The evolutionary diversification of spiders is attributed to spectacular innovations in silk. Spiders are unique in synthesizing many different kinds of silk, and using silk for a variety of ecological functions throughout their lives, particularly to make preycatching webs. Here, we construct a broad higher-level phylogeny of spiders combining molecular data with traditional morphological and behavioral characters. We use this phylogeny to test the hypothesis that the spider orb web evolved only once. We then examine spider diversification in relation to different web architectures and silk use. We find strong support for a single origin of orb webs, implying a major shift in the spinning of capture silk and repeated loss or transformation of orb webs. We show that abandonment of costly cribellate capture silk correlates with the 2 major diversification events in spiders (1). Replacement of cribellate silk by aqueous silk glue may explain the greater diversity of modern orb-weaving spiders (Araneoidea) compared with cribellate orb-weaving spiders (Deinopoidea) (2). Within the ''RTA clade,'' which is the sister group to orb-weaving spiders and contains half of all spider diversity, >90% of species richness is associated with repeated loss of cribellate silk and abandonment of prey capture webs. Accompanying cribellum loss in both groups is a release from substrate-constrained webs, whether by aerially suspended webs, or by abandoning webs altogether. These behavioral shifts in silk and web production by spiders thus likely played a key role in the dramatic evolutionary success and ecological dominance of spiders as predators of insects.Araneidae ͉ behavioral evolution ͉ cribellate silk ͉ orb web ͉ speciation S piders are exceptionally diverse and abundant in terrestrial ecosystems. In contrast to megadiverse orders of insects, evolutionary diversification of spiders is not coupled with major trophic shifts. All spiders are predators of arthropods, and spiders are dominant consumers at intermediate trophic levels (1, 2). Spider diversification is instead linked to key innovations in silk use (3-7). For instance, the araneoid orb web (Fig. 1) with stretchy capture spirals, coated by adhesive viscid silk secretions, provides access to abundant flying insects (3,8). However, many spiders produce cribellate silk, a radically different dry adhesive that adheres to prey, using van der Waals interactions and hygroscopic forces (9). Some cribellate spiders also construct aerial orb webs, whereas most spin sheet-like webs on the substrate (Fig. S1) or have abandoned capture webs altogether. Furthermore, the most diverse families within ''orb-weavers'' (Orbiculariae) no longer build orb webs, but instead spin aerial sheet webs (Linyphiidae) or cobwebs (Theridiidae) (Fig. S2). Thus, discovering the pattern of evolution of web spinning behaviors is essential for understanding spider diversification.Orb webs possessing dry cribellate capture spirals are architecturally similar to those spun from aqueous viscid silk ( Fig. 1 ...

INTRODUCTIONThe sociobiology debates of the 1970s increased interest in the biology of behavior. At the same time, the growth of cladistics increased interest in how to do systematics and phylogenetic reconstruction. Yet, there are surprisingly few recent papers dealing explicitly with behavior from a phylogenetic perspective. Lack of communication between students of behavior and students of systematics is partly to blame. If one says to a behavioral ecologist, "Isn't it curious that there are white bears in the arctic?" he may say that there is nothing curious about it because they are white like all the other arctic mammals, and the fact that they are bears is irrelevant to the broad patterns of evolution. If one asks the same of a systematist he may reply that there is nothing curious about it because they are still bears like all the others, and the fact that they are white is irrelevant to the broad patterns of evolution. Both perspectives are partly right, and both are less than the whole story. Systematists tend to look for constraints of history, while behaviorists usually prefer to work with a warm ball of clay that lies ready to take on any shape the outside forces push upon it.Some of what follows is review and some is more philosophical, but the point of the paper is simple. Determining homology among behaviors is no different than determining homology among morphological structures. Behav ior is not special, it is only more difficult to characterize. Ethology (the study of behavior) is a relatively young science and does not yet have the benefit of centuries of debate and consensus, but that provides more reason for us to take up the challenge now. Ethology has made almost no advance with respect to a phylogenetic understanding of behavior since the late 1950s, and most Further ANNUAL REVIEWS 362 WENZEL modern ethologists simply do not work toward that goal. To honor the proud . heritage of Lorenz and Tinbergen we need only to be brave and begin.There is an immense literature dealing with "evolution of behavior," but only a tiny fraction of ethological efforts are relevant to the question of how one postulates homology among specific elements of an animal's behavioral repertoire. The majority of studies on behavioral evolution are related to theories of the process of evolution, and they therefore compare grades to illuminate the way in which analogous transitions occur in different groups (33). The focus of these studies is the transition itself, and homology of the steps is n01: an issue. Also the taxonomic literature is skewed toward finding species-spc:cific behaviors that allow identification more easily than morpho logical varii ation allows (1). Such unique traits do not assist in reconstructing phylogeny; only shared traits are useful for finding a nested hierarchy of order.I have tried! to include here both classical and more recent works that illustrate explicit postulates of homology, or cases where behavioral characters were critical for defining or supporting a phylogenetic scheme, but ...

1. Forest ecosystems are critical for the global regulation of carbon (C), a substantial portion of which is stored in above-ground biomass (AGB). While it is well understood that taxonomic and functional composition, stand structure and environmental gradients influence spatial variation in AGB, the relative strengths of these drivers at landscape scales have not been investigated in temperate forests. Furthermore, when biodiversity enhances C storage, it is unclear whether it is through mass-ratio effects (i.e. the dominant trait in communities regulates AGB) or through niche complementarity (i.e. increased AGB due to interspecific resource partitioning).2. To address these mechanisms, we analysed data from a census of 28,262 adult trees sampled across 900 ha of temperate deciduous forest in southwestern Pennsylvania. We used data on four key plant functional traits to determine if (1) there is a positive relationship between species diversity and AGB and (2) whether this is due to mass-ratio effects or niche complementarity. We also sought to (3) identify the physical stand structural attributes and topographic variables that influence AGB across this landscape.3. We found AGB was positively related to species richness and negatively related to species evenness, albeit weakly, while functional diversity indices had neutral effects. Above-ground biomass was enhanced in communities dominated by traits related to greater maximum tree height, deeper minimum rooting depths and larger seeds. Most importantly, areas with high AGB were dominated by Acer saccharum and Liriodendron tulipifera. Overall, these results support mass-ratio effects, with little evidence for niche complementarity. Synthesis.Stand structure, topography, and species and functional composition, but not taxonomic or functional diversity, were found to be key drivers of aboveground biomass at landscape scales (<900 ha) in this temperate deciduous forest.Our findings suggest that simultaneously managing for both high diversity andfor above-ground carbon storage may prove challenging in some forest systems.Our results further indicate that the impact of tree biodiversity loss on aboveground carbon stocks will depend greatly on the identity of the species that are lost. | Journal of EcologyFOTIS eT al. SUPPORTING INFORMATIONAdditional Supporting Information may be found online in the supporting information tab for this article.How to cite this article: Fotis AT, Murphy SJ, Ricart RD, et al.Above-ground biomass is driven by mass-ratio effects and stand structural attributes in a temperate deciduous forest.

In social insects, colony-level complexity may emerge from simple individual-level behaviors and interactions. Emergent global properties such as colony size, which can be viewed as a consequence of life history traits, may inf luence individual-level behaviors themselves. The effects of colony size on productivity, body size, behavioral f lexibility, and colony organization are examined here by considering colony size as an independent variable. Large colony size commonly corresponds with complex colony-level performance, small body size, and lower per capita productivity. Analyzing the construction behavior of various wasp societies reveals that complexity of individual behavior is inversely related to colony size. Parallel processing by specialists in large colonies provides f lexible and efficient colony-level functioning. On the other hand, individual behavioral f lexibility of jack-of-all trades workers ensures success of the small and early societies.Evolutionary biology recently has developed new interest in explanations of how autonomous units can cooperate to form more complex systems (1). Parallel-processing systems poised at the boundary between chaos and order are well able to adapt and evolve (2). Parallel processing requires the existence of several agents or units, plus mechanisms that ensure the specialization and organization of these units into a complex efficient system. An intriguing and simple system organized in this way can be found in social insects, where the colony conducts all of its operations concurrently instead of sequentially. Reliability theory posits that redundancy at the subunit level is more efficient than redundancy at the system level (3). In relation to insect colonies, a system of redundant components (labor is divided by task, the separate tasks are concatenated to form a complete sequence) is preferred to several separate systems (wherein each individual performs the entire sequence independently of other individuals

Through a phylogenetic analysis using adult morphological characters, we show that the origin of bioluminescence in cantharoid beetles appears to predate the origin of the family Lampyridae. The ability to produce and emit photic signals was first gained by larvae and appears to function as an aposematic warning display; it was subsequently gained in adults and is used as a sexual signal. Our analysis also suggests that while pheromonal sexual signals are used basally in the family, they are used in conjunction with and then subsequently replaced by photic signals in some lampyrid lineages. Both photic signals and the photic organs used to produce them have become greatly elaborated in the fireflies that no longer employ pheromonal sexual signals. In addition, the ability to produce a flashed sexual signal appears to have arisen at least three times in the family Lampyridae. Convergent evolution is also evident in a number of adult male photic organ morphologies. Further, we recommend that individual signal system components be compared rather than overall signal system complexity. The use of this strategy may allow one to recognize and better interpret adaptive correlations despite convergence or loss. We demonstrate that phylogenetic analysis is a powerful tool even for rapidly evolving traits.