Species turnover rates on islands: dependence on census interval

Measurements of species turnover in island bird communities demonstrate two trends with increasing census interval t: (i) Apparent turnover rates T decrease greatly with t, and (ii) the coefficient of variation of T decreases asymptotically to a constant value. These effects are predicted by a statistical model whose parameters are the immigration and extinction probabilities of each species. Available bird censuses at intervals of decades underestimate turnover rates by about an order of magnitude.

Distributional Ecology of New Guinea Birds: Recent ecological and biogeographical theories can be tested on the bird communities of New Guinea

The concepts by which MacArthur and Wilson have transformed the science of ecology in the past decade, and the results of ecological studies such as mine on New Guinea bird communities, have implications for conservation policies. For example, primary tropical rain forest, the most species-rich and ecologically complex habitat on earth, has for millions of years served as the ultimate evolutionary source of the world's dominant plant and animal groups. Throughout the tropics today, the rain forests are being destroyed at a rate such that little will be left in a few decades. When the rain forests have been reduced to isolated tracts separated by open country, the distribution of obligate rain forest species will come to resemble bird distributions on New Guinea land-bridge islands after severing of the land bridges. The smaller the tract, the more rapidly will forest species tend to disappear and be replaced by the widespread second-growth species that least need protection (13). This ominous process is illustrated by Barro Colorado Island, a former hill in Panama that became an island when construction of the Panama Canal flooded surrounding valleys to create Gatun Lake. In the succeeding 60 years several forest bird species have already disappeared from Barro Colorado and been unable to recolonize across the short intervening water gap from the forest on the nearby shore of Gatun Lake. The consequences of the species-area relation (Fig. 1) should be taken into consideration during the planning of tropical rain forest parks (13). In a geographical area that is relatively homogeneous with regard to the fauna, one large park would be preferable to an equivalent area in the form of several smaller parks. Continuous nonforest strips through the park (for example, wide highway swaths) would convert one rain forest "island" into two half-size islands and should be avoided. If other considerations require that an area be divided into several small parks, connecting them by forest corridors might significantly improve their conservation function at little further cost in land withdrawn from development. Modern ecological studies may also be relevant to the understanding of human populations. For instance, during a long period of human evolution there appear to have been not one but two coexistent hominid lines in Africa, the Australopithecus robustus-A. boisei ("Zinjanthropus") line, which became extinct, and the Australopithecus africanus-A. habilis line, which led to Homo sapiens (27). The need to maintain niche differences between these lines must have provided one of the most important selective pressures on the ancestors of modern man in the late Pliocene and early Pleistocene. Thus, any attempt to understand human evolution must confront the problem of what these ecological segregating mechanisms were. To what extent were contemporaneous species of the two lines separated by habitat, by diet, by size difference, or by foraging technique, and were their local spatial distributions broadly overlapping or else sharpened by behavioral interactions as in the case of the Crateroscelis warblers of Fig. 6? To take another example, there are striking parallels between the present distributions of human populations and of bird populations on the islands of Vitiaz and Dampier straits between New Guinea and New Britain. Some of these islands were sterilized by cataclysmic volcanic explosions within the last several centuries. The birds that recolonized these islands have been characterized as coastal and small-island specialists of high reproductive potential, high dispersal powers, and low competitive ability, unlike the geographically closer, competitively superior, slowly dispersing, and breeding birds of mainland New Guinea (10, 11, 13). It remains to be seen whether the people of the Vitiaz-Dampier islands, the Polynesians, and other human populations that colonize insular or unstable habitats also have distinctive population ecologies.

Zoological classification system of a primitive people

The Fore people of the New Guinea Highlands classify all animals in one of nine higher categories ("tábe aké"), and these are further subdivided into lower categories ("ámana aké"). There are 182 lower categories for vertebrates alone. The nearly one-to-one correspondence between Fore amana ake and species as recognized by European taxonomists reflects the objective reality of the gaps separating sympatric species. In 90 percent of the cases, when a species of animal unknown to the Fore is presented for naming, it is called by the name of the Fore species considered its closest relative by zoologists. The origin of Fore classification is probably utilitarian.

Ecological consequences of island colonization by southwest pacific birds, I. Types of niche shifts

The land and fresh-water birds of the southwest Pacific islands derive mainly from New Guinea and offer a favorable situation for studying ecological consequences of island invasions. The reduction of competition on species-poor islands permits some colonizing species to expand their niches spatially, by occupying altitudinal bands, types of habitats, and/or vertical strata of the forest from which they are excluded by other species on species-rich islands. Expansions to higher altitudes, or from second-growth into forest, are especially frequent. Other colonists become more abundant in the same type of habitat preferred on New Guinea. Instances of a change in diet are rare. Changes in foraging technique are noted mainly for those colonists that have been isolated long enough to have undergone morphological divergence. Approximately half of the colonizing populations experience no niche shift.

Avifaunal equilibria and species turnover rates on the channel islands of california

Insular species diversities, and their dependence on island size and isolation, have been postulated to represent a dynamic equilibrium between species immigration rates and species extinction rates. This interpretation has been tested by determining the land and freshwater birds breeding on the nine Channel Islands off southern California in 1968 and comparing the results with a similar survey for the years up to 1917. Most of the islands were found to be in equilibrium as to number of species, but between 17 and 62 per cent of the 1917 breeding species had disappeared by 1968, and an approximately equal number of new immigrant species had become established. Percentage turnover rates vary inversely as insular species diversities, with no effect of distance apparent.

Comparison of faunal equilibrium turnover rates on a tropical island and a temperate island

Rates of immigration and extinction of bird species on a tropical island, Karkar in the southwest Pacific Ocean, have been estimated from surveys made in 1914 and in 1969. Compared to a temperate-zone island of similar size and isolation (Santa Cruz off southern California), Karkar has a similar extinction rate, but a lower immigration rate expressed as a fraction of the mainland species pool, due to the sedentariness of many tropical forest birds. The probability of extinction is highest for species that are rare (due to narrow habitat requirements, large territory size, competition, recency of colonization, or marginal suitability of habitat), species with "in-and-out" tactics, and populations on small islands.

Biogeographic kinetics: estimation of relaxation times for avifaunas of southwest pacific islands

When species diversity S on an island is displaced from the equilibrium value by injection or removal of species, S relaxes to equilibrium by an imbalance between immigration and extinction rates. Estimates of exponential relaxation times, t(r), for avifaunas of New Guinea satellite islands are calculated from analysis of four "experiments of nature": recolonization of exploded volcanoes, contraction in island area due to rising sea level, severing of land bridges, and disappearance of landbridge relict species. t(r) is in the range 3,000-18,000 years for avifaunas of islands of 50-3000 square miles (130-7800 km(2)), and increases with island area. Immigration coefficients decrease and extinction coefficients increase with increasing S. The results may be relevant to the design of rainforest preserves.

Calculation of immigration and extinction curves from the species-area-distance relation

Quantitative models of the species-area-distance relation, based on equilibria between immigration and extinction rates, have been tested against data for birds on 52 Solomon islands. Biologically reasonable models account for 98% of the variance in species number. The data are adequate to permit determination of immigration and extinction curves and the values of seven associated parameters. The resulting curves are very concave. Extinction rates vary almost exactly as the reciprocal of area, but the effect of area on immigration rates is slight. Recognition of major differences among species in immigration and extinction rates and in dispersal distances proves essential to a successful model.

Species-area relation for birds of the Solomon Archipelago

Accurate values of number of breeding bird species have been obtained for 50 islands of the Solomon Archipelago. From information about species altitudinal distributions on each island, the values are apportioned into number of montane species (S(mt)) and of species present at sea-level (S(low)). S(low) increases linearly with the logarithm of island area A over a million-fold range of areas (correlation coefficient 0.99) and with a comparatively low slope, while the log S-log A relation is markedly curved. With increasing isolation of an archipelago, the species-area relation decreases in slope and may shift in form from a power function to an exponential. Comparison of Pacific archipelagoes at different distances from the colonization source of New Guinea shows that the decrease in slope is due to increasing intra-archipelago immigration rates, arising from overrepresentation of the most vagile inter-archipelago immigrants in more distant archipelagoes. When colonists are sorted into sets correlated with their dispersal abilities, the slope of the species-area relation for the most vagile set is close to zero, but for the least vagile set is close to the value predicted by Preston for "isolated universes."

Birds on islands in the sky: Origin of the montane avifauna of Northern Melanesia

Biogeographers have long been fascinated by the disjunct distributions of species stranded on mountaintops. This paper analyzes, for the montane bird populations of Northern Melanesian islands, how many such populations there are, why they are restricted to mountains, and how they dispersed to mountains. The number of populations increases with island elevation and with montane area, and decreases with lowland area, exemplifying the problem of continental species diversity. Most species with montane populations on some island(s) have sea-level populations on some other island(s). These altitudinal niche shifts can be variously related to interisland differences either in altitudinal distribution of area or else in competitive pressure in the lowlands or mountains. Restriction of Northern Melanesian bird populations to mountains is more often due to lowland competitors than to inability to survive under the physical conditions of the lowlands. Of four possible mechanisms for the origin of a montane population (referred to as jumping, land-bridge crossing, trickling, and push-pull shifts), only the first and last have been significant for Northern Melanesian birds.

Species-distance relation for birds of the Solomon Archipelago, and the paradox of the great speciators

For scattered remote islands and for likely forms of immigration and extinction curves, the equilibrium theory of island biogeography leads to the prediction [unk](2) log S/[unk]A[unk]D > 0, where S is the number of species on an island, A island area, and D island distance from the colonization source. This prediction is confirmed for birds of the Solomon Archipelago. Bird species can be classified into three types according to how distance affects their distributions: non-water-crossers, which are stopped completely (usually for psychological reasons) by water gaps of even 1 mile; short-distance colonists, successful at colonizing close but not remote islands; and long-distance colonists, successful at colonizing remote as well as close islands. Almost all of the "great speciators", the species for whose inter-island geographic variation the Solomons are famous, prove to be short-distance colonists. Lack's interpretation of the decrease in S with D is shown to rest on incorrect assumptions.

Severe venous and lymphatic obstruction after single-chamber pacemaker implantation in a patient with chest radiation therapy

A 73-year-old woman with a history of paroxysmal atrial fibrillation, sinus node dysfunction, bilateral breast cancer, and extensive chest radiation developed progressive edema, dyspnea, and recurrent pleural effusions soon after single-chamber pacemaker implantation. Thoracentesis yielded a diagnosis of chylothorax, and progressive refractory anasarca developed. A computed tomography angiogram suggested obstruction of the superior vena cava and left subclavian vein despite outpatient therapeutic anticoagulation. Autopsy confirmed venous thrombosis, along with mediastinal fibrosis. The presumed etiology of the chylothorax and anasarca was obstruction of the atretic central venous structures following pacemaker implantation, critically impairing the already tenuous venous and lymphatic drainage. (PACE 2010; 520-524).

Identifying sources of stress to native aquatic fauna using a watershed ecological risk assessment framework

The free-flowing Clinch and Powell River Basin, located in southwestern Virginia, United States, historically had one of the richest assemblages of native fish and freshwater mussels in the world. Nearly half of the species once residing here are now extinct, threatened, or endangered. The United States Environmental Protection Agency's framework for conducting an ecological risk assessment was used to structure a watershed-scale analysis of human land use, in-stream habitat quality, and their relationship to native fish and mussel populations in order to develop future management strategies and prioritize areas in need of enhanced protection. Our analyses indicate that agricultural and urban land uses as well as proximity to mining activities and transportation corridors are inversely related to fish index of biotic integrity (IBI) and mussel species diversity. Forward stepwise multiple regression analyses indicated that coal mining had the most impact on fish IBI followed by percent cropland and urban area in the riparian corridor (R2 = 0.55, p = 0.02); however, these analyses suggest that other site-specific factors are important. Habitat quality measures accounted for as much as approximately half of the variability in fish IBI values if the analysis was limited to sites within a relatively narrow elevation range. These results, in addition to other data collected in this watershed, suggest that nonhabitat-related stressors (e.g., accidental chemical spills) also have significant effects on biota in this basin. The number of co-occurring human land uses was inversely related to fish IBI (r = -0.49, p < 0.01). Sites with > or = 2 co-occurring land uses had >90% probability of having <2 mussel species present. Our findings predict that many mussel concentration sites are vulnerable to future extirpation. In addition, our results suggest that protection and enhancement of naturally vegetated riparian corridors, better controls of mine effluents and urban runoff, and increased safeguards against accidental chemical spills, as well as reintroduction or augmentation of threatened and endangered species, may help sustain native fish and mussel populations in this watershed.

Delayed disaccharidase development in a rabbit model of intrauterine growth retardation

Intrauterine growth retardation (IUGR) affects almost 10% of infants born in the United States. It may be responsible for delayed gastrointestinal function and is an important cause of perinatal morbidity and mortality. The New Zealand White rabbit provides an optimal model for the study of naturally occurring IUGR. At term, birth weight is determined by fetal position within the bicornuate uterus. The small intestinal disaccharidase enzymes are indicators of bowel maturity and function. To examine potential differences in disaccharidase development between normal and IUGR fetuses, this rabbit model was investigated. Jejunum was harvested at multiple stages in rabbit development including the third trimester fetus, neonate, and adult. Lactase, maltase, and sucrase enzyme activity, as well as total protein content, was determined. Results were analyzed by the 2-tailed t test and ANOVA. Lactase activity appeared in the mid-third trimester, peaked in the early neonatal period, then declined to adult levels. Maltase activity appeared in the early third trimester and gradually rose to adult levels. Sucrase remained at trace levels until the mid-neonatal period, reaching adult levels by weaning. Both lactase and maltase activity were depressed in IUGR fetuses compared with their normal littermates. This pattern of disaccharidase depression continued into the neonatal period until catch-up growth occurred at 2 wk when levels equalized. This report describes differential small intestinal disaccharidase development between normal and growth-retarded rabbit fetuses in a naturally occurring model of IUGR.

Thermodynamics of three-way multibranch loops in RNA

RNA multibranch loops (junctions) are loops from which three or more helices exit. They are nearly ubiquitous in RNA secondary structures determined by comparative sequence analysis. In this study, systems in which two strands combine to form three-way junctions were used to measure the stabilities of RNA multibranch loops by UV optical melting and isothermal titration calorimetry (ITC). These data were used to calculate the free energy increment for initiation of a three-way junction on the basis of a nearest neighbor model for secondary structure stability. Imino proton NMR spectra were also measured for two systems and are consistent with the hypothesized helical structures. Incorporation of the experimental data into the mfold and RNA structure computer programs has contributed to an improvement in prediction of RNA secondary structure from sequence.

Evolution of regulatory responses to feeding in snakes

Do animal species that normally consume large meals at long intervals evolve to down-regulate their metabolic physiology while fasting and to up-regulate it steeply on feeding? To test this hypothesis, we compared postfeeding regulatory responses in eight snake species: four frequent feeders on small meals and four infrequent feeders on large meals. For each species, we measured factorial changes in metabolic rate, in activities and capacities of five small intestinal brush border nutrient transporters, and in masses of eight organs that function in nutrient processing after consumption of a rodent meal equivalent to 25% of the snake's body mass. It turned out that, compared with frequent feeders, infrequent feeders digest that meal more slowly; have lower metabolic rates, organ masses, and nutrient uptake rates and capacities while fasting; have higher energy expenditure during digestion; and have higher postfeeding factorial increases in metabolic rate, organ masses, and nutrient uptake rates and capacities. These conclusions, which conform to the hypothesis mentioned above, remain after phylogeny has been taken into account. The small organ masses and low nutrient transporter activities during fasting contribute to the low fasting metabolism of infrequent feeders. Quantitative calculations of partial energy budgets suggest that energy savings drive the evolution of low mass and activities of organs during fasting and of large postfeeding regulatory responses in infrequent feeders. We propose further tests of this hypothesis among other snake species and among other ectotherms.

A new self-report scale for assessment of adolescent psychopathology: factor structure, reliability, validity, and diagnostic sensitivity

This paper describes four studies on self-reported problems in 2,243 adolescent males and females, 12 to 17 years of age. In Study 1, principal-axis factoring of 102 items covering 11 problem domains revealed six factors comprising 49.5% of the variance. Study 2 used confirmatory factor analysis of a 64-item reduced set on a new sample of 408 adolescents. Goodness-of-fit indicators suggested that the six-factor model had excellent fit to the data. Study 3 used data from the 2,157 adolescents used in the first two studies. Coefficient alphas ranged from .83 to .92. Median test-retest reliability for the six factors was .86. There was a consistent structure of the correlation matrix across age and gender. Study 4 was a study of criterion validity, using an additional sample of 86 children with attention-deficit hyperactivity disorder (ADHD). Sensitivity and specificity were high, with an overall diagnostic efficiency of 83%. This new self-report scale, the Conners/Wells Adolescent Self-Report of Symptoms (CASS), may provide a useful component of a multimodal assessment of adolescent psychopathology.