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Phenological events - defined points in the life cycle of a plant or animal - have been regarded as highly plastic traits, reflecting flexible responses to various environmental cues. The ability of a species to track, via shifts in phenological events, the abiotic environment through time might dictate its vulnerability to future climate change. Understanding the predictors and drivers of phenological change is therefore critical. Here, we evaluated evidence for phylogenetic conservatism - the tendency for closely related species to share similar ecological and biological attributes - in phenological traits across flowering plants. We aggregated published and unpublished data on timing of first flower and first leaf, encompassing ̃4000 species at 23 sites across the Northern Hemisphere. We reconstructed the phylogeny for the set of included species, first, using the software program Phylomatic, and second, from DNA data. We then quantified phylogenetic conservatism in plant phenology within and across sites. We show that more closely related species tend to flower and leaf at similar times. By contrasting mean flowering times within and across sites, however, we illustrate that it is not the time of year that is conserved, but rather the phenological responses to a common set of abiotic cues. Our findings suggest that species cannot be treated as statistically independent when modelling phenological responses. Synthesis. Closely related species tend to resemble each other in the timing of their life-history events, a likely product of evolutionarily conserved responses to environmental cues. The search for the underlying drivers of phenology must therefore account for species' shared evolutionary histories. Closely related species tend to resemble each other in the timing of their life-history events, a likely product of evolutionarily conserved responses to environmental cues. The search for the underlying drivers of phenology must therefore account for species' shared evolutionary histories. © 2013 British Ecological Society.

A growing body of work indicates that the timing of flowering of temperate angiosperms has been affected by shifts in climate since the 1970s. Sensitivity in flowering phenology to changing temperatures has been particularly well-documented, but widespread phenological sensitivity to changing precipitation patterns in temperate communities has only been shown in a few studies. The exception is relationships between snowpack and early flowering in alpine environments, whereby the timing of flowering herbs had strong associations with winter precipitation and the snowmelt timing. Based on these results, we hypothesized that populations in temperate latitudes characterized by strong seasonality and winter snowfall would demonstrate associations between timing of snowmelt and flowering phenology. We combined a historical dataset of first flowering dates in a Minnesota tallgrass prairie with climatic data to construct a structural equation model, testing hypotheses on the relationships between winter precipitation, temperature, and flowering phenology. While temperature had a strong effect on flowering phenology, winter precipitation had a significant relationship with only a few species. The species affected by snow were later flowering species, which is inconsistent with our prediction that winter precipitation affects early flowering phenology. These results suggest future changes in precipitation will have differing consequences depending on region. [ABSTRACT FROM AUTHOR]

Studies of the effects of climate change on migratory bird behavior have established that many species are shifting the average day of year of their arrival at nesting sites earlier. If migrating birds are adapted to arrive at the optimum stage in the growth season to maximize the availability of resources, then migration phenology shifts may result in arrival at nesting sites at selectively disadvantageous points in seasonal development of the nesting ecosystem. First arrival dates (FAD) are changing for many species, but we know little about shifts in the corresponding accumulated growing degree units (AGDU) of arrival date in association with increasing global temperatures. By transcribing field notes for migrant arrival times during the years of 1910-1950 in the region around Fargo, ND, we obtained a detailed and robust description of historical phenological patterns. Comparison of the arrival times of 83 of the same species in the same location over the past 10 years indicate that the majority of bird species studied are arriving earlier than they did historically. The accumulated growing degree units at the time of arrival deviated from past values by as much as 4-5% higher or lower depending on the species. In general, short-distance migrants have advanced their arrival times and reduced the AGDU at the time of arrival relative to long-distance migrants. These results indicate that changing climate is influencing bird migration patterns and leading to arrival of migrants at different points in the progress of the growing season relative to the past. The impacts of this divergence on fitness and selection are expected to influence the nature of future bird communities. [ABSTRACT FROM AUTHOR]