Period Of High Mortality Research Articles

Maternal responsiveness of sows towards piglet's screams during the first 24 h postpartum

In this study we focused on sow responsiveness towards piglet screams which are proposed to have an important link to posture changes and early piglet crushing. A sow's responsiveness to screams of her piglets was investigated along the first 24 h after birth, the period of highest mortality, in 15 lactating sows housed in farrowing crates. We compared the sow's response to playbacks of screams of trapped piglets to her response to a control sound during birth, 8–12 h postpartum and 20–24 h postpartum. We did the same with playbacks of screams of fighting piglets during nursings 8–12 h postpartum and 20–24 h postpartum. The sow’ responsiveness to screams of own trapped piglets was analyzed within the whole 24 h and to screams of fighting piglets 30 min between 8 and 12 h postpartum and 30 min between 20 and 24 h postpartum. A sow was scored as responsive if she changed her posture in response to the stimuli. Sows had a four times higher response towards playbacks with screams than towards the control stimulus. The proportion of the sows’ responsiveness to screams (44%) of trapped piglets did not change significantly between birth, 8–12 h postpartum and 20–24 h postpartum. Sows responded to 28% of playbacks of fighting piglets by terminating a nursing independently from the time after birth. Playbacks and real screams of own piglets were similarly effective in evoking a response for both types of screams. There was no significant association between the sows’ responsiveness to screams of trapped piglets and piglet mortality nor between screams of fighting piglets and weight gain. In conclusion our results indicate that sows maintained their responsiveness towards piglet screams during trapping and during fighting for teats within the first 24 h. Playbacks and real screams were similarly effective in evoking a response. We discuss the importance of the sound characteristics of piglet screams related to the sows’ response.

The death of birds on the sea coast of northeastern Sakhalin Island

The taxonomical composition of dead birds found on the northeastern coast of Sakhalin Island and the causes of their death were studied. Sites with high, average, and low concentration of dead birds were identified. The period of highest mortality of birds (July–August) coincided with the beginning of massive migrations of birds and large numbers of young birds after termination of the nesting season. Collection of bird remains in periods of bird migrations and breeding, in addition to other methods of ornithological research (visual observations, fowling, shooting), can provide useful information on the avifauna and ecological state of the investigated region.

Ontogenetic shifts in fusion?rejection thresholds in a colonial marine hydrozoan, Hydractinia symbiolongicarpus

Like many modular organisms, genetically distinct colonies of the hydrozoan Hydractinia symbiolongicarpus naturally fuse to produce chimeras. One of the principal cooperative benefits of fusion arises from the increased size of the resulting chimeric individual, which may enhance survivorship. However, fusion also promotes conflict through competition between cell lineages for representation in reproductive tissues. Previous studies on H. symbiologicarpus show that, consistent with kin selection theory, a highly polymorphic self/non-self recognition system limits fusion to close kin. However, these recognition systems are intrinsically subject to error. Conspecific acceptance threshold theory predicts that as the costs and benefits of making recognition errors change, or the frequencies of encounters between acceptable and unacceptable kin vary, the recognition system should respond. Specifically, as the benefits of acceptance decline or the frequency of encounters with unacceptable individuals increases, the acceptance threshold should become more restrictive. We tested this hypothesis by monitoring changes in the expression of fusion/rejection behaviors of H. symbiolongicarpus during colony establishment, a period of high mortality when the size-dependent benefits of fusion may be changing most rapidly, and the frequency of encounters with close kin declines. Across seven full-sib families, fusion frequencies between pairs of sibling colonies declined from 73% for 3-day-old colonies to 58% by day 12. This decline is consistent with optimal acceptance threshold theory. However, the period of maximum decline also corresponds to an interval during which the recognition effector mechanism becomes fully functional, suggesting that the shift to a more restrictive conspecific acceptance threshold may reflect an intrinsic constraint on recognition system maturation.

Use of participatory epidemiology in studies of the persistence of lineage 2 rinderpest virus in East Africa

In 1994, rinderpest virus of African lineage 2 was detected in East Africa after an apparent absence of more than 30 years. In 1996, a disease search, based on participatory...

Mortality of Largemouth Bass during Catch-and-Release Tournaments in a Puerto Rico Reservoir

In Puerto Rico, unique protocols are used during fishing tournaments for largemouth bass Micropterus salmoides. Live wells are not required, and many anglers retain their catch on metal stringers. During day tournaments, fish are collected and weighed by a roving weigh-in boat; night tournaments use a central weigh-in station. We monitored 15 fishing tournaments over 1 year in Lucchetti Reservoir, Puerto Rico, to quantify mortality rates and to evaluate the impact of tournaments on the adult fish population. Initial mortality was documented at weigh-in, and delayed mortality was determined by holding largemouth bass for 4 d in floating mesh pens with control (electrofished) largemouth bass. Initial and delayed mortality averaged 8% (range, 0–38%) and 43% (10–98%), respectively. The delayed mortality rate was adjusted by the control mortality rate (mean, 7%; range, 0–50%) for each tournament to yield adjusted delayed mortality rate (mean, 36%; range, 10–68%), which we used to calculate total mortality rate (mean, 42%; range, 13–68%). Although surface water temperature ranged only between 23°C and 28°C, total mortality was significantly lower (P ≤ 0.05) during January–February, being positively correlated with temperature. Night tournaments experienced significantly greater total mortality rates than day tournaments, most likely because of the eightfold longer retention of bass before weigh-in during night tournaments. Retention time was positively correlated with initial mortality rates. We estimated that tournament mortality removed 6% of the adult largemouth bass population and accounted for 23% of all fishing mortality. We recommended reducing tournament fishing during hotter, high-mortality periods; modification of night tournaments; and use of well-maintained live wells. Combined with angler education, such modifications of tournament procedures can reduce the impact of tournaments in tropical reservoirs.

Reproduction and summer mortality of blue mussels Mytilus edulis in the Magdalen Islands, southern Gulf of St. Lawrence

We examined the relationship of summer mortality to reproductive events for suspension-cultured mussels Mytilus edulis L. in the Magdalen Islands. Parameters associated with gametogenesis and spawning were followed along with the timing and intensity of mortality from mid-June to mid-September 1991. For mussels maintained in a shallow lagoon (the usual mussel culture site), summer mortality began in late July as a major spawning event was ending and as summer temperatures peaked (>20°C). Mussels from this group showed low energetic contents after spawning and during the period of highest mortality, glycogen content decreased rapidly and shell growth ceased. Thus, mussels weakened by a major spawning were at the same time submitted to stressful temperatures. Summer mortalities were observed until the end of the experimental period (mid-September) even though surviving mussels seemed to have improved their condition in late August (when glycogen content, tissue mass and shell length had increased). By mid-September approximately 65% of the mussels had been lost. In contrast, no summer mortality was observed for mussels from the same stock that were maintained at 16 m depth in the open sea. These mussels were exposed to lower temperatures and spawned less extensively than those in the lagoon. They had no major spawning in late July and were never completely empty of gametes. Our results suggest that suspension-cultured mussels in Magdalen Islands lagoons pay a high reproductive cost in terms of survival when a major spawning is completed during a period of stressful environmental conditions, such as high water temperatures.

Galium aparine L.

Galiun L., Section KOLGYDA Dumort. (Section Aparine Koch). An annual herb with prostrate or, more usually, scrambling-ascending diffusely branched stems 15-300cm, stout and hairy at the nodes, the four angles very rough with downwardly directed prickles. Leaves 12-60 x 3-8 mm, in whorls of 6-9, narrowly to widely oblanceolate or elliptical, mucronate, 1-veined, glabrous or with hooked bristles above, margins rough with backward-pointing prickles. Flowers 1.5 mm diameter in 2-5-flowered axillary cymes, their peduncles topped by a whorl of 4-8 bracts; hermaphrodite, sometimes male (andromonoecious). Calyx a minute annular ridge; corolla 1.5-1.7 mm in diameter, whitish, with four acute lobes. Stamens 4, exserted; styles 2, short, connate below; stigmas capitate. Two-seeded fruits with length of longest axis 3-5 mm (excluding setae), wider than the corolla, olive or purplish, covered with white hooked setae with tuberculate bases, their stalks divaricate. Mature fruit a dry mericarp with length of longest axis 2-3 mm, and a mean airdry mass of 9.65 mg ? 0.33 (10 samples of 100 from a hedgerow population). Salisbury (1974) reports the average mass of seed from shade-tolerant woodland and hedgerow plants as 3.7 mg, and Grime et al. (1988) record a mean seed mass of 7.25mg for a hedgerow population. Galiumn iparine is a highly variable species owing to a combination of phenotypic plasticity and genecological variation. The species has different responses to the environment corresponding to different environmentally conditioned life cycles [see VI (e)]; plasticity in the timing of seed germination, productivity, growth form, freezing tolerance, and the light and temperature dependence of photosynthesis enable G. apa7ine to establish itself in a wide variety of habitats. Potential variability concealed in the higher polyploid conditions, especially in the widespread hexaploids [see VI (d)], enabling them to respond to changing environmental conditions, is probably also the basis of their success. Among plants of G. apariine raised from seed collected from various sites in continental Europe, B6cher etal. (1955) distinguished at least five different climatic ecotypes or races that either may be discrete or more probably ranges of a large clinal variation: mediterranean, summer-annual (seed germinates in the spring) with accelerated development from Portugal; mediterranean, biennial from Spain; southern, winterto summer-annual from France; northern, rather late flowering winterto summerannual from Denmark and Poland; and northern, very late flowering winter-annual (seed germinates in autumn) from Denmark and Sweden. Ecotypes of G. aparine have been demonstrated by Berkefeld (1988), differing in shape of cotyledons, hairiness of stems, colour of stem edges and length of fruit spines in plants grown under uniform garden conditions from seed collected in several different habitats. In Britain, two discrete ecotypes of G. apa7i71e exist, one found in arable fields or open situations and the other growing in hedgerows (FroudWilliams 1985); the two ecotypes are very similar morphologically but differ markedly in seed dormancy and germination requirements [see VIII (d)]. Bain & Attridge (1988) provide evidence of genotypic differences in shade strategies between hedgerow and field populations [see VI (e)]. Two forms have been recognized, the rarer G. aparine f. interimediwan Bonnet, with smooth or tuberculate fruits without spiny hairs, and the common form G. apar-ine f. apari71e with spiny fruits (Moore 1975). Variants of G. spur-ium with setose fruits, apart from the flower characters and the diploid chromosome number, are often not easy to distinguish from G. caparine and have been described as G. spuritini ssp. infestlin (Hanf 1983). Galiuiml apariine is native on maritime shingle beaches, in primary tall-herb fen communities, and in primary alderwood in natural hydrarch successions, but is also a very variable cosmopolitan weed found in hedges, waste places, drained fen peat, on limestone scree, roadside verges, river and stream banks, and is a major arable weed, especially of cereal crops. *Abbreviated references are used for standard works, see Jolurnal of Ecology (1975), 63, 335-344. Nomenclature of vascular plants follows Florca Euri0opaea and Stace (1997) for British species.

Critical Stage in Developing Walleye Eggs

Egg mortality in walleye Stizostedion vitreum during various developmental stages was monitored at an incubation temperature of 10°C. More than 80% of the mortality occurred during 50–100 h postfertilization or 21–42 temperature units (TU = number of days postfertilization × incubation temperature in oC), particularly during the transformation of germinal layers into various organs of the embryo (i.e., gastrulation–early organogenesis). Mortality declined once the body (head and trunk) of the embryo was formed. This period of high mortality might be considered as a critical stage of walleye egg development. Any environmental stress during this period might cause even higher egg mortality.

Larval parameters determining preschooling juvenile production of Pacific saury (Cololabis saira) in the northwestern Pacific

Production of larvae in the hatching size-class of Pacific saury (Cololabis saira) was highest in autumn 1990-1994, implying that spawning activity was highest in this season. Growth and mortality rates were stable in the winter-spawned cohorts in Kuroshio waters (south of Honshu); variable rates were found in the autumn- and spring-spawned cohorts in the mixed water region to the northeast. Although no particular period of high mortality was detected through the larval and juvenile stages, overall percent survival through the larval and juvenile stages differed by an order of magnitude among seasons. Production of 40-mm preschooling juveniles was determined by larval production in the smallest size-class in the winter cohort, but by overall percent survival through the larval and juvenile stages in the spring and autumn cohorts. Over the last 44 yr, percentage of winter-spawned cohorts in commercial catches was stable, compared with large interannual variations of autumn- and spring-spawned cohorts. These observations were assumed to stem from stable juvenile production in winter and variable production in autumn and spring, suggesting the possibility of recruitment forecasts of seasonally spawned cohorts of saury based on preschooling juvenile production estimates in the northwestern Pacific.

A long‐term study of Pinus banksiana population dynamics

Abstract. The long‐term population dynamics of a pure, naturally‐established stand of Pinus banksiana (jack pine) in southeastern Manitoba, Canada is described. The study was initiated at stand age 15, when all 468 trees in a plot were mapped and their trunk diameter at breast height (DBH) measured. The plot was remeasured eight times — every five years (six years in one case) — and mortality and DBH changes recorded. Total mortality over the 41‐yr study period was ca. 84 %. Mortality was initially very low, increased once the stand entered the self‐thinning stage from ages 25–46, and declined at ages 46–56. Mortality was restricted to the smallest size classes throughout. The stand reached the self‐thinning line at ca. age 30. The self‐thinning slope was significantly less steep than the theoretically expected value of −0.5.The distribution of DBH values was initially symmetric, showed increasing positive skewness during the period of highest mortality, and became symmetric again at later stages. Size (DBH) inequality was highest just prior to the onset of density‐dependent mortality, and subsequently declined. Tree DBH values were positively autocorrelated both initially and at later stages of stand development, but were spatially independent during the period of highest density‐dependent mortality. The stand initially had a strongly clumped pattern at all spatial scales. Patterns of mortality were non‐random during stand development, however, resulting in increased spatial regularity over time. Mortality was initially restricted to high density patches of the stand, but occurred throughout the plot once the self‐thinning line was reached. Mortality during the self‐thinning stage deviated from random expectation at local spatial scales (1–2m radius), suggesting that individuals were competing with their immediate neighbours. It is argued that an integrated approach, incorporating both population size and spatial structures, is essential in improving our understanding of long‐term plant population dynamics.

AM218, a new polyanionic polysaccharide, induces radioprotection in mice when administered shortly before irradiation

We have shown that the polyanionic polysaccharide AM218 improves the survival rate of the potentially lethally irradiated mice. This radioprotective effect was highly dependent on the administration schedule, the most efficient protocol being that in which the drug was given shortly before irradiation. The haematopoietic implications in the pharmacological action of AM218 were confirmed by the improved recovery in the three peripheral blood lineages observed in the AM218-treated mice. However, because of a marked increase observed in the number of white blood cells during the period of highest mortality of the control irradiated mice, effects on the neutrophil lineage may account for the effects mediated by AM218 in the irradiated mice. Both in vitro and in vivo treatment with AM218 before irradiation improved the survival rate of CFU-GM progenitors, while no effects were observed on the CFU-S pool. This led us to postulate that the improved survival rate of the committed progenitors, at least the granulocyte-macrophage progenitors, accounts for the radioprotective capacity of AM218.

Density‐dependent mortality, growth and size inequality in roadside populations of the annual herb Galium aparine L.

AbstractBiomass, plant size, plant density and the inequality of sizes were assessed for autumn‐emerging roadside populations dominated by Galium aparine during early stages of growth in two independent studies. A third data set dealt with the survival of labelled seedlings belonging to different cohorts of emergence. One data set showed that the slope of the log‐log size/density relationship for all plant species present in the samples was closer to −1.5 and that for G. aparine was closer to −1.0 in five separate populations. Biomass increase and density decrease was not found to take place in any of these simultaneously. The size inequality of G. aparine tended to increase or to remain constant during periods of high mortality, and in the early harvests it was negatively related to population density. The second data set revealed simultaneous decreases of both biomass and density of G. aparine and of all plant species during a period of a month soon after emergence, and a higher size inequality of G. aparine in those patches where plant density (and that of G. aparine) was lower. The labelling of seedlings indicated density‐dependent mortality and a higher probability of survival for seedlings emerging very early. The size/density relationship of roadside populations dominated by G. aparine may follow a trajectory over time similar to that predicted by the 3/2 power law of self‐thinning, but this species seems to have a weak size hierarchy development and limited individual growth at high population densities. The importance of plant architecture in relation to this response is discussed.

Adult Mourning Dove Survival during Spring/Summer in Northcentral Missouri

We estimated spring/summer survival during 1990-91 with 315 radiomarked doves on 2 areas in northcentral Missouri to understand mourning dove (Zenaida macroura) population declines in the Eastern-Central Management Unit (E-CMU) states. No differences were found among areas, years, or sexes so data were pooled to calculate a composite spring/summer survival estimate. Overall survival of mourning doves during spring/summer was 0.716 (95% confidence interval [CI] 0.651-0.782). Although there are no other mourning dove period survival estimates with which to compare, our survival estimates indicate that spring/ summer is probably not a period of high mortality. Interpretation of these survival estimates and their associated management prescriptions, however, are tentative until additional estimates from other areas are available. Sample size suggestions are provided for future studies estimating mourning dove survival using radiomarked doves.

Dietary changes improve survival of CFTR S489X homozygous mutant mouse

Over 90% of untreated CFTR S489X homozygous (CF) mutant mice reportedly die of intestinal obstruction by 40 days of age, significantly limiting their usefulness as a model for the human disease. Because the period of highest mortality is during the week after weaning, we hypothesized that providing a low-residue liquid diet would improve survival and growth. When 99 CF mice that survived to 10 days of age were fed Peptamen (Clintec Nutrition), an elemental liquid diet, and housed on corn-cob bedding, 88% of them survived to maturity (50 days). The diet causes only minor histologic and ion transport changes in the intestines of normal mice and does not reduce growth rate or size. CF mice raised on Peptamen continue to display severe pathological changes in the intestine and completely lack a adenosine 3',5'-cyclic monophosphate-inducible chloride current in the cecum. This combination of dietary and bedding changes provides a reliable method for keeping CF mice alive well into adulthood and will be useful for the evaluation of the effect and duration of potential therapies for CF.

Role of Glutathione S-Transferase in the Activation of a S-Alkyl Phosphorothiolate Prothiophos Oxon

Prothiophos oxon or its S-alkyl homologs(alkyl: methyl, ethyl and butyl) was incubated with a mixture of rat liver microsome and cytosol at 37 °C for 30 min in the following conditions: (a) without NADPH and GSH, (b) with NADPH (condition for sulfoxide formation) and (c) with both NADPH and GSH. Each reaction mixture was lyophilized after adding sucrose and fed to adult female houseflies (susceptible Takatsuki strain). Their mortality was observed at intervals until 48 hr. Dose for each compound was adjusted based on its LD50 value so that the time required for the residual oxon to exert its insecticidal activity was delayed. In the case of S-methyl compound, the mortality in (c) was similar to that in (a), although the remaining oxon in (c) was about half of that in (a). This suggests that the insecticidal effect in (c) may also have been given by something other than the oxon. The mortality in (c) was also higher than that in (b), although the amount of the remaining oxon was the same. Considering the unstability of the sulfoxide formed in the reaction mixture in (b), something stabilized in (c) may have contributed to the insecticidal activity. Without cytosol, the mortality in (c) decreased. The similar tendency was observed with other compounds. When bovine erythrocyte AChE was added to the above incubation mixture, the AChE was inhibited by the reaction mixture strongly in (c) and when more GSH was added regardless of the S-alkyl groups used. The reaction mixture was given to susceptible and resistant (higher glutathione S-transferase activity) strains. The death started later in the resistant strain than in the susceptible strain in (a), but was accelerated in (c) and the period of high mortality was longer in (c) than in (a). The mortality was different between (a) and (c) only during the initial period in the susceptible strain. The above result is well explained by postulating that S-alkyl phosphorothiolate compounds produce sulfoxide that inhibit AChE, while the sulfoxide give another active intermediates conjugated by the GSH-glutathione S-transferase system that also inhibit AChE. These two actions combined are to give an insecticidal effect.

Population Dynamics of the Colorado Potato Beetle (Coleoptera: Chrysomelidae) on a Native Host in Mexico

The population dynamics of the Colorado potato beetle, Leptinotarsa decemlineata (Say), were studied in central Mexico in 1987 and 1988. During the June-October rainy season, three generations were observed in 1987 and two in 1988. Predation and parasitism were found to be important mortality factors, particularly late in the season, contributing to generation mortality as high as 99.8%. Time series cross-correlation was used to estimate synchrony of Colorado potato beetle eggs with predators. Predators, including asopine pentatomids, carabids, thomisid spiders, and coccinellids, were abundant and well synchronized with developing Colorado potato beetle late in 1987, corresponding to the period of highest mortality.

養殖ブリにおけるＹＡＶと抗ＹＡＶ中和抗体の保有の推移

The occurrence and levels of yellowtail ascites virus (YAV) and anti-YAV neutralizing antibody were examined in cultured yellowtail Seriola quinqueradiata sampled from one net-pen in Uranouchi-Bay, Kochi Prefecture where an outbreak of viral pancreatic-hepatic necrosis occurred. The sampling period was May 22 to December 2, 1986, the disease was prevalent during May 22 to June 18. The percentage of YAV positive samples in organs of the sampled fish increased after the outbreak of the disease showing 100% during and just after the period of highest mortality, then with decreasing disease prevalence. YAV was not further isolated after 2 weeks from the period of prevalent disease. The mean virus titer (TCID50/g or ml) was 106.6 in the liver, 106.5 in the pyloric caeca, 106.4 in the intestine, 105.7 in the gill, 105.4 in the stomach, 105.3 in the kidney and 106.7 in the ascites fluid. Neutralizing antibody was detected in 10.8% of the fish sampled after July 5. The titers (ND50) ranged from 1:22 to 1:3, 822. No relationship was noted between the level of neutralizing antibody titer and the sampling period or the body weight of the fish.

Three days in October of 1630: detailed examination of mortality during an early modern plague epidemic in Venice.

The epidemiology of medieval and early modern European plague remains highly controversial. It now seems likely that the epidemiology was not uniform throughout either the geographic or temporal boundaries of the plague in Western Europe. The Venetian plague of 1630 was extensively documented; day-by-day records were kept, and each mortality in the city was recorded in a set format. The days 23-25 October 1630, representing a period when mortality was beginning to increase sharply, are examined. In all, 1,163 deaths were recorded. They show a large preponderance of women; a mean age of 28, but a majority of cases clumped between ages 0 and 25 years; and an unequal sex ratio among children. Further, there was an identifiable smallpox epidemic raging simultaneously with plague, and more than one-quarter of all the deaths in this period of high mortality were clearly due to nonplague causes. Deaths due to wounds and associated with violence were prominent in one parish, which suggests that in times of plague the breakdown in the normal machinery of government, in everyday patterns of life, and possibly of mental well being resulted in an even more exaggerated death toll. These factors--violence, accidents, and other epidemics--have never been so definitively tied to a European plague epidemic. In addition, there are hints that plague has a marked proclivity to kill pregnant women--their deaths far outnumber those anticipated--and that plague was very localized at a given moment within Venice itself, even during times of peak mortality.

Spatial distribution, life history and estimates of survivorship in a fourteen‐species assemblage of larval dragonflies (Odonata: Anisoptera)

SUMMARY. 1. Spatial and temporal changes in larval densities were used to infer patterns of habitat use and survivorship in a fourteen‐species assemblage of dragonflies (Odonata: Anisoptera) in a small fishless pond. The density of all species combined peaked at >1000 m−2 in late summer, Most species (e.g. Libellula spp.) were restricted to shallow, nearshore habitats (<1.0m in depth), but a few (e.g. Epitheca spp.) also used deeper areas of the pond. Only Perithemis tenera was most abundant in deep habitats.2. Because many species exhibited temporal shifts in their use of habitats, it was necessary to estimate survival from changes in population size, calculated as the product of density and habitat area, summed across habitats. In most species, periods of high mortality in autumn and spring were separated by 3–4 months of negligible mortality in winter. Survivorship was linear only in the two species that completed all of larval development in summer (Sympetrum vicinum and Pantala flavescens). Average survival rates for these two species (−0.0049 and −0.0079 log density d−1) were similar to those in previous studies (Lawton, 1970; Benke & Benke, 1975).3. Survivorship in many species was confounded by other life history phenomena such as (i) mixed voltinism, (ii) overlapping migrant and resident cohorts, and (iii) asynchronous development within species. Asynchrony made it difficult to estimate initial and final population sizes, hence total larval survivorship. However, based on emergence data, only 0.4–3% of larvae survived after peak abundance. None of this mortality can be ascribed to vertebrate predation, and only a little to overwintering stress and starvation. Thus, predation by invertebrates might play a major role in the regulation of these populations.

THE MEASUREMENT OF SELECTION ON CORRELATED CHARACTERS.

Natural selection acts on phenotypes, regardless of their genetic basis, and produces immediate phenotypic effects within a generation that can be measured without recourse to principles of heredity or evolution. In contrast, evolutionary response to selection, the genetic change that occurs from one generation to the next, does depend on genetic variation. Animal and plant breeders routinely distinguish phenotypic selection from evolutionary response to selection (Mayo, 1980; Falconer, 1981). Upon making this critical distinction, emphasized by Haldane (1954), precise methods can be formulated for the measurement of phenotypic natural selection. Correlations between characters seriously complicate the measurement of phenotypic selection, because selection on a particular trait produces not only a direct effect on the distribution of that trait in a population, but also produces indirect effects on the distribution of correlated characters. The problem of character correlations has been largely ignored in current methods for measuring natural selection on quantitative traits. Selection has usually been treated as if it acted only on single characters (e.g., Haldane, 1954; Van Valen, 1965a; O'Donald, 1968, 1970; reviewed by Johnson, 1976 Ch. 7). This is obviously a tremendous oversimplification, since natural selection acts on many characters simultaneously and phenotypic correlations between traits are ubiquitous. In an important but neglected paper, Pearson (1903) showed that multivariate statistics could be used to disentangle the direct and indirect effects of selection to determine which traits in a correlated ensemble are the focus of direct selection. Here we extend and generalize Pearson's major results. The purpose of this paper is to derive measures of directional and stabilizing (or disruptive) selection on each of a set of phenotypically correlated characters. The analysis is retrospective, based on observed changes in the multivariate distribution of characters within a generation, not on the evolutionary response to selection. Nevertheless, the measures we propose have a close connection with equations for evolutionary change. Many other commonly used measures of the intensity of selection (such as selective mortality, change in mean fitness, variance in fitness, or estimates of particular forms of fitness functions) have little predictive value in relation to evolutionary change in quantitative traits. To demonstrate the utility of our approach, we analyze selection on four morphological characters in a population of pentatomid bugs during a brief period of high mortality. We also summarize a multivariate selection analysis on nine morphological characters of house sparrows caught in a severe winter storm, using the classic data of Bumpus (1899). Direct observations and measurements of natural selection serve to clarify one of the major factors of evolution. Critiques of the adaptationist program (Lewontin, 1978; Gould and Lewontin, 1979) stress that adaptation and selection are often invoked without strong supporting evidence. We suggest quantitative measurements of selection as the best alternative to the fabrication of adaptive scenarios. Our optimism that measurement can replace rhetorical claims for adaptation and selection is founded in the growing success of field workers in their efforts to measure major components of fitness in natural populations (e.g., Thornhill, 1976; Howard, 1979; Downhower and Brown, 1980; Boag and Grant, 1981; Clutton-Brock et