“We Used to Say Rats Fell from the Sky After a Flood:” Temporary Recovery of Muskrat Following Ice Jams in the Peace-Athabasca Delta

Elders and Indigenous land users in the Peace-Athabasca Delta (PAD) have observed a dramatic decline in the relative abundance of muskrat in recent decades (~1935–2014). The main explanation for the decline has been reduction in suitable habitat as a result of decades with reduced frequency of ice-jam flooding on the Peace River. Under favourable conditions, ice jams can cause flooding of perched basins within the PAD that would otherwise receive no recharge from floodwaters. To examine whether abundance of muskrat in the PAD is driven by flooding, we tested the predictions that the density of muskrat (estimated by winter counts of houses) (1) was inversely related to the number of years since major ice jam floods and (2) increased with water depth. An ongoing collaborative monitoring program initiated in 2011, combined with analysis of data from past surveys (1973–2015), allowed Indigenous land users and scientists to document a 10 to 100-fold increase in the density of muskrat houses in 24 basins, over the two years following ice-jam flood events in the PAD. During 1973–2015, in the periods between major floods, density of houses dropped by approximately 79% for every year after a significant flood. In 27 basins surveyed from 2011 to 2015, density of muskrat houses increased by two orders of magnitude in the two years following a flood in the spring of 2014. Density of muskrat houses had a non-linear relationship with estimated depth of water at the time of fall freeze-up; the highest densities of muskrat houses were in basins with about 60 – 250 cm of water at the time of freeze-up. The depth of snow at the time of surveys did not have a strong relationship with the density of muskrat houses. However, few houses were counted in basins with more than 20 cm of snow, likely because deeper snow made it more difficult to conduct surveys and spot houses. Factors other than an increase in the depth of water at fall freeze-up may provide the mechanisms by which flooding affects muskrat. Density of muskrat houses is clearly tied to ice-jam flooding in the PAD. However, the local mechanisms by which floods affect muskrat are best understood by Indigenous land users and remain poorly understood by Western science. Indigenous peoples continue to regard muskrat as an indicator of ecological and cultural health of the PAD. This study highlights the value of consistent ecological monitoring that includes Indigenous knowledge.Les aînés et les utilisateurs des terres autochtones du delta des rivières de la Paix et Athabasca ont observé une baisse draconienne de l’abondance du rat musqué au cours des dernières décennies (~1935-2014). La principale explication du déclin est la diminution d’abris convenables, et ce, en raison de plusieurs décennies marquées par la fréquence réduite d’inondations causées par des embâcles dans la rivière de la Paix. Dans des conditions favorables, les embâcles peuvent causer l’inondation des bassins perchés au sein du delta des rivières de la Paix et Athabasca qui autrement ne recevraient pas de recharge des eaux de crue. Afin d’examiner si l’abondance du rat musqué dans le delta des rivières de la Paix et Athabasca est favorisée par les inondations, nous avons testé des prévisions selon lesquelles la densité du rat musqué (estimée par le nombre d’abris en hiver) 1) était inversement liée au nombre d’années depuis les dernières importantes inondations causées par des embâcles et 2) augmentait avec la profondeur de l’eau. Un programme collaboratif de suivi continu lancé en 2011, combiné à l’analyse de données des relevés antérieurs (1973-2015), a permis aux utilisateurs des terres autochtones et aux scientifiques de multiplier de 10 à 100 fois la densité d’abris du rat musqué dans 24 bassins, au cours des deux années suivant des événementsd’inondation causés par des embâcles dans le delta des rivières de la Paix et Athabasca. Entre 1973 et 2015, durant les périodes se situant entre les inondations importantes, la densité d’abris a diminué d’environ 79 % chaque année suivant une inondation importante. Dans 27 bassins sondés entre 2011 et 2015, la densité d’abris du rat musqué a augmenté de deux ordres de grandeur au cours des deux années ayant suivi une inondation survenue au printemps de 2014. La densité d’abris du rat musqué avait une relation non linéaire avec la profondeur de l’eau estimée au moment de la prise des glaces en automne; les plus fortes densités d’abris du rat musqué se trouvaient dans les bassins ayant de 60 à 250 cm d’eau au moment de la prise des glaces. La profondeur de la neige au moment des relevés n’avait pas de relation solide avec la densité d’abris du rat musqué. Cependant, nous avons compté peu d’abris dans les bassins comptant plus de 20 cm de neige, probablement parce qu’il était plus difficile d’effectuer des relevés et de trouver les abris dans la neige plus épaisse. Des facteurs autres que l’augmentation de la profondeur de l’eau au moment de la prise des glaces en automne pourraient fournir les mécanismes par lesquels les inondations se répercutent sur les rats musqués. La densité d’abris du rat musqué est manifestement liée aux inondations causées par des embâcles dans le delta des rivières de la Paix et Athabasca. Toutefois, les utilisateurs des terres autochtones comprennent mieux les mécanismes locaux par lesquels les inondations se répercutent sur les rats musqués, tandis qu’ils demeurent mal compris par la science occidentale. Les peuples autochtones continuent de considérer le rat musqué comme un indicateur de la santé écologique et culturelle du delta des rivières de la Paix et Athabasca. Cette étude fait ressortir la valeur d’un suivi écologique constant qui tient compte des connaissances autochtones

Evolution of a supergene that regulates a trans-species social polymorphism

Supergenes are clusters of linked genetic loci that jointly affect the expression of complex phenotypes, such as social organization. Little is known about the origin and evolution of these intriguing genomic elements. Here we analyse whole-genome sequences of males from native populations of six fire ant species and show that variation in social organization is under the control of a novel supergene haplotype (termed Sb), which evolved by sequential incorporation of three inversions spanning half of a 'social chromosome'. Two of the inversions interrupt protein-coding genes, resulting in the increased expression of one gene and modest truncation in the primary protein structure of another. All six socially polymorphic species studied harbour the same three inversions, with the single origin of the supergene in their common ancestor inferred by phylogenomic analyses to have occurred half a million years ago. The persistence of Sb along with the ancestral SB haplotype through multiple speciation events provides a striking example of a functionally important trans-species social polymorphism presumably maintained by balancing selection. We found that while recombination between the Sb and SB haplotypes is severely restricted in all species, a low level of gene flux between the haplotypes has occurred following the appearance of the inversions, potentially mitigating the evolutionary degeneration expected at genomic regions that cannot freely recombine. These results provide a detailed picture of the structural genomic innovations involved in the formation of a supergene controlling a complex social phenotype

Semileptonic Branching Fraction of Charged and Neutral B Mesons

An examination of leptons in ${\Upsilon (4S)}$ events tagged by reconstructed $B$ decays yields semileptonic branching fractions of $b_-=(10.1 \pm 1.8\pm 1.4)\%$ for charged and $b_0=(10.9 \pm 0.7\pm 1.1)\%$ for neutral $B$ mesons. This is the first measurement for charged $B$. Assuming equality of the charged and neutral semileptonic widths, the ratio $b_-/b_0=0.93 \pm 0.18 \pm 0.12$ is equivalent to the ratio of lifetimes. A postscript version is available through World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994Comment: 9 pages (in REVTEX format) Preprint CLNS94-1286, CLEO 94-1

Measurement of the branching fraction for Υ(1S)→τ+τ−\Upsilon (1S) \to \tau^+ \tau^-

We have studied the leptonic decay of the $\Upsilon (1S)$ resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find $B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})$. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

Measurement of the Decay Asymmetry Parameters in Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+→Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode $\Lambda_c^+ \to \Lambda\pi^+$ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode $\Lambda_c \to \Sigma^+\pi^0$. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p

Observation of the Isospin-Violating Decay Ds∗+→Ds+π0D_s^{*+}\to D_s^+\pi^0

Using data collected with the CLEO~II detector, we have observed the isospin-violating decay $D_s^{*+}\to D_s^+\pi^0$. The decay rate for this mode, relative to the dominant radiative decay, is found to be $\Gamma(D_s^{*+}\to D_s^+\pi^0)/\Gamma(D_s^{*+}\to D_s^+\gamma)= 0.062^{+0.020}_{-0.018}\pm0.022$.Comment: 8 page uuencoded postscript file, also available through http://w4.lns.cornell.edu/public/CLN

Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

We have investigated $D^{+}\pi^{-}$ and $D^{*+}\pi^{-}$ final states and observed the two established $L=1$ charmed mesons, the $D_1(2420)^0$ with mass $2421^{+1+2}_{-2-2}$ MeV/c$^{2}$ and width $20^{+6+3}_{-5-3}$ MeV/c$^{2}$ and the $D_2^*(2460)^0$ with mass $2465 \pm 3 \pm 3$ MeV/c$^{2}$ and width $28^{+8+6}_{-7-6}$ MeV/c$^{2}$. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the $j_{light}=3/2$ doublet predicted by HQET. We also obtain constraints on {\footnotesize $\Gamma_S/(\Gamma_S + \Gamma_D)$} as a function of the cosine of the relative phase of the two amplitudes in the $D_1(2420)^0$ decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

Improved Measurement of the Pseudoscalar Decay Constant fDsf_{D_{s}}

We present a new determination of the Ds decay constant, f_{Ds} using 5 million continuum charm events obtained with the CLEO II detector. Our value is derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of 0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6 +/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

First Observation of τ→3πηντ\tau\to 3\pi\eta\nu_{\tau} and τ→f1πντ\tau\to f_{1}\pi\nu_{\tau} Decays

We have observed new channels for $\tau$ decays with an $\eta$ in the final state. We study 3-prong tau decays, using the $\eta\to\gamma\gamma$ and \eta\to 3\piz decay modes and 1-prong decays with two \piz's using the $\eta\to\gamma\gamma$ channel. The measured branching fractions are \B(\tau^{-}\to \pi^{-}\pi^{-}\pi^{+}\eta\nu_{\tau}) =(3.4^{+0.6}_{-0.5}\pm0.6)\times10^{-4} and \B(\tau^{-}\to \pi^{-}2\piz\eta\nu_{\tau} =(1.4\pm0.6\pm0.3)\times10^{-4}. We observe clear evidence for $f_1\to\eta\pi\pi$ substructure and measure \B(\tau^{-}\to f_1\pi^{-}\nu_{\tau})=(5.8^{+1.4}_{-1.3}\pm1.8)\times10^{-4}. We have also searched for $\eta'(958)$ production and obtain 90% CL upper limits \B(\tau^{-}\to \pi^{-}\eta'\nu_\tau)<7.4\times10^{-5} and \B(\tau^{-}\to \pi^{-}\piz\eta'\nu_\tau)<8.0\times10^{-5}.Comment: 11 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Measurement of the Bˉ→Dℓνˉ\bar{B}\to D\ell\bar{\nu} Partila Width and Form Factor Parameters

We have studied the decay $\bar{B} \to D\ell\bar{\nu}$, where $\ell=e or \mu$. From a fit to the differential decay rate $d\Gamma/dw$ we measure the rate normalization ${\cal F}_D(1)|V_{cb}|$ and form factor slope $\hat{\rho}^2_D$, and, using measured values of $\tau_B$, find $\Gamma(\bar{B} \to D\ell\bar{\nu}) = (12.0 \pm 0.9 \pm 2.1) ns^{-1}$. The resulting branching fractions are ${\cal B}(\bar{B}^0 \to D^+\ell^-\bar{\nu})=(1.87 \pm 0.15 \pm 0.32)$ and ${\cal B}(B^- \to D^0\ell^-\bar{\nu})=(1.94 \pm 0.15 \pm 0.34)$. The form factor parameters are in agreement with those measured in $\bar{B} \to D^*\ell\bar{\nu}$ decays, as predicted by heavy quark effective theory.Comment: 11 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN