Neighbor Proximity Research Articles

Competing neighbors: light perception and root function.

Plant responses to competition have often been described as passive consequences of reduced resource availability. However, plants have mechanisms to forage for favorable conditions and anticipate competition scenarios. Despite the progresses made in understanding the role of light signaling in modulating plant-plant interactions, little is known about how plants use and integrate information gathered by their photoreceptors aboveground to regulate performance belowground. Given that the phytochrome family of photoreceptors plays a key role in the acquisition of information about the proximity of neighbors and canopy cover, it is tempting to speculate that changes in the red:far-red (R:FR) ratio perceived by aboveground plant parts have important implications shaping plant behavior belowground. Exploring data from published experiments, we assess the neglected role of light signaling in the control of root function. The available evidence indicates that plant exposure to low R:FR ratios affects root growth and morphology, root exudate profiles, and interactions with beneficial soil microorganisms. Although dependent on species identity, signals perceived aboveground are likely to affect root-to-root interactions. Root systems could also be guided to deploy new growth predominantly in open areas by light signals perceived by the shoots. Studying interactions between above- and belowground plant-plant signaling is expected to improve our understanding of the mechanisms of plant competition.

Cotyledon-Generated Auxin Is Required for Shade-Induced Hypocotyl Growth in Brassica rapa.

Plant architecture is optimized for the local light environment. In response to foliar shade or neighbor proximity (low red to far-red light), some plant species exhibit shade-avoiding phenotypes, including increased stem and hypocotyl growth, which increases the likelihood of outgrowing competitor plants. If shade persists, early flowering and the reallocation of growth resources to stem elongation ultimately affect the yield of harvestable tissues in crop species. Previous studies have shown that hypocotyl growth in low red to far-red shade is largely dependent on the photoreceptor phytochrome B and the phytohormone auxin. However, where shade is perceived in the plant and how auxin regulates growth spatially are less well understood. Using the oilseed and vegetable crop species Brassica rapa, we show that the perception of low red to far-red shade by the cotyledons triggers hypocotyl cell elongation and auxin target gene expression. Furthermore, we find that following shade perception, elevated auxin levels occur in a basipetal gradient away from the cotyledons and that this is coincident with a gradient of auxin target gene induction. These results show that cotyledon-generated auxin regulates hypocotyl elongation. In addition, we find in mature B. rapa plants that simulated shade does not affect seed oil composition but may affect seed yield. This suggests that in field settings where mutual shading between plants may occur, a balance between plant density and seed yield per plant needs to be achieved for maximum oil yield, while oil composition might remain constant.

Enumeration of substitutional isomers with restrictive mutual positions of ligands: I. Overall counts

We address systematics for the enumeration of substitutional isomers when there is constrained positioning of ligands on a molecular skeleton. One constraint involves ‘restrictive ligands’ where two of the same kind are forbidden to occupy adjacent sites in a molecular skeleton. This may arise because of steric hindrance, or because of groups which in neighbor proximity react to eliminate one. For instance, no pair of –OH groups attach to the same C atom in a molecular skeleton. In another case, malonic acid residues decarboxylate leaving no more than one decarboxylation in each residue. The enumeration with such restrictive ligands may be addressed via a Polya-theoretic cycle index hybridized with the graph-theoretic independence polynomial (when there is just a single such neighbor-excluding ligand and another which is not), while more generally a hybridization with the chromatic polynomial is needed. Another substitional-isomer constraint involves bidentate ligands, with each ligand-part occupying adjacent sites, and possibly also with additional separate unidentate ligands. Here, the set of all pure & mixed such ligand placements is analytically represented by a ‘symmetry-reduced’ matching polynomial (which is a hybrid now of the matching polynomial and Polya’s cycle index). This result gives the generating function for isomer enumeration, taking into account every possible so-restricted assortment of the employed ligands. Here we make such novel hybridizations (for these and other graphtheoretic polynomials) to deal with such oft-encountered chemical problems, which nevertheless transcend typical earlier unconstrained formulizations. Further subsymmetry classification & enumerations, along with examples are considered in a further article.

Influence of varying Germanium content on the optical function dispersion of Fe2MnSixGe1−x: An ab initio study

The optical dielectric functions of Fe2MnSi1−xGex alloys for selected concentrations (x=0.0, 0.25, 0.5, 0.75 and 1.0) were investigated. The ferromagnetic Fe2MnSixGe1−x is semiconducting with optical band gaps 0.507, 0.531, 0.539, 0.514 and 0.547eV for the minority spin and is metallic for the majority spin. From the calculated results the half-metallic character and stability of ferromagnetic state for Fe2MnSixGe1−x is determined. The total magnetic moment is found to be 3.0μB for all alloys with the most contribution from Mn local magnetic moments. Iron atoms however exhibit much smaller spin moments, about 10% of the bulk value, and the sp atoms have induced magnetic moments due to the proximity of Fe first nearest neighbors, which couple antiferromagnetically with Fe and Mn spin moments. We have employed full-potential linearized augmented plane wave method based on spin-polarized density functional theory. The generalized gradient approximation exchange-correlation potential was used. The edge of optical absorption for ε2(ω) of spin-down varies between 0.507 (Fe2MnGe) and 0.547eV (Fe2MnSi). Since the spin-up shows metallic nature, the Drude term was included in the spin-up optical dielectric functions. This confirms our finding that these materials are half-metallic. Furthermore, the reflectivity, refractivity and the absorption coefficient were calculated. These results show that the materials possess half-metallic character.

Linking photoreceptor excitation to changes in plant architecture

Plants sense neighbor proximity as a decrease in the ratio of red to far-red light, which triggers a series of developmental responses. In Arabidopsis, phytochrome B (PHYB) is the major sensor of shade, but PHYB excitation has not been linked directly to a growth response. We show that the basic helix-loop-helix (bHLH) transcription factor PIF7 (phytochrome-interacting factor 7), an interactor of PHYB, accumulates in its dephosphorylated form in shade, allowing it to bind auxin biosynthetic genes and increase their expression. New auxin synthesized through a PIF7-regulated pathway is required for shade-induced growth, linking directly the perception of a light quality signal to a rapid growth response.

Testing mechanisms and context dependence of costs of plastic shade avoidance responses inImpatiens capensis(Balsaminaceae)

Many plant species elongate their shoots in response to neighbor proximity and neighbor height. Although these plastic responses may be beneficial in terms of enhancing light interception, they also may have costs in terms of increased risk of mechanical failure (i.e., lodging or breaking) because of thinner stems. This trade-off between light acquisition and stability may shape the evolution of plastic elongation responses to foliage shade. In a field experiment manipulating elongation phenotypes and densities, we tested two hypotheses. We predicted that the risks of mechanical failure depend on plastic elongation and/or on characteristics of the immediate neighborhood, such as density and neighbor height. Further, we predicted that plants that fail mechanically would have reduced fitness. Mechanical failure was earlier and more frequent at high density and showed a complex interaction with neighborhood characteristics such as relative height of the neighbors and the expression of early plasticity. Plants that broke earlier had shorter lifespan and lower reproductive output. Our results show that depending on the height and density of the group, plastic elongation responses can remain advantageous despite costs of increased risk of mechanical failure of the taller stems, as mechanical failure was not associated with strong costs in terms of reduced lifespan or seed production. The overall benefits of elongation outweigh the costs resulting in selection for elongation at the population level.

Out of Sight, Out of Mind? Visual Obstructions Affect Settlement Patterns in Barn Swallows (Hirundo Rustica)

ABSTRACT. Neighbor visibility is thought to influence territory size and shape, and visual obstructions may allow for greater nesting density within a breeding colony. We studied the effects of neighbor visibility and neighbor proximity on settlement patterns in a colony of Barn Swallows (Hirundo rustica) using artificial nest cups placed in parallel rows on the underside of a pier. Nest cups were placed 61 cm apart so that the distance between adjacent cups matched the distance between adjacent rows. Rows were separated by the vertical panels to which the nest cups were attached. To a swallow perched on a cup, cups in the same row were visible but cups in adjacent rows were visually obstructed. We compared the observed nest-settlement patterns with expected distributions generated both by calculating cup availability and by simulating random settlement events. Barn Swallows avoided settling 61 cm from an active nest only if that neighbor was visible; visually obstructed neighbors at the same distance wer...

Study on spatial distribution and integration of Rwandan Cities

The primary purpose of this research work was to investigate and analyze the spatial distribution and the integration of Rwandan Cities. The results revealed that the economy of Rwandan Cities is subordinated to Kigali City in which the intensity of economic is very little higher than others. The analysis of their spatial distribution using the distribution of neighbor proximity analysis revealed that the spatial distribution of cities in Rwanda is random where R tends to zero (0). The analysis of correlation between the number of cities in Rwanda and the number of superficies using the correlation coefficient formula indicated that no correlation exists for their distribution. Based on these result, a decongestion system may be a good solution to this dependency of Rwandan Cities. Key words: Rwanda, city group, neighbor proximity analysis, spatial distribution, spatial integration.

Light quality-mediated petiole elongation in Arabidopsis during shade avoidance involves cell wall modification by xyloglucan endotransglucosylase/hydrolases.

Some plants can avoid shaded conditions via rapid shoot elongation, thus growing into better lit areas in a canopy. Cell wall-modifying mechanisms promoting this elongation response, therefore, are important regulatory points during shade avoidance. Two major cell wall-modifying protein families are expansins and xyloglucan endotransglucosylase/hydrolases (XTHs). The role of these proteins during shade avoidance was studied in Arabidopsis (Arabidopsis thaliana). In response to two shade cues, low red to far-red light (implying neighbor proximity) and green shade (mimicking dense canopy conditions), Arabidopsis showed classic shade avoidance features: petiole elongation and leaf hyponasty. Measurement of the apoplastic proton flux in green shade-treated petioles revealed a rapid efflux of protons into the apoplast within minutes, unlike white light controls. This apoplastic acidification probably provides the acidic pH required for the optimal activity of cell wall-modifying proteins like expansins and XTHs. Acid-induced extension, expansin susceptibility, and extractable expansin activity were similar in petioles from white light- and shade-treated plants. XTH activity, however, was high in petioles exposed to shade treatments. Five XTH genes (XTH9, -15, -16, -17, and -19) were positively regulated by low red to far-red light conditions, while the latter four and XTH22 showed a significant up-regulation also in response to green shade. Consistently, knockout mutants for two of these XTH genes also had reduced or absent shade avoidance responses to these light signals. These results point toward the cell wall as a vital regulatory point during shade avoidance.

Asymmetric Density Dependence Shapes Species Abundances in a Tropical Tree Community

The factors determining species commonness and rarity are poorly understood, particularly in highly diverse communities. Theory predicts that interactions with neighbors of the same (conspecific) and other (heterospecific) species can influence a species' relative abundance, but empirical tests are lacking. By using a hierarchical model of survival for more than 30,000 seedlings of 180 tropical tree species on Barro Colorado Island, Panama, we tested whether species' sensitivity to neighboring individuals relates to their relative abundance in the community. We found wide variation among species in the effect of conspecific, but not heterospecific, neighbors on survival, and we found a significant relationship between the strength of conspecific neighbor effects and species abundance. Specifically, rare species suffered more from the presence of conspecific neighbors than common species did, suggesting that conspecific density dependence shapes species abundances in diverse communities.

Heteroblastic Development and Shade‐avoidance in Response to Blue and Red Light Signals in Acacia implexa

Information from blue (400-500 nm) and red (660-730 nm) wavelengths is used by plants to determine proximity of neighbors or actual shading. Plants undergo trait changes in order to out-compete neighbors or accommodate shading. Heteroblasty, the dramatic shift from one leaf type to another during juvenility, can be influenced by the light environment although it is unknown whether cues from blue or red (or both) are driving the developmental process. Seedlings of three populations of Acacia implexa (Mimosaceae) collected from low, medium and high rainfall habitats were grown in a factorial design of high/low blue and red light to determine how light signals affect heteroblasty and patterns of biomass allocation. Low blue light significantly delayed heteroblasty in the low rainfall population and low red light significantly delayed in the low and high rainfall populations. Low blue light increased stem elongation and decreased root biomass whereas low red light induced a strong shade-avoidance response. These results were consistent across populations although the low rainfall population showed greater trait variability in response to red light signals. We conclude that red light conveys a greater information signal than blue light that affects heteroblasty and seedling development in A. implexa.

Vietoris–Rips Complexes of Planar Point Sets

Fix a finite set of points in Euclidean n-space \(\mathbb{E}^{n}\) , thought of as a point-cloud sampling of a certain domain \(D\subset\mathbb{E}^{n}\) . The Vietoris–Rips complex is a combinatorial simplicial complex based on proximity of neighbors that serves as an easily-computed but high-dimensional approximation to the homotopy type of D. There is a natural “shadow” projection map from the Vietoris–Rips complex to \(\mathbb{E}^{n}\) that has as its image a more accurate n-dimensional approximation to the homotopy type of D.

Ecological modulation of plant defense via phytochrome control of jasmonate sensitivity.

For plants, the tradeoff between resource investment in defense and increased growth to out-compete neighbors creates an allocation dilemma. How plants resolve this dilemma, at the mechanistic level, is unclear. We found that Arabidopsis plants produced an attenuated defense phenotype under conditions of crowding and when exposed to far-red (FR) radiation, a light signal that plants use to detect the proximity of neighbors via the photoreceptor phytochrome. This phenotype was detectable through standard bioassays that measured the growth of Spodoptera frugiperda caterpillars. Two possible explanations for the effect of FR are: (i) a simple by-product of the diversion of resources to competition, and (ii) a specific effect of phytochrome on defense signaling. The first possibility was ruled out by the fact that the auxin-deficient sav3 mutant, which fails to induce growth responses to FR, still responded to FR with an attenuated defense phenotype. In support of the second hypothesis, we found that phytochrome inactivation by FR caused a strong reduction of plant sensitivity to jasmonates, which are key regulators of plant immunity. The effects of FR on jasmonate sensitivity were restricted to certain elements of the pathway. Supporting the idea that the FR effects on jasmonate signaling are functionally significant, we found that FR failed to increase tissue quality in jar1, a mutant impaired in jasmonate response. We conclude that the plant modulates its investment in defense as a function of the perceived risk of competition, and that this modulation is effected by phytochrome via selective desensitization to jasmonates.

Auxin and Ethylene Regulate Elongation Responses to Neighbor Proximity Signals Independent of Gibberellin and DELLA Proteins in Arabidopsis

Plants modify growth in response to the proximity of neighbors. Among these growth adjustments are shade avoidance responses, such as enhanced elongation of stems and petioles, that help plants to reach the light and outgrow their competitors. Neighbor detection occurs through photoreceptor-mediated detection of light spectral changes (i.e. reduced red:far-red ratio [R:FR] and reduced blue light intensity). We recently showed that physiological regulation of these responses occurs through light-mediated degradation of nuclear, growth-inhibiting DELLA proteins, but this appeared to be only part of the full mechanism. Here, we present how two hormones, auxin and ethylene, coregulate DELLAs but regulate shade avoidance responses through DELLA-independent mechanisms in Arabidopsis (Arabidopsis thaliana). Auxin appears to be required for both seedling and mature plant shoot elongation responses to low blue light and low R:FR, respectively. Auxin action is increased upon exposure to low R:FR and low blue light, and auxin inhibition abolishes the elongation responses to these light cues. Ethylene action is increased during the mature plant response to low R:FR, and this growth response is abolished by ethylene insensitivity. However, ethylene is also a direct volatile neighbor detection signal that induces strong elongation in seedlings, possibly in an auxin-dependent manner. We propose that this novel ethylene and auxin control of shade avoidance interacts with DELLA abundance but also controls independent targets to regulate adaptive growth responses to surrounding vegetation.

Approaching neighbor proximity and load balance for range query in P2P networks

We present a platform for building a range-queriable system. A distinguishing characteristic of the platform is that objects are not bound to any particular node. Rather, they can be freely moved between neighboring nodes to balance load as long as some ordering between objects in different nodes is respected. Decoupling the link between nodes and objects allows the overlay network to be constructed independently of object placement , focusing only on its own concerns, e.g. proximity and balanced load in routing. The main focus then is to present several heuristics for proximity-aware node joining to reduce communication costs in the platform. These heuristics are based on a novel process called hierarchical neighborhood search , which utilizes the overlay links to provide incoming nodes an overview of the network topology , thereby to guide them to find their neighborhood in the overlay. The experimental results show that some of the heuristics are very effective; they can reduce as much as 80% of the communication costs for neighboring nodes, and 40% overall.

PLASTICITY AND ENVIRONMENT-SPECIFIC COVARIANCES: AN INVESTIGATION OF FLORAL–VEGETATIVE AND WITHIN FLOWER CORRELATIONS

Floral traits are commonly thought to be more canalized than vegetative ones. In addition, floral and vegetative traits are hypothesized to be genetically decoupled, enabling vegetative structures to respond plastically to environmental heterogeneity, and to evolve in response to selection without disrupting the reproductive function of flowers. To test these hypotheses, we evaluate the genetic architecture of floral and vegetative traits in natural populations of Arabidopsis thaliana raised under variable light-quality environments. Plants were grown either under high or low ratios of red to far-red (R:FR) light, an aspect of light quality that varies with neighbor proximity and regulates competitive shade-avoidance responses. Across environments, we detected significant genetic variation for the average expression of all measured floral traits (petal length and width, stamen length, pistil length, stigma-anther separation, and exsertion of both the stamen and pistil beyond the corolla). Light quality significantly influenced the absolute size of several floral traits as well as the allometry (i.e., relative scaling) of all floral traits, and genotypes differed in the plasticity of floral traits to the light treatments. Exposure to low relative to high R:FR resulted in significantly greater elongation in the vegetative trait, petiole length, and genotypes again differed in the plasticity of this trait to R:FR. Consistent with prior studies, most floral traits were less plastic than the vegetative trait; herkogamy (i.e., stigma-anther separation) was the exception and expressed more variable trait values across environments than petiole length, apparently as a consequence of the independent responses of stamens and pistils. Flowers also showed strong phenotypic integration; genotypic correlations were significantly positive among floral traits within each light treatment. Although floral-vegetative correlations were not significant in the high R:FR light treatment, significant correlations were detected between petal traits, pistil length, and petiole length under low R:FR, in contrast to the widely held hypothesis that floral and vegetative traits are genetically independent. Finally, we detected selection for reduced herkogamy in the low R:FR light treatment. The observed correlation between functional trait groups suggest that vegetative plasticity may affect the expression of floral traits in some environments, and that environment-specific constraints may exist on the evolution of floral and vegetative traits.

ROC-based assessments of 3D cortical surface-matching algorithms

Algorithms for the semi-automated analysis of brain surfaces have recently received considerable attention, and yet, they rarely receive a rigorous assessment of their performance. We present a method for the quantitative assessment of performance across differing surface analysis algorithms and across various modifications of a single algorithm. The sensitivity and specificity of an algorithm for detecting known deformations added synthetically to the brains being studied are assessed using curves for Receiver Operating Characteristics (ROC). We also present a method for the isolation of sources of variance in MRI data sets that can contribute to degradation in performance of surface-matching algorithms. Isolation of these sources of variance allows determination of whether degradation in performance of surface-matching algorithms derives primarily from errors in registration of brains to a common coordinate space, from errors in placement of the known deformation, or from interindividual or between-group variability in morphology of the cortical surface. We apply these methods to the study of surface-matching algorithms that are based on fluid flow (FF) deformation, geodesic (GD) interpolation, or nearest neighbor (NN) proximity. We show that the performances of surface-matching algorithms depend on the presence of interindividual and between-group variability in the surfaces surrounding the cortical deformation. We also show that, in general, the FF algorithm performs as well as or better than the GD and NN algorithms. The large variance in identifying point correspondences across brain surfaces using the GD and the NN algorithms suggests strongly that these point correspondences are less valid than those determined by the FF algorithm. The GD and NN algorithms, moreover, are both vulnerable to detecting false-positive activations at points of high curvature, particularly along large fissures, cisterns, and cortical sulci.

Neighbor Proximity Analysis, A Technique for Assessing Spatial Patterns in The Fossil Record

Other| August 01, 2004 Neighbor Proximity Analysis, A Technique for Assessing Spatial Patterns in The Fossil Record LINDSEY R. LEIGHTON; LINDSEY R. LEIGHTON 1Department of Geological Sciences & Allison Center for Marine Research, San Diego State University, San Diego, CA 92182, leighton@geology.sdsu.edu Search for other works by this author on: GSW Google Scholar CHRIS L. SCHNEIDER CHRIS L. SCHNEIDER 2Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712 Current Address: Department of Geology, Cornell College, Mt. Vernon, IA 52314 Search for other works by this author on: GSW Google Scholar Author and Article Information LINDSEY R. LEIGHTON 1Department of Geological Sciences & Allison Center for Marine Research, San Diego State University, San Diego, CA 92182, leighton@geology.sdsu.edu CHRIS L. SCHNEIDER Current Address: Department of Geology, Cornell College, Mt. Vernon, IA 52314 2Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712 Publisher: SEPM Society for Sedimentary Geology Accepted: 30 Jan 2004 First Online: 03 Mar 2017 Online ISSN: 1938-5323 Print ISSN: 0883-1351 Society for Sedimentary Geology PALAIOS (2004) 19 (4): 396–407. https://doi.org/10.1669/0883-1351(2004)019<0396:NPAATF>2.0.CO;2 Article history Accepted: 30 Jan 2004 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation LINDSEY R. LEIGHTON, CHRIS L. SCHNEIDER; Neighbor Proximity Analysis, A Technique for Assessing Spatial Patterns in The Fossil Record. PALAIOS 2004;; 19 (4): 396–407. doi: https://doi.org/10.1669/0883-1351(2004)019<0396:NPAATF>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyPALAIOS Search Advanced Search Abstract Time-averaging can be a major obstacle in reconstructing fine-scale ecological processes in the fossil record. This study presents a technique, Neighbor Proximity Analysis that attempts, despite time-averaging, to elucidate fine-scale ecological information on a single bedding plane. The technique takes advantage of the tendency for most sessile organisms to cluster in conspecific clumps, and assumes that time-averaging will tend to overprint patterns of conspecific clustering given sufficient time. The fossil species of interest is mapped onto an appropriate grid, point-counted, and the number of conspecific neighbors for each individual is counted. The community distribution is then permuted randomly for multiple iterations; and for each iteration, the number of randomly generated conspecific neighbors is compared to the observed number of conspecific neighbors. Taxa that exhibit clustering greater than expected under the random model probably clustered in life, revealing features of the local spatial structure. An example of the method is presented, using bedding planes from the Rapid Member of the Little Cedar Formation at the Devonian Fossil Gorge, Coralville, Iowa. The results indicate that of the common brachiopod present, Spinatrypa bellula clustered conspecifically during life. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Allometric gender allocation in Ambrosia Artemisiifolia (Asteraceae) has adaptive plasticity

Evidence is reported for size-dependent (allometric) gender allocation in the monoecious, wind-pollinated annual Ambrosia artemissifolia. Consistent with established theory, the pattern of allometry displayed adaptive plasticity, depending on the environmental cause of variation in plant size. Plant size gradients were generated in both field and greenhouse experiments using separate and combined gradients of shading, soil nutrient levels, and neighbor proximity. When plant size constraints involved light limitation from shading (e.g., because of close neighbor proximity), decreasing plant size was generally associated with decreasing maleness and increasing femaleness (based on relative male and female flower production, respectively). This is consistent with the "pollen-dispersal" hypothesis in which the consequences of relatively small plant size (among larger neighbors) imposes less severe limitation for female reproductive success than for male reproductive success (because success as an outcrossing donor of wind-dispersed pollen increases with increasing plant height, especially when neighbors are present). However, when size was constrained by soil nutrient limitation alone (i.e., without shading effects), the results had the converse allometric relationship; i.e., decreasing plant size was generally associated with increasing maleness and decreasing femaleness. This is consistent with the "size-advantage" and "time-limitation" hypotheses in which energetic and time limitations (respectively) associated with relatively small plant size impose a less severe limitation for male reproductive success than for female reproductive success.

Space use in territorial amberwing dragonflies: are residents female maximizers or neighbor minimizers?

Residents of mating territories interact with different categories of conspecifics: females, nonneighbor males, and neighbor males. Interaction with these differ- ent types of conspecifics is likely to have different costs and benefits; for example, interactions with females will be beneficial, while interactions with neighbors are more likely to be costly. In this study, we investigated patterns of intrusions and space use in territorial male amberwing dragonflies (Perithemis tenera) to test the idea that residents will adjust their use of space to maximize their beneficial interactions with conspecifics while minimiz- ing their costly interactions with conspecifics. Because territories were arranged linearly around the edge of a pond, each resident had two neighbors, one of which was often closer to the focal resident than the other. Residents experienced more intrusions by neighbors and fewer intrusions by females on the side of their closer neighbor. Residents generally perched on the side of their territory that experienced the fewest intrusions by neighbors and the most intrusions by females, but the pattern was more strongly related to neighbor intrusions than female intrusions. Subsequent to pursuits of neighbors and females, residents tended to shift their perches away from where they pursued neighbors but toward where they pursued females. Nonneighbor intrusions were not affected by neighbor proximity, nor did residents adjust their space use in response to nonneighbor intrusions. Our results suggest that residents do adjust their space use in response to intrusions by conspecifics, that their adjust- ment depends on the type of conspecific that intruded, and that residents may be using a simple decision rule such as "move away from male intrusions, move closer to female intrusions" to adjust their within-territory space use.