Reengineering in a university setting

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1997.Includes bibliographical references.by Anthony Ives.M.C.P

Can functional traits account for phylogenetic signal in community composition?

© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust Phylogenetic and functional trait-based analyses inform our understanding of community composition, yet methods for quantifying the overlap in information derived from functional traits and phylogenies remain underdeveloped. Does adding traits to analyses of community composition reduce the phylogenetic signal in the residual variation? If not, then measured functional traits alone may be insufficient to explain community assembly. We propose a general statistical framework to quantify the proportion of phylogenetic pattern in community composition that remains after including measured functional traits. We then illustrate the framework with applications to two empirical data sets. Both data sets showed strong phylogenetic attraction, with related species likely to co-occur in the same communities. In one data set, including traits eliminated all phylogenetic signals in the residual variation of both abundance and presence/absence patterns. In the second data set, including traits reduced phylogenetic signal in residuals by 25% and 98% for abundance and presence/absence data, respectively. Our framework provides an explicit way to estimate how much phylogenetic community pattern remains in the residual variation after including measured functional traits. Knowing that functional traits account for most of the phylogenetic pattern should provide confidence that important traits for phylogenetic community structure have been identified. Conversely, knowing that there is unexplained residual phylogenetic information should spur the search for additional functional traits or other processes underlying community assembly

Do Movement Patterns and Habitat Use Differ Between Optimal- and Suboptimal-sized Northern Bobwhite Coveys?

The group size of social animals and spatial structure of the environment can affect group behavior and movement decisions. Our objective was to investigate movement patterns and habitat use of northern bobwhite coveys (Colinus virginianus) of different size. Using radiotelemetry, we continuously monitored covey group size, daily movement, and habitat use on 12 independent 259-ha study areas in eastern Kansas, USA, during the winters between 1997 and 2000. We used correlated random walk models and fractal dimension models to determine if covey size affected movement characteristics or habitat selection. Intermediate-sized coveys (9–12 individuals, close to optimal covey size) exhibited daily movements that were substantially smaller and weekly home ranges that were more composed of woody escape cover than coveys of smaller or larger sizes. From the fractal dimension analyses, these coveys exhibited movement in between linear and a random walk at small spatial scales but very linear at large spatial scales. Large coveys had increased daily movement and tended to move in straighter lines (as indicated by the high proportion of turning angles [i.e., the angle between an initial direction and a new direction] around 0° and 180° and their multiscale fractal dimension) and they incorporated more cropland into their range, presumably to meet the feeding requirements of a larger group. In contrast, small coveys (1–4 individuals) tended to move more and increase the size of their home range, travel with a greater diversity of turning angles, and show movement patterns that were largely tortuous across a greater number of habitat patches at larger spatial scales (700 m). Small coveys have lower fitness and add new membership to increase fitness so it is possible that the movement behavior we observed represented a shift into a foray mode where bobwhites were searching for new membership. For areas with small populations and covey sizes, this information will help biologists better plan for habitat management to assist these coveys with their winter fitness

Behavioral Flexibility and the Evolution of Primate Social States

Comparative approaches to the evolution of primate social behavior have typically involved two distinct lines of inquiry. One has focused on phylogenetic analyses that treat social traits as static, species-specific characteristics; the other has focused on understanding the behavioral flexibility of particular populations or species in response to local ecological or demographic variables. Here, we combine these approaches by distinguishing between constraining traits such as dispersal regimes (male, female, or bi-sexual), which are relatively invariant, and responding traits such as grouping patterns (stable, fission-fusion, sometimes fission-fusion), which can reflect rapid adjustments to current conditions. Using long-term and cross-sectional data from 29 studies of 22 species of wild primates, we confirm that dispersal regime exhibits a strong phylogenetic signal in our sample. We then show that primate species with high variation in group size and adult sex ratios exhibit variability in grouping pattern (i.e., sometimes fission-fusion) with dispersal regime constraining the grouping response. When assessing demographic variation, we found a strong positive relationship between the variability in group size over time and the number of observation years, which further illustrates the importance of long-term demographic data to interpretations of social behavior. Our approach complements other comparative efforts to understand the role of behavioral flexibility by distinguishing between constraining and responding traits, and incorporating these distinctions into analyses of social states over evolutionary and ecological time

Congressional health, congressional failure

The United States Congress is one of the most disparaged institutions in contemporary political life. Citizens and pundits decry it. Many experts also concur, calling that branch of government “broken,” “dysfunctional,” “decayed,” “disastrous,” and even, “a constitutional shrinking violet.” The institution is even attacked from within, by Members of Congress (MCs) themselves. Yet, amongst all this reasonable critique, something is missing: the standard of health against which one ought to assess the Congress. This work aims to remedy this gap in the literature by providing “a well-thought-through ideal which we can use to hold up to [the Congress] for comparison” (cf. Waldron 2009), along with evidence of the viability of that standard in empirical cases. To develop a comprehensive conception of congressional health, I turn to the Constitution. I argue that the constitutional design of Congress, including the Preamble, shows that the Congress was designed to remediate the flaws of the Confederation Congress and to better promote the general welfare of the nation. I thus find that the chief desideratum of legislative health is the tendency of Congress’s rules, structures and norms to foster a representative lawmaking process responsive a popular majority in a deliberate way. The constitutional approach to Congress is then enriched through a treatment of three historical cases, namely, the First Congress, the Antebellum Congress, and the New Deal Congress. These case studies provide particularly clear examples of institutional structures and norms that past congresses used successfully (or failed to employ) to meet the extensive challenges of a national lawmaking assembly in a large, diverse, federal republic. Returning to the present, armed with the appropriate positive standards for evaluating that institution, I find that the contemporary Congress’s rules and norms fail to consistently generate an effective and representative lawmaking process. The United States Congress avoids the sobriquet of “failure,” only through a limited respect for its dwindling norms held by a small number of MCs and the open acknowledgement of its difficulties by a wider group of legislators. A lack of independent institutional perspective, however, stands between the body and any realistic prospects for reformGovernmen

phyr: Anrpackage for phylogenetic species-distribution modelling in ecological communities

Model-based approaches are increasingly popular in ecological studies. A good example of this trend is the use of joint species distribution models to ask questions about ecological communities. However, most current applications of model-based methods do not include phylogenies despite the well-known importance of phylogenetic relationships in shaping species distributions and community composition. In part, this is due to a lack of accessible tools allowing ecologists to fit phylogenetic species distribution models easily. To fill this gap, therpackagephyr(pronounced fire) implements a suite of metrics, comparative methods and mixed models that use phylogenies to understand and predict community composition and other ecological and evolutionary phenomena. Thephyrworkhorse functions are implemented in C++ making all calculations and model estimations fast. phyrcan fit a variety of models such as phylogenetic joint-species distribution models, spatiotemporal-phylogenetic autocorrelation models, and phylogenetic trait-based bipartite network models.phyralso estimates phylogenetically independent trait correlations with measurement error to test for adaptive syndromes and performs fast calculations of common alpha and beta phylogenetic diversity metrics. Allphyrmethods are united under Brownian motion or Ornstein-Uhlenbeck models of evolution, and phylogenetic terms are modelled as phylogenetic covariance matrices. The functions and model formula syntax we propose inphyrprovide an easy-to-use collection of tools that we hope will ignite the use of phylogenies to address a variety of ecological questions

Ecological history affects zooplankton community responses to acidification

The effects of ecological history are frequently ignored in attempts to predict community responses to environmental change. In this study, we explored the possibility that ecological history can cause differences in community responses to perturbation using parallel acidification experiments in three sites with different pH histories in the Northern Highland Lake District of Wisconsin, USA. In Trout Lake, high acid neutralizing capacity had historically buffered changes in pH. In contrast, the two basins of Little Rock Lake (Little Rock-Reference and Little Rock-Treatment) had experienced seasonal fluctuations in pH. Furthermore, the two lake basins were separated with a curtain and Little Rock-Treatment was experimentally acidified in the late 1980s. In each site, we conducted mesocosm experiments to compare zooplankton community dynamics in control (ambient pH) and acidified (pH 4.7) treatments. Zooplankton community responses were strongest in Trout Lake and weakest in Little Rock-Treatment suggesting that ecological history affected responses to acidification. In part, variation in community sensitivity to acidification was driven by differences in species composition. However, the results of a reciprocal transplant experiment indicated that changes in the acid tolerance of populations during past acidification events may make zooplankton communities less sensitive to subsequent pH stress. Our study highlights the role that ecological history may play in community-level responses to environmental change

Midge-stabilized sediment drives the composition of benthic cladoceran communities in Lake Mývatn, Iceland

The importance of environmental disturbances as drivers of ecological communities depends not only on the magnitude of the disturbance, but also on the disturbance-specific sensitivity of the community. Organisms that alter the physical structure of their surroundings can affect the sensitivity of their habitat to environmental disturbance, and may alter the potential for disturbance to shape ecological communities. Such organisms therefore act as ecosystem engineers by indirectly modifying the resources available to other species. The benthos of shallow, eutrophic Lake Mývatn, Iceland, is frequently disturbed by wind events that lead to sediment resuspension. The impact of wind, however, depends on the abundance of midges (Chironomidae) whose larval tubes bind sediment and reduce wind-driven resuspension. Here, we investigate the long-term effect of fluctuations in midge abundance on the benthic cladoceran community using two lake sediment cores representing 30 and 140 years of deposition. In both cores, midge remains show a significant positive correlation with abundance of a large benthic surface-dwelling cladoceran, Eurycercus lamellatus, relative to the abundance of a small within-sediment-dwelling cladoceran, Alona rectangula. To experimentally investigate whether this shift could have been caused by midges acting as ecosystem engineers, we subjected cladoceran communities to sediment resuspension events within mesocosms. We found a significant decrease in abundance of the large epibenthic E. lamellatus relative to the abundance of small infaunal Alona spp. when subjected to disturbance. These findings show that physical alteration of benthic sediment and hence the sensitivity of the sediment to disturbance may explain the community shift in cladocerans observed with fluctuating midge abundance in Lake Mývatn.National Science Foundation Graduate Research Fellowship. Grant Number: DGE-1256259 LTREB. Grant Number: DEB-1052160Peer Reviewe