Time after time: flowering phenology and biotic interactions.
ABSTRACT The role of biotic interactions in shaping plant flowering phenology has long been controversial; plastic responses to the abiotic environment, limited precision of biological clocks and inconsistency of selection pressures have generally been emphasized to explain phenological variation. However, part of this variation is heritable and selection analyses show that biotic interactions can modulate selection on flowering phenology. Our review of the literature indicates that pollinators tend to favour peak or earlier flowering, whereas pre-dispersal seed predators tend to favour off-peak or later flowering. However, effects strongly vary among study systems. To understand such variation, future studies should address the impact of mutualist and antagonist dispersal ability, ecological specialization, and habitat and plant population characteristics. Here, we outline future directions to study how such interactions shape flowering phenology.
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ABSTRACT: Organisms develop through multiple life stages that differ in environmental tolerances. The seasonal timing, or phenology, of life-stage transitions determines the environmental conditions to which each life stage is exposed and the length of time required to complete a generation. Both environmental and genetic factors con-tribute to phenological variation, yet predicting their combined effect on life cycles across a geographic range remains a challenge. We linked submodels of the plasticity of individual life stages to create an in-tegrated model that predicts life-cycle phenology in complex envi-ronments. We parameterized the model for Arabidopsis thaliana and simulated life cycles in four locations. We compared multiple "ge-notypes" by varying two parameters associated with natural genetic variation in phenology: seed dormancy and floral repression. The model predicted variation in life cycles across locations that quali-tatively matches observed natural phenology. Seed dormancy had larger effects on life-cycle length than floral repression, and results suggest that a genetic cline in dormancy maintains a life-cycle length of 1 year across the geographic range of this species. By integrating across life stages, this approach demonstrates how genetic variation in one transition can influence subsequent transitions and the geo-graphic distribution of life cycles more generally. Plant life cycles are composed of multiple life stages (e.g., seed, vegetative, reproductive) that differ in environmental sensitivities and tolerances. In seasonal environments, the timing, or phenology, of life-stage transitions (e.g., germi-nation, flowering, seed dispersal) may have importantThe American Naturalist 02/2015; 93513(4). · 4.45 Impact Factor
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ABSTRACT: Citation: Lisi, P. J., and D. E. Schindler. 2011. Spatial variation in timing of marine subsidies influences riparian phenology through a plant-pollinator mutualism. Ecosphere 2(9):101. Abstract. Migratory animals are well-recognized for transporting energy and nutrients across habitat boundaries as resource subsidies but less is known about the secondary effects of these subsidies in supporting biodiversity in recipient ecosystems. In southwestern Alaska, fly-pollinated plants in the carrot family (Apiaceae) flower during the annual arrival of semelparous Pacific salmon to their natal streams to spawn. Blowflies (Calliphoridae) are an important consumer of salmon carcasses as larvae and pollinate Apiaceae as adults. Stable isotope analyses indicate that adult blowflies received the majority (85%) of their carbon and nitrogen from salmon carcasses and the remainder from riparian plants. A large terrestrial signature was passed maternally to blowfly eggs but quickly replaced by marine-derived resources as eggs developed into larvae on salmon carcasses. We also monitored the flowering phenology of kneeling Angelica (Angelica genuflexa) across salmon bearing streams (n ¼ 20) that differ in the timing of salmon spawning. We found that salmon spawning date explained a substantial amount of the observed seasonal variation in peak flowering dates among streams and, when combined with longitude, explained 88% of the variation in seasonal phenology of Angelica among streams. By comparison, distance from the ocean, stream temperature, slope, aspect, and elevation in the riparian area had no relationship with Angelica bloom date. Together, these results suggest that spatial variation in salmon spawning timing is transmitted via the phenology of salmon-dependent consumers that affect the bloom timing of a common riparian plant.Ecosphere 09/2011; 2(9). · 2.60 Impact Factor
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ABSTRACT: Flowering phenology is central to the ecology and evolution of most flowering plants. In highly-specific nursery pollination systems, such as that involving fig trees (Ficus species) and fig wasps (Agaonidae), any mismatch in timing has serious consequences because the plants must balance seed production with maintenance of their pollinator populations. Most fig trees are found in tropical or subtropical habitats, but the dioecious Chinese Ficus tikoua has a more northerly distribution. We monitored how its fruiting phenology has adapted in response to a highly seasonal environment. Male trees (where fig wasps reproduce) had one to three crops annually, whereas many seed-producing female trees produced only one fig crop. The timing of release of Ceratosolen fig wasps from male figs in late May and June was synchronized with the presence of receptive figs on female trees, at a time when there were few receptive figs on male trees, thereby ensuring seed set while allowing remnant pollinator populations to persist. F. tikoua phenology has converged with those of other (unrelated) northern Ficus species, but there are differences. Unlike F. carica in Europe, all F. tikoua male figs contain male flowers, and unlike F. pumila in China, but like F. carica, it is the second annual generation of adult wasps that pollinate female figs. The phenologies of all three temperate fig trees generate annual bottlenecks in the size of pollinator populations and for female F. tikoua also a shortage of fig wasps that results in many figs failing to be pollinated.PLoS ONE 12/2014; 9(12):e114344. · 3.53 Impact Factor