We find in general that predator numerical responses are crucial to predict the response of ecosystems to changes in key prey species exhibiting outbreaks, and extend the apparent competition/mutualism theory to asymmetric interactions

Dolphins and Boats : When Is a Disturbance, Disturbing?

Acknowledgments A draft of this manuscript was presented (manuscript SC66b/WW10) to the Whalewatching Sub-Committee at the 66th meeting of the Scientific Committee of the International Whaling Commission, 4–20 June 2016, in Bled, Slovenia. Funding RH supported in part by a Sitka Sound Science Centre Scientist in Residency Fellowship.Peer reviewedPublisher PD

Central place foragers and moving stimuli : a hidden-state model to discriminate the processes affecting movement

We thank Orkney Islands Council for access to Eynhallow and Talisman Energy (UK) Ltd for fieldwork and equipment support. Marine Scotland provided access to anonymized VMS data. Handling and tagging of fulmars was conducted under licenses from the British Trust for Ornithology and the UK Home Office. EE was funded by a Marine Alliance for Science and Technology for Scotland/University of Aberdeen College of Life Sciences and Medicine studentship. We are grateful to Jason Matthiopoulos, Thomas Cornulier, Beth Scott, David Lusseau, Julien Martin and Tiago Marques for suggestions on model development, and to the many colleagues who assisted with fieldwork. We thank Emer Rogan and University College Cork for providing desk space to EP. Finally, we thank Editor-in-Chief Ben Sheldon, Associate Editor Luca Borger and three anonymous reviewers for their useful comments on the paper. Data available from the Dryad Digital Repository: https://doi:10.5061/dryad.0d377r6 (Pirotta et al., 2018)Peer reviewedPostprintPostprintPostprintPostprin

Discovering the roots: Uniform closure results for algebraic classes under factoring

Newton iteration (NI) is an almost 350 years old recursive formula that approximates a simple root of a polynomial quite rapidly. We generalize it to a matrix recurrence (allRootsNI) that approximates all the roots simultaneously. In this form, the process yields a better circuit complexity in the case when the number of roots $r$ is small but the multiplicities are exponentially large. Our method sets up a linear system in $r$ unknowns and iteratively builds the roots as formal power series. For an algebraic circuit $f(x_1,\ldots,x_n)$ of size $s$ we prove that each factor has size at most a polynomial in: $s$ and the degree of the squarefree part of $f$. Consequently, if $f_1$ is a $2^{\Omega(n)}$-hard polynomial then any nonzero multiple $\prod_{i} f_i^{e_i}$ is equally hard for arbitrary positive $e_i$'s, assuming that $\sum_i \text{deg}(f_i)$ is at most $2^{O(n)}$. It is an old open question whether the class of poly($n$)-sized formulas (resp. algebraic branching programs) is closed under factoring. We show that given a polynomial $f$ of degree $n^{O(1)}$ and formula (resp. ABP) size $n^{O(\log n)}$ we can find a similar size formula (resp. ABP) factor in randomized poly($n^{\log n}$)-time. Consequently, if determinant requires $n^{\Omega(\log n)}$ size formula, then the same can be said about any of its nonzero multiples. As part of our proofs, we identify a new property of multivariate polynomial factorization. We show that under a random linear transformation $\tau$, $f(\tau\overline{x})$ completely factors via power series roots. Moreover, the factorization adapts well to circuit complexity analysis. This with allRootsNI are the techniques that help us make progress towards the old open problems, supplementing the large body of classical results and concepts in algebraic circuit factorization (eg. Zassenhaus, J.NT 1969, Kaltofen, STOC 1985-7 \& Burgisser, FOCS 2001).Comment: 33 Pages, No figure

The Dixie Volunteers / music by Harry Ruby; words by Edgar Leslie

Cover: drawing of Soldiers; photo inset of Eddie Cantor; Publisher: Waterson Berlin and Snyder Co. (New York)https://egrove.olemiss.edu/sharris_c/1128/thumbnail.jp

When Alexander Takes His Ragtime Band to France / music by Cliff Hess and Edgar Leslie; words by Alfred; Bryan

Cover: drawing of a marching band, with battle scenes in the background; Publisher: Waterson Berlin and Snyder Co. (New York)https://egrove.olemiss.edu/sharris_c/1141/thumbnail.jp

Among My Souvenirs / music by Horatio Nicholls; words by Edgar Leslie

Cover: drawing of a chest filled with letters and a Rose; Publisher: De Sylvia Brown and Henderson (New York)https://egrove.olemiss.edu/sharris_d/1086/thumbnail.jp

Tain\u27t No Sin (to Dance around in Your Bones) / music by Walter Donaldson; words by Edgar Leslie

Cover: drawing of a Caucasian couple, with skeleton bodies, dancing, caricatures of African American musicians surround the couple; Publisher: Walter Donaldson Douglas and Gumble Inc. (New York)https://egrove.olemiss.edu/sharris_d/1103/thumbnail.jp

Take Your Girlie To The Movies (If You Can\u27t Make Love At Home) / music by Pete Wendling; words by Edgar Leslie and Bert Kalmar

Cover: a drawing of people in the cinema; Publisher: Waterson Berlin and Snyder Co. (New York)https://egrove.olemiss.edu/sharris_c/1174/thumbnail.jp

Modeling the functional link between movement, feeding activity, and condition in a marine predator

The ability to quantify animals’ feeding activity and the resulting changes in their body condition as they move in the environment is fundamental to our understanding of a population’s ecology. We use satellite tracking data from northern elephant seals (Mirounga angustirostris), paired with simultaneous diving information, to develop a Bayesian state-space model that concurrently estimates an individual’s location, feeding activity, and changes in condition. The model identifies important foraging areas and times, the relative amount of feeding occurring therein, and thus the different behavioral strategies in which the seals engage. The fitness implications of these strategies can be assessed by looking at the resulting variation in individuals’ condition, which in turn affects the condition and survival of their offspring. Therefore, our results shed light on the processes affecting an individual’s decision-making as it moves and feeds in the environment. In addition, we demonstrate how the model can be used to simulate realistic patterns of disturbance at different stages of the trip, and how the predicted accumulation of lipid reserves varies as a consequence. Particularly, disturbing an animal in periods of high feeding activity or shortly after leaving the colony was predicted to have the potential to lead to starvation. In contrast, an individual could compensate even for very severe disturbance if such disturbance occurred outside the main foraging grounds. Our modeling approach is applicable to marine mammal species that perform drift dives and can be extended to other species where an individual’s buoyancy can be inferred from its diving behavior