Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Journal of Animal Ecology 87 (2018): 682-690, doi:10.1111/1365-2656.12790.
Description:
Phenological changes have been observed in a variety of systems over the past century.
There is concern that, as a consequence, ecological interactions are becoming
increasingly mismatched in time, with negative consequences for ecological function.
Significant spatial heterogeneity (inter-site) and temporal variability (inter-annual) can
make it difficult to separate intrinsic, extrinsic, and stochastic drivers of phenological
variability. The goal of this study was to understand the timing and variability of
breeding phenology of Adélie penguins under fixed environmental conditions, and to use
those data to identify a ‘null model’ appropriate for disentangling the sources of variation
in wild populations.
Data on clutch initiation were collected from both wild and captive populations of Adélie
penguins. Clutch initiation in the captive population was modeled as a function of year,
individual, and age to better understand phenological patterns observed in the wild
population.
Captive populations displayed as much inter-annual variability in breeding phenology as
wild populations, suggesting that variability in breeding phenology is the norm and thus
may be an unreliable indicator of environmental forcing. The distribution of clutch
initiation dates was found to be moderately asymmetric (right skewed) both in the wild
and in captivity, consistent with the pattern expected under social facilitation.
The role of stochasticity in phenological processes has heretofore been largely ignored.
However, these results suggest that inter-annual variability in breeding phenology can
arise independent of any environmental or demographic drivers and that synchronous
breeding can enhance inherent stochasticity. This complicates efforts to relate
phenological variation to environmental variability in the 53 wild. Accordingly, we must be
careful to consider random forcing in phenological processes, lest we fit models to data
dominated by random noise. This is particularly true for colonial species where breeding
synchrony may outweigh each individual’s effort to time breeding with optimal
environmental conditions. Our study highlights the importance of identifying appropriate
null models for studying phenology.
Description:
Funding to HJL and CY was provided by the National
Science Foundation Grant OPP/GSS 1255058, and to SJ, HJL, and CY, by the National Science
Foundation Grant 1341474.
Keywords:
Antarctica
;
Adélie penguin
;
Bayesian hierarchical model
;
Climate change
;
Coloniality
;
Phenological mismatch
;
Pygoscelis adeliae
;
Stochasticity
;
Synchrony
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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