1. | Ecol Evol. 2014 Apr;4(8):1222-32. doi: 10.1002/ece3.994. Epub 2014 Mar 11.Color expression in experimentally regrown feathers of an overwintering migratory bird: implications for signaling and seasonal interactions.Tonra CM1, Marini KL2, Marra PP3, Germain RR4, Holberton RL5, Reudink MW2.Author information:1Migratory Bird Center, Smithsonian Conservation Biology Institute National Zoological Park, Washington, District of Columbia ; School of Biology and Ecology, University of Maine Orono, Maine. 2Department of Biological Sciences, Thompson Rivers University Kamloops, BC V2C 0C8, Canada. 3Migratory Bird Center, Smithsonian Conservation Biology Institute National Zoological Park, Washington, District of Columbia. 4Centre for Applied Conservation Research, University of British Columbia Vancouver, BC V6T 1Z4, Canada. 5School of Biology and Ecology, University of Maine Orono, Maine. Abstract
Plumage
coloration in birds plays a critical role in communication and can be
under selection throughout the annual cycle as a sexual and social
signal. However, for migratory birds, little is known about the
acquisition and maintenance of colorful plumage during the nonbreeding
period. Winter habitat could influence the quality of colorful plumage,
ultimately carrying over to influence sexual selection and social
interactions during the breeding period. In addition to the annual
growth of colorful feathers, feather loss from agonistic interactions or
predator avoidance could require birds to replace colorful feathers in
winter or experience plumage degradation. We hypothesized that
conditions on the wintering grounds of migratory birds influence the
quality of colorful plumage. We predicted that the quality of American
redstart (Setophaga ruticilla) tail feathers regrown after experimental
removal in Jamaica, West Indies, would be positively associated with
habitat quality, body condition, and testosterone. Both yearling (SY)
and adult (ASY) males regrew feathers with lower red chroma, suggesting
reduced carotenoid content. While we did not observe a change in hue in
ASY males, SY males shifted from yellow to orange plumage resembling
experimentally regrown ASY feathers. We did not observe any effects of
habitat, testosterone, or mass change. Our results demonstrate that
redstarts are limited in their ability to adequately replace colorful
plumage, regardless of habitat, in winter. Thus, feather loss on the
nonbreeding grounds can affect social signals, potentially negatively
carrying over to the breeding period.
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PMID: 24834321 [PubMed] | |
2. | Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Apr;89(4-1):042806. Epub 2014 Apr 15.Impact fragmentation of model flocks.Miller PW1, Ouellette NT2.Author information:1Department of Physics, Yale University, New Haven, Connecticut 06520, USA. 2Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA. Abstract
Predicting
the bulk material properties of active matter is challenging since
these materials
are far from equilibrium and standard statistical-mechanics approaches
may fail. We report a computational study of the surface properties of a
well known active matter system: aggregations of self-propelled
particles that are coupled via an orientational interaction and that
resemble bird flocks. By simulating the impact of these models flocks on
an impermeable surface, we find that they fragment into subflocks with
power-law mass distributions, similar to shattering brittle solids but
not to splashing liquid drops. Thus, we find that despite the
interparticle interactions, these model flocks do not possess an
emergent surface tension.
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PMID: 24827292 [PubMed - as supplied by publisher] | |
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3. | Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Apr;89(4-1):042707. Epub 2014 Apr 16.Dynamical maximum entropy approach to flocking.Cavagna A1, Giardina I1, Ginelli F2, Mora T3, Piovani D4, Tavarone R4, Walczak AM5.Author information:1Istituto Sistemi Complessi, Consiglio Nazionale delle Ricerche, UOS Sapienza, Rome, Italy and Dipartimento di Fisica, Università Sapienza, Rome, Italy and Initiative for the Theoretical Sciences, The Graduate Center, The City University of New York, New York, USA. 2SUPA, Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen, UK. 3Laboratoire de physique statistique, CNRS, UPMC and École normale supérieure, Paris, France. 4Dipartimento di Fisica, Università Sapienza, Rome, Italy. 5Laboratoire de physique théorique, CNRS, UPMC and École normale supérieure, Paris, France. Abstract
We
derive a new method to infer from data the out-of-equilibrium alignment
dynamics of collectively moving animal groups, by considering the
maximum entropy model distribution consistent with temporal and spatial
correlations of flight direction. When bird neighborhoods evolve
rapidly, this dynamical inference correctly learns the parameters of the
model, while a static one relying only on the spatial correlations
fails. When neighbors change slowly and the detailed balance is
satisfied, we recover the static procedure. We demonstrate the validity
of the method on
simulated data. The approach is applicable to other systems of active
matter.
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PMID: 24827278 [PubMed - as supplied by publisher] | |
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4. | Evol Appl. 2014 Apr;7(4):506-18. doi: 10.1111/eva.12154. Epub 2014 Mar 20.Joint effects of population size and isolation on genetic erosion in fragmented populations: finding fragmentation thresholds for management.Méndez M1, Vögeli M2, Tella JL1, Godoy JA1.Author information:1Estación Biológica de Doñana (EBD-CSIC) Sevilla, Spain. 2Estación Biológica de Doñana (EBD-CSIC) Sevilla, Spain ; Department of Biology, University of Saskatchewan Saskatoon, SK, Canada ; Schulstrasse 47, 5423, Freienwil, Switzerland. Abstract
Size
and isolation of local populations are main parameters of interest when
assessing the genetic consequences of habitat fragmentation. However,
their relative influence on the genetic erosion of local populations
remains unclear. In this study, we first analysed how size and isolation
of habitat patches influence the genetic variation of local populations
of the Dupont's lark (Chersophilus duponti), an endangered songbird. An
information-theoretic approach to model selection allowed us to address
the importance of interactions between habitat
variables, an aspect seldom considered in fragmentation studies, but
which explained up to 65% of the variance in genetic parameters. Genetic
diversity and inbreeding were influenced by the size of local
populations depending on their degree of isolation, and genetic
differentiation was positively related to isolation. We then identified a
minimum local population of 19 male territories and a maximum distance
of 30 km to the nearest population as thresholds from which genetic
erosion becomes apparent. Our results alert on possibly misleading
conclusions and suboptimal management recommendations when only additive
effects are taken into account and encourage the use of most
explanatory but easy-to-measure variables for the evaluation of genetic
risks in conservation programmes.
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PMID: 24822084 [PubMed] | |
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