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Reproduction in plants often requires animal vectors. Fruit and flower colors are traditionally viewed as an adaptation to facilitate detection for pollinators and seed dispersers. This longstanding hypothesis predicts that fruits are easier to detect against their own leaves compared with those of different species. We tested this hypothesis by analyzing the chromatic contrasts between 130 bird-dispersed fruits and their respective backgrounds according to avian vision. From a bird's view, fruits are not more contrasting to their own background than to those of other plant species. Fruit colors are therefore not adapted toward maximized conspicuousness for avian seed dispersers. However, secondary structures associated with fruit displays increase their contrasts. We used fruit colors to assess whether the ultraviolet and violet types of avian visual systems are equally efficient in detecting color signals. In bright light, the chromatic contrasts between fruit and background are stronger for ultraviolet vision. This advantage is due to the lesser overlap in spectral sensitivities of the blue and ultraviolet cones, which disappears in dim light conditions. We suggest that passerines with ultraviolet cones might primarily use epigamic signals that are less conspicuous to their avian predators (presumably with violet vision). Possible examples for such signals are carotenoid-based signals.

In cooperatively breeding species, in which non-breeding helpers assist in rearing the offspring of breeding individuals, conflicts of interest commonly occur between breeders and helpers over their respective contributions to offspring care. During such conflicts, breeders might use aggressive behavior to enforce contributions of helpers to offspring care, especially if helpers are not related to the breeders and their offspring and thus do not stand to gain indirect fitness benefits by helping. Using a combination of behavioral and genetic data, we investigated in the cooperatively breeding El Oro parakeet Pyrrhura orcesi (i) whether breeders are commonly dominant over helpers, (ii) whether they use aggressive behavior toward helpers to enforce offspring provisioning, and (iii) whether the relatedness of helpers to the nestlings affects the frequency of --or the reaction of helpers to--such aggressions. Even though breeders were generally dominant over helpers, we found no evidence for the enforcement of alloparental care. This finding was independent of the relatedness between helpers and nestlings, even though distantly related helpers overall contributed little to offspring care. We suggest that the inability of breeders to properly assess the work rates of their helpers at least partly explains the absence of enforcement. More generally, our results add to a body of evidence suggesting that enforcement might be an exceptional rather than a general mechanism underlying the expression of alloparental care in cooperatively breeding species. [ABSTRACT FROM AUTHOR]

Using 454 pyro-sequencing, we established a microsatellite dataset of 12 polymorphic markers for the endangered Pale-headed Brushfinch ( Atlapetes pallidiceps). Within 24 individuals, mean number of alleles ranged from 2 to 13, observed heterozygosity from 0.17 to 1.0, expected heterozygosity from 0.16 to 0.91, and polymorphic information content from 0.15 to 0.88. Additionally, we tested our marker set for cross-amplification in two related brushfinch species. Whereas all 12 markers amplified and were polymorphic in A. latinuchus, only 5 of the 11 markers amplified variable loci in Buarremon torquatus. This panel of microsatellites will allow a comparison between the genetic diversity of the threatened Atlapetes pallidiceps and two co-occurring non-endangered brushfinch species. [ABSTRACT FROM AUTHOR]