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Determining whether pollination occurs competitively or rather facilitatively among co‐flowering plants is a central question in plant reproductive ecology. Kobayashi [2018; Journal of Ecology 107: 1433–1438] theoretically investigated the scenario in which intraspecific pollen tube competition (male–male competition) can lead to regulation of population growth due to reduced female success. Kobayashi (2018) showed that evolutionary dynamics in intraspecific pollen tube competition can reduce female success and consequently generate negative density‐dependence of population growth, which allows for numerous species to coexist in a spatially subdivided metacommunity. Kobayashi (2018) hypothesized that trait evolution driven by sexual selection may maintain biodiversity. However, the models proposed by Kobayashi (2018) allow for the assumptions to be relaxed; he assumed: (i) fully global seed dispersal (instead of limited dispersal, albeit the spatial subdivision), (ii) fully local pollination (i.e., pollination occurred exclusively within patches), (iii) selfing rate was exactly proportionate (i.e., pollen grains distributed equally among all individuals within a patch, irrespective of their parental origins), (iv) haploid mode of inheritance, and most importantly, (v) each individual was mutually competitive, rather than facilitative for pollination. Here, I extend the models of Kobayashi (2018) and show that when I relax assumptions (i)–(v), facilitativeness, as opposed to competitiveness, is more likely to be favoured by selection. The present results are attributed to kin selection in gametopythic competition among relatives in spatially subdivided populations. If facilitativeness for pollination is favoured by kin selection, then the premise that the evolution of pollen traits can generate negative density‐dependence does not necessarily follow. I also discuss the potential mechanisms by which pollen phenotypes can either strengthen or attenuate intraspecific and interspecific competition. Flowering plants undergo two modes of dispersal, namely pollen‐ and seed‐dispersal. These may each contribute to makeup of genetic structure in space. How shall we model kin selection in plants under such two modes of dispersal? This article attempts to generalize Kobayashi's (2018) recent modeling work by incorporating both dispersal methods, and aims at drawing more attention to eco‐evolutionary dynamics in spatially structured plant populations.

Negative interspecific mating interactions, known as reproductive interference, can hamper species coexistence in a local patch and promote niche partitioning or geographical segregation of closely related species. Conspecific sperm precedence (CSP), which occurs when females that have mated with both conspecific and heterospecific males preferentially use conspecific sperm for fertilization, might contribute to species coexistence by mitigating the costs of interspecific mating and hybridization. We discussed whether two species exhibiting CSP can coexist in a local environment in the presence of reproductive interference. First, using a behaviorally explicit mathematical model, we demonstrated that two species characterized by negative mating interactions are unlikely to coexist because the costs of reproductive interference, such as loss of mating opportunity with conspecific partners, are inevitably incurred when individuals of both species are present. Second, we experimentally examined differences in mating activity and preference in two Harmonia ladybird species known to exhibit CSP. These behavioral differences may lead to local extinction of H. yedoensis because of reproductive interference by H. axyridis. This prediction is consistent with field observations that H. axyridis uses various food sources and habitats whereas H. yedoensis is confined to a less preferred prey item and a pine tree habitat. Finally, by a comparative approach, we observed that niche partitioning or parapatric distribution, but not sympatric coexistence in the same habitat, is maintained between species with CSP belonging to a wide range of taxa, including vertebrates and invertebrates living in aquatic or terrestrial environments. Taken together, it is possible that reproductive interference may destabilize local coexistence even in closely related species that exhibit CSP. We discussed whether two closely related species exhibiting conspecific sperm precedence can coexist in a local environment in the presence of reproductive interference. We used mathematical models, behavioral experiment, and comparative study. We suggested that conspecific sperm precedence does not reduce the overall cost of reproductive interference sufficiently to allow the interacting species to coexist in the same local environment.

Ecological and evolutionary processes show various population dynamics depending on internal interactions and environmental changes. While crucial in predicting biological processes, discovering general relations for such nonlinear dynamics has remained a challenge. Here, we derive a universal information-theoretical constraint on a broad class of nonlinear dynamical systems represented as population dynamics. The constraint is interpreted as a generalization of Fisher’s fundamental theorem of natural selection. Furthermore, the constraint indicates nontrivial bounds for the speed of critical relaxation around bifurcation points, which we argue are universally determined only by the type of bifurcation. Our theory is verified for an evolutionary model and an epidemiological model, which exhibit the transcritical bifurcation, as well as for an ecological model, which undergoes limit-cycle oscillation. This work paves a way to predict biological dynamics in light of information theory, by providing fundamental relations in nonequilibrium statistical mechanics of nonlinear systems. In evolutionary theory, Fisher’s fundamental theorem of natural selection establishes a simple relation between the variance of the growth rate and the temporal increase in the average growth rate. Here, the authors extend the theorem based on statistical physics and information theory and show that the speed in dynamical systems describing nonlinear population dynamics is bounded by Fisher information with universal limit exponents only depending on the kind of bifurcation and not on the specific systems.

Hamilton's local mate competition theory provided an explanation for extraordinary female‐biased sex ratios in a range of organisms. When mating takes place locally, in structured populations, a female‐biased sex ratio is favored to reduce competition between related males, and to provide more mates for males. However, there are a number of wasp species in which the sex ratios appear to more female biased than predicted by Hamilton's theory. It has been hypothesized that the additional female bias in these wasp species results from cooperative interactions between females. We investigated theoretically the extent to which cooperation between related females can interact with local mate competition to favor even more female‐biased sex ratios. We found that (i) cooperation between females can lead to sex ratios that are more female biased than predicted by local competition theory alone, and (ii) sex ratios can be more female biased when the cooperation occurs from offspring to mothers before dispersal, rather than cooperation between siblings after dispersal. Our models formally confirm the verbal predictions made in previous experimental studies, which could be applied to a range of organisms. Specifically, cooperation can help explain sex ratio biases in Sclerodermus and Melittobia wasps, although quantitative comparisons between predictions and data suggest that some additional factors may be operating.

The impact of infectious disease is often very different in juveniles and adults, but theory has focused on the drivers of stage‐dependent defense in hosts rather than the potential for stage‐dependent virulence evolution in parasites. Stage structure has the potential to be important to the evolution of pathogens because it exposes parasites to heterogeneous environments in terms of both host characteristics and transmission pathways. We develop a stage‐structured (juvenile–adult) epidemiological model and examine the evolutionary outcomes of stage‐specific virulence under the classic assumption of a transmission‐virulence trade‐off. We show that selection on virulence against adults remains consistent with the classic theory. However, the evolution of juvenile virulence is sensitive to both demography and transmission pathway with higher virulence against juveniles being favored either when the transmission pathway is assortative (juveniles preferentially interact together) and the juvenile stage is long, or in contrast when the transmission pathway is disassortative and the juvenile stage is short. These results highlight the potentially profound effects of host stage structure on determining parasite virulence in nature. This new perspective may have broad implications for both understanding and managing disease severity.

Understanding how community assembly during the initial faunization phases determines the difference in species richness is a fundamental question in ecology. However, there are few predictions for when and to what degree the differences in species richness between subcommunities will emerge. Here, we investigate the expectation of richness difference in a pair of subcommunities, assuming that species may have different and independent presence probabilities. We then introduce several indices and examine how expected richness difference is determined by the indices. We found that (i) species differences (the average of species presence probabilities in two subcommunities divided by the total presence probability) have inconsistent effects on richness difference; (ii) the degree of spatial heterogeneity (average of differences in species presence probabilities in two subcommunities across species) may, but not always, have a good predictive ability for richness difference; and (iii) the absolute difference in average presence probabilities (site-suitability difference) has robust predictive ability for richness difference unless richness difference is very small. This work provides a theoretical framework for predicting and analyzing species richness difference from presence-absence data based on null models.Competing Interest StatementThe authors have declared no competing interest.Footnotes* Some technical errors corrected.

The puzzling sex ratio behavior of Melittobia wasps has long posed one of the greatest questions in the field of sex allocation. Laboratory experiments have found that, in contrast to the predictions of theory and the behavior of numerous other organisms, Melittobia females do not produce fewer female-biased offspring sex ratios when more females lay eggs on a patch. We solve this puzzle by showing that, in nature, females of Melittobia australica have a sophisticated sex ratio behavior, in which their strategy also depends on whether they have dispersed from the patch where they emerged. When females have not dispersed, they lay eggs with close relatives, which keeps local mate competition high even with multiple females, and therefore, they are selected to produce consistently female-biased sex ratios. Laboratory experiments mimic these conditions. In contrast, when females disperse, they interact with nonrelatives, and thus adjust their sex ratio depending on the number of females laying eggs. Consequently, females appear to use dispersal status as an indirect cue of relatedness and whether they should adjust their sex ratio in response to the number of females laying eggs on the patch.

A fundamental problem in ecology is understanding the changes in species composition among sites (i.e. beta-diversity). It is unclear how spatial heterogeneity in species occupancy across sites shapes patterns of beta-diversity. To address this question, we develop probabilistic models that consider two spatial or temporal sites, where presence probabilities vary both among species and between the sites. We derive analytical and approximate formulae for the expectation of pairwise beta-diversity. Using a graphical tool, stochastic incidence plots (SIPs), which depict the presence probabilities in two sites along species labels, we develop a means to conceptualize the heterogeneity in presence probabilities: the steepness or unevenness of SIPs reflects species-level heterogeneity, while the degree of overlap between SIPs indicates site-level heterogeneity. We find that when SIPs completely overlap (i.e. two sites have the same presence probability for each species), flat SIPs - with all species having the same presence probability - maximize the expected beta-diversity. We refer to this prediction as the ‘transfer principle for beta'. Second, using SIPs and the probabilistic method in a two-species scenario, we demonstrate that beta-diversity is lower when SIPs are parallel compared to when they are anti-parallel. We also find that this prediction is consistent with the well-known checkerboard pattern in incidence matrices. Finally, we apply the method to the species distribution models for five woodpecker species in Switzerland, showing that their spatial distributions will change significantly. Overall, this work improves our understanding of how pairwise beta-diversity responds to occupancy heterogeneity

Abstract Hamilton’s local mate competition theory provided an explanation for extraordinary female biased sex ratios in a range of organisms. When mating takes place locally, in structured populations, a female biased sex ratio is favoured to reduce competition between related males, and to provide more mates for males. However, there are a number of wasp species where the sex ratios appear to more female biased than predicted by Hamilton’s theory. We investigated theoretically the extent to which cooperative interactions between related females can interact with local mate competition to favour even more female biased sex ratios. We found that: (i) cooperative interactions between females can lead to sex ratios that are more female biased than predicted by local competition theory alone; (ii) sex ratios can be more female biased when the cooperative interactions are offspring helping parents before dispersal, rather than cooperation between siblings after dispersal. Our results can be applied to a range of organisms, and provide an explanation for the extreme sex ratio biases that have been observed in Sclerodermus and Melittobia wasps. Competing Interest Statement The authors have declared no competing interest. Footnotes * Thorough revision following reviewers' comments

Parasitoid wasps exhibit remarkable diversity in life-history traits and are categorized into two major groups based on the timing of emergence: those that begin consuming host tissues immediately after hatching (\"idiobiont\") and those that can delay the emergence depending on host maturation (\"koinobiont\"). Although delayed emergence allows parasitoids to exploit unparasitized, young hosts, it incurs a mortality cost during the waiting period. While numerous empirical studies have examined the adaptive significance of this trait, how host stage-structure and ecological factors jointly shape the evolution of emergence timing remains poorly understood in a formalized context. Here, we develop a stage-structured mathematical model to analyze the evolutionary dynamics of delayed emergence and its consequences for host exploitation. By explicitly incorporating host developmental stages, our model explores the joint evolution of two traits: the preference for young versus old host, and the timing of emergence. Our results reveal that the optimal strategy is determined by the relative reproductive value of host stages, which depends on the balance between host growth and mortality. We demonstrate that delayed emergence evolves when the future value of a growing host outweighs the immediate cost of mortality, thereby driving the divergence between idiobiont and koinobiont strategies. These findings provide a theoretical framework that unifies the diversity of parasitoid life histories.Competing Interest StatementThe authors have declared no competing interest.Footnotes* We have restructured the narrative of our study after identifying empirical studies on the same topicFunder Information DeclaredJapan Society for the Promotion of Science, 20K15882, 24H01528, 24H02291Mathematics-Based Creation of Science Program (MACS program; Kyoto University)