Narrower Body Research Articles

Morphological variation in relation to flower use in bumblebees

AbstractTo understand resource partitioning in a bumblebee community, we analyzed various morphological characters. A total of 1269 individuals of six bumblebee species, Bombus ardens, B. hypocrita, B. diversus, B. ignitus, B. honshuensis and B. beaticola, were examined and principal component analysis showed that the bumblebee species were clearly differentiated. Glossa, prementa and head lengths were positively correlated with the second component, and a longer proboscis was associated with a narrower body, which may help bees to intrude into and access deep‐lying nectar sources. Bombus diversus, with a long proboscis and narrow body, preferred flowers with a long corolla tube, whereas B. hypocrita and B. ignitus, which have short proboscises and wide bodies, visited flowers with short corollas or dish‐shaped flowers. Two pairs of consubgeneric species that have similar morphological characteristics, B. ardens and B. beaticola, and B. hypocrita and B. ignitus, divided flower resources by habitat selection and seasonal partitioning. For resource partitioning among bumblebee species, not only morphology but also other factors, such as habitat and seasonal preference, flower use, foraging behavior, and interspecific interactions, are responsible.

The comparisons of anthropometric characteristics among four peoples in East Asia

This study presents comparisons of ethnic difference in anthropometric characteristics among four peoples, i.e., Chinese, Japanese, Korean, and Taiwanese, in East Asia. Anthropometric data from the four East Asian countries were compared. The means of 33 body dimensions and 31 bodily proportions are presented. Also, 15 segmental proportions are illustrated. The results of statistical analyses showed that there is a significant morphological difference among these peoples in the same region. The Mainland Chinese body shape has a narrower body with mid-range limbs. The Japanese body shape is wider with shorter limbs. The Korean body shape is mid-range among the four peoples, but the upper limbs are longer. The Taiwanese body shape has wide shoulder and narrow hip with large hands and long legs. The ethnic diversity in bodily proportions should be considered as well as the mean dimensions.

THE LASTING EFFECTS OF ADAPTIVE PLASTICITY: PREDATOR-INDUCED TADPOLES BECOME LONG-LEGGED FROGS

Changes in environmental conditions often alter the traits of individuals; however, we have a poor understanding of how changes in phenotypically plastic traits early in development may affect traits later in life. Such effects are of particular interest in organisms with complex life cycles in which early and late life stages can have drastically different morphologies and occupy different habitats. In this study, I examined how differences in the mass, morphology, and larval period of wood frog tadpoles (Rana sylvatica) subsequently affected the mass and morphology of metamorphic frogs. I found three major patterns: (1) larval mass and larval period were positively related to metamorphic mass; (2) larval period was positively related to metamorph hindlimb and forelimb length and negatively related to metamorph body width; and (3) larval body length was positively related to metamorph forelimb size. I then used these correlations to interpret the connection between the traits of predator-induced tadpoles and the subsequent traits of metamorphic frogs. Tadpoles reared with caged predators (aeshnid dragonflies) developed relatively deeper tail fins and had shorter bodies, lower mass, and longer developmental times than tadpoles reared without predators. Metamorphs emerging from larval predator environments exhibited no differences in mass but developed relatively large hindlimbs and forelimbs and narrower bodies than metamorphs emerging from predator-free larval environments. These differences arose primarily due to predator-induced changes in larval development time and not due to the predator-induced changes in larval morphology. By focusing on a large number of traits and a wide range of trait values, one can readily generate predictions about how a variety of environments, which alter traits early in development, can subsequently alter traits later in development.

The Lasting Effects of Adaptive Plasticity: Predator-Induced Tadpoles Become Long-Legged Frogs

Changes in environmental conditions often alter the traits of individuals; however, we have a poor understanding of how changes in phenotypically plastic traits early in development may affect traits later in life. Such effects are of particular interest in organisms with complex life cycles in which early and late life stages can have drastically different morphologies and occupy different habitats. In this study, I examined how differences in the mass, morphology, and larval period of wood frog tadpoles (Rana sylvatica) subsequently affected the mass and morphology of metamorphic frogs. I found three major patterns: (1) larval mass and larval period were positively related to metamorphic mass; (2) larval period was positively related to metamorph hindlimb and forelimb length and negatively related to metamorph body width; and (3) larval body length was positively related to metamorph forelimb size. I then used these correlations to interpret the connection between the traits of predator-induced tadpoles and the subsequent traits of metamorphic frogs. Tadpoles reared with caged predators (aeshnid dragonflies) developed relatively deeper tail fins and had shorter bodies, lower mass, and longer developmental times than tadpoles reared without predators. Metamorphs emerging from larval predator environments exhibited no differences in mass but developed relatively large hindlimbs and forelimbs and narrower bodies than metamorphs emerging from predator-free larval environments. These differences arose primarily due to predator-induced changes in larval development time and not due to the predator-induced changes in larval morphology. By focusing on a large number of traits and a wide range of trait values, one can readily generate predictions about how a variety of environments, which alter traits early in development, can subsequently alter traits later in development.

Application of Turbidite Facies of the Stevens Oil Zone for Reservoir Management, Elk Hills Field, California: ABSTRACT

A detailed depositional model for the uppermost sand reservoirs of the Stevens Oil Zone, Elk Hills Field, California, contains three facies: turbidite channel-fill sand bodies, overbank Sandstone and mudstone, and pelagic and hemipelagic siliceous shale. Sand bodies are the primary producing facies and consist of layered, graded sandstone with good permeability. The presence of incipient anticlines with subsea relief in the late Miocene resulted in deposition of lenticular and sinuous sand Was within structurally created channels. Relief of these structural channels was low when the earliest sand bodies were deposited, leading to a wide channel complex bounded by broad overbank deposits of moderate to low permeability. As deposition proceeded, increased structural relief constrained the channels, resulting in narrower sand body width and relatively abrupt channel terminations against very low permeability siliceous shale. With post-Miocene uplift and differential compaction, stratigraphic mounding of sand bodies helped create structural domes such as the 24Z reservoir. Stratigraphic traps including the 26R reservoir were also created. Such traps vary in seal quality from very effective to leaky, depending on the lateral transition from sand bodies to siliceous shale. Application of the Elk Hills turbidity model (1) provides a framework for monitoring production performance in themore » 24Z and Northwest Stevens waterflood projects; and for tracking gas migration into and out of the 26R reservoir, (2) helps b identify undeveloped locations in the 26R reservoir ideally suited for horizontal wells, (3) has led to the identification of two new production trends in the 29R area, and (4) makes possible the development of exploration plays in western Elk Hills.« less

The association between distribution and octopodid morphology: implications for classification

The Octopodidae occur in virtually all benthic marine habitats; however, species in the family show little overt morphological differentiation. Subfamilies are currently defined by the presence or absence of an ink sac and the number of sucker rows (the presence of an ink sac and a single row of suckers are primitive characters) (Voss, 1988b); subfamily depth ranges are cited in the diagnoses. Examination of external octopodid morphology through principal components analysis reveals that octopodid morphology correlates with geographic distribution. Low-latitude, shallow-water octopuses typically have narrower bodies and larger suckers on longer arms than do deep sea and high-latitude species. Sucker size inversely correlates with depth distribution, as studies of sucker functional morphology predict (Kier & Smith, 1990). The same characters contribute in a very similar manner to the discrimination of species when grouped by subfamily and when grouped by mean depth distribution. That depth distributions, which correlate with morphology and with the loss of the ink sac, contribute to the definition of these subfamilies, suggests that the subfamilies constitute phenetically similar rather than monophyletic groups. Cladistic analysis is required to reassess octopodid phylogeny.

The association between distribution and octopodid morphology: implications for classification

Abstract The Octopodidae occur in virtually all benthic marine habitats; however, species in the family show little overt morphological differentiation. Subfamilies are currently defined by the presence or absence of an ink sac and the number of sucker rows (the presence of an ink sac and a single row of suckers are primitive characters) (Voss, 1988b); subfamily depth ranges are cited in the diagnoses. Examination of external octopodid morphology through principal components analysis reveals that octopodid morphology correlates with geographic distribution. Low-latitude, shallow-water octopuses typically have narrower bodies and larger suckers on longer arms than do deep sea and high-latitude species. Sucker size inversely correlates with depth distribution, as studies of sucker functional morphology predict (Kier & Smith, 1990). The same characters contribute in a very similar manner to the discrimination of species when grouped by subfamily and when grouped by mean depth distribution. That depth distributions, which correlate with morphology and with the loss of the ink sac, contribute to the definition of these subfamilies, suggests that the subfamilies constitute phenetically similar rather than monophyletic groups. Cladistic analysis is required to reassess octopodid phylogeny.

Two new generic names for some Australian pufferfishes (Tetraodontiformes: Tetraodontidae), with species' redescriptions and osteological comparisons

Marilyna n. gen. is proposed for three Australian pufferfish species, M. pleurosticta (Gunther), M. meraukensis (de Beaufort), and M. darwinii (Castelnau). M. meraukensis is recorded extensively from Australia for the first time, and M. darwinii, long ignored by ichtyalogists is confirmed as a valid, applicable name.Marilyna is characterised by a broad, heavily built body, eyes set below the dorsal profile, nasal organ with two openings, eye rim completely adnate, a large olfactory foramen in each prefrontal, and a deep caudal peduncle.Reicheltia n. gen. is proposed for the single species R. halsteadi (Whitley). It differs from Marilyna in the lighter built, narrower body, eyes interrupting the dorsal profile, a small olfactory foramen in each prefrontal, and a shallow caudal peduncle.

Magnetic smooth zones in the World's oceans

The distribution and geologic environment of magnetic smooth zones in the world's oceans are examined in order to determine their possible origins. The smooth zones are divided into two categories: (1) marginal smooth zones associated with the sedimentary deposits of continental rises, and (2) abyssal smooth zones located far from the continental margins in the deep sea. Abyssal smooth zones appear to result from two uniform polarity intervals, one in the Cretaceous and the second in the Jurassic, combined with some process, such as a fast spreading rate or crustal subsidence, that eliminates topographic anomalies. Many marginal smooth zones having ages coincident with the polarity intervals might have the same origins as abyssal smooth zones. However, marginal smooth zones are found almost solely on rifted continental margins, thus suggesting that they may owe their origin in part to the breakup of Pangea. As an alternate origin for marginal zones not having ages coincident with polarity intervals or as an additional process for those that do, we suggest that they are formed during the initial rifting of continents. Spreading rates are at first slow, producing narrow magnetic bodies. When these narrower bodies subside to continental margin depth, their anomalous magnetic field is attenuated at the sea surface. Marginal smooth zones might result from either or both processes, but all are accompanied by basement subsidence and deep sedimentary burial. Until the actual time spans (maximum and minimum ages) for certain marginal zones are known, sea floor spreading magnetic models cannot meaningfully be applied to test the various proposed origins.

Description and Ecology of Hyalella texana n. sp. (Crustacea: Amphipoda) from the Edwards Plateau of Texas

Hyalella texana, a new species of amphipod crustacean, is described from Clear Creek Spring, Menard Co., Texas, 16.7 km W of Menard. It is distinguished from H. azteca, which also occurs at this locality, by the presence of four large tergite spines, enlarged mouth parts, more antennal segments and narrower body and appendage seg- ments. Each species is found predominantly in different habitats of the spring area.