scholarly journals How the zebra got its stripes: a problem with too many solutions

2015 ◽  
Vol 2 (1) ◽  
pp. 140452 ◽  
Author(s):  
Brenda Larison ◽  
Ryan J. Harrigan ◽  
Henri A. Thomassen ◽  
Daniel I. Rubenstein ◽  
Alec M. Chan-Golston ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Environmental Variables ◽  
Adaptive Significance ◽  
Entire Body ◽  
Biological Processes ◽  
Stripe Pattern ◽  
Black And White ◽  
Selective Agents ◽  
White Striping ◽  
Plains Zebra

The adaptive significance of zebra stripes has thus far eluded understanding. Many explanations have been suggested, including social cohesion, thermoregulation, predation evasion and avoidance of biting flies. Identifying the associations between phenotypic and environmental factors is essential for testing these hypotheses and substantiating existing experimental evidence. Plains zebra striping pattern varies regionally, from heavy black and white striping over the entire body in some areas to reduced stripe coverage with thinner and lighter stripes in others. We examined how well 29 environmental variables predict the variation in stripe characteristics of plains zebra across their range in Africa. In contrast to recent findings, we found no evidence that striping may have evolved to escape predators or avoid biting flies. Instead, we found that temperature successfully predicts a substantial amount of the stripe pattern variation observed in plains zebra. As this association between striping and temperature may be indicative of multiple biological processes, we suggest that the selective agents driving zebra striping are probably multifarious and complex.

The adaptive significance of dorsal spine variation in the fourspine stickleback, Apeltes quadracus, I. Geographic variation in spine number

1984 ◽  
Vol 62 (7) ◽  
pp. 1329-1339 ◽  
Author(s):  
D. M. Blouw ◽  
D. W. Hagen
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Adaptive Significance ◽  
Maritime Provinces ◽  
Selective Agents ◽  
Apeltes Quadracus ◽  
Remarkable Result ◽  
Fourspine Stickleback ◽  
Very High Frequencies ◽  
Spine Number

The goal of our research is to investigate the adaptive significance of a polymorphism for the number of dorsal spines in Apeltes quadracus, the fourspine stickleback. One approach we take is to search for correlations between phenotypes and environments. To this end we collected Apeltes and scored environments at 570 sites in the Maritime Provinces of Canada. In this paper we describe geographic variation in spine number and evaluate how reliably it reflects genetic differentiation among sites. Morph frequencies are highly differentiated geographically. We describe four kinds of variation: relatively constant frequencies, gentle clines, steep clines, and remarkably abrupt changes (called "intrusions") where frequencies at some sites differ greatly from those at a larger number of surrounding sites. Most of the variation among sites is due to differences in the frequencies of the four- and five-spined morphs. However, a remarkable result is that the three-spined morph, which is rare or absent elsewhere in the range, reaches very high frequencies in Bras D'Or Lake. Our evidence suggests this variation among sites reflects substantial genetic differentiation. The differentiation is favorable for detecting selective agents, if indeed selection is responsible.

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals Variations on the larval incubation of Anodontites trapesialis (Unionoida, Mycetopodidae): Synergetic effect of the environmental factors and host availability

2012 ◽  
Vol 72 (3) ◽  
pp. 545-552 ◽  
Author(s):  
CT. Callil ◽  
D. Krinski ◽  
FA. Silva
Keyword(s):  
Environmental Factors ◽  
Temporal Variation ◽  
Environmental Variables ◽  
Freshwater Mussels ◽  
Synergetic Effect ◽  
Flood Pulse ◽  
Host Availability

The unionid Anodontites trapesilais (Lamarck, 1819) like most freshwater mussels is a parasite of fish. So it is trivial to assume that the availability of hosts is an important factor for the maintenance of unionoid populations. What seems obvious is not always so easy to demonstrate. This study proposes to investigate the effects of abiotic and biotic variables related to the incubation of larvae in A. trapesialis. For this, we estimate different biological indexes and try to capture the dimensionality of the fish, along with the temporal variation of environmental variables. From the application of a CCA, it was demonstrated that there was a synchronicity among the factors and variables proposed here, and we infer that the flood pulse acts as a synergistic factor in this process.

scholarly journals Geographically weighted regression modelling of the spatial association between malaria cases and environmental factors in Cameroon.

2020 ◽  
Author(s):  
Marlvin Anemey Tewara ◽  
Liu Yunxia ◽  
Weiqiang Ling ◽  
Binang Helen Barong ◽  
Prisca Ngetemalah Mbah-Fongkimeh ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Spatial Variability ◽  
Geographically Weighted Regression ◽  
Environmental Variables ◽  
Vegetation Index ◽  
Spatial Association ◽  
Ordinary Least Squares ◽  
Variable Coefficients ◽  
Weighted Regression ◽  
Gwr Model

Abstract Background: Studies have illustrated the association of malaria cases with environmental factors in Cameroon but limited in addressing how these factors vary in space for timely public health interventions. Thus, we want to find the spatial variability between malaria hotspot cases and environmental predictors using Geographically weighted regression (GWR) spatial modelling technique.Methods: The global Ordinary least squares (OLS) in the modelling spatial relationships tool in ArcGIS 10.3. was used to select candidate explanatory environmental variables for a properly specified GWR model. The local GWR model used the global OLS candidate variables to examine, predict and explore the spatial variability between environmental factors and malaria hotspot cases generated from Getis-Ord Gi* statistical analysis. Results: The OLS candidate environmental variable coefficients were statistically significant (adjusted R2 = 22.3% and p < 0.01) for a properly specified GWR model. The GWR model identified a strong spatial association between malaria cases and rainfall, vegetation index, population density, and drought episodes in most hotspot areas and a weak correlation with aridity and proximity to water with an overall model performance of 0.243 (adjusted R2= 24.3%).Conclusion: The generated GWR maps suggest that for policymakers to eliminate malaria in Cameroon, there should be the creation of malaria outreach programs and further investigations in areas where the environmental variables showed strong spatial associations with malaria hotspot cases.

scholarly journals Hormonal endogenous changes in response to the exogenous 6-benzylaminopurine application in pre- and post-harvesting lilium flower stalks

2021 ◽  
Author(s):  
Gunther Mantilla ◽  
Gabriel Antonio Lorenzo ◽  
Libertad Mascarini
Keyword(s):  
Environmental Variables ◽  
Lilium Longiflorum ◽  
Vase Life ◽  
Plant Responses ◽  
Biological Processes ◽  
Hormonal Changes ◽  
Post Harvest ◽  
Growth Development ◽  
Post Harvesting

Abstract Phyto-hormones play a key role in regulating plant responses to stress. Cytokines are a type of phyto-hormones involved in the regulation of many important biological processes related to growth, development, and response to environmental variables. The exogenous application of cytokines increases the possibility of delaying senescence; however, this is a physiological process, and, under certain conditions, degradation processes may be triggered. The effect of 6-bencilaminopurine application and the endogenous hormonal changes involved in lilies floral stalks after their cutting were studied. In order to improve vase life and quality of Lilium longiflorum ‘Brindisi’ flower stalks, they were sprayed with 6-BAP, at a concentration of 300 ppm at pre-harvest, post-harvest, and pre- and post-harvest stages. After that, they were compared to non-sprayed control stalks. The application of 6-BAP caused endogenous hormonal changes in abscisic acid and cytokinin levels, and the most effective treatment was pre-harvest spraying. This treatment proved to be an appropriate method to improve the stalk tolerance to post-harvest stress as it delayed the appearance of senescence symptoms and reduced the speed of chlorophyll degradation with differences of up to 10% with respect to untreated stalks. In addition, the opening of flowers was delayed by up to 2 days, although there were no significant differences in total vase life.

scholarly journals Longitudinal and seasonal succession of algal periphyton colonization in lowland river (Tundzha River Part of Turkey)

2016 ◽  
Author(s):  
Burak Öterler
Keyword(s):  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Green Algae ◽  
Environmental Variables ◽  
Diversity Index ◽  
Seasonal Succession ◽  
Lowland River ◽  
Blue Green Algae ◽  
Periphytic Algae ◽  
Wiener Diversity Index

The aim of this paper is to determine and compare the environmental factors controlling longitudinal colonisation of periphytic algae in agricultural and urbanization effects of a lowland river, the Tundzha River, located in Turkish Tunca. To investigate the effect of the environmental factors on periphyton colonization at the river, 6 stations were selected and samples were collected between April 2012 and March 2013. Canonical correspondence analyses have been applied to clarify relationships between environmental variables and periphytic algae. During the study, the Shannon-Wiener diversity index (H′) varied from 1.62 to 3.91. The phytoplankton biovolume was positively related to pH, temperature, salinity, chlorophyll- a and nutrients, and was negatively correlated with dissolved oxygen, turbidity, and silicate. Out of the 5 divisions and of 73 identified species of phytoplankton, the diatoms, namely Fragilaria ulna, Cymbella tumida, Cocconeis placentula, Gomphonema acuminatum and Cymbella cystula were found to be dominant. In addition to these species, the biovolumes of filamentous diatom Melosira varians, filamentous blue-green algae Oscillatoria limosa, and placcoderm desmids Cosmarium botrytis were determined to be at high levels during the year. The euglenoid blooms in St.5 showed many times during the study period.

scholarly journals Longitudinal and seasonal succession of algal periphyton colonization in lowland river (Tundzha River Part of Turkey)

2016 ◽  
Author(s):  
Burak Öterler
Keyword(s):  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Green Algae ◽  
Environmental Variables ◽  
Diversity Index ◽  
Seasonal Succession ◽  
Lowland River ◽  
Blue Green Algae ◽  
Periphytic Algae ◽  
Wiener Diversity Index

The aim of this paper is to determine and compare the environmental factors controlling longitudinal colonisation of periphytic algae in agricultural and urbanization effects of a lowland river, the Tundzha River, located in Turkish Tunca. To investigate the effect of the environmental factors on periphyton colonization at the river, 6 stations were selected and samples were collected between April 2012 and March 2013. Canonical correspondence analyses have been applied to clarify relationships between environmental variables and periphytic algae. During the study, the Shannon-Wiener diversity index (H′) varied from 1.62 to 3.91. The phytoplankton biovolume was positively related to pH, temperature, salinity, chlorophyll- a and nutrients, and was negatively correlated with dissolved oxygen, turbidity, and silicate. Out of the 5 divisions and of 73 identified species of phytoplankton, the diatoms, namely Fragilaria ulna, Cymbella tumida, Cocconeis placentula, Gomphonema acuminatum and Cymbella cystula were found to be dominant. In addition to these species, the biovolumes of filamentous diatom Melosira varians, filamentous blue-green algae Oscillatoria limosa, and placcoderm desmids Cosmarium botrytis were determined to be at high levels during the year. The euglenoid blooms in St.5 showed many times during the study period.

Environmental factors responsible for shaping an open peatland – forest complex on the hypermaritime north coast of British Columbia

2003 ◽  
Vol 33 (12) ◽  
pp. 2380-2394 ◽  
Author(s):  
Taro Asada ◽  
Barry G Warner ◽  
Jim Pojar
Keyword(s):  
British Columbia ◽  
Environmental Factors ◽  
Plant Communities ◽  
Environmental Variables ◽  
Groundwater Table ◽  
North Coast ◽  
Minimum Level ◽  
Peat Accumulation ◽  
Upland Forest ◽  
Vegetation Gradient

The relationships between the distribution of plant communities and environmental factors were studied in an open peatland – forest complex of the hypermaritime north coast of British Columbia. The entire vegetation gradient, from open through forested peatlands to upland forest, was primarily explained by slope and minimum level of groundwater table. Environmental conditions in the upland Tsuga–Rhytidiadelphus forest were considerably different from those of the other communities; differences were small among the Sphagnum open peatland, the Pinus–Sphagnum woodland, the Chamaecyparis–Fauria forest, and the Thuja–Gaultheria forest. Highest level of groundwater table, conductivity minimum, pH, and dissolved oxygen merely helped distinguish the upland Tsuga–Rhytidiadelphus forest from all other communities. The wet Thuja–Gaultheria forest could be more vulnerable than the upland Tsuga–Rhytidiadelphus forest to local hydrological changes caused by harvesting. Consecutive intraannual measurements of environmental variables are important in clarifying the relationships between distribution of plant communities and environmental variables, especially for communities with peat accumulation.

Identification of key environmental variables associated with the presence of Toothed Leionema (Leionema bilobum serrulatum) in the Strzelecki Ranges, Victoria, Australia

2011 ◽  
Vol 59 (3) ◽  
pp. 207
Author(s):  
Wendy Wright ◽  
Xuan Zhu ◽  
Mateusz Okurowski
Keyword(s):  
Environmental Factors ◽  
Habitat Suitability ◽  
Rare Species ◽  
Environmental Variables ◽  
Geographical Information Systems ◽  
Predictive Modelling ◽  
Geographical Information ◽  
Suitable Habitat ◽  
Small Tree ◽  
Disturbed Areas

Toothed Leionema is one of four subspecies of Leionema bilobum from the Rutaceae family. A dense shrub or small tree, growing to ~4 m high, it is a poorly investigated species which is considered rare in Victoria, Australia. This paper presents the results of a study using Geographical Information Systems and Weights-of-Evidence predictive modelling to assess the importance of seven environmental factors in determining habitat suitability for this species in the Strzelecki Ranges, Victoria. This method is particularly useful in understanding the distribution of rare species, especially where the ecology of the species of interest is not well understood. Of the seven environmental factors considered here, four were found to be important: elevation, aspect, distance to water and distance to plantation (disturbed) areas. The modelling results indicate that areas with elevations between 350 and 550 m and a dominant south-western aspect that are close to plantation areas (within 700 m), and to water (within 1100–1200 m), provide potentially suitable habitat for Toothed Leionema in the region.

scholarly journals Depth detection in interactive projection system based on one-shot black-and-white stripe pattern

2017 ◽  
Vol 25 (5) ◽  
pp. 5341 ◽  
Author(s):  
Qian Zhou ◽  
Xiaorui Qiao ◽  
Kai Ni ◽  
Xinghui Li ◽  
Xiaohao Wang
Keyword(s):  
Stripe Pattern ◽  
Projection System ◽  
White Stripe ◽  
Black And White ◽  
Depth Detection
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