Insect immune priming: ecology and experimental evidences

1. Immune priming refers to improved protection of the host after a second encounter with the same parasite or pathogen. This phenomenon is similar to that of adaptive immunity in vertebrates. 2. There is evidence to suggest that this improved protection can be species/strain‐specific and can protect organisms for a lifetime. These two attributes, along with a biphasic immune response, are essential characteristics of immune priming and form the basis for the effectiveness of resistance to parasites and pathogens. 3. This paper considers the effect of immune priming within and across generations, the influence of a heterologous challenge during immune priming and the importance of testing the immune response with natural pathogens. 4. The analysis presented takes into account the multifaceted nature of the invertebrate immune response. The lack of evidence suggesting that the bacterial microbiome plays a complementary role in the immune priming outcome is discussed. 5. Finally, the cost of immune priming is explored. This is a poorly investigated issue, which could help to explain why there is a paucity of evidence in support of immune priming.     

Multiple mating increases cocoon hatching success in the earthworm Eisenia andrei (Oligochaeta: Lumbricidae)

In simultaneous hermaphrodites with reciprocal mating, multiple mating may be a male strategy that conflicts with female interests, and therefore an intra‐individual sexual conflict regarding the number of matings may be expected. The evolutionary outcome of this sexual conflict will depend on the costs and benefits that extra mating entails for each sexual function. In the present study, we investigated the costs and benefits of multiple mating on cocoon number, cocoon mass, and cocoon hatching success in the redworm Eisenia andrei, a simultaneous hermaphrodite with reciprocal insemination, by manipulating the number of matings with different partners. We did not detect any reduction in the female reproductive output (number and mass of cocoons) with increasing number of mating partners. However, we found that multiple mating showed benefits for female reproduction that increased the hatching success of the cocoons. This effect may be a result of increased quantity and/or diversity of sperm in the spermathecae of multiple mated earthworms. Further studies are required to clarify the mechanism underlying the increased cocoon hatching success when redworms engage in multiple matings. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Local richness and distribution of the lizard fauna in natural habitat mosaics of the Brazilian Cerrado

We investigate local lizard richness and distribution in central Brazilian Cerrado, harbouring one of the least studied herpetofaunas in the Neotropical region. Our results are based on standardized samplings at 10 localities, involving 2917 captures of 57 lizard species in 10 families. Local richness values exceeded most presented in earlier studies and varied from 13 to 28 species, with modal values between 19 and 28 species. Most of the Cerrado lizard fauna is composed of habitat‐specialists with patchy distributions in the mosaic of grasslands, savannas and forests, resulting in habitat‐structured lizard assemblages. Faunal overlap between open and forested habitats is limited, and forested and open areas may act as mutual barriers to lizard distribution. Habitat use is influenced by niche conservatism in deep lineages, with iguanians and gekkotans showing higher use of forested habitats, whereas autarchoglossans are richer and more abundant in open habitats. Contrary to trends observed in Cerrado birds and large mammals, lizard richness is significantly higher in open, interfluvial habitats that dominate the Cerrado landscape. Between‐localities variation in lizard richness seems tied to geographical distance, landscape history and phylogenetic constraints, factors operating in other well‐studied lizard faunas in open environments. Higher richness in dominant, open interfluvial habitats may be recurrent in Squamata and other small‐bodied vertebrates, posing a threat to conservation as these habitats are most vulnerable to the fast, widespread and ongoing process of habitat destruction in central Brazil.     

Demography of the clonal palm Geonoma brevispatha in a Neotropical swamp forest

Abstract We expected that in clonal plants with the phalanx growth form, prereproductive ramets function as a meristem bank that helps buffer ramet demography against environmental fluctuations. Specifically, we evaluated four expectations for the forest understorey clonal palm Geonoma brevispatha in a swamp forest in south‐eastern Brazil. Our expectations were are follows: (i) the vital rates of prereproductive ramets are more responsive to genet‐related characteristics (genet size, distance and size of the nearest genet neighbour, and reproductive ramet survivorship) than to environmental variables (canopy openness, basal area of small trees, flooding, and distance and size of the nearest large tree neighbour), whose effects are expected to affect ramet dynamics indirectly through physiological integration; (ii) the progress of prereproductive ramets to later stages is dependent on the death of reproductive ramets; (iii) the population dynamics of G. brevispatha is resistant to significant interannual changes in the vital rates of ramets, (i.e. the occurrence of good and bad years); and (iv) there are large negative covariances among demographic transitions within a given year, as well as between years, reflecting the flexibility of G. brevispatha to adjust to environmental variability. Expectations 1, 2 and 4 were confirmed, while expectation 3 was only partially confirmed. Matrix models predicted that the growth rate of the overall ramet population was significantly greater than unity in the first study year, but it was significantly smaller than 1.0 in the second study year. Ramet population growth rates at the level of individual genets were greater than unity in the majority of genets in the first year, but in the second year genets with growth rates smaller than unity prevailed. Ramet population dynamics seems to be resistant to the succession of good and bad years; in effect, the presence of a meristem bank of ramets helps stabilize λ.     

The Effects of Plant Density on Shoot and Leaf Lamina Angles in Lolium multiflorum and Paspalum dilatatum

The effects of plant density on shoot and leaf lamina zenithangles (i e the angles with respect to the vertical) were investigatedin Lolium multiflorum and Paspalum dilatatum plants grown inpots either outdoors or in a glasshouse Tillers appeared abovethe ligule of their subtending leaf with a small zenith anglebut, in plants grown at low densities, gradually adopted a morehorizontal position In plants grown at high densities this gradualincrease in shoot zenith angle with age was strongly reducedThe average shoot zenith angle at a given time was lower (ie tillers were more erect) at high, compared to low plant densitiesShoot number per plant and average shoot zenith angle per plantwere directly related In P dilatatum plants the leaf lamina remained nearly horizontalat any plant density This observation indicates that the movementof the leaf lamina, pivoting at the point of attachment to theleaf sheath, compensated the movement of the shoot, pivotingat the base of the leaf sheath-tube Shoot angle responses to plant density would place leaf laminaeat different heights within the canopy, affecting their abilityto compete for light and their susceptibility to wind impactand herbivore grazing Foliage architecture, Lolium multiflorum Lam, Paspalum dilatatum Poir, plant density, neighbour effects, shoot angle, leaf angle     

Bone histological correlates of high-frequency flapping flight and body mass in the furculae of birds: a phylogenetic approach

A parsimony optimization of the presence of high-frequency flapping flight onto a phylogeny of 29 species of birds shows that this is a derived character state that has been acquired at least four independent times: by the last common ancestor of Alcidae, that of Podicipedidae, that of Anatidae, and that of Rallidae. Cineradiographic analysis has shown that the furculae of birds underwent extraordinary deformations during the wingbeat cycle. Cyclical deformations are known to produce microfractures in the bone tissue, which may be a stimulus for Haversian remodelling, a mechanism of resorption and reconstruction of bone tissue that may repair bone microdamage. In the present study, we performed a comparative analysis in a phylogenetic context to test the effect of the frequency of cyclical deformations and body mass on the rate of Haversian remodelling in the furculae of birds. A variation partitioning analysis showed that the type of flight (high-frequency flapping flight vs. other kinds of flight of lower wing beat frequency) and body mass explained a significant portion of Haversian bone density (the outcome of Haversian remodelling) and that the phylogeny also explained a significant part of this variation. This phylogenetic signal on Haversian bone density variation may be the outcome of phylogenetic signal on the proximate causes producing Haversian remodelling.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 729–738.     

Testing for MacArthur-Wilson Equilibrium with the Arthropods of the Miniature Spartina Archipelago at Oyster Bay, Florida

SYNOPSIS. The unique features of the MacArthur-Wilson modelof equilibrium biogeography are the immigration and extinctioncurves. In the model, the immigration rate for each island isnegatively correlated with species number, and island extinctionrate is positively correlated with species number. Direct tests of the sign and statistical significance of immigrationand extinction curves were done, with data on arthropods oftiny Spartina alterniflora islets, in north Florida. Rey (1981)defaunated six islets in the spring, then censused the recolonizationweekly, for one year. Two control islets and a mainland plotwere also censused. Distinct tendencies in favor of MacArthur-Wilsoncorrelations were present for both immigration and extinction.But sufficient extraneous variation occurs in immigration andextinction rates to make correspondence to MacArthur-Wilsoncurves statistically non-significant, unless probabilities arecombined among islands. Thus, mathematical deductions from theMacArthur-Wilson model, which treat the curves as deterministiclines with no variance, are less appropriate than approachesthat incorporate stochastic variation. The study of community patterns, by models such as the MacArthur-Wilsonmodel, are not a substitute for careful autecological studies.Mechanisms of colonization and co-existence are only dimly hintedat by gross community patterns.     

Rats dying for mice: Modelling the competitor release effect

Abstract Introduced vertebrate predators are one of the most important threats to endemic species throughout a range of ecosystems, in particular on islands in biodiversity hot spots. Consequently, the reduction of predator numbers is considered a key conservation action in the management of many native vertebrates vulnerable to predators. It is now established that control attempts may affect non‐target species through trophic interactions, but little is known concerning their consequences on competitive relationships. We study a mathematical model mimicking the effects of controlling introduced species in the presence of their competitors. We used two competing rodents to illustrate our study: black rats, Rattus rattus, and mice, Mus musculus. Analyses of the model show that control of only one introduced species logically results in the dramatic increase of the overlooked competitor. We present empirical data that confirm our theoretical predictions. Less intuitively, this process, which we term ‘the competitor release effect’, may also occur when both introduced competitors are simultaneously controlled. In our setting, controlling both predators can promote their coexistence. This occurs as soon as the inferior competitor benefits from the differential effect of the simultaneous control of both competitors, that is, when the indirect positive effect of control (the removal of their competitors) exceeds its direct negative effect (their own removal). Both control levels and target specificity have a direct influence on the extent of this process: counter‐intuitively, the stronger and more specific the control, the greater the effect. The theoretical validation of the competitor release effect has important implications in conservation, especially for control management.