Perspective: Matching, Mate Choice, and Speciation

Matching was developed in the 1960s to match such entities as residents and hospitals, colleges and students, or employers and employees. This approach is based on “preference lists,” whereby each participant ranks potential partners according to his/her preferences and tries to match with the highest-ranking partner available. Here, we discuss the implications of matching for the study of mate choice and speciation. Matching differs from classic approaches in several respects, most notably because under this theoretical framework, the formation of mating pairs is context-dependant (i.e., it depends on the configuration of pairings in the entire population), because the stability of mating pairs is considered explicitly, and because mate choice is mutual. The use of matching to study mate choice and speciation is not merely a theoretical curiosity; its application can generate counter-intuitive predictions and lead to conclusions that differ fundamentally from classic theories about sexual selection and speciation. For example, it predicts that when mate choice is mutual and the stability of mating pairs is critical for successful reproduction, sympatric speciation is a robust evolutionary outcome. Yet the application of matching to the study of mate choice and speciation has been largely dominated by theoretical studies. We present the hamlets, a group of brightly colored Caribbean coral reef fishes in the genus Hypoplectrus (Serranidae), as a particularly apt system to test empirically specific predictions generated by the application of matching to mate choice and speciation

PLAN DE NEGOCIOS PARA LA CREACIÓN DE LA PLANTA PURIFICADORA DE AGUA “LAS ESMERALDAS” EN TEJUPILCO ESTADO DE MÉXICO

Tesis LicenciaturaSegún datos de la Secretaria de Economía (2012), las pymes en México juegan un papel importante en la economía nacional, ya que aportan un 52% del producto interno bruto PIB, y por consecuente contribuye al desarrollo económico del país. Los emprendedores constituyen la base de la pirámide empresarial y para materializar sus iniciativas en negocios rentantes, requieren estructurar un esquema completo de apoyos que faciliten la constitución de empresas, la permanencia de estas y su crecimiento de mercado. En la búsqueda de alternativas se optó por la elaboración de un plan de negocios de una planta purificadora de agua y el servicio a ofrecer será de buena calidad y estará ubicada en el libramiento Oriente carretera Tejupilco - Amatepec. Cabe mencionar que en dicho municipio existen establecimientos del mismo giro, pero no de calidad, es por ello que se decidió crear esta planta purificadora para realmente ofrecer un producto de calidad que llegue a beneficiar a todos nuestros consumidores. En el presente trabajo se describirán cada uno de los procesos que se realizaran en el tratamiento del agua, así como los costos de la maquinaria y demás gastos. El plan de negocios estará distribuido en diez apartados para su fácil comprensión, iniciando con una introducción general a la naturaleza del proyecto y la manera en que este surge, posteriormente el apartado dos se muestra la metodología empleada para conocer la posible demanda y oferta presentada en el proyecto. El capítulo tres está constituido por el marco teórico y conceptual donde se explican los conceptos que fueron necesarios conocer para la realización del plan, en un capítulo más se presenta un resumen ejecutivo con resultados finales y un panorama general al final del plan de negocios.Universidad Autónoma del Estado de México. Centro Universitario UAEM Temascaltepec, Ext. Tejupilco, Lic. en Administració

Belize Barrier Reef Transect: How Far Do Coral Reef Fish Larvae Travel In Marine Currents?

The vast majority of coral reef fishes go through a pelagic larval stage, which provides potential for long-distance dispersal by marine currents. Yet planktonic larvae are notoriously difficult to track owing to their small size, and as a consequence the spatial scale of dispersal in coral reef fishes is largely unknown. Robust estimates of dispersal are needed owing to the fundamental importance of this parameter for the design and management of networks of marine protected areas. If larvae disperse locally, geographically nearer individuals are anticipated to be more similar genetically. A pattern of increasing genetic differentiation with geographic distance, referred to as genetic 'isolation by distance', is expected in this case and provides an opportunity to estimate dispersal. A specific aspect of this approach is that it requires the continuous sampling of individuals along a continuous population. The 250 km long Belize Barrier Reef provides an unparalleled opportunity to sample continuously along continuous populations of coral reef fishes. Individuals were collected continuously along a 250-km transect following the Belize Barrier Reef to estimate larval dispersal in seven species of coral reef fish with different life histories

El sector productivo y el mercado de valores en Ecuador

El mercado de capitales, también conocido como mercado de valores, es un tipo de mercado financiero en el que se ofrecen y demandan fondos o medios de financiación a mediano y largo plazo. Su principal objetivo es participar como intermediario, canalizando los recursos frescos y el ahorro; para que los emisores, lleven a cabo propuestas de inversión con financiamiento adecuado a sus necesidades específicas. Por otro lado, el mercado monetario se caracteriza por la oferta y demanda de fondos a corto plazo. Las Bolsas de Valores han sido precisamente las instituciones que proveen la infraestructura necesaria para facilitar la aproximación de los inversores con los ahorristas, a través de la compra – venta de títulos valores, emitidos en función de las necesidades específicas de financiamiento en el corto, mediano y largo plazos El establecimiento de las Bolsas de Valores en el Ecuador, no solamente fue un proyecto largamente esperado, sino que también respondió a la evolución y naturaleza de los procesos económicos y comerciales que se vienen dando en nuestro país a través del tiempo. El punto fundamental fue la necesidad de proveer a los comerciantes, de un medio idóneo y moderno para distribuir la riqueza, promover el ahorro interno e impulsar su canalización hacia las actividades productivas Las Ratios financieros (también llamados razones financieras o indicadores financieros), son coeficientes o razones que proporcionan unidades contables y financieras de medida y por comparación, permiten analizar el estado actual o pasado de una organización, en función a niveles óptimos y que pueden estar predeterminados o con aquellos de empresas líderes. Se pretende analizar el Mercado de Valores del Ecuador y medir los beneficios económicos de las empresas cotizantes y no cotizantes, mediante el uso de indicadores financieros que permitan comparar diferentes escenarios, con el fin de utilizarlos en la toma de decisiones

The evolution of egg trading in simultaneous hermaphrodites

Egg trading, whereby simultaneous hermaphrodites exchange each other’s eggs for fertilization, constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of non-trading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (“cheaters” who only mate in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of inter-mediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions traders can invade—and resist invasion from—providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites

Diet and stable isotope analyses reveal the feeding ecology of the orangeback squid Sthenoteuthis pteropus (Steenstrup 1855) (Mollusca, Ommastrephidae) in the eastern tropical Atlantic

In the eastern tropical Atlantic, the orangeback flying squid Sthenoteuthis pteropus (Steenstrup 1855) (Cephalopoda, Ommastrephidae) is a dominant species of the epipelagic nekton community. This carnivore squid has a short lifespan and is one of the fastest-growing squids. In this study, we characterise the role of S. pteropus in the pelagic food web of the eastern tropical Atlantic by investigating its diet and the dynamics of its feeding habits throughout its ontogeny and migration. During three expeditions in the eastern tropical Atlantic in 2015, 129 specimens were caught by hand jigging. Stomach content analyses (via visual identification and DNA barcoding) were combined with stable isotope data (∂15N and ∂13C) of muscle tissue to describe diet, feeding habits and trophic ecology of S. pteropus. Additionally, stable isotope analyses of incremental samples along the squid’s gladius—the chitinous spiniform structure supporting the muscles and organs—were carried out to explore possible diet shifts through ontogeny and migration. Our results show that S. pteropus preys mainly on myctophid fishes (e.g. Myctophum asperum, Myctophum nitidulum, Vinciguerria spp.), but also on other teleost species, cephalopods (e.g. Enoploteuthidae, Bolitinidae, Ommastrephidae), crustaceans and possibly on gelatinous zooplankton as well. The squid shows a highly opportunistic feeding behaviour that includes cannibalism. Our study indicates that the trophic position of S. pteropus may increase by approximately one trophic level from a mantle length of 15 cm to 47 cm. The reconstructed isotope-based feeding chronologies of the gladii revealed high intra- and inter-individual variability in the squid’s trophic position and foraging area. These findings are not revealed by diet or muscle tissue stable isotope analysis. This suggests a variable and complex life history involving individual variation and migration. The role of S. pteropus in transferring energy and nutrients from lower to higher trophic levels may be underestimated and important for understanding how a changing ocean impacts food webs in the eastern Atlantic

ACTIVATION OF THE HYPOTHALAMIC– PITUITARY–ADRENAL AXIS INDUCES THE DIFFERENTIAL RELEASE OF PRO– INFLAMMATORY CYTOKINES IN BALB/C MICE

Physiological processes are associated with interactions between the nervous, endocrine and immune systems, which communicate through neurotransmitters, hormones and cytokines. The key to this communication is the hypothalamic–pituitary–adrenal (HPA) axis which can be activated by stress and pro–inflammatory cytokines. We have investigated the effects of acute and chronic stress on the release of pro–inflammatory cytokines through activation of the HPA axis. Accordingly, BALB/c mice were exposed to acute stress through the single application of bi–frontal electrical stimulation (ESa, 20V/10 mA/0.05s) and the effect produced by a single i.p. dose of Lipopolysacharide (LPS) (250 μg/100g). Chronic stress was (ESc) induced by applying the electrical stimulus to the animals in the same way for 7 consecutive days, as well as the effects of ascending LPS administration over 7 days (35–250 μg/100g i.p./day). Following stimulation, the levels of pro–inflammatory cytokines and corticosterone were quantified by ELISA. Unlike LPS that provoked an increase in TNF–α, IL–1β, IL–6, and corticosterone levels, acute electrical stress did not induce any change in the levels of pro–inflammatory cytokines or corticosterone. In contrast, chronic ESc stress produced an increase in the levels of TNF–α, while in the animals treated with LPS the IL–6 levels increased. These data suggest that the response of the HPA axis to stress depends on the duration, intensity and etiology of the stress agent, also suggest a suitable model for the evaluation of drugs with potential effect on inflammatory stress

A novel metabarcoding primer pair for environmental DNA analysis of Cephalopoda (Mollusca) targeting the nuclear 18S rRNA region

Cephalopods are pivotal components of marine food webs, but biodiversity studies are hampered by challenges to sample these agile marine molluscs. Metabarcoding of environmental DNA (eDNA) is a potentially powerful technique to study oceanic cephalopod biodiversity and distribution but has not been applied thus far. We present a novel universal primer pair for metabarcoding cephalopods from eDNA, Ceph18S (Forward: 5′-CGC GGC GCT ACA TAT TAG AC-3′, Reverse: 5′-GCA CTT AAC CGA CCG TCG AC-3′). The primer pair targets the hypervariable region V2 of the nuclear 18S rRNA gene and amplifies a relatively short target sequence of approximately 200 bp in order to allow the amplification of degraded DNA. In silico tests on a reference database and empirical tests on DNA extracts from cephalopod tissue estimate that 44-66% of cephalopod species, corresponding to about 310-460 species, can be amplified and identified with this primer pair. A multi-marker approach with the novel Ceph18S and two previously published cephalopod mitochondrial 16S rRNA primer sets targeting the same region (Jarman et al. 2006 Mol. Ecol. Notes. 6, 268-271; Peters et al. 2015 Mar. Ecol. 36, 1428-1439) is estimated to amplify and identify 89% of all cephalopod species, of which an estimated 19% can only be identified by Ceph18S. All sequences obtained with Ceph18S were submitted to GenBank, resulting in new 18S rRNA sequences for 13 cephalopod tax

ACTIVATION OF THE HYPOTHALAMIC– PITUITARY–ADRENAL AXIS INDUCES THE DIFFERENTIAL RELEASE OF PRO– INFLAMMATORY CYTOKINES IN BALB/C MICE

Physiological processes are associated with interactions between the nervous, endocrine and immune systems, which communicate through neurotransmitters, hormones and cytokines. The key to this communication is the hypothalamic–pituitary–adrenal (HPA) axis which can be activated by stress and pro–inflammatory cytokines. We have investigated the effects of acute and chronic stress on the release of pro–inflammatory cytokines through activation of the HPA axis. Accordingly, BALB/c mice were exposed to acute stress through the single application of bi–frontal electrical stimulation (ESa, 20V/10 mA/0.05s) and the effect produced by a single i.p. dose of Lipopolysacharide (LPS) (250 μg/100g). Chronic stress was (ESc) induced by applying the electrical stimulus to the animals in the same way for 7 consecutive days, as well as the effects of ascending LPS administration over 7 days (35–250 μg/100g i.p./day). Following stimulation, the levels of pro–inflammatory cytokines and corticosterone were quantified by ELISA. Unlike LPS that provoked an increase in TNF–α, IL–1β, IL–6, and corticosterone levels, acute electrical stress did not induce any change in the levels of pro–inflammatory cytokines or corticosterone. In contrast, chronic ESc stress produced an increase in the levels of TNF–α, while in the animals treated with LPS the IL–6 levels increased. These data suggest that the response of the HPA axis to stress depends on the duration, intensity and etiology of the stress agent, also suggest a suitable model for the evaluation of drugs with potential effect on inflammatory stress