This book is the second of two volumes in a series on terrestrial and marine comparisons, focusing on the temporal complement of the earlier spatial analysis of patchiness and pattern (Levin et al. 1993). The issue of the relationships among pattern, scale, and patchiness has been framed forcefully in John Steele’s writings of two decades (e.g., Steele 1978). There is no pattern without an observational frame. In the words of Nietzsche, “There are no facts… only interpretations.”

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.2307/1941447

The Problem of Pattern and Scale in Ecology: The Robert H. MacArthur Award Lecture

▪ Abstract The focus of most ideas on diversity maintenance is species coexistence, which may be stable or unstable. Stable coexistence can be quantified by the long-term rates at which community members recover from low density. Quantification shows that coexistence mechanisms function in two major ways: They may be (a) equalizing because they tend to minimize average fitness differences between species, or (b) stabilizing because they tend to increase negative intraspecific interactions relative to negative interspecific interactions. Stabilizing mechanisms are essential for species coexistence and include traditional mechanisms such as resource partitioning and frequency-dependent predation, as well as mechanisms that depend on fluctuations in population densities and environmental factors in space and time. Equalizing mechanisms contribute to stable coexistence because they reduce large average fitness inequalities which might negate the effects of stabilizing mechanisms. Models of unstable coexitence...

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Mechanisms of Maintenance of Species Diversity

This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments. This approach offers a unified framework for the mechanical and statistical properties of living matter: biofilaments and molecular motors in vitro or in vivo, collections of motile microorganisms, animal flocks, and chemical or mechanical imitations. A major goal of this review is to integrate several approaches proposed in the literature, from semimicroscopic to phenomenological. In particular, first considered are ``dry'' systems, defined as those where momentum is not conserved due to friction with a substrate or an embedding porous medium. The differences and similarities between two types of orientationally ordered states, the nematic and the polar, are clarified. Next, the active hydrodynamics of suspensions or ``wet'' systems is discussed and the relation with and difference from the dry case, as well as various large-scale instabilities of these nonequilibrium states of matter, are highlighted. Further highlighted are various large-scale instabilities of these nonequilibrium states of matter. Various semimicroscopic derivations of the continuum theory are discussed and connected, highlighting the unifying and generic nature of the continuum model. Throughout the review, the experimental relevance of these theories for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material is discussed. Promising extensions toward greater realism in specific contexts from cell biology to animal behavior are suggested, and remarks are given on some exotic active-matter analogs. Last, the outlook for a quantitative understanding of active matter, through the interplay of detailed theory with controlled experiments on simplified systems, with living or artificial constituents, is summarized.

Hydrodynamics of soft active matter

■ Abstract Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and demographic models may be valuable for examining the introduction of invasive species and identifying life history stages where management will be most effective. Evolutionary processes may be key features in determining whether invasive species establish and spread. Studies of genetic diversity and evolutionary changes should be useful for

/pdf/the-population-biology-of-invasive-species-bdndjv53b3.pdf

The Population Biology of Invasive Species

Community ecology theory can be used to understand biological invasions by applying recent niche concepts to alien species and the communities that they invade. These ideas lead to the concept of ‘niche opportunity', which defines conditions that promote invasions in terms of resources, natural enemies, the physical environment, interactions between these factors, and the manner in which they vary in time and space. Niche opportunities vary naturally between communities but might be greatly increased by disruption of communities, especially if the original community members are less well adapted to the new conditions. Recent niche theory clarifies the prediction that low niche opportunities (invasion resistance) result from high species diversity. Conflicting empirical patterns of invasion resistance are potentially explained by covarying external factors. These various ideas derived from community ecology provide a predictive framework for invasion ecology.

/pdf/community-ecology-theory-as-a-framework-for-biological-2tep5nf3cd.pdf

Community ecology theory as a framework for biological invasions

Cuckoo parasitism in Nagano Prefecture in Japan has shown dramatic changes in the parasitism rate, host usage by the cuckoo, and defensive behavior of hosts during the past 60 yr. To gain insights into these phenomena, we model the population dynamics of a cuckoo-host association together with the population genetics of a rejecter gene in the host population. Analysis shows that both the dynamical change in the host-parasite association and the establishment of the host's counteradaptation crucially depend on the product of two factors, the carrying capacity of the host and cuckoo's searching efficiency. When the product is less than a critical value, the host population cannot evolve a counteradaptation even if parasitized by the cuckoo. Hence, the lack of counteradaptation does not necessarily imply that the host population only recently has become parasitized. As the product becomes larger, the rejection behavior will be eventually established at higher levels in the host population In this case, the s...

https://www.jstor.org/stable/pdfplus/2462718.pdf

Modeling the population dynamics of a cuckoo-host association and the evolution of host defenses.

The whole-colony morphology of the coral, Porites sillimaniani, varies dramatically in accordance with light intensity from plate-like shape to branching shape. To determine whether the variation is based on genetic difference or phenotypic plasticity, we conducted a field experiment by transplanting coral fragments taken from seven plate-like colonies to different light conditions. The fragments that transplanted to the high-light condition started to have branches in 8 mo period of the experiment, whereas those to the low-light condition remained to be flat. This result suggests that the morphological variation is the phenotypic plasticity in response to light availability. To examine the adaptive significance of this plasticity, a simple mathematical model of coral shape is constructed, in which the number of branches, their angles and lengths are morphological parameters. The circumference of the model coral is assumed to be uniformly covered with polyps. Each polyp survives if its light flux is larger than a certain threshold value. The optimal morphology that can support a maximum number of viable polyps is calculated for a given light intensity. The optimal coral shape changes with light intensity, which agrees qualitatively with the observation of P. sillimaniani colony in natural habitats.

Morphological plasticity in the coral Porites sillimaniani and its adaptive significance

An epidemic of pine wilt disease has been spreading in wide areas of Japan for nearly a century. The disease is caused by the pinewood nematode, Bursaphelenchus xylophilus, with the pine sawyer, Monochamus alternates, as vector. The spread of disease is facilitated by an obligatory mutualism between the nematode and the pine sawyer: the pine sawyer helps the nematode transmit to a new host tree, while the nematode supplies the pine sawyer with newly killed trees on which to lay eggs. We present a mathematical model to describe the host-vector interaction between pines and pine sawyers carrying nematodes, on the basis of detailed data on the population dynamics of pine sawyers and the incidence of pine wilt disease at a study site located on the northwest coast of Japan. We used the model to simulate the dynamics of the disease and predict how the epidemic could be controlled by eradication of the pine sawyer. The main results are as follows: (1) There is a minimum pine density below which the disease always fails in invasion. However, even if the pine density exceeds this minimum, the disease fails in invasion due to the Allee effect when the density of pine sawyers is very low. (2) The minimum pine density increases disproportionately with increase in the eradication rate. (3) The probability that a healthy tree will escape from infection until the epidemic dies out decreases sharply with increase in the initial pine density or the initial density of pine sawyers.

Modeling the spread of pine wilt disease caused by nematodes with pine sawyers as vector

Switching effect of predation on competitive prey species

The pinewood nematode, Bursaphelenchus xylophilus, is the causative agent of pine wilt of Pinus thunbergii and P. densiflora in Japan. The nematode is vectored by cerambycid beetles of the genus Monochamus. It is inferred to have been introduced from North America early in the 1900s and then to have distributed in China, Korea, and Taiwan. Intensive and/or long-term studies of pine wilt systems have elucidated the pattern and mechanism of the nematode’s spread within a pine stand, dispersal of vector beetles, and spread pattern of pine wilt within a prefecture. The modeling of nematode spread over pine stands, which involves beetle reproduction within a pine stand, has been developing and should elucidate the factors influencing the rate at which the nematode range expands. In this review, we summarize the biologies of the nematode, beetle, and tree, and then characterize the spread of the nematode within a pine stand, locally over pine stands, and regionally over unit administrative districts. Local and regional spreading of the nematode is related primarily to long-distance dispersal by insect vectors and to the artificial transportation of pine logs infested with the nematode and its vector, respectively.

Nanako Shigesada

Papers

Modeling the population dynamics of a cuckoo-host association and the evolution of host defenses.

Morphological plasticity in the coral Porites sillimaniani and its adaptive significance

Modeling the spread of pine wilt disease caused by nematodes with pine sawyers as vector

Switching effect of predation on competitive prey species

Spread of the pinewood nematode vectored by the Japanese pine sawyer: modeling and analytical approaches.