Causes of exotic bird establishment across oceanic islands

The probability that exotic species will successfully establish viable populations varies between regions, for reasons that are currently unknown. Here, we use data for exotic bird introductions to 41 oceanic islands and archipelagos around the globe to test five hypotheses for this variation: the effects of introduction effort, competition, predation, human disturbance and habitat diversity (island biogeography). Our analyses demonstrate the primary importance of introduction effort for avian establishment success across regions, in concordance with previous analyses within regions. However, they also reveal a strong negative interaction across regions between establishment success and predation; exotic birds are more likely to fail on islands with species-rich mammalian predator assemblages

A comparison of success rates of introduced passeriform birds in New Zealand, Australia and the United States

In this study, we compiled lists of successful and unsuccessful passeriform introductions to nine sites in New Zealand, Australia and the United States. We limited our analysis to introductions during the 19th century to minimize potential variation in transport modes and habitat quality changes, such as those due to increasing urbanization. We compared introduction success rates at three levels. First we included all passeriforms introduced to any of the sites in the three locations, then we compared the fates of just those species with a European origin and finally we compared success rates of just the 13 species released into all three locations. We found that the pattern of success or failure differed significantly across the three locations: Passeriforms introduced by acclimatization organizations to the United States were significantly more likely to fail than those introduced to New Zealand or Australia. Several species that succeeded in either New Zealand or Australia failed in the United States, even after the introduction of seemingly sufficient numbers

Representing Partitions on Trees

In evolutionary biology, biologists often face the problem of constructing a phylogenetic tree on a set X of species from a multiset Π of partitions corresponding to various attributes of these species. One approach that is used to solve this problem is to try instead to associate a tree (or even a network) to the multiset ΣΠ consisting of all those bipartitions {A,X − A} with A a part of some partition in Π. The rational behind this approach is that a phylogenetic tree with leaf set X can be uniquely represented by the set of bipartitions of X induced by its edges. Motivated by these considerations, given a multiset Σ of bipartitions corresponding to a phylogenetic tree on X, in this paper we introduce and study the set P(Σ) consisting of those multisets of partitions Π of X with ΣΠ = Σ. More specifically, we characterize when P(Σ) is non-empty, and also identify some partitions in P(Σ) that are of maximum and minimum size. We also show that it is NP-complete to decide when P(Σ) is non-empty in case Σ is an arbitrary multiset of bipartitions of X. Ultimately, we hope that by gaining a better understanding of the mapping that takes an arbitrary partition system Π to the multiset ΣΠ, we will obtain new insights into the use of median networks and, more generally, split-networks to visualize sets of partitions

Distinct high-T transitions in underdoped Ba1−x_{1-x}Kx_{x}Fe2_{2}As2_{2}

In contrast to the simultaneous structural and magnetic first order phase transition $T_{0}$ previously reported, our detailed investigation on an underdoped Ba$_{0.84}$K$_{0.16}$Fe$_{2}$As$_{2}$ single crystal unambiguously revealed that the transitions are not concomitant. The tetragonal ($\tau$: I4/mmm) - orthorhombic ($\vartheta$: Fmmm) structural transition occurs at $T_{S}\simeq$ 110 K, followed by an adjacent antiferromagnetic (AFM) transition at $T_{N}\simeq$ 102 K. Hysteresis and coexistence of the $\tau$ and $\vartheta$ phases over a finite temperature range observed in our NMR experiments confirm the first order character of the structural transition and provide evidence that both $T_{S}$ and $T_{N}$ are strongly correlated. Our data also show that superconductivity (SC) develops in the $\vartheta$ phase below $T_{c}$ = 20 K and coexists with long range AFM. This new observation, $T_{S}\neq T_{N}$, firmly establishes another similarity between the hole-doped BaFe$_{2}$As$_{2}$ via K substitution and the electron-doped iron-arsenide superconductors.Comment: 4 pages, 3 figure

Institutional Ownership and Return Predictability Across Economically Unrelated Stocks

We document strong weekly lead-lag return predictability across stocks from different industries with no customer-supplier linkages (economically unrelated stocks). Between 1980 and 2010, the industry-neutral long-short hedge portfolio earns an average of over 19 basis points per week. This return predictability arises exclusively from pairs of stocks in which there are common institutional owners. This predictability is a new phenomenon which does not originate from the slow information diffusion underlying previously documented lead-lag effects, weekly reversals, momentum, nonsynchronous trading, or other known factors. Our findings suggest that institutional portfolio reallocations can induce return predictability among otherwise unrelated stocks

The effects of vitamin K1-rich plant foods on the efficacy of the anticoagulant rodenticides chlorophacinone and diphacinone, used against Montane Voles (\u3ci\u3eMicrotus montanus\u3c/i\u3e)

Voles can cause significant losses to agriculture and wood fibre production. California growers typically rely on baits containing chlorophacinone and diphacinone to reduce vole population densities, but the efficacy of those rodenticides has been decreasing. One hypothesis suggests that voles are consuming high levels of an antidote (vitamin K1) to the anticoagulants, contained within green leafy plants. We tested that hypothesis by first feeding Montane Voles (Microtus montanus) diets that were high in vitamin K1, and then providing the animals with either: (1) chlorophacinone-containing bait, (2) diphacinone-containing bait, or (3) a control diet. We found that the chlorophacinone-containing bait remained efficacious (100% mortality), whereas the diphacinone-containing bait had a much lower efficacy (60% mortality). When only the diphacinone-containing bait was presented, the efficacy was somewhat better (80%). We infer that a diet rich in vitamin K1 did not negate the effects of the chlorophacinone for voles, and so we recommend its continued use in California unless anticoagulant resistance is known to have developed in the vole population. We hypothesise that: (1) diphacinone has a relatively low efficacy against Montane Voles when compared to chlorophacinone, and (2) this lower efficacy could be further reduced by a vitamin K1-rich diet