Trophic level asynchrony in rates of phenological change for marine,freshwater and terrestrial environments

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services.     

A phylogenetic analysis of the monogenomic Triticeae (Poaceae) based on morphology

A cladistic analysis, primarily based on morphology, is presented from 40 diploid taxa representing the 24 monogenomic genera of the Triticeae. General problems related to the treatment of hybrids and supposedly allopolyploid heterogenomic taxa are highlighted. Special emphasis is given to taxa not traditionally included in Aegilops s.J. Most of the 33 characters used in the analysis are coded as binary. The only four multistate characters in the matrix are treated as unordered. Three diploid species of Bromus are used as outgroup. The number of equally parsimonious trees found is very large (approx. 170000; length = 107, ci = 0.36, ri = 0.75) and the strict consensus tree has an expectedly low level of resolution. However, most of the equally parsimonious trees owe their existence to an unresolved Aegilops clade. If this clade is replaced by its hypothetical ancestor, the number of equally parsimonious trees drops dramatically (48; length = 78, ci = 0.45, ri = 0.76). When trees for which more highly resolved compatible trees exist are excluded, only two trees remain. Bremer support is used as a measure of branch support. The trees based on morphology and on molecular data are largely incongruent.     

Among‐colony synchrony in the survival of Common Guillemots Uria aalge reflects shared wintering areas

Spatiotemporal variation in survival may be an important driver of multi‐population dynamics in many wild animal species, yet few scientific studies have addressed this issue, primarily due to a lack of sufficiently comprehensive and detailed datasets. Synchrony in survival rates among different, often distant, subpopulations appears to be common, caused by spatially correlated environmental conditions or by movement of animals from different sites such that their ranges overlap. Many seabird populations are effectively isolated during the breeding season because colonies are widely separated, but over the winter, birds disperse widely and there may be much mixing between different populations. The non‐breeding season is also the period of main mortality for seabirds. Using mark–recapture and ring‐recovery data, we tested for spatial, temporal and age‐related correlations in survival of Common Guillemots Uria aalge among three widely separated Scottish colonies that have varying overlap in their overwintering distributions. Survival was highly correlated over time for colonies/age‐classes sharing wintering areas and, except in 2004, was essentially uncorrelated for those with separate wintering areas. These results strongly suggest that one or more aspects of the winter environment are responsible for spatiotemporal variation in survival of British Guillemots, and provide insight into the factors driving large‐scale population dynamics of the species.     

Landscape genetics, historical isolation and cross-Andean gene flow in the wax palm, Ceroxylon echinulatum (Arecaceae)

Knowledge of the role of landscapes in shaping genetic connectivity and divergence is essential for understanding patterns of biogeography and diversity. This is particularly relevant for the Andes region, a major biodiversity hotspot of relatively recent origin. We examined the phylogeography and landscape genetics of the Andean wax palm Ceroxylon echinulatum (Arecaceae) that occurs in two narrow bands of montane forests on each side of the Andes in Ecuador and northeastern Peru. First, we tested the hypothesis of C. echinulatum being a geographic cline species crossing the Andes in the Amotape–Huancabamba zone (AHZ) of southern Ecuador/northern Peru, as indicated by observations on fruit morphology. Second, we assessed the timeframe of cross-Andean divergence, and third, we investigated the impact of contemporary and historical landscape features on observed spatio-genetic patterns. Individual-based Bayesian clustering (BC) identified a northeastern, southeastern, southwestern, and northwestern cluster, with areas of genetic discontinuity coinciding with the Andes and the Giron–Paute deflection. F -statistics derived from BC suggested an east-to-west dispersal history. Population-based analyses revealed strong genetic structuring at both small and large geographic scales. Interpopulation relationships and Mantel tests strongly supported the cline model with cross-Andean dispersal in the AHZ. Along the cline, gene flow measured as F _ST was mainly limited by distance, with less but significant impact of climatic friction. Coalescent analysis revealed that cross-Andean divergence took place during the Quaternary. Significant historical isolation ( R _ST >  F _ST) was found in the southwestern population. The current study illustrates a joint effect of founder dynamics, divergence by distance and historical isolation on patterns of Andean diversity and distribution.     

Crassulacean acid metabolism contributes significantly to the in situ carbon budget in a population of the invasive aquatic macrophyte Crassula helmsii

1. The ecophysiological significance of Crassulacean acid metabolism (CAM) in the invasive aquatic macrophyte Crassula helmsii was studied in an English soft‐water lake. The extent and the contribution of CAM to the carbon budget was examined in spring (April) and summer (July) along a depth gradient (0.5–2.2 m), covering the growth range of C. helmsii in the lake. 2. Significant in situ CAM activity (30–80 meq kg⁻¹ FW) was present in all specimens, although it decreased with depth and hence correlated with the decline in photon irradiance. Potential CAM activity (60–161 meq kg⁻¹ FW), measured after exposure to low concentrations of CO₂ in the day and high concentrations at night, were on average 2.7‐times greater than in situ CAM activity. Overall CAM activity increased from April to July, which is consistent with higher potential carbon limitation caused by increased temperature and light availability. 3. CAM activity in C. helmsii appeared to be carbon‐limited at night because night‐time carbon‐fixation increased at raised, compared to ambient, concentrations of CO₂. 4. The high in situ CAM activity in C. helmsii was reflected in the contribution of CAM to the total carbon budget which, independent of depth and season, ranged from 18% to 42%. The amount of CO₂ taken up in the night via CAM was 0.74 to 2.94 times the amount of CO₂ lost in respiration, thus emphasizing the importance of CAM in refixation of potentially lost respiratory CO₂. 5. The onset of decarboxylation in the morning appeared to be under circadian control as there was a delay of up to 5.5 h between the start of the light period and a decline in cell acidity level. 6. There was little variation in δ¹³C content (−21.69 to 23.49‰) with season or depth suggesting, along with the estimated contribution to the carbon‐budget, that CAM is important for the whole population of C. helmsii. CAM may confer a competitive advantage in relation to growth, which may be one of the reasons for the invasiveness of this species.     

Climate change and plant distribution: local models predict high-elevation persistence

Mountain ecosystems will likely be affected by global warming during the 21st century, with substantial biodiversity loss predicted by species distribution models (SDMs). Depending on the geographic extent, elevation range, and spatial resolution of data used in making these models, different rates of habitat loss have been predicted, with associated risk of species extinction. Few coordinated across-scale comparisons have been made using data of different resolutions and geographic extents. Here, we assess whether climate change-induced habitat losses predicted at the European scale (10 × 10' grid cells) are also predicted from local-scale data and modeling (25 m × 25 m grid cells) in two regions of the Swiss Alps. We show that local-scale models predict persistence of suitable habitats in up to 100% of species that were predicted by a European-scale model to lose all their suitable habitats in the area. Proportion of habitat loss depends on climate change scenario and study area. We find good agreement between the mismatch in predictions between scales and the fine-grain elevation range within 10 × 10' cells. The greatest prediction discrepancy for alpine species occurs in the area with the largest nival zone. Our results suggest elevation range as the main driver for the observed prediction discrepancies. Local-scale projections may better reflect the possibility for species to track their climatic requirement toward higher elevations.     

Within- and between-year variation in the juvenile survival of Common Guillemots Uria aalge

We studied juvenile survival of 20 cohorts of Common Guillemot Uria aalge chicks colour-ringed on the Isle of May, Scotland, using both live observations at the colony and dead recoveries, allowing estimation of fidelity to the colony as well as survival. In this seabird, chicks leave the colony when only partly grown and are cared for by the male parent for several weeks afterwards. First-year survival varied strongly between cohorts, with a mean of 56% (range 30–91%). We did not identify any covariates which could explain this variation, whether relating to climate, population size or prey density. Survival was low during two regime shift episodes in the North Sea (1987–90 and 2000 onwards). Early hatched chicks were substantially more likely to survive than those hatching later in most years, whereas body condition at ringing had no detectable effect. Ringing recoveries indicated that mortality was highest in mid-winter, i.e. well after the cessation of paternal care. These results do not support the hypothesis that variation in prey quantity or energy content before fledging is a primary driver of variation in juvenile survival. Rather, it seems that chicks of high-quality parents are more likely to survive, as high-quality females tend to lay earlier in the season, and high-quality males presumably are better able to prepare their chicks to survive their first winter at sea. Very few (4%) Guillemots emigrated permanently before age 3 years, but from age 5 onwards 25–30% of birds annually left the colony or otherwise became unobservable.     

Significance of monosulcate pollen abundance in Mesozoic sediments

Monosulcate pollen was produced by at least six plant orders in the Mesozoic. Megafossils of these orders are abundant in many Mesozoic sediments, but dispersed monosulcate pollen grains are commonly less than 10% of total sporomorphs (spores and pollen) in a sample. This paper presents possible explanations for the different relative frequencies of megafossils and pollen grains of monosulcate-producing plants (some of the explanations apply to only a few taxa): fragility of the pollen exines, destruction of the pollen on the plant by insects, poor pollen dispersal because of zoophily and small plant size, and, probably most importantly, overrepresentation of the plants by their generally deciduous leaves. Mesozoic monosulcate pollen was different in several ways from pollen of modern gymnosperms; furthermore, monosulcate-producing plants were not as abundant in the Mesozoic vegetation as has been generally thought.