Science as a Way of Knowing--Human Ecology

This essay is part of the second presentation of an educationalproject of the American Society of Zoologists. The purpose ofthe project is to offer suggestions for improving the first-yearbiology courses in the universities. The method consists ofemphasizing the conceptual framework of the biological sciences,showing how scientific information is obtained and evaluated,pointing out the strengths and limitations of scientific procedures,and above all showing the relevance of science for human hopesand welfare. Each year a major topic will be considered. Lastyear it was Evolutionary Biology. This year it is Human Ecology.     

Long-range Perspectives on Neurobiology and Behavior

This essay is part of the seventh presentation of a yearly educationalproject of the American Society of Zoologists. The purpose isto provide background materials for those who teach the first-yearbiology courses in colleges and universities. The Science asa Way of Knowing project emphasizes the conceptual frameworkof the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is Neurobiology and Behavior.The introductory essay is concerned mainly with the conceptualframework of neurobiology, as developed over the ages, and afew examples of behavioral studies which can be related to neurobiologyor which are of special interest through links to human considerationsand problems.     

Science as a way of knowing--form and function

Synopsis. These essays are part of the fifth yearly presentationof an educational project of the American Society of Zoologists.The purpose is to provide background materials for those whoteach the first-year biology courses in colleges and universities.The Science as a way of knowing project emphasizes the conceptualframework of the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is the broadest so farattempted—form and function. These introductory essaysare concerned mainly with the conceptual framework of morphologyand physiology as it developed over the ages.     

A Conceptual Framework for Biology Part I

These essays are part of the sixth yearly presentation of aneducational project of the American Society of Zoologists. Thepurpose is to provide background materials for those who teachthe first-year biology courses in colleges and universities.The Science as a Way of Knowing project emphasizes the conceptualframework of the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is Cell and MolecularBiology.     

Hypoxic Reptiles: Blood Gases, Body Temperature and Control of Breathing

Our contribution to this symposium is a review of recent modelsand experimental cdata on oxygen homeostasis in vertebrateswith normal intracardiac shunts; i.e., amphibians and reptiles.We focus on the interactions among hemoglobin function, bodytemperature regulation, and cardiovascular shunts under normalconditions (i.e., breathing fresh air at or near sea level)and during external hypoxia (e.g., altitude, burrows) and internalhypoxia (e.g., anemia, hemorrhage). Mathematical models andexperimental data suggest that animals with venous admixturefrom cardiovascular shunts will show biphasic arterial and mixedvenous Po₂ responses to warming; i.e., first increasing andthen, as the dissociation curve shifts too far to the right,decreasing. This has implications for many physiological functionsincluding oxygen consumption by tissues, control of breathing,as well as preferred body temperature and its regulation. Wepresent some of the recent experiments that have explored theseimplications.     

Modelling the Masting Behaviour of Betula platyphylla var. japonica using the Resource Budget Model

A masting model of Betula platyphylla var. japonica, a majorwind-pollinated tree in Hokkaido, northern Japan, was constructedfrom the perspective of the resource budget model. An 11-yeardata series of pollen dispersal by birch showed marked annualfluctuations in flowering. Although flowering fluctuated widelyamong years, a reciprocal relationship was observed betweentwo consecutive years; very little flowering occurred aftera mast year. This suggests that there is a negative relationshipbetween current fruiting and flower bud induction. There wasa significant positive relationship in flowering between regions,which suggests that weather conditions regulate flowering inbirch. A model that included weather variables and resourceallocation systems among years explained 94·5% of theobserved annual fluctuations in flowering. In the model, warmspring conditions from bud burst to flower bud development andlittle flowering in the previous year (t-1) resulted in increasedflowering in the current year (t), whereas abundant floweringin year t-2 resulted in a decrease in flowering in the currentyear (t). The latter indicates that flowering in year t-2 affectsresource storage after overwintering; the balance is carriedforward to year t-1 and affects the initiation of flower primordiabefore bud burst. In the model, fluctuating weather conditionsin the previous spring strongly affected the masting behaviourof birch. Copyright 2001 Annals of Botany Company Betula platyphylla var. japonica, flowering, masting, modelling, pollen dispersal, resource allocation, resource budget model, weather conditions     

Roots: the dynamic interface between plants and the Earth. * Abe J, ed. 2003. * Dordrecht: Kluwer Academic Publishers. * {euro}165 (hardback). 460 pp

All but five of the 46 contributionsin this symposium volume have been published already as a specialissue in Volume 255 of Plant and Soil in 2003. They are reproducedin exactly the same format and with the same pagination as inthe journal. To anyone who has access to Plant and Soil thisbook would therefore not be a sensible purchase. This is allthe more true because the editor has not provided any commentaryon the papers or subdivided them     

In Friendly Disagreement: Wilson, Morgan, and the Embryological Origins of the Gene Theory

The foundations of American embryology and genetics were establishedby four former graduate students of Johns Hopkins University.Edmund Beecher Wilson ('81) and Thomas HuntMorgan ('90) interactedover a thirty year period to provide the foundations of genetics,while Edwin Grant Conklin ('91) and Ross Granville Harrison('94) focused their studies on embryonic determination. Together,they founded the Journal of Experimental Zoology and were influentialin framing the shape of American experimental zoology for decadesto come. This essay will attempt to outline the interactionsbetween Wilson and Morgan leading up to the formation of thegene theory, and it will try to place this controversy in thecontext of a larger conflict among experimental biologists ofthe first two decades of this century—the conflict overwhether biological processes are effected by molecules in solutionor by fixed microscopic morphological structures.     

Systems biology: new institute and applications

The Yale Systems Biology Institute (YSBI) sponsored its first symposium at the university's West Campus in October 2010. The symposium served to provide Yale's scientific community with a glimpse into the wide range of research at the forefront of this interdisciplinary field. YSBI was conceived less than a year ago, and the event was the perfect forum for its debut, both at Yale and in the U.S. scientific community. This article includes a brief overview of the different topics presented at the symposium, followed by a discussion of the advantages and challenges of practical application of systems biology.     

THE ECOLOGY OF THE HONG KONG LIMPETS CELLANA GRATA (GOULD, 1859) AND PATELLOIDA PYGMAEA(DUNKER, 1860): DISTRIBUTION AND POPULATION DYNAMICS

Cellana grata is a high-zoned, exposed-shore limpet with a lifespanof 3 years. Patclloida pygmaeais a low-zoned, sheltered-shorelimpet with a lifespan of I year. C. grata migrates up-shorein winter, but occurs lower on the shore in summer. This migrationis synchronized with variations in algal availability high onthe shore; such variations are, however, themselves relatedto seasonal changes in wave height. P. pygmaea is restrictedto the low shore, year round. The movements upwards in winterand downwards in summer are still evident. Algal species richnessincreased from September to reach a peak between December andMarch, and to abruptly diminish between May and June. The encrustingalgae Brachytrichia maculans, Hildenbrandia prototypus, Lithothamnionsp. and Ralfsia vcrrucosa were present year round. The timingof juvenile recruitment of C. grata and P. pygmaea was fromOctober to July and February to October, respectively. Temperaturemay be important in enhancing juvenile survival by affectingthe seasonal pattern of algal occurrence on the shore. Seasonalfluctuations in the rate of growth were recorded for both specieswith the time of fastest growth of C. grata and P. pygmaea occurringbetween October and March and September and February, respectively.Mortality of both species occurred mainly in summer. Summerheat, predation and intra-specific competition for food appearto be the major causes of death. (Received 1 December 1992; accepted 5 May 1993)     

The role of temperature in the seed germination of two species of the Solanum nigrum complex

The germination behaviour of S. nigrum L. and S. physalifoliumRusby var. nitidibacatum (Bitter) Edmonds is compared, basedon temperature requirements during imbibition. Three seed lotsof S. nigrum had base temperatures (T_b) between 7.5C and 10C,showing a lower T_b when the period of freezing days, duringwhich each population was collected, was reduced. S. physalifoliumhas a higher value for T_b at constant temperatures (21C) thatcan be interpreted as a dormancy constraint. This constraintis released by alternating temperatures at amplitudes exceeding5C and with the high temperature above 21C by apparently reducingT_b to 12.5C. This implies that for S. physaiifolium temperature has a dualeffect on germination. It is the driving force for changes indormancy, but germination also depends on the temperature. Therole of temperature for S. nigrum is simpler: each populationcollected showed differences in the thermal time required forgermination that could be related to the temperature regimenof the original environment. Key words: Dormancy, S. nigrum, S. physalifolium, thermal time     

An Analysis of Growth Rates in the Early Life of Apple Trees

A long-term continuing experiment to study the effect of rootstockand pruning on composite apple trees is described. Cox's OrangePippin was worked on to either M·26 or MM·104rootstocks. Two pruning regimes were applied to give a totalof four treatments. The course of whole plant growth expressed by the cumulativedry weight during the first 9 years is described by means ofgrowth curves. Special reference is made to the growth and functionof the perennial structure, and its contribution to whole plantgrowth is quantified by means of the parameter Unit ProductionRate. This expresses the rate of growth per unit weight of theperennating structure. Unit Production Rate declined with increasingtree age; in the first 5 years spur pruning and invigoratingrootstock treatments gave the highest values whilst later thissituation was reversed. The efficiency of the process of perennation is quantified interms of the production rate of the deciduous fraction per unitweight of the perennating structure. In this respect dwarfingrootstock treatments were appreciably superior to invigoratingrootstock treatments only after the fifth year. Spur pruninggave lower values than minimal pruning at 7 years with spur-prunedCox/MM·ro4 alone showing a decline with increasing ageafter 5 years.     

Seasonal variations in the condition of two Daphnia species and their hybrid in a eutrophic lake: evidence for food limitation

As seston and chlorophyll concentrations in eutrophic lakesare usually high all year round, it was hypothesized in thepast that food limitation is of major importance for the seasonaldynamics of herbivorous zooplankton in such lakes. Since directmeasurements of food are hampered by the lack of knowledge onthe exact nature of the food in eutrophic conditions, indirectmeasurements are necessary to estimate the degree of food limitationin these circumstances. Hence, we used laboratory- and field-derivedrelationships between the body length and body carbon contentof different species of Daphnia, which were collected from thehighly eutrophic Tjeukemeer, the Netherlands. From a seasonalsurvey of the carbon content of the daphnids. we concluded thatin Tjeukemeer D.galeata, D.galeata x cucullata and D.cucullataare food limited during the largest part of the year. Sincethe condition of the hybrids was relatively high as comparedwith the parental species when the food concentration was high,D.galeata x cucutlaia is expected to be the more successfultaxon during periods of high food availability.     

A 91-year record of seasonal and interannual variability of diatoms from laminated sediments in Saanich Inlet, British Columbia

Diatom seasonal succession and interannual variability werestudied using laminated sediments from Saanich Inlet, BritishColumbia, for the years 1900–1991. Frozen sediment coresallowed fine-scale sampling of laminae for each year. Thus,three ‘seasons’ for each year were identified basedon species composition. Thalassiosira species were indicatorsof spring deposition. Skeletonema costatum was abundant in samplesfollowing Thalassiosira, probably deposited in late spring andsummer. Rhizosolenia sp. was most abundant in fall/winter samples.Diatom stratigraphies were related to sea surface temperature,salinity, sea level and the Pacific North American Index (PNA)using canonical correspondence analysis (CCA). CCA showed thatspecies of a particular season generally had optima for temperatureand salinity characteristic of that time. Interannual changesin diatom species composition and abundance were most prevalentin the decades 1920–1940, with the exception of S.costatumwhich showed cyclic changes in abundance. Skeletonema was moreabundant during periods of cool temperatures, while littoraldiatoms were more abundant during times of heavy winter rains.Sea level was an important variable in CCA and while its relationshipto diatoms is not clear, it may be related to variations innutrient supply to diatoms in surface waters.     

First report of the presence of Acartia margalefi (Copepoda: Calanoida) in Southampton Water and Horsea Lake, UK

Acartia margalefi is recorded for the first time in Britishwaters, where it is found to be an important copepod in themesozooplankton community structure of Southampton Water andHorsea Lake. Within the genus Acartia. this species occurs allthrough the annual cycle. Abundance is higher in the upper estuary,where the range of temperature and salinity is relatively widerover the year. It is clear that A.margalefi is an estuarinespecies which can tolerate a significant range of temperature.     

Interannual variability in the distribution of the phytoplankton standing stock across the seasonal sea-ice zone west of the Antarctic Peninsula

The spatial distribution of phytoplankton cell abundance, carbon(C) biomass and chlorophyll a (Chl a) concentration was analysedduring three summers (1996, 1997 and 1999) in a seasonal sea-icearea, west of the Antarctic Peninsula. The objective of thestudy was to assess interannual variability in phytoplanktonspatial distribution and the mechanisms that regulate phytoplanktonaccumulation in the water column. Phytoplankton C biomass andChl a distributions were consistent from year to year, exhibitinga negative on/offshore gradient. The variations in C concentrationhad a close and non-linear relationship with the upper mixedlayer depth, suggesting that the vertical mixing of the watercolumn is the main factor regulating phytoplankton stock. Themagnitude of C gradients was 5-fold higher during 1996 thanduring 1997 and 1999. This was ascribed to interannual variationsin the concentration of diatom blooms in the region influencedby sea-ice melting. Vertical distribution of the phytoplankton,as estimated from Chl a profiles, also varied along an on/offshoregradient: Chl a was distributed homogeneously in the upper mixedlayer in coastal and mid-shelf stations and concentrated inthe deep layer (40–100 m) occupied by the winter waters(WW, remnants of the Antarctic surface waters during summer)in more offshore stations. The region with a deep Chl a maximumlayer (DCM layer) was dominated by a phytoplankton assemblagecharacterized by a relatively high concentration of diatoms.The extent of this region varied from year to year: it was restrictedto pelagic waters during 1996, extended to the shelf slope during1997 and occupied a major portion of the area during 1999. Itis hypothesized that iron depletion in near surface waters dueto phytoplankton consumption, and a higher concentration inWW, regulated this vertical phytoplankton distribution pattern.Furthermore, we postulate that year-to-year variations in thespatial distribution of the DCM layer were related to interannualvariations in the timing of the sea-ice retreat. The similaritybetween our results and those reported in literature for otherareas of the Southern Ocean allows us to suggest that the mechanismsproposed here as regulating phytoplankton stock in our areamay be applicable elsewhere.     

Observations on the Biology of Fomes annosus, with Particular Reference to East Anglian Pine Plantations: II. Spore Production, Stump Infection, and Saprophytic Activity in Stumps

F. annosus produces conidia abundantly in culture but rarelyunder natural conditions. Sporophorea are formed on stumps anddying trees throughout the year provided that the humidity issufficiently high. Spore discharge in the plantations may occurat any time of year, but slowa down or ceases during very dryweather. It takes place at low temperatures, ceasing only whensporophores freeze. In the laboratory, F. annosus basidiospores germinate in relativehumidity exceeding 92 per cent. on freshly cut, unsterilizedpine wood. Viability is lost rapidly in light at temperaturesabove 15°C. Under humid conditions F. annosus spores will infect freshlycut pine stumps. There is evidence that spores of F. annosus washed down intosoil remain viable for at least a short period and that stumpscovered with soil are infected from this source. F. annosusspores can infect stumps for only a few weeks after felling,colonization after a longer interval probably beingprevdntedby competing fungi. In stumps inoculated with a mixed suspensionof F. annosus and Peniophora gigantea spores, Fomes at firstcolonized the wood but was soon replaced by P. gigantea. Otheraspects of competition are discussed. The incidence of natural infection in stumps and the factorsaffecting it are discussed Growth rates of F. annosus on malt agar and in lengths of pineroot are given. The fungus grows in stump roots at about 1 m.per year, and so closely approaches adjacent trees within ayear of thinning the plantation: In large stumps, F. annosusmay survive 15 or even 30 years after felling. Data are givenwhich suggest that the infective capacity of stumps containingF. annosus is greater in alkaline than in acid mils, while replacementby other fungi is slower. Competition of F. annosus with other fungi during colonizationof stumps is discussed. The parasite can grow along roots alreadyoccupied by certain fungi but not along roots containing others.The probable course of succession in stumps rotted by F. annousis described.     

Wheeler, E.A. and Manchester, S.R. Woods of the Eocene nut beds flora, Clarno Formation, Oregon, USA. IAWA Journal, Supplement 3

IAWA (International Asso ciation of Wood Anato mists) publishesa high quality journal in four parts, comprising about 500 pagesa year. Every so often they publish supplements that are muchlonger and more comprehensive than traditional scientific papers.The first two were Bibliography of systematic wood anatomy ofdicotyledons (265 pages) by Mary Gregory (1994) and Wood anatomyof Sapindaceae (214 pages) by René Klaasen (1999). Thisthird supplement is on a fossil flora which has many well-preservedwoods that have now been studied in detail. The only minor criticismI have is that the title of     

Structure of forest canopies as related to their primary productivity

Some structural features of forest canopy were analysed in relationto their role in photosynthetic production by forest communitieswhich are thought to produce more organic matter than herbaceouscommunities under the same environment. 1) Leaf area density was found to be much smaller in forestthan in herbaceous canopies. 2) Light extinction in forest canopy followed the BEER-LAMBERT'Slaw as was found for herbaceous canopy, though the coefficientof light extinction (K) was relatively small in the former. 3) A geometrical model was proposed to account for the smallvalue of K and the resultant large leaf area index, based onthe characteristically clustered distribution of tree leavesin forest canopy. 4) Stratification in forest community was interpreted as theuneven vertical distribution of leaf area density. 5) Deterioration of leaf functions, such as photosynthesis andrespiration, toward the bottom of forest canopy was noticed. 6) An attempt to estimate total canopy photosynthesis is presentedtaking this into consideration. 7) A new method for estimating total canopy respiration is proposedand discussed. ¹Contributions from JIBP-PT No. 36. The essential parts of thispaper were presented by KIRA to the IBP symposium The BiologicalBasis of Productivity held at Varna, Bulgaria, on April 4, 1968. (Received August 15, 1968; )     

Callus Induction and Plant Regeneration from Barley Mature Embryos

Callus cultures were induced starting from excised mature embryosin spring barley, Hordeum vulgare cv Maxima On a medium containinga high level of auxin, a first primary callus was induced whichwas friable, unorganized and capable of direct plant regenerationin the tested conditions This callus type was characterizedby fast growth and high variability in chromosome number Subsequently,a secondary callus type arose from the primary calli subculturedon the same medium in the light This callus type was white andcompact and consisted predominantly of diploid cells When transferredto hormone-free medium it gave rise to green shoots Completerooting of the shoots was achieved on half-strength basal mediumfollowed by exposure to higher light intensity Regenerated plantletscould then be transferred directly into soil without sufferingany loss in vitality Although showing different degrees in morphologicalvariability, they all maintained the diploid chromosome number Hordeum vulgare L, spring barley, morphogenic calli, organogenesis