  In this paper, we study the flux of electrons and positrons injected by
pulsars and by annihilating or decaying dark matter in the context of recent
ATIC, PAMELA, Fermi, and HESS data. We review the flux from a single pulsar and
derive the flux from a distribution of pulsars. We point out that the particle
acceleration in the pulsar magnetosphere is insufficient to explain the
observed excess of electrons and positrons with energy E ~ 1 TeV and one has to
take into account an additional acceleration of electrons at the termination
shock between the pulsar and its wind nebula. We show that at energies less
than a few hundred GeV, the flux from a continuous distribution of pulsars
provides a good approximation to the expected flux from pulsars in the
Australia Telescope National Facility (ATNF) catalog. At higher energies, we
demonstrate that the electron/positron flux measured at the Earth will be
dominated by a few young nearby pulsars, and therefore the spectrum would
contain bumplike features. We argue that the presence of such features at high
energies would strongly suggest a pulsar origin of the anomalous contribution
to electron and positron fluxes. The absence of features either points to a
dark matter origin or constrains pulsar models in such a way that the
fluctuations are suppressed. Also we derive that the features can be partially
smeared due to spatial variation of the energy losses during propagation.
