Species Replacements among Orconectes Crayfishes in Wisconsin Lakes: The Role of Predation by Fish

1993 ◽  
Vol 50 (7) ◽  
pp. 1484-1488 ◽  
Author(s):  
Guy T. DiDonato ◽  
David M. Lodge
Keyword(s):  
Littoral Zone ◽  
Carapace Length ◽  
Fish Predation ◽  
Species Selection ◽  
Adult Size ◽  
Selective Predation ◽  
Native Fishes ◽  
Native Crayfish ◽  
Species Replacements

To test the role of size- and species-selective predation by fishes in species replacements among congeneric crayfishes in northern Wisconsin lakes, we tethered the same three sizes of each of three species of Orconectes at six sites in the littoral zone of Trout Lake, Vilas County, Wise. Small crayfish (15–18 mm carapace length) were removed by fish at significantly higher rates than medium (23–25 mm) and large (33–35 mm) crayfish. Orconectes virilis was removed at significantly higher rates than O. propinquus and O. rusticus. These species-selection results suggest that predation by native fishes contributes to the previously documented replacement of the native crayfish O. virilis by the exotic crayfishes O. propinquus and O. rusticus. In combination with the observations of others that adult size of O. rusticus is typically larger than that of O. propinquus in northern Wisconsin lakes, our size-selection results suggest that fish predation may also hasten the ongoing replacement of O. propinquus by O. rusticus. Thus, fish predation is probably an important mechanism driving the replacement of O. virilis by O. propinquus and the replacement of both congeners by O. rusticus.

ACCURACY OF ALLOMETRICALLY PREDICTED PHARMACOKINETIC PARAMETERS IN HUMANS: ROLE OF SPECIES SELECTION

2005 ◽  
Vol 33 (9) ◽  
pp. 1288-1293 ◽  
Author(s):  
Huadong Tang ◽  
Michael Mayersohn
Keyword(s):  
Species Selection ◽  
Pharmacokinetic Parameters

The role of sea urchins in mediating fish predation on a commensal isopod (Crustacea: Isopoda)

1988 ◽  
Vol 124 (2) ◽  
pp. 97-113 ◽  
Author(s):  
Timothy D. Stebbins
Keyword(s):  
Sea Urchins ◽  
Fish Predation

The role of emergent macrophytes in nutrient cycling in Lake Niepruszewskie (western Poland)

2010 ◽  
Vol 39 (2) ◽  
Author(s):  
Agnieszka Ławniczak
Keyword(s):  
Nutrient Cycling ◽  
Littoral Zone ◽  
Advanced Stage ◽  
Emergent Macrophytes ◽  
High Concentrations

The role of emergent macrophytes in nutrient cycling in Lake Niepruszewskie (western Poland)The role of emergent macrophytes in nutrient cycling was investigated in the littoral zone of Lake Niepruszewskie, which is dominated by this type of vegetation. The lake is characterized by an advanced stage of eutrophication as is evident in the frequent blooms that cause low transparency and high concentrations of chlorophyll

Effects of fish predation in erosional and depositional habitats in a temperate stream

2000 ◽  
Vol 57 (7) ◽  
pp. 1369-1379 ◽  
Author(s):  
Jordan Rosenfeld
Keyword(s):  
Coho Salmon ◽  
Resource Limitation ◽  
Fish Predation ◽  
Benthic Invertebrate ◽  
Invertebrate Community ◽  
Ceramic Tiles ◽  
Organic Detritus ◽  
Predation Effects ◽  
Temperate Stream

Combined effects of predation by benthic and drift-foraging fish (prickly sculpin (Cottus asper) and coho salmon (Onchorhynchus kisutch) parr) on benthic invertebrate community and trophic structure were evaluated in Mayfly Creek, a previously fishless stream in the Coast Range Mountains of British Columbia. The role of microhabitat (substrate) in mediating predation effects was assessed by comparing invertebrate community structure on unglazed ceramic tiles and gravel baskets nested within enclosures. The role of macrohabitat was evaluated by placing enclosures in pool and riffle habitats. Effects of fish predation were most pronounced on tile substrate and in riffle habitat and least pronounced on gravel substrate in pool habitat. The presence of fish caused a decrease in abundance of larger-bodied herbivores (primarily the mayflies Ameletus and Baetis) and had positive indirect effects on algae and smaller invertebrates (primarily Orthocladiinae chironomids and nemourid stoneflies), probably through competitive release. In contrast with herbivores, detritivorous invertebrates were less influenced by fish predation and more highly correlated with the abundance of organic detritus. The distribution and abundance of detritivores in Mayfly Creek appear to be primarily influenced by bottom-up forces (implying resource limitation), while grazers in algal-based food chains are more strongly influenced by top-down effects (fish predation).

scholarly journals Carotenoid-based colour of acanthocephalan cystacanths plays no role in host manipulation

2008 ◽  
Vol 276 (1654) ◽  
pp. 169-176 ◽  
Author(s):  
Nicolas Kaldonski ◽  
Marie-Jeanne Perrot-Minnot ◽  
Raphaël Dodet ◽  
Guillaume Martinaud ◽  
Frank Cézilly
Keyword(s):  
Bird Species ◽  
Intermediate Hosts ◽  
Selective Predation ◽  
Trophic Transmission ◽  
Pomphorhynchus Laevis ◽  
Fish Predators ◽  
Yellow Orange ◽  
Behavioural Alteration ◽  
Orange Spot

Manipulation by parasites is a catchy concept that has been applied to a large range of phenotypic alterations brought about by parasites in their hosts. It has, for instance, been suggested that the carotenoid-based colour of acanthocephalan cystacanths is adaptive through increasing the conspicuousness of infected intermediate hosts and, hence, their vulnerability to appropriate final hosts such as fish predators. We revisited the evidence in favour of adaptive coloration of acanthocephalan parasites in relation to increased trophic transmission using the crustacean amphipod Gammarus pulex and two species of acanthocephalans, Pomphorhynchus laevis and Polymorphus minutus . Both species show carotenoid-based colorations, but rely, respectively, on freshwater fish and aquatic bird species as final hosts. In addition, the two parasites differ in the type of behavioural alteration brought to their common intermediate host. Pomphorhynchus laevis reverses negative phototaxis in G. pulex , whereas P. minutus reverses positive geotaxis. In aquaria, trout showed selective predation for P. laevis -infected gammarids, whereas P. minutus -infected ones did not differ from uninfected controls in their vulnerability to predation. We tested for an effect of parasite coloration on increased trophic transmission by painting a yellow–orange spot on the cuticle of uninfected gammarids and by masking the yellow–orange spot of infected individuals with inconspicuous brown paint. To enhance realism, match of colour between painted mimics and true parasite was carefully checked using a spectrometer. We found no evidence for a role of parasite coloration in the increased vulnerability of gammarids to predation by trout. Painted mimics did not differ from control uninfected gammarids in their vulnerability to predation by trout. In addition, covering the place through which the parasite was visible did not reduce the vulnerability of infected gammarids to predation by trout. We discuss alternative evolutionary explanations for the origin and maintenance of carotenoid-based colorations in acanthocephalan parasites.

scholarly journals Pasture establishment on non-cultivable hill country: a review of the New Zealand literature

2016 ◽  
Vol 16 ◽  
pp. 213-224
Author(s):  
K.N. Tozer ◽  
G.B. Douglas
Keyword(s):  
Land Surface ◽  
Seed Quality ◽  
Species Selection ◽  
Future Research ◽  
Large Contribution ◽  
Key Factors ◽  
Livestock Farming ◽  
Sowing Time ◽  
Hill Country

Steep, non-cultivable hill country below 1000 m comprises about 40% of New Zealand's land surface and is known as "hill country". It is used predominantly for mixed livestock farming, and makes a large contribution to the national economy. Recently there has been renewed interest by industry and government in germplasm introduction through pasture establishment to increase forage supply in these difficult environments. In this review, establishment is defined as development of a sown pasture species to a stage where it is able to reseed. The aim of this review was to determine the effect of key factors associated with pre-sowing management, sowing, and post-sowing management on establishment, including: site selection, herbicides, the role of litter, grazing management, burning, weed and pest control, fallow, fertiliser, species selection, seed quality, sowing time, sowing method, sowing rate, seed inoculation, coating and pelleting, natural reseeding and dissemination of seeds by animals. Over 120 studies were reviewed. A secondary aim was to highlight directions for future research. Keywords: establishment success, sowing, pasture renewal, oversowing

scholarly journals Melanocortin-1 receptor (MC1R) genotypes do not correlate with size in two cohorts of medium-to-giant congenital melanocytic nevi

2020 ◽  
Author(s):  
Neus Calbet-Llopart ◽  
Mirella Pascini-Garrigos ◽  
Gemma Tell-Martí ◽  
Miriam Potrony ◽  
Vanessa Martins da Silva ◽  
...  
Keyword(s):  
Epidemiological Studies ◽  
Compound Heterozygous ◽  
Control Analysis ◽  
Large Set ◽  
Adult Size ◽  
Loss Of Function ◽  
Melanocytic Nevi ◽  
Pigmented Lesions ◽  
Congenital Melanocytic Nevi

ABSTRACTCongenital melanocytic nevi (CMN) are cutaneous malformations whose prevalence is inversely correlated with projected adult size. CMN are caused by somatic mutations, but epidemiological studies suggest that germline genetic factors may influence CMN development. In CMN patients from the U.K., genetic variants in the MC1R gene, such as p.V92M and loss-of-function variants, have been previously associated with larger CMN. We analyzed the association of MC1R variants with CMN characteristics in 113 medium-to-giant CMN patients from Spain and from a distinct cohort of 53 patients from France, Norway, Canada and the U.S. These cohorts were similar at the clinical and phenotypical level, except for the number of nevi per patient. We found that the p.V92M or loss-of-function MC1R variants either alone or in combination did not correlate with CMN size, in contrast to the U.K. CMN patients. An additional case-control analysis with 259 unaffected Spanish individuals, showed a higher frequency of MC1R compound heterozygous or homozygous variant genotypes in Spanish CMN patients compared to the control population (15.9% vs. 9.3%; P=0.075). Altogether, this study suggests that MC1R variants are not associated with CMN size in these non-U.K. cohorts. Additional studies are required to define the potential role of MC1R as a risk factor in CMN development.SIGNIFICANCECongenital melanocytic nevi (CMN) are common pigmented lesions that originate during prenatal life, without clear evidence of a genetic predisposition. To date, limited data exist regarding the role of the MC1R gene, a key regulator of human pigmentation, in the development of the class of rarer CMN that are greater than 10 cm diameter at projected adult size and associated with increased morbidity or mortality risks. This study provides data from a large set of such CMN patients to support the hypothesis that MC1R could be involved in the development of these types of lesions, but at the same time discounting its influence on the size of CMN across distinct populations. Improving our understanding of genetic susceptibility to rare types of CMN is necessary to determine whether routine germline genotyping is relevant in clinical practice.

Developmental aspects of morphological disparity dynamics: a simple analytical exploration

Paleobiology ◽  
2011 ◽  
Vol 37 (2) ◽  
pp. 237-251 ◽  
Author(s):  
Sylvain Gerber ◽  
Gunther J. Eble ◽  
Pascal Neige
Keyword(s):  
Developmental Changes ◽  
Potential Contribution ◽  
Adult Size ◽  
Morphological Disparity ◽  
Standard Curve ◽  
Evolutionary Changes ◽  
Developmental Dynamics ◽  
Developmental Scheme ◽  
Average Adult

We have devised a simple model for assessing the role of development in shaping the evolution of morphological disparity. Disparity of a clade at any given time is expressed in terms of the developmental dynamics that lead to the variety of adult morphotypes observed. We use assumed phenotypic manifestations of developmental processes, as they could be detected from allometric characterizations, to distinguish a few, nonexclusive types of evolutionary changes in ontogeny. On the basis of this formalization, we describe the diversification of hypothetical clades, using the standard curve of adult morphological disparity, the curve of juvenile disparity, and the curve of allometric disparity, the latter quantifying the diversification of clades in allometric space. Contrasts of these curves reflect the underlying developmental scheme that drives temporal changes in disparity. We then vary the parameters of the model to assess the expected signature of each metric under specific conditions: changes in the relative frequencies of the types of evolutionary developmental changes, changes in the transition magnitude attached to each of them, and effects of temporal variation in average adult size on disparity curves and patterns of morphospace occupation. Results emphasize the potential contribution of these proxies for developmental dynamics—juvenile morphological disparity, allometric disparity, and average adult size—in enriching the interpretation of standard disparity curves and the description of clade histories, with possible process-oriented inferences.

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