Life History Characteristics of Placental Nonvolant mammals

The purpose of this data set was to compile general life history characteristics for a variety of mammalian species in order to perform comparative life history analyses among different taxa and different body size groups. Data were collected from the literature, and data sources are documented for each species within the data file. Since life history characteristics will show minor variation with environmental conditions (resource availability, climate, competitive environment, and predation pressure) a general life history for each species was sought to average over minor differences in local populations. To create a general life history for each species, life history values are often an average from several literature sources. Life history variables included in the data set are: maximum lifespan (months), age of first reproduction (months), gestation time (months), weaning age (months), weaning mass (grams), litter size, litters per year, newborn mass (grams), and adult body mass (grams). Since these data were collected with the intent to examine general life history patterns, they are good for examining large-scale patterns, specifically in comparing life history characteristics for different orders or families of mammals. All orders of placental mammals, except Chiroptera (bats) are represented in this data set: Artiodactyla (161 species), Carnivora (197 species), Cetacea (55 species), Dermoptera (2 species), Hydracoidea (4 species), Insectivora (91 species), Lagomorpha (42 species), Macroscelidea (10 species), Perissodactyla (15 species), Pholidota (7 species), Primates (156 species), Proboscidea (2 species), Rodentia (665 species), Scandentia (7 species), Sirenia (5 species), Tubulidentata (1 species), and Xenarthra (20 species). There are two caveats on this data set, however. First, these data are not appropriate for asking population-level questions where the integration of life history parameters with specific environmental conditions is important. Second, while this data set is extensive, it is not exhaustive. The creation of an exhaustive data set is the ultimate goal, but that goal is still several years from completion. In the meantime, researchers utilizing the data set are urged to conduct their own search for data not reported within the current data set. Researchers are also encouraged to contact the author of the data set and alert her to literature sources containing data for missing variables or species

Education Among The Ourika: A Study Of The Schools, 1957-1963

The purpose of the study was (1) to examine the establishment, growth, curriculum, schedules, practices, and objectives of the public schools in the Moroccan Berber tribal region of Ourika; (2) to point out a number of cultural aspects of the school community during the school years 1957-1958 through 1962-1963 that have significant implications for education; (3) to determine to what extent the existing school program is meeting the needs of the community; and (4) to make recommendations for the improvement of those schools

Tradeoffs in Community Properties Through Time in a Desert Rodent Community

Resource limitation represents an important constraint on ecological communities, which restricts the total abundance, biomass, and community energy flux a given community can support. However, the exact relationship among these three measures of biological activity remains unclear. Here we use a simple framework that links abundance and biomass with an energetic constraint. Under constant energetic availability, it is expected that changes in abundance and biomass can result from shifts in the distribution of individual masses. We test these predictions using long-term data from a desert rodent community. Total energy use for the community has not changed directionally for 25 years, but species composition has. As a result, the average body size has decreased by almost 50% and average abundance has doubled. These results lend support to the idea of resource limitation on desert rodent communities and demonstrate that systems are able to maintain community energy flux in the face of environmental change, through changes in composition and structure

Using Life History Trade-Offs to Understand Core-Transient Structuring of a Small Mammal Community

An emerging conceptual framework suggests that communities are composed of two main groups of species through time: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local versus regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local versus regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also typically exhibit different life-history strategies. Specifically, core species should display relatively low movement rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily in a nomadic fashion. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and movement probabilities, and reproductive effort relative to transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating transience in local communities, such as source-sink dynamics at larger regional scales or nomadic life history strategies. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study

Intra-guild compensation regulatesspecies richness in desert rodents

Evidence from numerous studies suggests that species richness is an emergent property of local communities. The maintenance of species richness, despite changes in species composition and environmental conditions, requires compensatory colonization and extinction events with species coming from a regional pool. Using long-term data from a rodent community in the Chihuahuan Desert, we use randomization methods to test the null hypothesis that changes in species richness occur randomly. We find that the dynamics of species richness differ significantly from a random process, and that these nonrandom dynamics occur largely within the most speciose guild. Finally, we propose a general framework for assessing the importance of species compensation in maintaining biodiversity within local communities. Our results highlight the importance of niche complementarity and compensation in maintaining relatively constant species richness over time

Zero-sum, the niche,and metacommunities: long-term dynamics of community assembly

Recent models of community assembly, structure, and dynamics have incorporated, to varying degrees, three mechanistic processes: resource limitation and interspecific competition, niche requirements of species, and exchanges between a local community and a regional species pool. Synthesizing 30 years of data from an intensively studied desert rodent community, we show that all of these processes, separately and in combination, have influenced the structural organization of this community and affected its dynamical response to both natural environmental changes and experimental perturbations. In addition, our analyses suggest that zero-sum constraints, niche differences, and metacommunity processes are inextricably linked in the ways that they affect the structure and dynamics of this system. Explicit consideration of the interaction of these processes should yield a deeper understanding of the assembly and dynamics of other ecological communities. This synthesis highlights the role that long-term data, especially when coupled with experimental manipulations, can play in assessing the fundamental processes that govern the structure and function of ecological communities