Year‐to‐year variation in the topology of a plant–pollinator interaction network

Abstract

Vigorous discussion of the degree of specialization in pollination interactions, combined with advances in the analysis of complex networks, has revitalized the study of entire plantÁpollinator communities. Noticeably rare, however, are attempts to quantify temporal variation in the structure of plantÁpollinator networks, and to determine whether the status of species as specialists or generalists is stable. Here we show that network structure varied through time in a montane meadow community from southern California, USA, in that pollinator species did not form the same links with plant species across years. Furthermore, composition of the generalized core group of species in the network varied among summers, as did the identity of those species involved in relationships that appeared to be reciprocally specialized within any one summer. These differences appear to be related to severe drought conditions experienced in the second summer of the 3 year study. In contrast to this variation, the pollinator community remained similarly highly nested in all three summers, even though species were packed into the nested matrix differently from year to year. These results suggest that plantÁpollinator networks vary in detail through time, while retaining some basic topological properties. This dynamic aspect of community-scale interactions has implications for both ecological and evolutionary inferences about pollination mutualisms.

Biodiversity, Species Interactions and Ecological Networks in a Fragmented World

“…Plants and pollinators exposed to similar environmental changes may react in synchrony, decreasing the occurrence of mismatches (Hegland et al, 2009). In pollination networks, high turnover in species composition and interactions over time are well documented (Alarcón et al, 2008;Dupont and Olesen, 2009;Olesen et al, 2008;Petanidou et al, 2008), but the consequences of adding the spatial component of a fragmented landscape to temporal mismatches are virtually unknown.…”

Cross-depth analysis of marine bacterial networks suggests downward propagation of temporal changes

“…Time scale appears to be an important determinant of organismal associations. We previously reported that members of the SAR11 cluster were correlated on a daily time scale but not monthly (Fuhrman and Steele, 2008;Steele et al, 2011;Needham et al, 2013;Fuhrman et al, 2015), reflecting patterns of temporal variability in network structure seen in other systems (Alarcón et al, 2008). A common feature of networks is the presence of modules, that is, highly interconnected groups of nodes (Newman, 2006;Olesen et al, 2007;Ings et al, 2009) and microbial networks are no exception Chow et al, 2013).…”

The temporal dynamics of resource use by frugivorous birds: a network approach

“…Fortunately, an increasing number of studies are progressively filling these gaps by providing both improved spatially explicit approaches (Holt 2002, Rooney et al 2008) and empirically exhaustive descriptions of the temporal dynamics of networks (Winemiller 1990, Neutel et al 2007, Alarco´n et al 2008, Olesen et al 2008, OwenSmith and Mills 2008. Similarly, another unsolved challenge is to identify and quantitatively assess the relative importance of the diverse ecological and evolutionary processes that ultimately shape network structures , Cattin et al 2004, OwenSmith and Mills 2008, Rooney et al 2008.…”