Aphid reproductive investment in response to mortality risks

<p>Abstract</p> <p>Background</p> <p>Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. An alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness loss from infection. Such a response would reduce the need to mount a potentially energetically costly immune response, and would parallel that of other hosts that alter life-history traits when there is a risk of infection. Here we examined whether pea aphids (<it>Acyrthosiphon pisum</it>) respond to immunological challenges by increasing reproduction. As a comparison to the response to the internal cue of risk elicited by immunological challenge, we also exposed pea aphids to an external cue of risk - the aphid alarm pheromone (<it>E</it>)-<it>β</it>-farnesene (EBF), which is released in the presence of predators. For each challenge, we also examined whether the presence of symbionts modified the host response, as maintaining host fitness in the face of challenge would benefit both the host and its dependent bacteria.</p> <p>Results</p> <p>We found that aphids stabbed abdominally with a sterile needle had reduced fecundity relative to control aphids but that aphids stabbed with a needle bearing heat-killed bacteria had reproduction intermediate, and statistically indistinguishable, to the aphids stabbed with a sterile needle and the controls. Aphids with different species of facultative symbiotic bacteria had different reproductive patterns overall, but symbionts in general did not alter aphid reproduction in response to bacterial exposure. However, in response to exposure to alarm pheromone, aphids with <it>Hamiltonella defensa </it>or <it>Serratia symbiotica </it>symbiotic infections increased reproduction but those without a facultative symbiont or with <it>Regiella insecticola </it>did not.</p> <p>Conclusions</p> <p>Overall, our results suggest that pea aphids are able to increase their reproduction in response to specific cues and that symbiont presence sometimes moderates this response. Such increased reproduction in response to risk of death increases the fitness of both aphids and their vertically transmitted symbionts, and since these organisms have high reproductive capacity, slight increases in reproduction could lead to a very large numerical advantage later in the season. Thus both symbiotic partners can benefit by increasing host fecundity under dangerous conditions.</p

Complex host-pathogen coevolution in the Apterostigma fungus-growing ant-microbe symbiosis

BACKGROUND: The fungus-growing ant-microbe symbiosis consists of coevolving microbial mutualists and pathogens. The diverse fungal lineages that these ants cultivate are attacked by parasitic microfungi of the genus Escovopsis. Previous molecular analyses have demonstrated strong phylogenetic congruence between the ants, the ants-cultivated fungi and the garden pathogen Escovopsis at ancient phylogenetic levels, suggesting coevolution of these symbionts. However, few studies have explored cophylogenetic patterns between these symbionts at the recent phylogenetic levels necessary to address whether these parasites are occasionally switching to novel hosts or whether they are diversifying with their hosts as a consequence of long-term host fidelity. RESULTS: Here, a more extensive phylogenetic analysis of Escovopsis lineages infecting the gardens of Apterostigma ants demonstrates that these pathogens display patterns of phylogenetic congruence with their fungal hosts. Particular clades of Escovopsis track particular clades of cultivated fungi, and closely-related Escovopsis generally infect closely-related hosts. Discordance between host and parasite phylogenies, however, provides the first evidence for occasional host-switches or acquisitions of novel infections from the environment. CONCLUSION: The fungus-growing ant-microbe association has a complex coevolutionary history. Though there is clear evidence of host-specificity on the part of diverse Escovopsis lineages, these pathogens have switched occasionally to novel host fungi. Such switching is likely to have profound effects on how these host and parasites adapt to one another over evolutionary time scales and may impact how disease spreads over ecological time scales

Identification of Heart Failure Events in Medicare Claims: The Atherosclerosis Risk in Communities (ARIC) Study

We examined the accuracy of CMS Medicare HF diagnostic codes in the identification of acute decompensated and chronic stable HF (ADHF and CSHF)

Life-history strategy determines constraints on immune function

Determining the factors governing investment in immunity is critical to understanding host-pathogen ecological and evolutionary dynamics. Studies often consider disease resistance in the context of life-history theory, with the expectation that investment in immunity will be optimized in anticipation of disease risk. Immunity, however, is constrained by context-dependent fitness costs. How the costs of immunity vary across life-history strategies has yet to be considered. Pea aphids are typically unwinged but produce winged offspring in response to high population densities and deteriorating conditions. This is an example of polyphenism, a strategy used by many organisms to adjust to environmental cues. The goal of this study was to examine the relationship between the fitness costs of immunity, pathogen resistance and the strength of an immune response across aphid morphs that differ in life-history strategy but are genetically identical. We measured fecundity of winged and unwinged aphids challenged with a heat-inactivated fungal pathogen, and found that immune costs are limited to winged aphids. We hypothesized that these costs reflect stronger investment in immunity in anticipation of higher disease risk, and that winged aphids would be more resistant due to a stronger immune response. However, producing wings is energetically expensive. This guided an alternative hypothesis - that investing resources into wings could lead to a reduced capacity to resist infection. We measured survival and pathogen load after live fungal infection, and we characterized the aphid immune response to fungi by measuring immune cell concentration and gene expression. We found that winged aphids are less resistant and mount a weaker immune response than unwinged aphids, demonstrating that winged aphids pay higher costs for a less effective immune response. Our results show that polyphenism is an understudied factor influencing the expression of immune costs. More generally, our work shows that in addition to disease resistance, the costs of immunity vary between individuals with different life-history strategies. We discuss the implications of these findings for understanding how organisms invest optimally in immunity in the light of context-dependent constraints

Disease management in two sympatric Apterostigma fungus-growing ants for controlling the parasitic fungus Escovopsis

Antagonistic interactions between host and parasites are often embedded in networks of interacting species, in which hosts may be attacked by competing parasites species, and parasites may infect more than one host species. To better understand the evolution of host defenses and parasite counterdefenses in the context of a multihost, multiparasite system, we studied two sympatric species, of congeneric fungus-growing ants (Attini) species and their symbiotic fungal cultivars, which are attacked by multiple morphotypes of parasitic fungi in the genus, Escovopsis. To assess whether closely related ant species and their cultured fungi are evolving defenses against the same or different parasitic strains, we characterized Escovopsis that were isolated from colonies of sympatric Apterostigma dentigerum and A. pilosum. We assessed in vitro and in vivo interactions of these parasites with their hosts. While the ant cultivars are parasitized by similar Escovopsis spp., the frequency of infection by these pathogens differs between the two ant species. The ability of the host fungi to suppress Escovopsis growth, as well as ant defensive responses toward the parasites, differs depending on the parasite strain and on the host ant species

Ancient Host–Pathogen Associations Maintained by Specificity of Chemotaxis and Antibiosis

Switching by parasites to novel hosts has profound effects on ecological and evolutionary disease dynamics. Switching requires that parasites are able to establish contact with novel hosts and to overcome host defenses. For most host–parasite associations, it is unclear as to what specific mechanisms prevent infection of novel hosts. Here, we show that parasitic fungal species in the genus Escovopsis, which attack and consume the fungi cultivated by fungus-growing ants, are attracted to their hosts via chemotaxis. This response is host-specific: Escovopsis spp. grow towards their natural host cultivars more rapidly than towards other closely related fungi. Moreover, the cultivated fungi secrete compounds that can suppress Escovopsis growth. These antibiotic defenses are likewise specific: in most interactions, cultivars can inhibit growth of Escovopsis spp. not known to infect them in nature but cannot inhibit isolates of their naturally infecting pathogens . Cases in which cultivars are susceptible to novel Escovopsis are limited to a narrow set of host–parasite strain combinations. Targeted chemotactic and antibiotic responses therefore explain why Escovopsis pathogens do not readily switch to novel hosts, consequently constraining long-term dynamics of host–parasite coevolution within this ancient association

I Jornadas Científicas del Museo Nacional de Ciencias Naturales

I Jornadas Científicas del Museo Nacional de Ciencias Naturales, celebradas el 21-22 Febrero 2017, en el Museo Nacional de Ciencias Naturales (Madrid)El objetivo de las I Jornadas Científicas del Museo Nacional de Ciencias Naturales es dar a conocer las diferentes líneas de investigación que están realizando los distintos Departamentos de este Centro, además de dar la oportunidad de conocerse y facilitar la interacción entre todos. Las jornadas constan de 26 charlas (con sus presentaciones) y en principio, son representativas de todos los departamentos de forma equitativa de acuerdo con el número de miembros de cada uno de los participantes. Además dos o tres charlas "plenarias" de interés general. Se da prioridad a participar a los jóvenes investigadores, estudiantes de doctorado o jóvenes postdoctorandos. Participación de miembros de: Departamento de Biogeografía y Cambio Global, Dept. Ecología Evolutiva, Dept. Geología, Dept. Biodiversidad y Biología Evolutiva, Dept. Biogeoquímica y Ecología Microbiana, Dept. Paleobiología.01 Pequeña historia. 02 Programa de las Jornadas. 03 Libro de resumenes. 04 Cartel anunciador. 05 Menus de desayuno y almuerzo. 06 Balance de las Jornadas. 07 AgradecimientosPresentaciones disponibles: Álvarez-Cobelas: "Los científicos hispanos como insectos sociales?".-- Mikel Calle: "Cuando el río suena... agua lleva. Caracterizando la dinámica de los cauces efímeros mediterráneos”.-- María Cristina Casero: “"Aquí no hay quien viva: Microorganismos litobiónticos en el desierto de Atacama".-- Cepeda, Diego; Soler-Hurtado, M. Mar; Lattig, Patricia: "Un océano de gusanos marinos: la importancia de conocer la biodiversidad de anélidos asociados a corales".-- Flores, Omar; Rey, Ana; Curiel Yuste, Jorge; Valladares Ros, Fernando: “Modelización de la descomposición de la hojarasca en climas áridos”.-- Forner, Alicia; Aranda, Ismael; Valladares Ros, Fernando: “Árboles mediterráneos en la cuerda floja: sequías extremas, ¿un crimen con atenuantes?”.-- García-Ángulo, Daniel: “Ojos que no ven… Efecto del cambio climático y del manejo histórico de los encinares en el suelo bajo nuestros pies”.- García Morato, Sara: “Hienas, humanos y micromamíferos”.-- García-Tabernero, Antonio: “Aplicaciones de antropología virtual: colecciones virtuales y paleoneurología”.-- Garrido-Benavent, Isaac: Estudios filogeográficos de dos especies de hongos liquenizados muestran orígenes distintos de la biota liquénica antártica".-- Garrido, Fernando; García-Guinea, Javier; Gómez-González, Miguel A.: Presencia de arsénico en suelos contaminados de la provincia de Madrid.-- Gaspar, Leticia: “Técnicas radiométricas en el estudio de la erosión y la redistribución del suelo”.-- Doadrio, Ignacio; Pardos Blas, José Ramón: Desenredando el género Gambusia (Poeciliidae) en el noreste de México.-- Riesco López, Alberto; Bastir, Markus: Morfología virtual en 3D del Megatherium americanum del MNCNPeer reviewe

Patient-physician discordance in assessment of adherence to inhaled controller medication: a cross-sectional analysis of two cohorts

We aimed to compare patient's and physician's ratings of inhaled medication adherence and to identify predictors of patient-physician discordance.(SFRH/BPD/115169/2016) funded by Fundação para a Ciência e Tecnologia (FCT); ERDF (European Regional Development Fund) through the operations: POCI-01-0145-FEDER-029130 ('mINSPIRERS—mHealth to measure and improve adherence to medication in chronic obstructive respiratory diseases—generalisation and evaluation of gamification, peer support and advanced image processing technologies') cofunded by the COMPETE2020 (Programa Operacional Competitividade e Internacionalização), Portugal 2020 and by Portuguese Funds through FCT (Fundação para a Ciência e a Tecnologia).info:eu-repo/semantics/publishedVersio

Immunity and other defenses in pea aphids, Acyrthosiphon pisum

The genome of the pea aphid Acyrthosiphon pisum lacks genes thought to be crucial in other insects for recognition, signaling and killing of microbes