Light deficit in shaded environment critically impacts the growth and development of turf plants. Despite this fact, past research has predominantly concentrated on shade avoidance rather than shade ...tolerance. To address this, our study examined the photosynthetic adjustments of Bermudagrass when exposed to varying intensities of shade to gain an integrative understanding of the shade response of C4 turfgrass. We observed alterations in photosynthetic pigment-proteins, electron transport and its associated carbon and nitrogen assimilation, along with ROS-scavenging enzyme activity in shaded conditions. Mild shade enriched Chl b and LHC transcripts, while severe shade promoted Chl a, carotenoids and photosynthetic electron transfer beyond Q.sub.A.sup.- (ET.sub.0/RC, phiE.sub.0, Ψ.sub.0). The study also highlighted differential effects of shade on leaf and root components. For example, Soluble sugar content varied between leaves and roots as shade diminished SPS, SUT1 but upregulated BAM. Furthermore, we observed that shading decreased the transcriptional level of genes involving in nitrogen assimilation (e.g. NR) and SOD, POD, CAT enzyme activities in leaves, even though it increased in roots. As shade intensity increased, considerable changes were noted in light energy conversion and photosynthetic metabolism processes along the electron transport chain axis. Our study thus provides valuable theoretical groundwork for understanding how C4 grass acclimates to shade tolerance.
The crescent perch Terapon jarbua is a demersal and catadromous fish that is widespread in the Indo-West Pacific region. It is a commercially important species in the Philippines and other Asian ...countries. Morphological differentiation among populations of T. jarbua throughout Philippine waters was investigated using morphometric and meristic characters. A total of 609 crescent perch (428 male, 181 female) were collected from nine localities in the Philippines. Meristic analyses showed the highest significant differences among populations in the lateral line scale and gill raker counts. Morphometric analyses revealed significant differences in shape among the nine T. jarbua populations. Allometry was found to be independent of size differences. Morphological differences were detected in the head, lip, and caudal peduncle regions. Specimens from General Santos City and Navotas were the most morphologically distinct from each other, whereas specimens from Sariaya and Balayan had the most similar shape. These can be attributed to the latitudinal gradient of the localities. Sexual dimorphism was also detected as significant differences were found in the specimens' lip positions, anal fin spine positions, caudal peduncle width, lateral line scale counts, gill raker counts, and pectoral fin ray counts. These morphological and meristic variations could be attributed to differences in feeding habits because T. jarbua is an omnivorous fish with a broad diet and can be found across marine, freshwater, and brackish environments. Further investigation of its diversity is recommended through the evaluation of T. jarbua feeding habits and their habitat's physicochemical characteristics. Additional sampling of populations outside of the Philippines is also recommended.
The differences in rorqual feeding ecology have been linked to the presence of different morphological markers. The Antarctic minke whale (Balaenoptera bonaerensis Burmeister, 1867) and the common ...minke whale (Balaenoptera acutorostrata Lacepede, 1804) are closely related species, but their morphological differences have not been fully investigated. In this study, we compared 21 skull and 11 feeding apparatus (baleen and mouth-related parts) measurement points between these two species using hundreds of individuals covering a wide range of body lengths in both sexes. Their engulfment capacities were estimated using these measurements. Our results show that Antarctic minke whales have (i) proportionally larger skulls to the body length, (ii) more dorsoventrally and laterally curved rostra, (iii) proportionally larger feeding apparatuses to the condylobasal length, and (iv) significantly larger engulfment capacity than common minke whales. These differences could indicate that Antarctic minke whales have developed a feeding strategy suitable for feeding on krill, which forms large schools. In contrast, common minke whales have adapted to prey on small pelagic fishes that are agile and form small schools.
The differences in rorqual feeding ecology have been linked to the presence of different morphological markers. The Antarctic minke whale (Balaenoptera bonaerensis Burmeister, 1867) and the common ...minke whale (Balaenoptera acutorostrata Lacepede, 1804) are closely related species, but their morphological differences have not been fully investigated. In this study, we compared 21 skull and 11 feeding apparatus (baleen and mouth-related parts) measurement points between these two species using hundreds of individuals covering a wide range of body lengths in both sexes. Their engulfment capacities were estimated using these measurements. Our results show that Antarctic minke whales have (i) proportionally larger skulls to the body length, (ii) more dorsoventrally and laterally curved rostra, (iii) proportionally larger feeding apparatuses to the condylobasal length, and (iv) significantly larger engulfment capacity than common minke whales. These differences could indicate that Antarctic minke whales have developed a feeding strategy suitable for feeding on krill, which forms large schools. In contrast, common minke whales have adapted to prey on small pelagic fishes that are agile and form small schools.
The tigrina Leopardus tigrinus (Schreber, 1775) is a small-sized Neotropical spotted cat found from northern Argentina and southern Brazil to Costa Rica. Four subspecies are traditionally recognized: ...L. t. tigrinus (Schreber, 1775) from northern Brazil, the Guianas and eastern Venezuela; L. t. pardinoides (Gray, 1867) from western Venezuela, Colombia, Ecuador and Peru; L. t. guttulus (Hensel, 1872) from southern Brazil, Paraguay and northern Argentina; and L. t. oncillus (Thomas, 1903) from Costa Rica. We studied external and craniodental morphology in quantitative and qualitative terms from 250 specimens in order to clarify the taxonomic status of tigrina. Based on the characters analyzed in this study, we recognize three diagnosable morphogroups, each with a distinct geographic distribution: northern/northwestern/west (samples from northern Brazil, the Guianas, Venezuela, Colombia, Ecuador, Peru, northwestern Argentina and Costa Rica), eastern (samples from northeastern and central Brazil), and southern (samples from southern Brazil, Paraguay and northeastern Argentina). Taking into account the morphologic evidence presented here, supported by biogeographic data and molecular studies available, we recognize three full species for tigrinas: L. tigrinus (including the putative subspecies L. t. pardinoides and L. t. oncillus as junior synonyms) for northern/northwestern/west group; L. emiliae (Thomas, 1914) for eastern group; and L. guttulus for southern group.
Interpréter et comprendre la variation morphologique au sein des hominines fossiles représente l’un des défis majeurs de la paléoanthropologie. L’absence d’une définition consensuelle du concept ...d’espèce en paléontologie, associée à la nature fragmentaire du registre fossile, affecte notre appréciation de la diversité taxinomique des hominines fossiles. Les débats historiques autour des restes fossiles attribués à Australopithecus en Afrique australe constituent un exemple marquant de l’impact de ces questionnements sur notre compréhension actuelle de l’évolution humaine. Dès les premières découvertes, les rapports scientifiques font état d’une très forte variation morphologique au sein de cet assemblage. Les fouilles qui ont suivi ainsi que l’étude des fossiles ont depuis confirmé cette variation remarquable. Alors que certains y décèlent la présence de plusieurs espèces du genre Australopithecus, d’autres explorent des hypothèses alternatives pour tenter d’expliquer cette surprenante variation. Loin d’être anecdotique, une forte diversité taxinomique au sein de ce genre modifierait profondément notre conception des mécanismes de spéciation des hominines du Plio-Pleistocène. Dans cette synthèse, je m’attache tout d’abord à rappeler les facteurs susceptibles de jouer un rôle dans la variation morphologique au sein du registre fossile et les discussions autour du concept d’espèce en paléoanthropologie avant d’aborder l’histoire des découvertes et les études qui ont soulevé certains questionnements autour de la diversité chez Australopithecus en Afrique australe et d’examiner les facteurs qui en seraient à l’origine.
Adaptations to low light and water depth stresses are crucial for the survival of submerged macrophytes. To determine the phenotypic responses of Vallisneria natans to such stresses, we combined a ...field investigation, a light control experiment and an in situ response experiment to evaluate adaptive variations in fresh weight and morphological and physiological characteristics. In the field investigation and the light control experiment, water depth and light intensity were the main environmental factors affecting the fresh weight and morphological characteristics of V. natans. Fresh weight and leaf length were the most significant responding variables, and they were positively correlated with water depth and negatively correlated with underwater light intensity, although the root length and leaf number exhibited no variation. The leaf length elongated more rapidly at sites with intermediate water depth and low light intensity, and the allometric slopes were steeper. Furthermore, the in situ response experiment results showed a unimodal distribution of the chlorophyll-a concentrations of V. natans along with increasing water depths (from 0.5 m to 8.5 m). The turning point of the chlorophyll-a concentration occurred at 5.5 m, which is almost the maximum water depth at which V. natans occurs in Lake Erhai. Overall, our results evidenced that light availability is an important driving factor that controls the status of V. natans by affecting not only its morphology and physiology but also its biomass allocation and ramet production. An alternative resource allocation pattern of V. natans could be a shift between light acquisition and clonal reproduction.
Display omitted
•Phenotypic responses of V. natans were studied in different scale experiments.•Light availability affects the morphology and physiology of V. natans.•Resource allocation pattern could shift between light acquisition and clonal reproduction.•Changes occur in the chlorophyll-a concentration to compensate for light attenuation.
PDF
