scholarly journals From forest to city: urbanization modulates relative abundance of anti-predator coloration

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Nigel K Anderson ◽  
Stephanie O Gutierrez ◽  
Ximena E Bernal
Keyword(s):  
Urban Areas ◽  
Complex Nature ◽  
Urbanization Gradient ◽  
Avian Predators ◽  
Color Morphs ◽  
Coloration Pattern ◽  
Tungara Frogs ◽  
Forested Areas ◽  
Distinct Color ◽  
Predation Rates

Abstract Increased urbanization has resulted in community changes including alteration of predator communities. Little is known, however, about how such changes affect morphological anti-predator traits. Given the importance of coloration in predator avoidance, this trait in particular is expected to be susceptible to novel selective environments in urban areas. Here, we investigate the coloration pattern of a Neotropical anuran species, the túngara frog (Engystomops pustulosus), along an urbanization gradient. Túngara frogs have two distinct color patterns (unstriped and striped) which we found to occur at different frequencies along an urbanization gradient. Striped individuals increased in frequency with urbanization. To assess the strength of selection imposed by predators on the two color morphs, we deployed clay models of túngara frogs in forest and semi-urban populations. In addition, we examined microhabitat selection by individuals of the different morphs. We found higher predation rates associated with urbanization than forested areas. In particular, frogs from forested habitats had lower number of attacks by avian predators. Contrary to our predictions, however, predation rates were similar for both color morphs independent of urbanization. Also, coloration of the frogs did not affect their microhabitat preference. Overall, túngara frogs are more likely to have a striped coloration pattern in semi-urban areas where predation by birds is higher than in the forest. Our findings suggest that factors other than predation pressure shape the coloration pattern of urban frogs and emphasize the complex nature of effects that anthropogenic changes in habitat and predator communities may have on prey morphology.

scholarly journals Orb-web spider color polymorphism through the eyes of multiple prey and predators

2017 ◽  
Author(s):  
Nathalia Ximenes ◽  
Felipe M. Gawryszewski
Keyword(s):  
Color Vision ◽  
Warning Signal ◽  
Sensory Systems ◽  
Color Polymorphism ◽  
Avian Predators ◽  
Web Spider ◽  
Color Morphs ◽  
Orb Web ◽  
Distinct Color ◽  
Orb Web Spiders

ABSTRACTThe sensory drive theory predicts that signals, sensory systems, and signaling behavior should coevolve. Variation in the sensory systems of prey and predators may explain the diversity of color signals, such as color polymorphism. The spider Gasteracantha cancriformis (Araneidae) possesses several conspicuous color morphs. The aim of the present study was to assess whether the color polymorphism of G. cancriformis may be maintained by pressure from multiple signal receivers, such as prey and predators with distinct color vision systems. Although, the multiple receivers world is a more realistic scenario, it has received little attention. In orb-web spiders, the prey attraction hypothesis states that conspicuous colors are prey lures that increase spider foraging success via flower mimicry. However, in highly defended species, conspicuous colors could also be a warning signal to predators. We used color vision modelling to estimate chromatic and achromatic contrast of G. cancriformis morphs as perceived by potential prey and predator taxa. Our results revealed that individual prey and predator taxa perceive the conspicuousness of morphs differently. For instance, the red morph is perceived as quite conspicuous to lepidopteran prey and avian predators, but not by other insects. Therefore, the multiple prey and predator hypotheses may explain the evolution of color polymorphism in G. cancriformis. However, flower mimicry hypothesis was weakly corroborated. Other parameters that are not evaluated by color vision models, such as distance, shape, angle, and pattern geometry could also affect the perception of color morphs by both prey and predators and thereby influence morph survival.

scholarly journals The history and characteristics of the 1980–2005 Portuguese rural fire database

2011 ◽  
Vol 11 (12) ◽  
pp. 3343-3358 ◽  
Author(s):  
M. G. Pereira ◽  
B. D. Malamud ◽  
R. M. Trigo ◽  
P. I. Alves
Keyword(s):  
Urban Areas ◽  
Unit Area ◽  
Fire Regime ◽  
Minimum Area ◽  
Burnt Area ◽  
Forested Areas ◽  
Large Fires ◽  
Burnt Areas

Abstract. We focus here on a mainland Continental Portuguese Rural Fire Database (PRFD) that includes 450 000 fires, the largest such database in Europe in terms of total number of recorded fires in the 1980–2005 period. In this work, we (a) list the most important factors for triggering and controlling the fire regime in mainland Continental Portugal, (b) describe the dataset's production, (c) discuss procedures adopted to identify and correct different fire data inconsistencies, creating a modified PRFD which we use here and make available as Supplement, (d) explore some basic temporal and completeness properties of the data. We find that the dataset's minimum measured burnt areas have changed with time between AF = 0.1 ha (1980–1990), AF = 0.01 ha (1991–1992), and AF = 0.001 ha (1992–2005), with varying degrees of completeness down to these values. These changes in minimum area measured are responsible for greater numbers of fires being recorded. A relatively small number of large fires in the PRFD are responsible for the majority of the burnt area. For example, fires with AF > 100 ha represent about 1% of all fire records but 75% of total burnt area. Finally, we consider for each Continental Portugal district and for the 26-yr period, the total number of rural fires and area burnt in forests and shrublands, each normalized by district areas. We find that the highest numbers of fires per unit area are in highly populated districts, and that the largest fraction of burnt area is in forested areas, coinciding with large parcels of continuous forests (predominantly rural and moderately urban areas).

scholarly journals We need to worry about Bella and Charlie: the impacts of pet cats on Australian wildlife

2020 ◽  
Vol 47 (8) ◽  
pp. 523 ◽  
Author(s):  
Sarah Legge ◽  
John C. Z. Woinarski ◽  
Chris R. Dickman ◽  
Brett P. Murphy ◽  
Leigh-Ann Woolley ◽  
...  
Keyword(s):  
Introduced Species ◽  
Urban Areas ◽  
Native Species ◽  
Population Decline ◽  
Domestic Cat ◽  
Natural Environments ◽  
Residential Areas ◽  
Management Options ◽  
Feral Cats ◽  
Predation Rates

Research and management attention on the impacts of the introduced domestic cat (Felis catus) on Australian fauna have focussed mainly on the feral population. Here, we summarise the evidence for impacts of predation by pet cats on Australian wildlife. We collate examples of local wildlife population decline and extirpation as a result, at least in part, of predation by pet cats. We assemble information across 66 studies of predation by pet cats worldwide (including 24 Australian studies) to estimate the predation toll of pet cats in Australia, plus the predation pressure per unit area in residential areas. We compared these estimates to those published for feral cats in Australia. The per capita kill rate of pet cats is 25% that of feral cats. However, pet cats live at much higher densities, so the predation rate of pets per square kilometre in residential areas is 28–52 times larger than predation rates by feral cats in natural environments, and 1.3–2.3 times greater than predation rates per km2 by feral cats living in urban areas. Pet cats kill introduced species more often than do feral cats living in natural environments, but, nonetheless, the toll of native animals killed per square kilometre by pet cats in residential areas is still much higher than the toll per square kilometre by feral cats. There is no evidence that pet cats exert significant control of introduced species. The high predation toll of pet cats in residential areas, the documented examples of declines and extirpations in populations of native species caused by pet cats, and potential pathways for other, indirect effects (e.g. from disease, landscapes of fear, ecological footprints), and the context of extraordinary impacts from feral cats on Australian fauna, together support a default position that pet cat impacts are serious and should be reduced. From a technical perspective, the pet cat impacts can be reduced more effectively and humanely than those of feral cats, while also enhancing pet cat welfare. We review the management options for reducing predation by pet cats, and discuss the opportunities and challenges for improved pet cat management and welfare.

Predation rates of artificial nests in the edge and interior of a southern Victorian forest

2002 ◽  
Vol 29 (4) ◽  
pp. 341 ◽  
Author(s):  
Lainie Berry
Keyword(s):  
Small Mammals ◽  
Nest Predation ◽  
Forest Edge ◽  
Forest Edges ◽  
Artificial Nests ◽  
Avian Predators ◽  
Forest Interior ◽  
Grey Shrike ◽  
Predation Rates

Predation rates of nests at human-induced habitat edges may be greater than in forest interior due to differences in predator assemblages and predator activity. I compared the predation rates on 192 artificial nests containing plasticine eggs placed in forest edge and interior sites at Bunyip State Park, Victoria. The nest-predation rates at the forest edge sites were significantly greater (mean = 52–58%) than that at the forest interior sites (mean = 30–39%). The relative rates of predation by birds compared with mammals were significantly greater at forest edge sites (mean = 78–94%) than at forest interior sites (mean = 36–67%). Higher rates of nest predation at forest edges appeared to be due to greater densities of avian predators such as the grey shrike-thrush (Colluricincla harmonica), and/or lower abundances of small mammals. However, biases towards certain predator types may mask real, or create false, patterns in predation rates of artificial nests. A better understanding of how predators respond to artificial nests compared with natural nests is required. Until then, results of predation studies that use artificial nests should be interpreted with caution.

scholarly journals Defense against predators incurs high reproductive costs for the aposematic moth Arctia plantaginis

2020 ◽  
Vol 31 (3) ◽  
pp. 844-850
Author(s):  
Carita Lindstedt ◽  
Kaisa Suisto ◽  
Emily Burdfield-Steel ◽  
Anne E Winters ◽  
Johanna Mappes
Keyword(s):  
Chemical Defense ◽  
Reproductive Output ◽  
Defensive Secretion ◽  
Reproductive Costs ◽  
Heritable Variation ◽  
White Males ◽  
Avian Predators ◽  
Invertebrate Predators ◽  
Color Morphs ◽  
Tiger Moth

Abstract To understand how variation in warning displays evolves and is maintained, we need to understand not only how perceivers of these traits select color and toxicity but also the sources of the genetic and phenotypic variation exposed to selection by them. We studied these aspects in the wood tiger moth Arctia plantaginis, which has two locally co-occurring male color morphs in Europe: yellow and white. When threatened, both morphs produce defensive secretions from their abdomen and from thoracic glands. Abdominal fluid has shown to be more important against invertebrate predators than avian predators, and the defensive secretion of the yellow morph is more effective against ants. Here, we focused on the morph-linked reproductive costs of secretion of the abdominal fluid and quantified the proportion of phenotypic and genetic variation in it. We hypothesized that, if yellow males pay higher reproductive costs for their more effective aposematic display, the subsequent higher mating success of white males could offer one explanation for the maintenance of the polymorphism. We first found that the heritable variation in the quantity of abdominal secretion was very low (h2 = 0.006) and the quantity of defensive secretion was not dependent on the male morph. Second, deploying the abdominal defensive secretion decreased the reproductive output of both color morphs equally. This suggests that potential costs of pigment production and chemical defense against invertebrates are not linked in A. plantaginis. Furthermore, our results indicate that environmentally induced variation in chemical defense can alter an individual’s fitness significantly.

scholarly journals Urban development of the territory using environmental organizational and technological solutions

2019 ◽  
Vol 135 ◽  
pp. 03013
Author(s):  
Artem Subbotin ◽  
Aleksandra Dostovalova ◽  
Vladislava Smirnova
Keyword(s):  
Environmental Impact ◽  
Urban Development ◽  
Urban Areas ◽  
Technological Progress ◽  
Urban Spaces ◽  
Ecological Development ◽  
Level Of Economic Development ◽  
Forested Areas ◽  
Responsible Attitude ◽  
The One

This article discusses issues aimed at determining the perception of modern urbanization. On the one hand, technological progress more and more enhances the environmental impact, thereby creating the prerequisites for the emergence of various environmental crises. On the other hand, it expands the possibilities of eliminating problems in this area. Therefore, there is a relationship between environmental impact, the level of economic development, and the level of development of civil society. Responsible attitude to the environment - an indicator of the high development of civilization - these are the aspects of the ecological development of megacities that urbanism deals with. Particular attention is paid to the need for an environmentally friendly modernization of modern urban spaces. The problem of reducing landscaped and forested areas in connection with the rapid increase in urban areas is considered. In order to clarify the latest urban development trends, innovative technologies and approaches to construction, as well as to the ecological organization of the urban environment, are considered.

scholarly journals The influence of preparation methodology on the concentrations of heavy metals in Pleurozium schreberi moss samples prior to use in active biomonitoring studies

2020 ◽  
Author(s):  
Paweł Świsłowski ◽  
Grzegorz Kosior ◽  
Małgorzata Rajfur
Keyword(s):  
Heavy Metals ◽  
Indicator Species ◽  
Urban Areas ◽  
Absorption Spectrometry ◽  
Tree Canopy ◽  
Wilcoxon Test ◽  
Pleurozium Schreberi ◽  
Active Biomonitoring ◽  
Forested Areas ◽  
Simultaneous Conditioning

Abstract Active biomonitoring is used to assess environmental pollution of elements such as heavy metals by indicator species such as mosses. They are used, among others, in urbanized areas where no indicator species are found. In such study areas, mosses collected from sites considered to be ecologically clean shall be exposed. In this context, it is very important to prepare the mosses properly before the exposure, so that the information received about the condition of the environment is reliable. In 2018, studies were conducted in the forested areas of southern Poland—in Opolskie Province. Pleurozium schreberi mosses were used in these studies. Atomic absorption spectrometry with flame atomiser (F-AAS) was used to determine the concentrations of Mn, Fe, Ni, Cu, Zn and Pb present. The aim was to study the influence of preparation methodology on Pleurozium schreberi moss samples prior to use in active biomonitoring studies. Four different methodologies were tested across four different sample locations (with varying levels of pollution). The results of the research were analysed and the coefficient of variation (CV) was determined. The value of the CV is influenced, among other things, by the location of the particular sample and the level of pollution by, for example heavy metals, in the moss. The research conducted proves that of the four methods used to prepare mosses for later exposure in active biomonitoring, the best method is averaging with simultaneous conditioning of mosses in demineralised water. This treatment causes the CV coefficient to fall below 10% for most of the metals determined in the moss samples. It has also been shown that maintaining moss collection methodology in accordance with ICP Vegetation standards (open/wooded area—tree canopy) also has a significant impact on the result obtained. Statistical analysis confirmed (Wilcoxon test) that the method of processing the mosses significantly influenced the results obtained. Thanks to the appropriate preparation of the mosses before exposition, they can be used in active biomonitoring of, for example, urban areas.

scholarly journals Factors influencing the predation rates of Anisops breddini (Hemiptera: Notonectidae) feeding on mosquito larvae

2014 ◽  
Vol 46 (3) ◽  
pp. 107 ◽  
Author(s):  
R. Weterings ◽  
K.C. Vetter ◽  
C. Umponstira
Keyword(s):  
Biological Control ◽  
Urban Areas ◽  
Prey Density ◽  
Biological Control Agent ◽  
Prey Type ◽  
Control Agent ◽  
Mosquito Larvae ◽  
Predator Density ◽  
Water Bugs ◽  
Predation Rates

Notonectidae are a family of water bugs that are known to be important predators of mosquito larvae and have great potential in the biological control of vector mosquitoes. An experiment was conducted to assess mosquito larvae predation by <em>Anisops</em> <em>breddini</em>, a species common to Southeast Asia. The predation rates were recorded in context of prey density, predator density, predator size and prey type. Predation rates were strongly affected by prey type and less by prey density and predator density. They ranged between 1.2 prey items per day for pupae of <em>Aedes</em> <em>aegeypti</em> and <em>Armigeres</em> <em>moultoni</em> to 5.9 for <em>Ae</em>. <em>aegypti</em> larvae. Compared with studies on other Notonectidae species, the predation rates appear low, which is probably caused by the relative small size of the specimens used in this study. <em>An</em>. <em>breddini</em> is very common in the region and often found in urban areas; therefore, the species has potential as a biological control agent.

scholarly journals Using ALS Data to Improve Co-Registration of Photogrammetry-Based Point Cloud Data in Urban Areas

2020 ◽  
Vol 12 (12) ◽  
pp. 1943
Author(s):  
Ranjith Gopalakrishnan ◽  
Daniela Ali-Sisto ◽  
Mikko Kukkonen ◽  
Pekka Savolainen ◽  
Petteri Packalen
Keyword(s):  
Standard Deviation ◽  
Urban Areas ◽  
Laser Scanning ◽  
Point Clouds ◽  
Image Point ◽  
Vertical Coordinate ◽  
Cloud Data ◽  
Suburban Areas ◽  
Aerial Photogrammetry ◽  
Forested Areas

Globally, urban areas are rapidly expanding and high-quality remote sensing products are essential to help guide such development towards efficient and sustainable pathways. Here, we present an algorithm to address a common problem in digital aerial photogrammetry (DAP)-based image point clouds: vertical mis-registration. The algorithm uses the ground as inferred from airborne laser scanning (ALS) data as a reference surface and re-aligns individual point clouds to this surface. We demonstrate the effectiveness of the proposed method for the city of Kuopio, in central Finland. Here, we use the standard deviation of the vertical coordinate values as a measure of the mis-registration. We show that such standard deviation decreased substantially (more than 1.0 m) for a large proportion (23.2%) of the study area. Moreover, it was shown that the method performed better in urban and suburban areas, compared to vegetated areas (parks, forested areas, and so on). Hence, we demonstrate that the proposed algorithm is a simple and effective method to improve the quality and usability of DAP-based point clouds in urban areas.

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