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Germination behavior is one of the earliest phenotypes expressed by plants. This fact has several consequences for the evolution of postgermination traits, ecological niches, and geographic ranges. By determining the conditions that plants experience after they germinate, germination influences phenotypic expression of postgermination traits, natural selection on them, and their genetic basis. The breadth of germination niches may influence the ecological breadth and geographic ranges of species. Because germination is expressed early, it is frequently subjected to natural selection before other traits are expressed. We review evidence for natural selection on and adaptation of germination and discuss how the breadth of the germination niche is associated with the ecological niche and range of plant species. We review evidence for the coevolution of germination and postgermination traits and compare germination to postgermination niches. Finally, we discuss how germination responses to altered environments can influence species distribution and the evolution of postgermination traits after environmental change.

Identifying the processes that maintain highly diverse plant communities remains a central goal in ecology. Species variation in growth and survival rates across ontogeny, represented by tree size classes and life history stage‐specific niche partitioning, are potentially important mechanisms for promoting forest diversity. However, the role of ontogeny in mediating competitive dynamics and promoting functional diversity is not well understood, particular in high‐diversity systems such as tropical forests. The interaction between interspecific functional trait variation and ontogenetic shifts in competitive dynamics may yield insights into the ecophysiological mechanisms promoting community diversity. We investigated how functional trait (seed size, maximum height, SLA, leaf N, and wood density) associations with growth, survival, and response to competing neighbors differ among seedlings and two size classes of trees in a subtropical rain forest in Puerto Rico. We used a hierarchical Bayes model of diameter growth and survival to infer trait relationships with ontogenetic change in competitive dynamics. Traits were more strongly associated with average growth and survival than with neighborhood interactions, and were highly consistent across ontogeny for most traits. The associations between trait values and tree responses to crowding by neighbors showed significant shifts as trees grew. Large trees exhibited greater growth as the difference in species trait values among neighbors increased, suggesting trait‐associated niche partitioning was important for the largest size class. Our results identify potential axes of niche partitioning and performance‐equalizing functional trade‐offs across ontogeny, promoting species coexistence in this diverse forest community.

Epiphytic bromeliads represent a major component of Neotropical forests, but the potential effect of climate change on these plants is unclear. We investigated whether and how bromeliads are affected by the predicted 3°C temperature rise by the end of the century. We conducted growth experiments with 17 epiphytic bromeliad species at different temperatures to determine their fundamental thermal niches. By comparing those with niches for germination, we tested whether ontogenetic niche shift or niche contraction occurs in Bromeliaceae. Applying a classical growth analysis, we assessed the relative importance of the underlying growth components on interspecific variations in growth. Members of two bromeliad subfamilies differed in their response to elevated temperatures: Tillandsioideae may be negatively affected, whereas Bromelioideae moved closer to their thermal optimum. Across different ontogenetic stages, thermal niche characteristics revealed both niche shift and niche contraction. Interspecific variation in growth was driven almost exclusively by net assimilation rate at all temperatures. We conclude that the vulnerability of tropical plants to a future increase in temperature may be more variable than suggested by previous studies. We emphasize the importance of assessing niche breadth over multiple life stages and the need for better microclimatic data to link laboratory data with field conditions.

Stable isotope analysis (SIA) is a powerful tool for assessing resource use and trophic structure, enhancing understanding of coexistence mechanisms among sympatric species. In this study, we analyzed carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes in bone collagen of three coexisting anuran species— Bombina orientalis , Rana uenoi , and R. huanrenensis —from South Korean forest to evaluate their isotopic niches, resource partitioning, and within-population variation. Rana uenoi and R. huanrenensis utilized a broad range of resources with high overlap, suggesting they likely share dietary habits and occupy similar trophic roles. In contrast, relative δ¹⁵N enrichment of B. orientalis indicates a distinct trophic niche, although its resource utilization was not entirely segregated from that of the two Rana species. Furthermore, large groups of both Rana species tended to exploit a wider variety of resources than smaller ones, whereas B. orientalis showed no isotopic sex differences. All three species displayed ontogenetic niche shifts, with B. orientalis increasingly relying on aquatic-origin resources, while the two Rana species shifting toward terrestrial-origin resources. These findings provide insight into the trophic dynamics of forest-dwelling anurans and may serve as a baseline for ecological and conservation research in the future.

Consumers can influence ecological patterns and processes through their trophic roles and contributions to the flow of energy through ecosystems. However, the diet and associated trophic roles of consumers commonly change during ontogeny. Despite the prevalence of ontogenetic variation in trophic roles of most animals, we lack an understanding of whether they change consistently across local populations and broad geographic gradients. We examined how the diet and trophic position of a generalist marine predator varied with ontogeny across seven broadly separated locations (~ 750 km). We observed a high degree of heterogeneity in prey consumed without evidence of spatial structuring in this variability. However, compound-specific isotope analysis of amino acids revealed remarkably consistent patterns of increasing trophic position through ontogeny across local populations, suggesting that the roles of this generalist predator scaled with its body size across space. Given the high degree of diet heterogeneity we observed, this finding suggests that even though the dietary patterns differed, the underlying food web architecture transcended variation in prey species across locations for this generalist consumer. Our research addresses a gap in empirical field work regarding the interplay between stage-structured populations and food webs, and suggests ontogenetic changes in trophic position can be consistent in generalist consumers.

Key messageSpecific leaf area (SLA, cm2g− 1) is a fundamental leaf economics spectrum trait, which predicted the total carbon sequestered at the individual level in understory palms of Socratea exorrhiza.Evaluating intraspecific and ontogenetic variation in SLA is critical to understand how functional traits influence plant fitness and regeneration strategies. SLA is usually expressed as an average value per species. Its variation across ontogenetic stages and environmental gradients is poorly known, particularly in palms. I measured SLA in 112 palms of Socratea exorrhiza in the understory of a tropical rainforest in Costa Rica. Total carbon content sequestered per palm (kg) was estimated from an allometric equation. I determined the regression between Ln SLA and Ln carbon content, and then used principal components to summarize the regeneration strategy of S. exorrhiza by examining the allometry of stem length and diameter, number of fronds, number of stilt roots, stilt root cone height, slenderness ratio, SLA, and carbon content. SLA predicted total sequestered carbon (slope = − 4.33, r2 = 0. 52). Smaller values of SLA were associated with increased carbon content and larger palms. Two components explained 77% of the variation in functional traits. The first (76%) was dominated by stem diameter, height, stilt root cone, and carbon content (negatively associated with SLA) and reflected palm size; the second (15%) was dominated by slenderness ratio and number of leaves and reflected allocation to growth in height. The inverse relationship between SLA and sequestered carbon is consistent with the initial shade tolerant, conservative resource use strategy of S. exorrhiza.

Recent climate warming has fueled interest into climate-driven range shifts of tree species. A common approach to detect range shifts is to compare the divergent occurrences between juvenile and adult trees along environmental gradients using static data. Divergent occurrences between life stages can, however, also be caused by ontogenetic effects. These include shifts of the viable environmental conditions throughout development ('ontogenetic niche shift') as well as demographic dependencies that constrain the possible occurrence of subsequent life stages. Whether ontogenetic effects are an important driver of divergent occurrences between juvenile and adult trees along large-scale climatic gradients is largely unknown. It is, however, critical in evaluating whether impacts of environmental change can be inferred from static data on life stage occurrences. Here, we first show theoretically, using a two-life stage simulation model, how both temporal range shift and ontogenetic effects can lead to similar divergent occurrences between adults and juveniles (juvenile divergence). We further demonstrate that juvenile divergence can unambiguously be attributed to ontogenetic effects, when juveniles diverge from adults in opposite direction to their temporal shift along the environmental gradient. Second, to empirically test whether ontogenetic effects are an important driver of divergent occurrences across Europe, we use repeated national forest inventories from Sweden, Germany and Spain to assess juvenile divergence and temporal shift for 40 tree species along large-scale climatic gradients. About half of the species-country combinations had significant juvenile divergences along heat sum and water availability gradients. Only a quarter of the tree species had significant detectable temporal shifts within the observation period. Furthermore, significant juvenile divergences were frequently associated with opposite temporal shifts, indicating that ontogenetic effects are a relevant cause of divergent occurrences between life stages. Our study furthers the understanding of ontogenetic effects and challenges the practice of inferring climate change impacts from static data.

Accounting for the variation that occurs within species in food webs can theoretically result in significant changes in both network structure and dynamics. However, there has been little work exploring their role with empirical data. In particular, the variation associated with species’ life cycles, which is prevalent and represents both trait variation and taxonomic identity, has received little attention. Here, we characterize the structural consequences of life stage variation in five food webs, including a newly compiled web from the Arabian Gulf. We show that making life stage variation explicit in food webs results in larger food webs that possess consistent structural changes that are separate from the changes in structure that come simply from increasing the number of nodes in the webs. Furthermore, we show that the magnitude of these changes is related to ontogenetic specialism, the degree of overlap in the ecological niches of life stages. These results demonstrate the capacity of intraspecific variation to affect ecological networks and indicate the potential usefulness of stage-structured food webs, which capture size and taxonomic information, to represent variation below the species level.

Spatial and temporal variation can confound interpretations of relationships within and between species in terms of diet composition, niche size, and trophic position (TP). The cause of dietary variation within species is commonly an ontogenetic niche shift, which is a key dynamic influencing community structure. We quantified spatial and temporal variations in ringed seal (Pusa hispida) diet, niche size, and TP during ontogeny across the Arctic—a rapidly changing ecosystem. Stable carbon and nitrogen isotope analysis was performed on 558 liver and 630 muscle samples from ringed seals and on likely prey species from five locations ranging from the High to the Low Arctic. A modest ontogenetic diet shift occurred, with adult ringed seals consuming more forage fish (approximately 80 versus 60 %) and having a higher TP than subadults, which generally decreased with latitude. However, the degree of shift varied spatially, with adults in the High Arctic presenting a more restricted niche size and consuming more Arctic cod (Boreogadus saida) than subadults (87 versus 44 %) and adults at the lowest latitude (29 %). The TPs of adult and subadult ringed seals generally decreased with latitude (4.7–3.3), which was mainly driven by greater complexity in trophic structure within the zooplankton communities. Adult isotopic niche size increased over time, likely due to the recent circumpolar increases in subarctic forage fish distribution and abundance. Given the spatial and temporal variability in ringed seal foraging ecology, ringed seals exhibit dietary plasticity as a species, suggesting adaptability in terms of their diet to climate change.

White sharks undergo pronounced ecological and dietary shifts across ontogeny, and their teeth play a central role in mediating these changes. Understanding the complexity within shark tooth and jaw mechanics, plus the fine‐scale tooth morphology, can provide insights into how feeding strategies and, hence, dietary niches and ecological function evolve with age and size. These morphological changes underpin ontogenetic niche shifts, revealing how functional adaptations in dentition enable white sharks to exploit different prey resources throughout development. This study provides novel insights into the ontogenetic and positional variation in C. carcharias dentition, integrating both Elliptic Fourier Analysis (EFA) and traditional morphometric approaches. We reveal significant patterns of tooth morphology that vary with jaw position and ontogenetic stage, reflecting functional adaptations to changing dietary and biomechanical demands. A key ontogenetic shift was identified as teeth transitioned from narrow, cuspidate forms with accessory cusplets in juveniles to broader, serrated teeth in larger individuals. We found no significant differences in tooth morphology between sexes, aligning with known similarities in diet and body shape in the eastern Australian white shark population. Significant anterior‐to‐posterior variation in tooth form was observed within the jaw, with lateral teeth becoming more compressed and recurved, suggesting functional transitions in prey handling throughout the jaw. Additionally, we documented structural changes in jaw morphology at approximately 210 cm PCL, corresponding to broader teeth and increased bite capacity. These shifts likely reflect developmental milestones in feeding capability, supporting the transition from a solely piscivorous diet to the inclusion of marine mammal prey. White sharks exhibit distinct ontogenetic shifts in tooth morphology that underpin changes in diet and ecological function. Using Elliptic Fourier Analysis and traditional morphometrics, we reveal significant variation in dentition across jaw position and developmental stage, with a major transition occurring at 210 cm PCL and at the sixth tooth within the jaw. These findings highlight functional adaptations in feeding strategies that support shifts from piscivory to marine mammal predation.