Fathers' Multiple-Partner Fertility and Children's Educational Outcomes

Fathers' multiple-partner fertility (MPF) is associated with substantially worse educational outcomes for children. We focus on children in fathers' second families that are nuclear: households consisting of a man, a woman, their joint children, and no other children. We analyze outcomes for almost 75,000 Norwegian children, all of whom lived in nuclear families until at least age 18. Children with MPF fathers are more likely than other children from nuclear families to drop out of secondary school (24% vs. 17%) and less likely to obtain a bachelor's degree (44% vs. 51%). These gaps remain substantial—at 4 and 5 percentage points, respectively—after we control for child and parental characteristics, such as income, wealth, education, and age. Resource competition with the children in the father's first family does not explain the differences in educational outcomes. We find that the association between a father's previous childless marriage and his children's educational outcomes is similar to that between a father's MPF and his children's educational outcomes. Birth order does not explain these results. This similarity suggests that selection is the primary explanation for the association between fathers' MPF and children's educational outcomes.

rescomp: An R package for defining, simulating and visualizing ODE models of consumer-resource interactions

Mechanistic models of resource competition underpin numerous foundational concepts and theories in ecology, and continue to be employed widely to address diverse research questions. Nevertheless, current software tools present a comparatively steep barrier to entry. I introduce the R package rescomp to support the specification, simulation and visualisaton of a broad spectrum of consumer-resource interactions. rescomp is compatible with diverse model specifications, including an unlimited number of consumers and resources, different consumer functional responses (type I, II and III), different resource types (essential or substitutable) and supply dynamics (chemostats, logistic and/or pulsed), delayed consumer introductions, time dependent growth and consumption parameters, and instantaneous changes to consumer and/or resource densities. Several examples on implementing rescomp are provided. In addition, a wide variety of additional examples can be found in the package vignettes, including using rescomp to reproduce the results of several well known studies from the literature. rescomp provides users with an accessible tool to reproduce classic models in ecology, to specify models resembling a wide range of experimental designs, and to explore diverse novel model formulations.

Land-use history impacts spatial patterns and composition of woody plant species across a 35-hectare temperate forest plot

Land-use history is the template upon which contemporary plant and tree populations establish and interact with one another and exerts a legacy on the structure and dynamics of species assemblages and ecosystems. We use the first census (2010–2014) of a 35-ha forest-dynamics plot at the Harvard Forest in central Massachusetts to describe the composition and structure of the woody plants in this plot, assess their spatial associations within and among the dominant species using univariate and bivariate spatial point-pattern analysis, and examine the interactions between land-use history and ecological processes. The plot includes 108,632 live stems ≥ 1 cm in diameter (2,215 individuals/ha) and 7,595 standing dead stems ≥ 5 cm in diameter. Live tree basal area averaged 42.25 m2/ha, of which 84% was represented by Tsuga canadensis (14.0 m2/ ha), Quercus rubra (northern red oak; 9.6 m2/ ha), Acer rubrum (7.2 m2/ ha) and Pinus strobus (eastern white pine; 4.4 m2/ ha). These same four species also comprised 78% of the live aboveground biomass, which averaged 245.2 Mg/ ha. Across all species and size classes, the forest contains a preponderance (> 80,000) of small stems (<10-cm diameter) that exhibit a reverse-J size distribution. Significant spatial clustering of abundant overstory species was observed at all spatial scales examined. Spatial distributions of A. rubrum and Q. rubra showed negative intraspecific correlations in diameters up to at least a 150-m spatial lag, likely indicative of crowding effects in dense forest patches following intensive past land use. Bivariate marked point-pattern analysis, showed that T. canadensis and Q. rubra diameters were negatively associated with one another, indicating resource competition for light. Distribution and abundance of the common overstory species are predicted best by soil type, tree neighborhood effects, and two aspects of land-use history: when fields were abandoned in the late 19th century and the succeeding forest types recorded in 1908. In contrast, a history of intensive logging prior to 1950 and a damaging hurricane in 1938 appear to have had little effect on the distribution and abundance of present-day tree species. Our findings suggest that current day composition and structure are still being influenced by anthropogenic disturbances that occurred over a century ago.

A versatile active learning workflow for optimization of genetic and metabolic networks

The study, engineering and application of biological networks require practical and efficient approaches. Current optimization efforts of these systems are often limited by wet lab labor and cost, as well as the lack of convenient, easily adoptable computational tools. Aimed at democratization and standardization, we describe METIS, a modular and versatile active machine learning workflow with a simple online interface for the optimization of biological target functions with minimal experimental datasets. We demonstrate our workflow for various applications, from simple to complex gene circuits and metabolic networks, including several cell-free transcription and translation systems, a LacI-based multi-level controller and a 27-variable synthetic CO2-fixation cycle (CETCH cycle). Using METIS, we could improve above systems between one and two orders of magnitude compared to their original setup with minimal experimental efforts. For the CETCH cycle, we explored the combinatorial space of ~1025 conditions with only 1,000 experiments to yield the most efficient CO2-fixation cascade described to date. Beyond optimization, our workflow also quantifies the relative importance of individual factors to the performance of a system. This allows to identify so far unknown interactions and bottlenecks in complex systems, which paves the way for their hypothesis-driven improvement, which we demonstrate for the LacI multi-level controller that we were able to improve by 100-fold after having identified resource competition as limiting factor. Overall, our workflow opens the way for convenient optimization and prototyping of genetic and metabolic networks with customizable adjustments according to user experience, experimental setup, and laboratory facilities.

Females restrict the position of domatia and suffer more herbivory than hermaphrodites in Myriocarpa longipes, a neotropical facultative myrmecophyte

Domatia are hollow structures in plants occupied by ant colonies, in turn ants provide protection against herbivores. In plants, competition for resources has driven sex-related changes in the patterns of resource allocation to life-history traits and defence traits. The resource-competition hypothesis (RCH) proposes that female plants due to their higher investment in reproduction will allocate fewer resources to defence production, showing greater herbivore damage than other sexual forms. We hypothesise the existence of sex-related differences in defensive traits of domatia-bearing plants, being female plants less defended due to differences in domatia traits, such as size, number of domatia and their position, exhibiting more herbivore damage than hermaphrodite plants of Myriocarpa longipes, a facultative neotropical myrmecophyte. We found eight species of ants inhabiting domatia; some species co-inhabited the same plant, even the same branch. Our results are consistent with the predictions of RCH, as female plants had ant-inhabited domatia restricted to the middle position of their branches and exhibited greater herbivore damage in leaves than hermaphrodites. However, we did not find differences in domatia size and leaf area between sexual forms. Our study provides evidence for intersexual differences in domatia position and herbivory in a facultative ant–plant mutualism in M. longipes. We highlight the importance of considering the plant sex in ant–plant interactions. Differences in resource allocation related to sexual reproduction could influence the outcome of ant–plant interactions.

The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly

In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling in aposematism is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments directly responsible for colouration and in protecting against oxidative lipid damage. Here we study a model aposematic system - the monarch butterfly (Danaus plexippus) and make use of the variable phytochemistry of its larval host-plant, milkweeds (Asclepiadaceae), to manipulate the concentration of sequestered cardenolides. We test two fundamental assumptions of resource competition models: that (1) the possession of secondary defences is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (2) that oxidative damage or decreases in antioxidant defences can reduce the capacity of individuals to produce aposematic displays. Monarch caterpillars that sequestered the highest concentrations of cardenolides exhibited higher levels of oxidative lipid damage as adults. The relationship between warning signals, cardenolide concentrations and oxidative damage differed between the sexes. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: as males sequester more cardenolides, those with high levels of oxidative damage become less conspicuous, while those that sequester lower levels of cardenolides equally invest in conspicuous with increasing oxidative damage. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate physiological linkage between the production of coloration and protection from autotoxicity, that warning signals can be honest indicators of defensive capability, and that the relationships are different between the sexes.

Dynamics of alpha suppression and enhancement may be related to resource competition in cross-modal cortical regions

In the face of multiple sensory streams, there may be competition for processing resources in multimodal cortical area devoted to establishing representations. In such cases, alpha oscillations may serve to maintain the relevant representations and protect them from interference, whereas theta oscillations may facilitate their updating when needed. It can be hypothesized that these oscillations would differ in response to an auditory stimulus when the eyes are open or closed, as intermodal resource competition may be more prominent in the former than in the latter case. Across two studies we investigated the role of alpha and theta power in multimodal competition using an auditory task with the eyes open and closed, respectively enabling and disabling visual processing in parallel with the incoming auditory stream. In a passive listening task (Study 1a), we found alpha suppression following a pip tone with both eyes open and closed, but subsequent alpha enhancement only with closed eyes. We replicated this eyes-closed alpha enhancement in an independent sample (Study 1b). In an active auditory oddball task (Study 2), we again observed the eyes open/eyes closed alpha pattern found in Study 1 and also demonstrated that the more attentionally demanding oddball trials elicit the largest oscillatory effects. Theta power did not interact with eye status in either study. We propose a hypothesis to account for the findings in which alpha may be endemic to multimodal cortical areas in addition to visual ones.