DOES TOTAL REPRODUCTIVE EFFORT EVOLVE INDEPENDENTLY OF OFFSPRING SIZE?

In all species, patterns of reproductive allocation have important fitness consequences and therefore important implications for life-history evolution. Nearly universally, theory in this field has modeled as independent the evolution of total allocation to offspring and the subsequent division of this allocation into many small versus few large offspring. Yet, some theory and a very small amount of experimental evidence suggest that these life-history traits may be evolutionarily linked. Using comparative analyses of copepod life histories, we illustrate that rather than being evolutionarily independent these traits can be linked, in this case, across a very large clade of invertebrates. Our results indicate that a more complete understanding of the evolution of these traits will require greater consideration of simultaneous allocation decisions, rather than sequential ones, and other genetic and selective mechanisms.     

HOW DEPRESSED? ESTIMATES OF INBREEDING EFFECTS DURING SEED DEVELOPMENT DEPEND ON REPRODUCTIVE CONDITIONS

Inbreeding depression can reduce the performance of offspring produced by mating between relatives, with consequences for population dynamics and sexual-system evolution. In flowering plants, inbreeding depression commonly acts most intensely during seed development. This predispersal component is typically estimated by comparing seed production following exclusive self- and cross-pollination, but such estimates are unbiased only if seed production is limited by ovule availability, rather than by pollen receipt or seed-development resources. To overcome this problem, we propose experimental and statistical methods based on a model of ovule fertilization and seed development that accounts for differential fertilization by self- and cross-pollen, limited ovule viability or receptivity, differential survival of self- and cross-zygotes and limited resource availability. Simulations illustrate that the proposed methods eliminate bias in estimated predispersal inbreeding depression caused by pollen limitation and can improve estimates under resource limitation. Application of these methods to two orchid species further demonstrates their utility in identifying and estimating diverse influences on reproductive performance under typical conditions. Although our theoretical results raise questions about the reported intensity of predispersal inbreeding depression, our proposed methods guard against bias while also providing insight into plant reproduction.     

REPRODUCTIVE CHARACTER DISPLACEMENT OF MALE STICKLEBACK MATE PREFERENCE: REINFORCEMENT OR DIRECT SELECTION?

Reproductive isolation can evolve between species as a byproduct of adaptation to different niches, through reinforcement, and by direct selection on mating preferences. We investigated the potential role of direct selection in the reproductive isolation between sympatric species of threespine sticklebacks. Each sympatric pair consists of a small-bodied limnetic species and large-bodied benthic species. We compared the mate preferences and courtship behavior of males from one sympatric limnetic population and two allopatric populations. We used limnetic-like allopatric populations to control for the effects of ecological character displacement and adaptation to different niches on mate preferences. The sympatric limnetic males preferred the small limnetic females, whereas the allopatric limnetic-like males preferred the large benthic females, suggesting that adaptation to the limnetic niche does not automatically confer a preference for small limnetic females. This reproductive character displacement of male preference is consistent with the predictions of both reinforcement and direct selection on mate preferences. To test for direct selection, we assessed a prediction of one proposed mechanism: predation by benthic females on eggs guarded by limnetic males. The allopatric males come from populations in which there is no egg predation. Sympatric limnetic males were more aggressive toward benthic females than toward limnetic females, whereas the allopatric limnetic-like males did not treat the two types of females differently. The contrast in male behavior suggests that egg predation has shaped male preferences. Direct selection is potentially more effective than indirect selection via reinforcement, and it is likely that it has been important in building up reproductive isolation between limnetic and benthic sticklebacks.     

THE EVOLUTION OF BODY SHAPE IN RESPONSE TO HABITAT: IS REPRODUCTIVE OUTPUT REDUCED IN FLAT LIZARDS?

Body size and shape are primary determinants of reproductive output in a variety of taxa, so selection favoring specific body sizes and shapes may, in turn, have a direct affect on reproductive output, and ultimately fitness. In reptiles, species that occupy rocky habitats are often flattened, a morphological character that aids locomotion and life on rocks, but which may constrain reproductive output by reducing the amount of abdominal space available to fill with eggs or offspring. Using 20 species of tropical skink from a wide range of habitats, we quantified habitat use, body height, body volume, and reproductive output, to determine whether the evolution of a flattened body was correlated with a reduction in abdominal volume, and, in turn, with reduced reproductive output. In this group of lizards, the occupation of rocky habitats has led (1) to the evolution of a flattened body, and this shift in body shape has (2) caused a reduction in abdominal volume. Despite this reduction in abdominal volume reproductive output was unaffected, as flatter species compensate by being more "full" of eggs. Thus, we demonstrate that morphological adaptation for enhanced performance in specific habitats did not cause a reduction in instantaneous reproductive output.     

EGG FREEZING: A BREAKTHROUGH FOR REPRODUCTIVE AUTONOMY?

This article describes the relatively new technology of freezing human eggs and examines whether egg freezing, specifically when it is used by healthy women as 'insurance' against age-related infertility, is a legitimate exercise of reproductive autonomy. Although egg freezing has the potential to expand women's reproductive options and thus may represent a breakthrough for reproductive autonomy, I argue that without adequate information about likely outcomes and risks, women may be choosing to freeze their eggs in a commercially exploitative context, thus undermining rather than expanding reproductive autonomy.     

EVOLUTION OF COURTSHIP SONG AND REPRODUCTIVE ISOLATION IN THE DROSOPHILA WILLISTONI SPECIES COMPLEX: DO SEXUAL SIGNALS DIVERGE THE MOST QUICKLY?

Reproductive isolation increases with genetic distance between species. Although sexual selection may drive divergence of sexual signals and traits, causing rapid evolution of sexual isolation, quantitative data supporting this idea are rare. We examine the rates of divergence of a species-specific courtship signal, sexual isolation, and postmating isolation in the Drosophila willistoni group. Both types of isolation increase with genetic distance and postmating isolation is the most strongly correlated with genetic divergence, suggesting this has the least variable divergence rate. Song divergence is not correlated with genetic divergence. Homoplasy in song pattern results in poorly resolved phylogenies that are different from molecular phylogenies. Song evolves more quickly than sexual isolation, which evolves more quickly than postmating isolation.     

POSTZYGOTIC ISOLATION OVER MULTIPLE GENERATIONS OF HYBRID DESCENDENTS IN A NATURAL HYBRID ZONE: HOW WELL DO SINGLE‐GENERATION ESTIMATES REFLECT REPRODUCTIVE ISOLATION?

Understanding speciation depends on an accurate assessment of the reproductive barriers separating newly diverged populations. In several taxonomic groups, prezygotic barriers, especially preferences for conspecific mates, are thought to play the dominant role in speciation. However, the importance of postzygotic barriers (i.e., low fitness of hybrid offspring) may be widely underestimated. In this study, we examined how well the widely used proxy of postzygotic isolation (reproductive output of F₁ hybrids) reflects the long‐term fitness consequences of hybridization between two closely related species of birds. Using 40 species‐specific single nucleotide polymorphism (SNP) markers, we genotyped a mixed population of collared and pied flycatchers (Ficedula albicollis and F. hypoleuca) to identify grand‐ and great grand‐offspring from interspecific crosses to derive an accurate, multigeneration estimate of postzygotic isolation. Two independent estimates of fitness show that hybridization results in 2.4% and 2.7% of the number of descendents typical of conspecific pairing. This postzygotic isolation was considerably stronger than estimates based on F₁ hybrids. Our results demonstrate that, in nature, combined selection against hybrids and backcrossed individuals may result in almost complete postzygotic isolation between two comparatively young species. If these findings are general, postzygotic barriers separating hybridizing populations may be much stronger than previously thought.     

A REPORT OF BIRDS OF NORTHEASTERN YUNNAN

A zoological expedition was made from March to June, 1975, in Northeastern Yunnan at Southeast of Yangtze River (27°30′—28°40′ N., 103°15′—104°25′E.). 450 specimens of birds were collected. Orders and families treated in this paper are listed below:     

TEMPERATURE COEFFICIENT OF THE ACTION OF β-RAYS UPON THE EGG OF NEREIS

The temperature coefficient of the action of β-rays from radium upon the egg of Nereis lies between 1.1 and 1.2. This is of a magnitude characteristic of photochemical reactions.     

ON NEW MATERIAL OF STEGODON WITH RECOLLECTIONS OF THE CLASSIFICATION OF STEGODON IN CHINA

ReviseddiagnoaisCraniumcompressedanteroposteriorlyandhighvertical1y.Superiortuskslargeandstraight,nolowerincisors'Ridge-platesprogressiveIymulti-plyingfromsixtoelevenintheintermediateteeth,fromninetofifteenandhaIfilltheposteriormolars.Thereisamediancleftoritsvestigesintheanteriorridge-platesoftheprimitivespecies.Conesrapidlysubdividingbybinaryorternary.fissionintomultipleconelets(8-l2).Ridge-plateselevatingfrombrachyodonttosubhypsodont.Cementdevelopingintheval1eys.RemarksSarwar(l977)propose…     

INCREASE OF CONTRAST SENSITIVITY FUNCTION OF RETINA BRAIN SYSTEM WITH INCREASE OF OPTIC DEMODULATION

Contrast sensitivity function(CSF or Tcs)of the visual system is generally regarded to be linearlyrelated to the product of optic MTF of the eye,Te,and MTF of the retina-brain system Trb,     

A STUDY OF INFLATION OF THE LUNGS OF THE NEWBORN—A Preliminary Report

There seems to be no reasonable doubt that the lungs in a newborn expand progressively during the first few days of life. Some degree of atelectasis seems to be perfectly normal. This is indicated by a number of roentgenographic studies (including those here reported); by the reported findings of pathologists; by the fact that in experimental animals the lungs inflated very unevenly; and by the fact that aeration of only a portion of the lung is needed for complete oxygenation of the blood. The relation of atelectasis to neonatal death is not entirely clear and is probably not always the same. The infant may die from other causes before the lungs are fully expanded. Atelectasis may develop secondarily to other debilitating conditions. The frequent coincidence of prematurity and extensive atelectasis is impressive. It may be that the lungs are so incompletely formed that they cannot expand. On the other hand, atelectasis and massive collapse in the adult is a serious condition and there seems to be no good reason to suppose that this cannot also occur in infants and be serious per se.The air pressures found necessary to expand the lungs in rabbit fetuses were found to be about ten times what adult humans use in quiet respiration and were of about the same magnitude as the pressures found necessary to expand the lungs of stillborn humans. An attempt to produce atelectasis in newborn rabbits by chilling was most inconclusive. Atelectasis did develop in three of 15 animals used in the experiment, but the relation to chilling was not at all clear.     

ON NEW MATERIAL OF PALAEOLOXODON NAMADICUS OF CHINA,WITH DISCUSSION ON THE CLASSIFICATION OF SOME PLEISTOCENE ELEPHANTS OF CHINA

(Summary)The content of this paper includes the following 5 parts:Ⅰ.Palaeoloxodon namadicus namadi(typicus)MatsumotoⅡ.Palaeolokodon namadicus naumanni(Makiyama)Ⅲ.Palaeoloxodon namadicus yabei?MatsumotoⅣ.Discussion on the systematic classification of P.namadicus and some otherPleistocene elephants of chinaⅤ.Conclusion     

EFFECT OF REMOVAL OF EXTERNAL CALCIUM ON PHOSPHOINOSITIDE HYDROLYSIS IN CULTURED MYOTUBES OF EMBRYONIC CHICKEN

本工作研究了去细胞外钙对取自9天来亨鸡胚的培养肌管磷脂酰肌醇水解的影响。80 mmol/L K     

SYSTEMATICS OF ISOPTERA FROM CHINA——2. DESCRIPTIONS OF THREE NEW SPECIES OF TERMITIDAE

The present paper deals with 3 new "Capritermes typus" termites belonging toMirocapritermes, Procapritermes and Homallotermes respectively. Holotypes, morphotypes,paratypes and thier duplications are deposited in Huanan Tropical Crops College, Tan-hsien, Hainan Is., China.     

NEW TAXA OF ILEX FROM THE PEOPLE''''S REPUBLIC OF CHINA

llex strigillosa T.R.DUDLEY,sp.nov. 〔Section Pseudoaquifolium S.-Y.HU(1950)Series Lougecaudatae S.-Y.HU(1950)〕. DIAGNOSIS: A I.kengii S.-Y.HU(1950)affinis sed ramulis et gemmis terminalis,dense cinerascentibus puberulento-strigillosis,stipulis tenuiter membranaceis minutis0.1mm longis vel minus fugacibus cito caducis,petiolis denso cinerascentibuspuberulento-strigillosis aliquado subglabris laminis versus,laminis foliorum mino-ribus 4—7.5cm longis 1—2cm latis basibus acutis ad attenuatis apicibussensim acuminatis vel caudato-acuminatis acuminibus brevioribus 5—10(—15)mm longis marginibus integris vel subintegris conspicue sinuolatis et apicibus     

THE RELATIVE PHYSIOLOGICAL EFFECTS OF β-RAYS OF DIFFERENT VELOCITIES

1. The physiological effect upon the eggs of Nereis of homogeneous groups of β-rays of different velocities is proportional to their ability to ionize air. 2. β-rays of low velocity produce a greater amount of physiological change than the same number of rays of high velocity. 3. These conclusions are consistent with, but do not prove, the view that the physiological effects of radiations from radium and x-rays are due to the production by them of an ionization of some substance in the egg.     

METAMORPHOSIS OF THE LARVA OF THE POLYCHAETE ARENICOLA CRISTATA. MORPHOLOGY OF THE ‘HOUR-GLASS’ STAGE

The constricted ‘waist’ of the metamorphosing larva of the polychaete Arenicola cristata is described, using light and electron microscopy. The constriction is shown to be the consequence of the discharge and collapse of a post-trochal ring of epithelial cells which remain as functional components of the post-metamorphic juvenile. Morphological differentiation of neuro-effector and interneuronal contacts is initiated at this time. Muscular and neural changes are discussed in terms of their role in effecting metamorphosis.