Wild record of an apple snail in the Waikato River, Hamilton, New Zealand and their incidence in freshwater aquaria

We report the discovery of a single specimen of a live apple snail Pomacea diffusa Blume 1957 (Ampullariidae: Prosobranchia), from the Waikato River, Hamilton city, central North Island, New Zealand. This species, along with the congeneric P. insularum, is imported for the aquarium trade, and its occurrence in the river likely stemmed from an aquarium release. A survey of 55 aquaria belonging to 43 hobbyists revealed 27 apple snails, with one owner having 22 snails. Assessment of environmental tolerances and impacts of P. diffusa, based largely on studies of the closely related and commonly confused congener P. bridgesii, suggests that direct habitat impacts by this species are likely to be minor. However, there could be indirect influences on native biodiversity through predation on eggs or competition for food supplies with other detritivorous species if densities were to become high. Water temperatures in the Waikato River below Hamilton (10-23˚C in 2009) may enable released individuals to persist for an extended period, and over summer may exceed the threshold required to enable breeding. However, population establishment would be most likely in locations where water is heated through geothermal influences or industrial cooling water discharges

Measuring category intuitiveness in unconstrained categorization tasks

What makes a category seem natural or intuitive? In this paper, an unsupervised categorization task was employed to examine observer agreement concerning the categorization of nine different stimulus sets. The stimulus sets were designed to capture different intuitions about classification structure. The main empirical index of category intuitiveness was the frequency of the preferred classification, for different stimulus sets. With 169 participants, and a within participants design, with some stimulus sets the most frequent classification was produced over 50 times and with others not more than two or three times. The main empirical finding was that cluster tightness was more important in determining category intuitiveness, than cluster separation. The results were considered in relation to the following models of unsupervised categorization: DIVA, the rational model, the simplicity model, SUSTAIN, an Unsupervised version of the Generalized Context Model (UGCM), and a simple geometric model based on similarity. DIVA, the geometric approach, SUSTAIN, and the UGCM provided good, though not perfect, fits. Overall, the present work highlights several theoretical and practical issues regarding unsupervised categorization and reveals weaknesses in some of the corresponding formal models

Where Predators and Prey Meet: Anthropogenic Contact Points Between Fishes in a Freshwater Estuary

The Sacramento–San Joaquin Delta has been invaded by several species of non-native predatory fish that are presumed to be impeding native fish population recovery efforts. Since eradication of predators is unlikely, there is substantial interest in removing or altering manmade structures in the Delta that may exacerbate predation on native fish (contact points). It is presumed that these physical structures influence predator-prey dynamics, but how habitat features influence species interactions is poorly understood, and physical structures in the Delta that could be remediated to benefit native fish have not been inventoried completely. To inform future research efforts, we reviewed literature that focused on determining the effects of predator-prey interactions between fish, based on contact points that are commonly found in the Delta. We also performed a geospatial analysis to determine the extent of potential contact points in the Delta. We found that the effects of submerged aquatic vegetation (SAV) and artificial illumination are well studied and documented to influence predation in other freshwater systems worldwide. Conversely, other common structures in the Delta—such as docks, pilings, woody debris, revetment, and water diversions—did not have the same breadth of research. In the Delta, the spatial extent of the different types of contact points differed considerably. For example, 22% of the Delta water surface area is occupied by SAV, whereas docks only cover 0.44%. Our conclusion, based on both the literature review and spatial analysis, is that the effects of SAV and artificial illumination on predation warrant the most immediate future investigation in the Delta.

Non-Native Fish Predator Density and Molecular-Based Diet Estimates Suggest Differing Impacts of Predator Species on Juvenile Salmon in the San Joaquin River, California

https://doi.org/10.15447/sfews.2018v16iss4art3 The Sacramento-San Joaquin Delta is a major survival bottleneck for imperiled California salmonid populations, which is partially due to a multitude of non-native fish predators that have proliferated there throughout the 20th century. Understanding the diets of salmonid predators is critical to understanding their individual impacts, role in the food web, and the implications for potential management actions. We collected the stomach contents of Striped Bass Morone saxatilis, Largemouth Bass Micropterus salmoides, Channel Catfish Ictalurus punctatus and White Catfish Ameiurus catus sampled from three 1-km reaches in the lower San Joaquin River in 2014 and 2015 during the peak juvenile salmon outmigration period. We tested each stomach (n = 582) for the presence of juvenile Chinook Salmon Oncorhynchus tshawytscha and other prey items using a genetic barcoding technique. Channel Catfish had significantly higher frequency of Chinook Salmon in their stomachs (27.8% of tested Channel Catfish contained Chinook Salmon DNA), compared to the other three predators (2.8% to 4.8%). However, non-native fish species occurred at greater frequencies in the diets of all four predator species than salmon. Using depletion estimation from electrofishing, we were able to generate population densities for Striped Bass and Largemouth Bass in our reaches. Largemouth Bass were evenly distributed throughout all three reaches, at a mean density of approximately 333 (± 195 SE) per km of river. Striped Bass were patchily distributed, ranging from 21 to 1,227 per km. Extrapolating the frequency of salmon detected in stomachs to the predator abundance estimates, we estimate that the population of Largemouth Bass we sampled consumed between 3 and 5 Chinook Salmon per day per 1-km study reach (consumption rate of 0.011 salmon per predator per day), whereas the Striped Bass population consumed between 0 and 24 Chinook Salmon per day (0.019 salmon per predator per day)

On the origin and evolution of thermophily:reconstruction of functional precambrian enzymes from ancestors of Bacillus

Thermophily is thought to be a primitive trait, characteristic of early forms of life on Earth, that has been gradually lost over evolutionary time. The genus Bacillus provides an ideal model for studying the evolution of thermophily as it is an ancient taxon and its contemporary species inhabit a range of thermal environments. The thermostability of reconstructed ancestral proteins has been used as a proxy for ancient thermal adaptation. The reconstruction of ancestral "enzymes" has the added advantages of demonstrable activity, which acts as an internal control for accurate inference, and providing insights into the evolution of enzymatic catalysis. Here, we report the reconstruction of the structurally complex core metabolic enzyme LeuB (3-isopropylmalate dehydrogenase, E. C. 1.1.1.85) from the last common ancestor (LCA) of Bacillus using both maximum likelihood (ML) and Bayesian inference. ML LeuB from the LCA of Bacillus shares only 76% sequence identity with its closest contemporary homolog, yet it is fully functional, thermophilic, and exhibits high values for k(cat), k(cat)/K(M), and ΔG(‡) for unfolding. The Bayesian version of this enzyme is also thermophilic but exhibits anomalous catalytic kinetics. We have determined the 3D structure of the ML enzyme and found that it is more closely aligned with LeuB from deeply branching bacteria, such as Thermotoga maritima, than contemporary Bacillus species. To investigate the evolution of thermophily, three descendents of LeuB from the LCA of Bacillus were also reconstructed. They reveal a fluctuating trend in thermal evolution, with a temporal adaptation toward mesophily followed by a more recent return to thermophily. Structural analysis suggests that the determinants of thermophily in LeuB from the LCA of Bacillus and the most recent ancestor are distinct and that thermophily has arisen in this genus at least twice via independent evolutionary paths. Our results add significant fluctuations to the broad trend in thermal adaptation previously proposed and demonstrate that thermophily is not exclusively a primitive trait, as it can be readily gained as well as lost. Our findings also demonstrate that reconstruction of complex functional Precambrian enzymes is possible and can provide empirical access to the evolution of ancient phenotypes and metabolisms.</p

Nykytilan analyysi Suomen taksimarkkinoista

Tämän opinnäytetyön tavoitteena on kartoittaa toimeksiantajalle taksialan Suomen markkinoiden nykytilaa sekä alan parhaita käytänteitä sosiaalisen median viestinnässä. Toimeksiantaja on suomalainen osa-aikaisille taksiyrittäjille tarkoitettu välityssovellus, joka aloittaa toimintansa vuoden 2019 aikana. Teoreettinen viitekehys koostuu sosiaalisesta mediasta sekä nykytilan analyysistä, joka käsittelee erityisesti PESTLE- ja SWOT-analyysejä. Opinnäytetyön tutkimusosa toteutettiin kaksiosaisena ja ensimmäisessä osassa taksialan Suomen markkinoita kartoitettiin PESTLE-analyysin avulla. Toisessa osiossa toimeksiantajalle tehtiin kilpailija-analyysi sosiaalisen median viestinnästä Facebook- ja Instagram-palveluiden osalta. Nykytilan analyysissä kartoitettiin markkinatilannetta yritysten ja työntekijöiden, asiakkaiden sekä yhteiskunnan näkökulmasta. Analyysissä selvisi esimerkiksi, että taksien hinnat ovat nousseet liikennekaaren voimaan astumisen myötä. Sosiaalisen median kilpailija-analyysin tuloksena selvisi, että taksialalla ei ole tällä hetkellä yhdenmukaisia käytänteitä viestinnässä ja yritykset tuottavat varsin erilaista sisältöä. Tutkittavaksi valitut kilpailijat eivät käyttäneet Instagramia kovin aktiivisesti, joka tarjoaa toimeksiantajalle mahdollisuuden hyödyntää sitä brändiviestintäkanavana. Seurantajakson aikana ilmeni myös, että videojulkaisuja hyödynnetään varsin vähän Facebookissa ja Instagramissa, vaikka ne toimivatkin keskimäärin tehokkaammin kuin kuvajulkaisut. Toimeksiantajalle suositeltiinkin videojulkaisujen hyödyntämistä osana sosiaalisen median viestintää ja markkinointia

Prudence in vacillatory language identification

10.1007/BF01303059Mathematical Systems Theory283267-27

Pedagogical Questions in Parent–Child Conversations

Questioning is a core component of formal pedagogy. Parents commonly question children, but do they use questions to teach? Here we define “pedagogical questions” as questions for which the questioner already knows the answer and intended to help the questionee learn. We investigate the frequency and distribution of pedagogical questions from parent-child conversations documented in the CHILDES database. By analyzing 2166 questions from 166 mother-child dyads and 64 father-child dyads, we find that pedagogical questions are commonplace during day-to-day parent-child conversations, and vary based on child’s age, family environment, and historical era. The results serve as a first step towards understanding the role of parent-child questions in facilitating children’s learning