scholarly journals Vegetation structure influences predation rates of early nests in subarctic breeding waders

Ibis ◽  
2020 ◽  
Vol 162 (4) ◽  
pp. 1225-1236 ◽  
Author(s):  
Rebecca A. Laidlaw ◽  
Tómas G. Gunnarsson ◽  
Verónica Méndez ◽  
Camilo Carneiro ◽  
Böðvar Þórisson ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
Breeding Waders ◽  
Predation Rates

scholarly journals Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

2014 ◽  
Author(s):  
Menno Schilthuizen ◽  
Sylvia Looijestijn ◽  
Sek Chuan Chua ◽  
Ruth F. Castillo Cajas
Keyword(s):  
Population Structure ◽  
Vegetation Structure ◽  
Predation Rate ◽  
Land Snail ◽  
Mirror Image ◽  
Single Population ◽  
Modelling Studies ◽  
Vegetation Parameters ◽  
Genetically Determined ◽  
Predation Rates

One of the very few snail taxa that display genetic antisymmetry (that is, roughly even mixes of genetically determined clockwise and anticlockwise individuals within a single population) are the circa 35 species of the tropical tree snail subgenus Amphidromus. Previous work has shown that this may be due to a particular type of sexual selection, in which sperm transfer is improved in copulations between the two mirror-image morphs. However, it is not yet clear why so often significant deviations from 50:50 proportions are found. Modelling studies show that population structure will affect the degree by which the dimorphism is skewed towards the morph associated with the recessive allele. In this study, we mapped the proportions of sinistrals (PropS) in 56 demes in A. inversus on the Malaysian island of Kapas. We also mapped population density, predation rates, and several measures of vegetation structure. Our results show that PropS amounts on average to 0.65, but across the island varies from 0.30 to 0.85. Density and overall predation are inversely correlated, but neither predicts PropS. Vegetation parameters also do not correlate with the proportion of sinistrals. We do, however, find a negative correlation between the predation rate on sinistrals and PropS, a finding which may warrant further study.

scholarly journals Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

2015 ◽  
Author(s):  
Menno Schilthuizen ◽  
Sylvia Looijestijn ◽  
Sek Chuan Chua ◽  
Jesús Aguirre Gutiérrez ◽  
Ruth F. Castillo Cajas
Keyword(s):  
Vegetation Structure ◽  
Selection Procedure ◽  
General Linear Model ◽  
Land Snail ◽  
Mirror Image ◽  
Single Population ◽  
Overwhelming Evidence ◽  
Modelling Studies ◽  
Genetically Determined ◽  
Predation Rates

One of the very few snail taxa that display genetic antisymmetry (that is, roughly equal mixes of genetically determined clockwise [D] and anticlockwise [S] coiled individuals within a single population) are the circa 35 species of the tropical tree snail subgenus Amphidromus. Previous work has shown that this may be due to a particular type of sexual selection, in which sperm transfer is improved in copulations between the two mirror-image morphs. However, it is not yet clear why so often significant deviations from 50:50 proportions are found. Modelling studies show that population structure will affect the degree by which the dimorphism is skewed towards the morph associated with the recessive allele. In this study, we mapped the proportions of sinistrals (PropS) in 56 demes in A. inversus on the Malaysian island of Kapas. We also mapped population density, predation rates, and several measures of vegetation structure. Our results show that PropS amounts on average to 0.65, but across the island it varies from 0.30 to 0.85. Density and overall predation are inversely correlated. A general linear model selection procedure results in the proportion of sinistrals to be positively correlated with density and predation on dextrals. We find no overwhelming evidence for a role for drift in explaining the deviations from equal S:D proportions, but we do argue that further study of crab-snail interactions may be warranted.

scholarly journals Does Habitat Fragmentation Influence Nest Predation in the Shortgrass Prairie?

The Condor ◽  
2001 ◽  
Vol 103 (3) ◽  
pp. 530-536 ◽  
Author(s):  
Melissa N. Howard ◽  
Susan K. Skagen ◽  
Patricia L. Kennedy
Keyword(s):  
Habitat Fragmentation ◽  
Vegetation Structure ◽  
Nest Predation ◽  
Patch Size ◽  
Mortality Rates ◽  
Artificial Nests ◽  
Vegetation Height ◽  
Native Grassland ◽  
Shortgrass Prairie ◽  
Predation Rates

Abstract We examined the effects of habitat fragmentation and vegetation structure of shortgrass prairie and Conservation Reserve Program (CRP) lands on predation rates of artificial and natural nests in northeastern Colorado. The CRP provides federal payments to landowners to take highly erodible cropland out of agricultural production. In our study area, CRP lands have been reseeded primarily with non-native grasses, and this vegetation is taller than native shortgrass prairie. We measured three indices of habitat fragmentation (patch size, degree of matrix fragmentation, and distance from edge), none of which influenced mortality rates of artificial or natural nests. Vegetation structure did influence predation rates of artificial nests; daily mortality decreased significantly with increasing vegetation height. Vegetation structure did not influence predation rates of natural nests. CRP lands and shortgrass sites did not differ with respect to mortality rates of artificial nests. Our study area is only moderately fragmented; 62% of the study area is occupied by native grassland. We conclude that the extent of habitat fragmentation in our study area does not result in increased predation in remaining patches of shortgrass prairie habitat. ¿La Fragmentación de Hábitat Influencia la Depredación de Nidos en Praderas de Pasto Corto? Resumen. Examinamos los efectos de fragmentación de hábitat y estructura de la vegetación sobre la tasa de depredación de nidos artificiales y naturales en praderas de pasto corto y tierras del Programa de Reserva de Conservación (CRP) en el noreste de Colorado. El CRP proporciona pagos federales para que los dueños de las tierras retiren sus cultivos de áreas agrícolas altamente erosionables. En nuestra área de estudio, las tierras de CRP han sido vueltas a sembrar principalmente con céspedes no nativos que son más altos que la vegetación nativa de las praderas de pasto corto. Medimos tres índices de fragmentación de hábitat (tamaño del parche, grado de fragmentación de la matriz, y distancia al borde), ninguno de los cuales influyó sobre la tasa de mortalidad de nidos artificiales o naturales. La estructura de la vegetación influenció la tasa de depredación de nidos artificiales: la mortalidad diaria disminuyó significativamente con incrementos en la altura de la vegetación. La estructura de la vegetación no influenció la tasa de depredación de nidos naturales. Los sitios de CRP y de pastos cortos no difirieron con respecto a la tasa de mortalidad de nidos artificiales. Nuestra área de estudio es sólo moderadamente fragmentada pues el 62% del área es ocupada por prado nativo. Concluimos que el grado de fragmentación de hábitat en nuestra área del estudio no causa aumentos en la depredación en los parches de hábitat remanentes.

scholarly journals Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

2015 ◽  
Author(s):  
Menno Schilthuizen ◽  
Sylvia Looijestijn ◽  
Sek Chuan Chua ◽  
Jesús Aguirre Gutiérrez ◽  
Ruth F. Castillo Cajas
Keyword(s):  
Vegetation Structure ◽  
Selection Procedure ◽  
General Linear Model ◽  
Land Snail ◽  
Mirror Image ◽  
Single Population ◽  
Overwhelming Evidence ◽  
Modelling Studies ◽  
Genetically Determined ◽  
Predation Rates

One of the very few snail taxa that display genetic antisymmetry (that is, roughly equal mixes of genetically determined clockwise [D] and anticlockwise [S] coiled individuals within a single population) are the circa 35 species of the tropical tree snail subgenus Amphidromus. Previous work has shown that this may be due to a particular type of sexual selection, in which sperm transfer is improved in copulations between the two mirror-image morphs. However, it is not yet clear why so often significant deviations from 50:50 proportions are found. Modelling studies show that population structure will affect the degree by which the dimorphism is skewed towards the morph associated with the recessive allele. In this study, we mapped the proportions of sinistrals (PropS) in 56 demes in A. inversus on the Malaysian island of Kapas. We also mapped population density, predation rates, and several measures of vegetation structure. Our results show that PropS amounts on average to 0.65, but across the island it varies from 0.30 to 0.85. Density and overall predation are inversely correlated. A general linear model selection procedure results in the proportion of sinistrals to be positively correlated with density and predation on dextrals. We find no overwhelming evidence for a role for drift in explaining the deviations from equal S:D proportions, but we do argue that further study of crab-snail interactions may be warranted.

scholarly journals The influence of landscape features on nest predation rates of grassland-breeding waders

Ibis ◽  
2015 ◽  
Vol 157 (4) ◽  
pp. 700-712 ◽  
Author(s):  
Rebecca A. Laidlaw ◽  
Jennifer Smart ◽  
Mark A. Smart ◽  
Jennifer A. Gill
Keyword(s):  
Nest Predation ◽  
Landscape Features ◽  
Breeding Waders ◽  
Predation Rates

Analisis Keragaman Tanaman Sebagai Jasa Lingkungan Pada Lanskap Agroforestri di Daerah Aliran Sungai Krueng Aceh

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Zulkifli Aiyub Kadir ◽  
Bahagia Bahagia
Keyword(s):  
Water Conservation ◽  
Vegetation Structure ◽  
Swot Analysis ◽  
Diversity Index ◽  
Middle Stream ◽  
Land Management System ◽  
Study Sites ◽  
Aleurites Moluccana ◽  
Lansium Domesticum ◽  
Agroforestry Practices

<p>Humans have utilized landscape for  produces a diverse character of the wider area of the watershed. Agroforestry is a land management system in addressing the problems that arise due to changes in land use of soil and water conservation. The aim of the study was to analyze plant diversity in agroforestry practices that have services in the Krueng watershed landscape in Aceh watershed. Develop strategies in the Krueng Aceh DAS agroforestry service. This research was conducted in the upper, middle and downstream of the Krueng Aceh watershed, with a rapid method of Agro-Biodiversity Appraisal and SWOT. The results showed that the composition of the vegetation structure found in the study sites tended to vary with the diversity index of agroforestry that was currently in the upstream and middle of the Krueng Aceh watershed. Based on SWOT analysis, internal scores are 2.45 and external scores are 3.21. Agroforestry practices in the upper stream of Krueng Aceh watershed were dominated by <em>Aleurites moluccana</em>, <em>Areca cathecu</em>, and  <em>Averrhoa bilimbi</em> L  species with the highest INP in the upper stream of Krueng Aceh watershed. Vegetation at the middle stream of Krueng Aceh watershed dominated by <em>Areca cathecu,</em> <em>Lansium domesticum</em> and Musa<em> paradisiaca</em>.  </p>

The Vegetation Structure of Evergreen Coniferous Forests of Daehuksan Island in the Dadohaehaesang National Park

2018 ◽  
Vol 30 (1) ◽  
pp. 173-193 ◽  
Author(s):  
Yeongjun Cho ◽  
Hasong Kim ◽  
Hyeonho Myeong ◽  
Jungwon Park ◽  
Janggeun Oh
Keyword(s):  
Vegetation Structure ◽  
National Park ◽  
Coniferous Forests

Effects of Predation and Trophic Conditions on the Reproduction of Tylototriton verrucosus (Caudata: Salamandridae) in Darjeeling

2011 ◽  
Vol 4 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Ritwik Dasgupta
Keyword(s):  
Frequency Distribution ◽  
Primary Productivity ◽  
Egg Size ◽  
Zooplankton Abundance ◽  
Trophic Conditions ◽  
Size Frequency Distribution ◽  
Size Frequency ◽  
High Predation ◽  
Hatchling Size ◽  
Predation Rates

The facts that small hatchlings emerged from small eggs laid under high predation levels prevailing at the lower altitudes of distribution of this species in Darjeeling while larger hatchlings emerged from larger eggs laid under lower levels of predation at higher altitudes, show that predation is not selected for large egg and initial hatchling size in this salamandrid species. Metamorphic size was small under high predation rates because this species relied on crypsis for evading predators. Egg and hatchling size are related inversely to levels of primary productivity and zooplankton abundance in lentic habitats. Hatchling sizes are related positively to egg size and size frequency distribution of zooplankton. Small egg and small hatchling size have been selected for at the lower altitudes of distribution of this salamandrid in Darjeeling because predation rates increased in step with improvement in trophic conditions at the lower altitudes.

Vegetation structure and environmental gradients in the Sallum area, Egypt

2005 ◽  
Vol 31 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Fawzy M. Salama ◽  
Monier Abd El-Ghani ◽  
Salah El Naggar ◽  
Khadija A. Baayo
Keyword(s):  
Vegetation Structure ◽  
Environmental Gradients
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