Species level phenotypic variation in lower Paleozoic trilobites

Paleobiology ◽  
1998 ◽  
Vol 24 (1) ◽  
pp. 17-36 ◽  
Author(s):  
Loren H. Smith
Keyword(s):  
Spatial Distribution ◽  
Natural Selection ◽  
Phenotypic Variation ◽  
Species Level ◽  
Raw Material ◽  
Evolutionary Mechanisms ◽  
Developmental Processes ◽  
Lower Paleozoic ◽  
Time Periods

Phenotypic variation within species provides the raw material acted upon by natural selection and other evolutionary mechanisms. As such, the range and variation of morphology within a species can play an important role in determining the tempo of evolution. The range and variance of aspects of cranidial morphology for nine lower Paleozoic trilobites were measured to identify microevolutionary correlates of macroevolutionary patterns. Comparisons were made among sets of homologous landmarks or upon partial warp vector matrices containing similar proportions of variance. Rarefaction and bootstrap analyses helped estimate the effects of sampling. Levels of variance and range of morphology differed considerably within and among time periods. There is no significant temporal decline in the variance or range of morphology, suggesting that developmental or genomic constraints may not have been the primary factors controlling the tempo of trilobite macroevolution. The spatial distribution of cranidial variance differed considerably among taxa, suggesting that a complex set of developmental processes governed the morphogenesis of cranidia within trilobites.

scholarly journals The neuroscience of primate intellectual evolution: natural selection and passive and intentional niche construction

2008 ◽  
Vol 363 (1500) ◽  
pp. 2229-2241 ◽  
Author(s):  
Atsushi Iriki ◽  
Osamu Sakura
Keyword(s):  
Natural Selection ◽  
Cognitive Abilities ◽  
Niche Construction ◽  
Morphological Changes ◽  
Japanese Macaque ◽  
Molecular Genetic ◽  
Raw Material ◽  
Evolutionary Mechanisms ◽  
In The Wild ◽  
Human Primate

We trained Japanese macaque monkeys to use tools, an advanced cognitive function monkeys do not exhibit in the wild, and then examined their brains for signs of modification. Following tool-use training, we observed neurophysiological, molecular genetic and morphological changes within the monkey brain. Despite being ‘artificially’ induced, these novel behaviours and neural connectivity patterns reveal overlap with those of humans. Thus, they may provide us with a novel experimental platform for studying the mechanisms of human intelligence, for revealing the evolutionary path that created these mechanisms from the ‘raw material’ of the non-human primate brain, and for deepening our understanding of what cognitive abilities are and of those that are not uniquely human. On these bases, we propose a theory of ‘intentional niche construction’ as an extension of natural selection in order to reveal the evolutionary mechanisms that forged the uniquely intelligent human brain.

Spatial distribution of the parasite Kroyeria carchariaeglauci Hesse, 1879 (Copepoda: Siphonostomatoida: Kroyeriidae) on gills of the blue shark (Prionace glauca (L., 1758))

1987 ◽  
Vol 65 (5) ◽  
pp. 1275-1281 ◽  
Author(s):  
George W. Benz ◽  
Kevin S. Dupre
Keyword(s):  
Spatial Distribution ◽  
Natural Selection ◽  
Distribution Pattern ◽  
Surface Area ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Homogeneous Groups ◽  
Secondary Lamellae ◽  
Gill Filaments ◽  
Gill Surface Area

Five blue sharks (Prionace glauca) were examined for gill-infesting copepods. Three species of siphonostomatoid copepods were collected: Gangliopus pyriformis, Phyllothyreus cornutus, and Kroyeria carchariaeglauci. The spatial distribution of K. carchariaeglauci was analyzed. The number of K. carchariaeglauci per shark was positively related to gill surface area and host size. Copepods were unevenly distributed amongst hemibranchs; flanking hemibranchs could be arranged into three statistically homogeneous groups. Female K. carchariaeglauci typically attached themselves within the middle 40% of each hemibranch; males were more evenly dispersed. Eighty percent of all K. carchariaeglauci attached themselves to secondary lamellae, the remainder were in the underlying excurrent water channels. Most K. carchariaeglauci were located between 10 and 25 mm along the lengths of gill filaments. Overall, the spatial distribution of K. carchariaeglauci was quite specific in all study planes. Explanation of this distribution is set forth in terms of natural selection pressures; however, the equally plausible explanation that the distribution pattern exhibited by these copepods is phylogenetically determined and may have little to do with contemporary selective constraints should not be ignored.

Contrasting evolutionary flexibility in sister groups: disparity and diversity in Mesozoic atelostomate echinoids

Paleobiology ◽  
2000 ◽  
Vol 26 (1) ◽  
pp. 56-79 ◽  
Author(s):  
Gunther J. Eble
Keyword(s):  
Morphological Evolution ◽  
Hierarchical Level ◽  
Developmental Constraint ◽  
Evolutionary Mechanisms ◽  
Lower Paleozoic ◽  
Time Period ◽  
Biological Hierarchy ◽  
Substantial Change ◽  
Test Architecture ◽  
Ordinal Level

Temporal asymmetries in clade histories have often been studied in lower Paleozoic radiations. Post-Paleozoic patterns, however, are less well understood. In this paper, disparity and diversity changes in Mesozoic heart urchins were analyzed at the ordinal level, with contrasts among the sister groups Holasteroida and Spatangoida, their paraphyletic stem group Disasteroida the more inclusive clade, the superorder Atelostomata. A 38-dimensional landmark-based morphospace representing test architecture was used to describe morphological evolution in terms of total variance and total range. Discordances between disparity and diversity were evident and were expressed both as deceleration in morphological diversification in all groups and as disproportionately higher disparity early in the histories of the Atelostomata, Holasteroida Spatangoida. The finding that the early atelostomate disparity peak coincides with the origin of the orders Holasteroida and Spatangoida lends support to the perception of orders as semi-independent entities in the biological hierarchy and as meaningful proxies for morphological distinctness.A comparison of holasteroid and spatangoid responses to the end-Cretaceous mass extinction revealed morphological selectivity. Paleocene spatangoid survivors showed no change in disparity relative to the Campanian-Maastrichtian sample, suggesting nonselectivity. Holasteroids suffered a pronounced loss in disparity (despite a rather high Late Cretaceous level of disparity), indicating morphological selectivity of extinction.Partitioning of disparity into plastral and nonplastral components, reflecting different degrees of developmental entrenchment and functionality, suggests that the origin of holasteroids and spatangoids is more consistent with an exploration of the developmental flexibility of nonplastral constructions than with uniform ecospace occupation. Within groups, several patterns were also most consistent with intrinsic controls. For plastral landmarks, there is an apparent increase in developmental modularity and decrease in developmental constraint from disasteroids to holasteroids and spatangoids. For nonplastral landmarks, no substantial change in disparity was observed from disasteroids to holasteroids and spatangoids, suggesting the maintenance of a developmental constraint despite the passage of time and ecological differentiation. More generally, this study suggests that certain topologies of disparity and evolutionary mechanisms potentially characteristic of the lower Paleozoic radiations of higher taxa (e.g., developmental flexibility) need not be confined to any given time period or hierarchical level.

scholarly journals Differentiation of Cyanthillium cinereum, a smoking cessation herb, from its adulterant Emilia sonchifolia using macroscopic and microscopic examination, HPTLC profiles and DNA barcodes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kannika Thongkhao ◽  
Veerachai Pongkittiphan ◽  
Thatree Phadungcharoen ◽  
Chayapol Tungphatthong ◽  
Santhosh Kumar J. Urumarudappa ◽  
...  
Keyword(s):  
Quality Control ◽  
Smoking Cessation ◽  
Microscopic Examination ◽  
Dna Barcode ◽  
Species Level ◽  
Raw Material ◽  
Phytochemical Analysis ◽  
Dna Barcodes ◽  
Leaf Base

Abstract Cyanthillium cinereum (L.) H.Rob. is one of the most popular herbal smoking cessation aids currently used in Thailand, and its adulteration with Emilia sonchifolia (L.) DC. is often found in the herbal market. Therefore, the quality of the raw material must be considered. This work aimed to integrate macro- and microscopic, chemical and genetic authentication strategies to differentiate C. cinereum raw material from its adulterant. Different morphological features between C. cinereum and E. sonchifolia were simply recognized at the leaf base. For microscopic characteristics, trichome and pappus features were different between the two plants. HPTLC profiles showed a distinct band that could be used to unambiguously differentiate C. cinereum from E. sonchifolia. Four triterpenoid compounds, β-amyrin, taraxasterol, lupeol, and betulin, were identified from the distinct HPTLC band of C. cinereum. The use of core DNA barcode regions; rbcL, matK, ITS and psbA-trnH provided species-level resolution to differentiate the two plants. Taken together, the integration of macroscopic and microscopic characterization, phytochemical analysis by HPTLC and DNA barcoding distinguished C. cinereum from E. sonchifolia. The signatures of C. cinereum obtained here can help manufacturers to increase the quality control of C. cinereum raw material in commercialized smoking cessation products.

scholarly journals Repeated modification of early limb morphogenesis programmes underlies the convergence of relative limb length in Anolis lizards

2011 ◽  
Vol 279 (1729) ◽  
pp. 739-748 ◽  
Author(s):  
Thomas J. Sanger ◽  
Liam J. Revell ◽  
Jeremy J. Gibson-Brown ◽  
Jonathan B. Losos
Keyword(s):  
Natural Selection ◽  
Developmental Trajectories ◽  
Limb Length ◽  
Long Bone ◽  
Length Variation ◽  
Developmental Processes ◽  
Independent Evolution ◽  
Limb Morphogenesis ◽  
Habitat Specialists ◽  
Phenotypic Convergence

The independent evolution of similar morphologies has long been a subject of considerable interest to biologists. Does phenotypic convergence reflect the primacy of natural selection, or does development set the course of evolution by channelling variation in certain directions? Here, we examine the ontogenetic origins of relative limb length variation among Anolis lizard habitat specialists to address whether convergent phenotypes have arisen through convergent developmental trajectories. Despite the numerous developmental processes that could potentially contribute to variation in adult limb length, our analyses reveal that, in Anolis lizards, such variation is repeatedly the result of changes occurring very early in development, prior to formation of the cartilaginous long bone anlagen.

scholarly journals Phenotypic Variation and Natural Selection at Catsup, a Pleiotropic Quantitative Trait Gene in Drosophila

2006 ◽  
Vol 16 (9) ◽  
pp. 912-919 ◽  
Author(s):  
Mary Anna Carbone ◽  
Katherine W. Jordan ◽  
Richard F. Lyman ◽  
Susan T. Harbison ◽  
Jeff Leips ◽  
...  
Keyword(s):  
Natural Selection ◽  
Phenotypic Variation ◽  
Quantitative Trait ◽  
Quantitative Trait Gene

The Simulated Evolution of Biochemical Guilds: Reconciling Gaia Theory and Natural Selection

1999 ◽  
Vol 5 (4) ◽  
pp. 291-318 ◽  
Author(s):  
Keith Downing ◽  
Peter Zvirinsky
Keyword(s):  
Natural Selection ◽  
Artificial Life ◽  
Large Scale ◽  
Resource Competition ◽  
Nutrient Recycling ◽  
Nutrient Ratios ◽  
Evolutionary Mechanisms ◽  
Life Model ◽  
Gaia Theory ◽  
Implicit Coordination

Gaia theory, which states that organisms both affect and regulate their environment, poses an interesting problem to Neo-Darwinian evolutionary biologists and provides an exciting set of phenomena for artificial-life investigation. The key challenge is to explain the emergence of biotic communities that are capable, via their implicit coordination, of regulating large-scale biogeochemical factors such as the temperature and chemical composition of the biosphere, but to assume no evolutionary mechanisms beyond contemporary natural selection. Along with providing an introduction to Gaia theory, this article presents simulations of Gaian emergence based on an artificial-life model involving genetic algorithms and guilds of simple metabolizing agents. In these simulations, resource competition leads to guild diversity; the ensemble of guilds then manifests life-sustaining nutrient recycling and exerts distributed control over environmental nutrient ratios. These results illustrate that standard individual-based natural selection is sufficient to explain Gaian self-organization, and they help clarify the relationships between two key metrics of Gaian activity: recycling and regulation.

scholarly journals Two practical approaches to monitoring the zooplanktonic community at Lago Grande do Curuai, Pará, Brazil

2015 ◽  
Vol 45 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Leonardo Fernandes GOMES ◽  
Ludgero Cardoso Galli VIEIRA ◽  
Marie Paule BONNET
Keyword(s):  
Spatial Distribution ◽  
Monitoring Program ◽  
Zooplankton Community ◽  
Species Level ◽  
Genus Level ◽  
Time Costs ◽  
Financial Costs ◽  
Long Term Monitoring ◽  
Term Monitoring

The use of substitute groups in biomonitoring programs has been proposed to minimize the high financial costs and time for samples processing. The objectives of this study were to evaluate the correlation between (i) the spatial distribution among the major zooplankton groups (cladocerans, copepods, rotifers, and testaceans protozoa), (ii) the data of density and presence/absence of species, and (iii) the data of species, genera, and families from samples collected in the Lago Grande do Curuai, Pará, Brazil. A total of 55 sample of the zooplanktonic community was collected, with 28 samples obtained in March and 27 in September, 2013. The agreement between the different sets of data was assessed using Mantel and Procrustes tests. Our results indicated high correlations between genus level and species level and high correlations between presence/absence of species and abundance, regardless of the seasonal period. These results suggest that zooplankton community could be incorporated in a long-term monitoring program at relatively low financial and time costs.

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