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Morphological Specialization (morphological + specialization)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Morphological specializations of baleen whales associated with hydrodynamic performance and ecological niche

JOURNAL OF MORPHOLOGY, Issue 11 2006
Becky L. Woodward
Abstract Feeding behavior, prey type, and habitat appear to be associated with the morphological design of body, fluke, and flippers in baleen whales. Morphometric data from whaling records and recent stranding events were compiled, and morphometric parameters describing the body length, and fluke and flipper dimensions for an "average" blue whale Balaenoptera musculus, humpback whale Megaptera novaeangliae, gray whale Eschrichtius robustus, and right whale Eubalaena glacialis were determined. Body mass, body volume, body surface area, and fluke and flipper surface areas were estimated. The resultant morphological configurations lent themselves to the following classifications based on hydrodynamic principles: fast cruiser, slow cruiser, fast maneuverer, and slow maneuverer. Blue whales have highly streamlined bodies with small, high aspect ratio flippers and flukes for fast efficient cruising in the open ocean. On the other hand, the rotund right whale has large, high aspect ratio flukes for efficient slow speed cruising that is optimal for their continuous filter feeding technique. Humpbacks have large, high aspect ratio flippers and a large, low aspect ratio tail for quick acceleration and high-speed maneuvering which would help them catch their elusive prey, while gray whales have large, low aspect ratio flippers and flukes for enhanced low-speed maneuvering in complex coastal water habitats. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source]

Detecting selection on morphological traits in social insect castes: the case of the social wasp Vespula maculifrons

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010
JENNIFER L. KOVACS
Highly social insects dominate terrestrial ecosystems because society members belong to discrete castes that undertake distinct tasks. The distinct functional roles of members of different castes may lead to divergent selective regimes, which may ultimately lead to morphological specialization and differentiation of the castes. This study used morphological and genetic analyses to identify traits that experienced caste-specific selection in the social wasp Vespula maculifrons (Buysson, 1905). Traits putatively under selection were identified based on their degree of caste dimorphism, levels of variability, strength of correlations with other traits, and patterns of allometric scaling. Analyses of trait characteristics suggested that queen thorax length, thorax width, and possibly mass, have experienced queen-specific selection. Additionally, trait dimorphism and intercaste phenotypic correlation values were negatively correlated, as expected if some morphological traits were subject to selection, leading to alternate phenotypic optima in the two castes. Overall, our analyses demonstrate how techniques used to identify selection between dimorphic groups can be applied to social species with distinct castes. In addition, our analyses suggest the operation of selection may be stronger in reproductive than in non-reproductive castes. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 93,102. [source]

Morphological correlates of ant eating in horned lizards (Phrynosoma)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006
JAY J. MEYERS
The North American horned lizards (Phrynosoma) represent a morphologically specialized group of ant-eating lizards. Although variation in dietary fidelity is observed among the species, all appear to possess morphological specializations thought to be related to their ant-eating diets. Previous studies have examined morphological specialization in Phrynosoma, but they have not taken into account the phylogenetic relationships of its member species. In the present study, the morphological characteristics of the head, jaws and teeth that are thought to be important in prey capture and prey processing were examined to test whether variation in cranial morphology is associated with diet in lizards of the genus Phrynosoma. It is suggested that lizards of the genus Phrynosoma are indeed morphologically specialized and that ant-eating is associated with reduced dentition and an overall reduction in the robustness of morphological structures important in prey processing. Although this trend holds for the highly myrmecophagous species of Phrynosoma, a robust cranial morphology is apparent in the short-horned lizard clade (Phrynosoma ditmarsi, Phrynosoma douglasii, Phrynosoma hernandesi, Phrynosoma orbiculare), implying the ability to process a variety of dietary items. The present study suggests that additional feeding specializations exist within an already specialized clade (i.e. the short-horned lizard clade) and highlights the need for more detailed dietary and behavioural studies of feeding behaviour in this uniquely specialized group of lizards. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 13,24. [source]

Mantophasmatodea and phylogeny of the lower neopterous insects

CLADISTICS, Issue 3 2005
Matthew D. Terry
Polyneoptera is a name sometimes applied to an assemblage of 11 insect orders comprising the lower neopterous or "orthopteroid" insects. These orders include familiar insects such as Orthoptera (grasshoppers), Blattodea (roaches), Isoptera (termites) (Mantodea) praying mantises, Dermaptera (earwigs), Phasmatodea (stick insects), Plecoptera (stoneflies), as well as the more obscure, Embiidina (web-spinners), Zoraptera (angel insects) and Grylloblattodea (ice-crawlers). Many of these insect orders exhibit a high degree of morphological specialization, a condition that has led to multiple phylogenetic hypotheses and little consensus among investigators. We present a phylogenetic analysis of the polyneopteran orders representing a broad range of their phylogenetic diversity and including the recently described Mantophasmatodea. These analyses are based on complete 18S rDNA, 28S rDNA, Histone 3 DNA sequences, and a previously published morphology matrix coded at the ordinal level. Extensive analyses utilizing different alignment methodologies and parameter values across a majority of possible ranges were employed to test for sensitivity of the results to ribosomal alignment and to explore patterns across the theoretical alignment landscape. Multiple methodologies support the paraphyly of Polyneoptera, the monophyly of Dictyoptera, Orthopteroidea (sensu Kukalova-Peck; i.e. Orthoptera + Phasmatodea + Embiidina), and a group composed of Plecoptera + Dermaptera + Zoraptera. Sister taxon relationships between Embiidina + Phasmatodea in a group called "Eukinolabia", and Dermaptera + Zoraptera ("Haplocercata") are also supported by multiple analyses. This analysis also supports a sister taxon relationship between the newly described Mantophasmatodea, which are endemic to arid portions of southern Africa, and Grylloblattodea, a small order of cryophilic insects confined to the north-western Americas and north-eastern Asia, in a group termed "Xenonomia". This placement, coupled with the morphological disparity of the two groups, validates the ordinal status of Mantophasmatodea. © The Willi Hennig Society 2005. [source]

The humerus of Panderichthys in three dimensions and its significance in the context of the fish,tetrapod transition

ACTA ZOOLOGICA, Issue 2009
Catherine A. Boisvert
Abstract The humerus of Panderichthys has been considered to represent a transitional form between that of tetrapodomorph fish such as Eusthenopteron and tetrapods such as Acanthostega. The previous description was based on flattened material and was analysed in the context of the few fossils known at the time. Since then, several new forms have been described such as Gogonasus, Tiktaalik and an isolated humerus from the Catskill Formation. The humeral morphology of Panderichthys rhombolepis and its interpretation in this new context are therefore reassessed with the help of a three-dimensional model produced with the mimics software based on a computed tomography scan of an unflattened specimen as well as comparisons with the originally described material. The humerus of Panderichthys displays a combination of primitive, derived, intermediate and unique characteristics. It is very similar to the morphology of Tiktaalik but when it differs from it, it is most often more derived despite the more basal phylogenetic position that Panderichthys occupies. What emerges from this study is a much more gradual transformation of the humerus morphology from fish to tetrapods and the ability to distinguish autapomorphies more easily. The picture is more complex than previously believed, with many morphological specializations probably reflecting the breadth of ecological specializations already present at the time. [source]

A set of 16 consensus primer pairs amplifying the complete mitochondrial genomes of orange-spotted grouper (Epinephelus coioides) and Hong Kong grouper (Epinephelus akaara)

MOLECULAR ECOLOGY RESOURCES, Issue 6 2009
XUAN ZHUANG
Abstract Groupers are of considerable economic value; however, their classification and evolutionary relationships have long been hindered by the overwhelming number of species and lack of morphological specializations. Mitochondrial genome is a source of original markers that are potentially useful in the study of phylogeny and population genetics of groupers. We describe a set of 16 new primer pairs that allow PCR amplification of the entire mitochondrial genomes of orange-spotted grouper and Hong Kong grouper. This primer set has been defined for consensus over eight other grouper species, facilitating further studies on the molecular evolution and population genetics of groupers. [source]