Intraspecific Variation Research Articles

Pressure-volume curves of fine roots reveal intraspecific variation across different elevations in a subalpine forest.

Water conservation in fine roots can be important for the adaptation of trees to cold, nutrient-poor ecosystems. Although pressure-volume (p-v) curve traits are commonly used to assess leaf water conservation, little is known about their intraspecific variation in fine roots and their association with root functional traits, such as morphology and chemistry. Here, we aimed to determine the p-v curve traits of Betula ermanii and Abies mariesii fine roots at 2,000 and 2,500m elevations and explore their intraspecific variation with root morphological and chemical traits in a subalpine forest. Turgor loss point (πtlp), relative water content at πtlp, osmotic potential at full hydration, and capacitance at full turgor (Cft) were evaluated as p-v curve traits. Additionally, root diameter, specific root length, and root tissue density (RTD) were assessed as morphological traits, and nitrogen (N) content was measured as a chemical trait. For A mariesii roots, the Cft was lower, and πtlp was more negative at 2,500m than at 2,000m. The p-v curve traits of B ermanii roots remained unchanged with elevation. There were strong correlations between RTD and πtlp and between N content and πtlp and Cft, especially for A. mariesii. These results indicated A. mariesii adjusted p-v curve traits with RTD and N content and achieved water conservation in fine roots at higher elevations. The p-v curve traits, particularly πtlp and Cft, reflected diverse tree strategies for environmental acclimation with fine-root carbon economy. Our findings highlighted the importance of adjusting water relation traits for acclimation to cold and nutrient-poor subalpine regions, particularly for evergreen coniferous species. The p-v curve traits revealed diverse fine-root water relation traits as a basis for water conservation capacity by preserving root function under stress conditions and enabling prolonged resource acquisition in a subalpine forest.

Diversity of beetles (Arthropoda, Insecta, Coleoptera) associated with coniferous forests in Honduras

Bark beetles are among the primary drivers of tree mortality in coniferous forests worldwide. Individuals belonging to the order Coleoptera were identified across different forest areas in Honduras. Descriptive statistics were used to calculate the number of families, subfamilies, genera, and species collected per department. Moreover, the barcoding approach was used by amplifying and sequencing the mitochondrial COI gene. The intraspecific genetic diversity of Ips apache was also analyzed. 1,131 individuals were examined and 27 genera were identified. Most of the specimens were identified as belonging to the genus Ips, accounting for 53.2% of the total. Xyleborus accounted for 16.5% and Temnoscheila accounted for 10%. Fewer than four individuals were found for fifteen genera. 68% of the specimens were identified to the species level, and all the specimens were identified to the genus level. Ips, Temnoscheila, Xyleborus, Hypothenemus, and Pityophthorus exhibited the most extensive geographic distribution among the sampled sites. At the genus level, Olancho, El Paraíso, and Copán displayed the highest diversity. This study also marks the first report of the genera Xylomeira and Stephanopachys in Honduran pine forests. Within I. apache, evidence of intraspecific genetic diversity was observed, although no population structure was detected. While this research provides an updated inventory of beetle species associated with Honduran coniferous forests, further taxonomic surveys and ecological studies are essential to better understand the spread and impact of bark beetles in pine ecosystems.

Intra-specific variation in mortality of even-aged Cryptomeria japonica (L. f.) D. Don. forests can be explained using relationships among long-term stand characteristics

ContextUnderstanding tree mortality is critical for sustainable forest management. Long-term tree mortality may differ depending on the stand development process and can be influenced by forest management regimes. Logistic regression is widely used to explain tree mortality based on site productivity, age, size, and competition. However, the explanatory variables are interrelated. Thus, we attempted to explain long-term Japanese cedar tree mortality by considering interrelated variables.AimsThe aim of this study was to elucidate the direct and indirect effects of site productivity, age, individual size, and competition on the long-term mortality of Japanese cedars.MethodsData were collected from 5130 even-aged Japanese cedar trees over approximately 50 years. We compared each variable between dead and living trees. We then constructed a mortality model using a conventional logistic approach and selected the best model for the stepwise methods. Finally, we applied a piecewise structural equation model (SEM) to identify these variables’ direct and indirect effects. We compared the conventional logistic model and piecewise SEM models and discussed the advantage of applying the SEM models.ResultsAnnual mortality was approximately 4% in the most fertile stands, increasing gradually with decreasing site fertility. Dead tree size and competition status differed according to age and site productivity. Competition, individual size, and stand density were selected for the best logistic model (area under the curve (AUC) = 0.74, Brier score = 0.042), whereas age and site productivity were not (p > 0.05). The piecewise SEM results showed that age and site productivity indirectly affected tree mortality through individual size and stand density (Fisher’s C = 4.569, p = 0.102).ConclusionLong-term Japanese cedar tree mortality can be explained by individual size and competition as direct influencing factors and age and site productivity as indirect influencing factors. This indicated that hidden factors cannot be explained using the conventional logistic approach. Further studies are required to explore the potential factors contributing to tree mortality thoroughly.

Cephisus siccifolia (Walker) (Hemiptera: Aphrophoridae): description of the immature and adult stages, including genital morphology, with notes on species delimitation challenges in the genus

Aphrophoridae is a worldwide distributed family, most diverse in the tropics and less represented in the Holartic region, including 157 genera and 925 species. The New World genus Cephisus currently comprises eight described species which are strongly homogeneous morphologically but have a considerable degree of intraspecific variation. Cephisus siccifolia is a species of potential economic interest which was recorded as a pest in cultures of Eucalyptus spp. in the state of Bahia, Brazil. Herein we describe and illustrate for the first time, in detail, the male and female genitalia of C. siccifolia as well as the immature stages from specimens collected on Tipuana tipu (Fabaceae) in the state of Paraná, Southern Brazil. A morphometric analysis is presented based on seven morphometric parameters to test measurements that can accurately help discriminate each nymphal stage. We also illustrate genital and general morphologic variations of Cephisus siccifolia and Cephisus spp., including specimens of a wide geographic sample, discussing the impacts of morphologic variation to the taxonomy of the genus and problems in species delimitation.

Female budgerigars prefer males with foraging skills that differ from their own

Foraging skills influence food intake and could therefore also play a role in mate choice decision. Previous empirical work has shown that individuals benefit from being in groups that include individuals with a variety of foraging skills as this increases foraging success. This idea, formalized in the skill-pool hypothesis, may extend to mate choice. Diverse foraging skills can expand the foraging niche of a pair and benefit offspring through enhanced parental provisioning, and exposure to a broader foraging skillset. To test this idea, we trained captive female and male budgerigars to solve one of two different novel foraging puzzle boxes. Then, females simultaneously observed two males that could solve either the same or the other box, and assessed female preferences in a binary mate choice apparatus. Females preferred males with foraging skills that differed from their own, independent of the skill type and the number of times males solved the foraging puzzle. These findings show that foraging skills can influence social preferences, including in a mate choice context, and support intraspecific diversity in foraging skills.

How do aboveground and belowground functional traits correlate with the demography of tree seedlings regenerated after landslide disturbances?

ABSTRACT Trait-based plant ecology is commonly used to study plant demography in forests, especially after disturbances. However, how functional traits affect the demography of regenerating seedlings after landslides remains largely unknown. This study conducted a 2-year monitoring of Abies sachalinensis (evergreen species) and Acer mono (deciduous species) seedlings dominantly regenerating in artificial landslide areas in northern Japan. We investigated the correlations between intraspecific variations in functional traits and two demographic properties (growth and mortality). We found that growth of evergreen tree seedlings was correlated with functional traits related to leaf and root construction costs and light capture capacity. However, there were no significant correlations between mortality and the functional traits for either species in the post-landslide forests. Our results emphasize the importance of both aboveground and belowground functional traits in understanding vegetation recovery after landslides. This work suggests that the intraspecific trait-demography relationships can vary depending on the demographic properties in post-landslide forests.

Intraspecific variation in the feeding habits of short-finned pilot whales based on blubber fatty acid profiles.

Understanding trophic interactions in deep-sea ecosystems is challenging and still largely unexplored. Here, fatty acid (FA) profiles were used as biochemical tracers to explore intraspecific feeding specialization in a deep-diving apex predator. The FA profiles of free-ranging short-finned pilot whale (Globicephala macrorhynchus) biopsies from two archipelagos (Canary Islands, n=30; Madeira Island, n=25) of the Macaronesia biogeographic region were determined to infer the dietary preferences, ecological adaptations, and population dynamics, considering geographic location, sex, and residency patterns (HIA: highly island-associated vs. "others": visitors or transients). Intraspecific variability (inferred through the representation of PERMANOVA analyses) was observed between HIA groups from the two archipelagos which exhibited distinct trophic niches. The "others" FA profiles largely overlapped with both groups, showing significant differences with HIA from the Canary Islands. This suggests that the "others" travel and forage across a broader area, likely encompassing these archipelagos. The differences between archipelagos were mainly attributed to a higher presence of the FA 20:1n-11 and 22:1n-11 in the animals from the Canary Islands, in contrast with a higher presence of 22:6n-3, 22:5n-3 and 20:5n-3 in the animals from Madeira. These findings suggest that short-finned pilot whales in Madeira may prefer a more pelagic diet, likely leveraging on nocturnal migrations of the Deep Scattering Layer and/or performing wider-ranging movements, while the animals in the Canary Islands may forage closer to the bottom and/or occupy a smaller core area. Overall, this study supports intraspecific feeding specialization by a deep-diving apex predator in two geographically related oceanic archipelagos.

Association between intraspecific variability and penicillin production in industrial strain, Penicillium chrysogenum revealed by RAPD and SRAP markers.

Penicillin represents antibiotic discovered for the first time that prevents bacterial infections. Production of penicillin using penicillin-producing fungi (Penicillium chrysogenum) mainly depends on activity of industrial strain, optimization of culture condition and purification efficiency. To contribute to management of penicillin-producing strains, we conducted phylogenetic study on 27 P. chrysogenum variants originated from industrial strain and selected on media supplemented with penicillin or phenylacetic acid (PAA) using 4 Random Amplified Polymorphic DNA (RAPD) primers and 2 Sequence-Related Amplified Polymorphic (SRAP) primer pairs. The UPGMA dendrogram distinguished 27 variants into 2 clusters at the genetic distance of 0.3, consistent with classification by penicillin titers of variants and supported by principal component analysis (PCA) and STRUCTURE analysis. These results suggest effectiveness of RAPD and SRAP markers in management of P. chrysogenum variants exhibiting different penicillin titers and may contribute to increase in penicillin production by enabling inoculation of confirmed industrial strain exhibiting high penicillin productivity at the beginning of culture.

Intraspecific divergence within Microcystis aeruginosa mediates the dynamics of freshwater harmful algal blooms under climate warming scenarios.

Intraspecific biodiversity can have ecosystem-level consequences and may affect the accuracy of ecological forecasting. For example, rare genetic variants may have traits that prove beneficial under future environmental conditions. The cyanobacterium responsible for most freshwater harmful algal blooms worldwide, Microcystis aeruginosa, occurs in at least three types. While the dominant type occurs in eutrophic environments and is adapted to thrive in nutrient-rich conditions, two additional types have recently been discovered that inhabit oligotrophic and eutrophic environments and have genomic adaptations for survival under nutrient limitation. Here, we show that these oligotrophic types are widespread throughout the Eastern USA. By pairing an experimental warming study with gene expression analyses, we found that the eutrophic type may be most susceptible to climate warming. In comparison, oligotrophic types maintained their growth better and persisted longer under warming. As a mechanistic explanation for these patterns, we found that oligotrophic types responded to warming by widespread elevated expression of heat shock protein genes. Reduction of nutrient loading has been a historically effective mitigation strategy for controlling harmful algal blooms. Our results suggest that climate warming may benefit oligotrophic types of M. aeruginosa, potentially reducing the effectiveness of such mitigation efforts. In-depth study of intraspecific variation may therefore improve forecasting for understanding future whole ecosystem dynamics.

Leaf Spectroscopy Reveals Drought Response Variation in Fagus sylvatica Saplings From Across the Species' Range

AbstractThe common European beech (Fagus sylvatica), sensitive to prolonged drought, is expected to shift its distribution with climate change. To persist in novel environments, young trees rely on the capacity to express diverse response phenotypes. Several methods exist to study drought effects on trees and their diverse adaptive mechanisms, but these are usually destructive and challenging for the large sample numbers needed to investigate biological variation. We conducted a common garden experiment outdoors, but under controlled watering conditions, with 180 potted 2‐year‐old saplings from 16 beech provenances across the species' range, representing three distinct genetic clusters. Drought stress was simulated by interrupting irrigation and stomatal conductance and soil moisture were used to assess drought severity. We measured leaf reflectance of visible to short‐wave infrared electromagnetic radiation to determine drought‐induced changes in biochemical and structural traits derived from spectral indices and a model of leaf optical properties. We quantified changes in pigmentation, water balance, nitrogen, lignin, epicuticular wax, and leaf mass per area in drought‐treated saplings, revealing differences in likely adaptive responses to drought. F. sylvatica saplings from the Iberian Peninsula showed signatures of greater drought resistance, that is, the least drought‐induced change in spectrally derived traits related to leaf pigments and leaf water content. We demonstrate that high‐resolution leaf spectroscopy is an effective and non‐destructive tool to assess individual drought responses that can characterize functional intraspecific variation among young beech trees. Next, this approach should be scaled up to canopy‐level or airborne spectroscopy to support drought response assessments of forests.

Effects of Bti on the diversity and community composition of three Chironomidae subfamilies across different micro-habitats.

The mosquito control agent Bacillus thuringiensis subsp. israelensis (Bti) is considered environmentally friendly due to its highly specific mode of action. Nevertheless, adverse effects of Bti have been observed in non-biting midges of the family Chironomidae. In this study, we applied the maximum field rate of Bti three times from April to May to six out of twelve floodplain pond mesocosms. Chironomidae larvae were sampled two weeks after the third application in three different micro-habitats and DNA metabarcoding was used to identify the larvae. We observed Bti effects on the Chironomidae subfamily Chironominae, while Tanypodinae and Orthocladiinae remained unaffected. The interspecific diversity of Chironominae was significantly reduced by 27% in the Bti treatment. Although the interaction between treatment and habitat was not significant, a notable decrease in interspecific diversity of Chironominae between the control and Bti treatment in two out of three micro-habitats was detected (47% and 41%, respectively). We observed a significant habitat-dependent change in intraspecific diversity of Chironominae, with a 28% decline in one habitat and a 21% increase in another. The Chironominae community composition differed between the control and Bti treatment in two out of three habitats. These outcomes highlight the variability of Bti's impact on Chironomidae communities across subfamilies and micro-habitats, potentially elucidating discrepancies reported in prior studies and emphasising the necessity for comprehensive risk assessments that encompass diversity at various taxonomic levels and environmental variation at different spatial scales.

Induction by caterpillars of stored and emitted volatiles in terpene chemotypes from populations of wild cotton (Gossypium hirsutum)

BackgroundUpland cotton (Gossypium hirsutum) plants constitutively store volatile terpenes in their leaves, which are steadily emitted at low levels. Herbivory leads to a greater release of these stored volatiles. Additionally, damaged plants increase the accumulation of volatile terpenes in their leaves and begin to synthesize and emit other terpenes and additional compounds. This has been well characterised for cultivated G. hirsutum, but little is known about volatile production in response to herbivory in wild populations. We investigated how damage by a generalist herbivore species, the beet armyworm (Spodoptera exigua), affects leaf-stored and emitted volatiles in wild G. hirsutum plants and compared the responses of two known chemotypes. Wild cotton plants were grown in a greenhouse from seeds collected from four distinct locations covering sixteen populations, along the Yucatan coast (Mexico), from where this cotton species originates. We assessed whether the differences in leaf terpene profiles between the two chemotypes persisted upon herbivory, in leaves and in headspace emissions, and whether these chemotypes also differed in the production and release of herbivory-induced volatiles. In addition to chemotypic variation, we further investigated intraspecific variation in the volatile response to herbivory among genotypes, populations, and the four geographic regions.ResultsThe difference between the two chemotypes persisted after herbivory in the stored volatile profile of induced leaves, as well as in the emissions from damaged plants. Therefore, wild cotton chemotypes may differ in their airborne interactions with their environment. The specific terpenes distinguishing these chemotypes showed a weak inducibility, raising questions about their functions. Herbivory triggered changes in stored and emitted volatiles similar to what is known for cultivated varieties of G. hirsutum. However, we report for the first time on the emission of volatile aldoximes by cotton plants, which were only detected in the headspace upon herbivory, and displayed chemotypic and interpopulation variation. Intraspecific variation was also observed in the induced emissions of nitriles and certain terpenes. Moreover, chemotypes differed in their induction of (E)-β-ocimene stored in the leaves.ConclusionsThis comprehensive insight into herbivore-induced volatiles of wild cotton reveals variation in production and emission among populations. A full understanding of their ecological role may help in the development of future pest-management strategies for cotton crops.

Integrative description of two new species of the Xenylla maritima species complex (Collembola: Hypogastruridae) from Crete (Greece), with notes on the high intraspecific genetic divergence found in X. maritima Tullberg, 1869

Integrative description of two new species of the Xenylla maritima species complex (Collembola: Hypogastruridae) from Crete (Greece), with notes on the high intraspecific genetic divergence found in X. maritima Tullberg, 1869

Convergent decoupling of individual specialization and niche width during ecological release.

Trophic niche has fundamental ecological importance, but many studies consider few niche metrics and most neglect critical structuring processes. Multiple processes shape trophic niches, including inter and intra-specific competition, predation and resource diversity. These processes interact and effects vary with time and taxa. The White Sands dunefield provides an ecological gradient ideal for understanding variation in niches. We measured population niche width, trophic position and individual specialization in four lizard species across habitats over 2years. The habitats include White Sands interior, the surrounding desert scrub, and their ecotone. We used arthropod, lizard and plant stable isotopes to quantify niches. We sampled lizard competitors, predators and prey as proxies for ecological processes. We found substantial variation in niches across populations but convergence between species. Individual specialization and population niche width were surprisingly decoupled. Specialization was highest in habitats with low species diversity (White Sands) and population niche width highest at intermediate diversity (ecotone). White Sands lizards may exhibit 'ultra partitioning'; high specialization alongside low individual niche widths. Population niche width is likely constrained within White Sands by low prey diversity. High ecotonal population niche widths may be due to fewer natural enemies than desert scrub but higher resource diversity than White Sands. Trophic position and specialization were positively correlated, suggesting stronger intraspecific competition at higher trophic levels. Prey diversity, inter and intra-specific competition, and predation all interacted to shape niches. Our results highlight the need for measuring multiple components of community structure and niches, as results are likely misleading in isolation.

Energy acquisition and allocation strategies in scleractinian corals: insights from intraspecific trait variability

Energy acquisition and allocation strategies in scleractinian corals: insights from intraspecific trait variability

Functional intraspecific variation in the base water potential for seed germination along soil microclimatic gradients

Functional intraspecific variation in the base water potential for seed germination along soil microclimatic gradients

Long-term impacts of salinity and temperature changes on Brachionus calyciflorus populations: understanding the role of intraspecific variability.

Worldwide, many coastal freshwater ecosystems suffer from seawater intrusion. In addition to this stressor, it is likely that the biota inhabiting these ecosystems will also need to deal with climate change-related temperature fluctuations. The resilience of populations to long-term exposure to these stressors will depend on their genetic diversity, a key for their adaptation to changing environments. Accordingly, this study aimed to understand the long-term effects of salinity and temperature on the population density dynamics of the rotifer Brachionus calyciflorus by considering intra-specific variability. Six clonal lineages of B. calyciflorus, exhibiting differential lethal sensitivity (LC50,24h) to salinity, were exposed for at least 34days, to a control and to artificial seawater (at a conductivity corresponding to the LC70,24h for the most tolerant clonal lineage = 9.89 mS/cm), under three temperatures: 17, 20 (standard) and 23°C. Long-term exposure to artificial seawater affected population densities, leading to the extirpation of some salinity-tolerant clonal lineages earlier than that of salinity-sensitive lineages. This inversion in short- and long-term sensitivity may suggest a higher susceptibility of populations when exposed to long periods of increased salinity. The negative effects caused by artificial seawater were enhanced at 17°C and 23°C, with an even earlier occurrence of extirpation of some clonal lineages, namely, two clonal lineages considered tolerant to artificial seawater. The results suggest the potential synergistic effects of the two abiotic stressors when combined. Overall, a lack of association between the clonal lineages' short- and long-term sensitivity to salinity or their sensitivity to salinity under different temperature scenarios was observed. These results suggest an increased risk to the resilience of B. calyciflorus populations exposed to climate change-related scenarios of increased salinity and temperature fluctuations owing to an enhanced reduction in their genetic variability.

Phenotypic Variation in Cone Scales and Seeds as Drivers of Seedling Germination Dynamics of Co-Occurring Cedar and Fir Species

The intraspecific trait variations in the reproductive structures and early growth of seedlings may be critical in determining further regeneration. However, modularly built organisms, such as trees, challenge our notion of the phenotype concept, as the arrays of nonidentical homologous organs, such as seed-bearing cone scales and seeds, depending on the individual capacity to produce phenotypically variable arrangements, but they also reflect abiotic selective effects. We investigated the variability in cone scale morphology, seed traits, and germination dynamics in coexisting fir (Abies marocana) and cedar (Cedrus atlantica) trees from northern Morocco. We quantified the degree of trait overlap in two co-occurring populations of both species, as a measure of population/species functional similarity. Cone scale size and seedling growth rate were species-dependent traits, as 70%–80% of the variance was explained by the species, while only 0%–2% was explained by the population. Conversely, seed weight was a tree-dependent trait, as 70% of the variation was observed among trees, while the species only explained 20% of the variation, and the contribution of the population was negligible. Species and populations showed the same characteristics in the correlations between variables, supporting different magnitudes but a constant relationship. Substantial variations in seed weight and early seedling growth occur concurrently among cones of a single tree, independently of the tree species or population. Further studies should consider both phenotype selection and inheritance of traits’ variance on the establishment, survival, and growth of seedlings in A. marocana and C. atlantica in nurseries and reforestation sites to improve adaptive capacity to changing environmental conditions.

Scanning electron microscopy analysis of the developmental, inter‐ and intraspecific variation in the otoliths of Anguilla anguilla (Linnaeus, 1758) collected from Bafa Lake in Western Anatolia, Türkiye

AbstractThis study aimed to identify unique traits, grounded in a thorough description of the sagitta otolith of Anguilla anguilla, to characterize its ontogenetic stages between juvenile and preadult individuals. Twenty‐one characteristics were designated to investigate the ontogenetic (when comparing the otolith characteristics of fishes of different sizes, interspecific variation (comparing the otolith characteristics of the studied species with those of related species), and intraspecific variation (comparing the otolith characteristics of the studied species with those of the same species from different localities, i.e. geographical variation). This investigation concluded that the sagittal otoliths exhibited ontogenetic disparities based on the shapes recorded by different age groups. Otoliths of the young individuals belonging to fish total length groups GI and GII have shown differences in shape from those of the older individuals in the other seven length groups surveyed. An assessment of previously available otolith descriptions of A. anguilla collected from other areas revealed differences between species across larger geographic areas, making some features unsuitable for further investigation. However, other otolith traits were found to be reliable across different length groups and could be considered species‐specific features for identification. These traits include otolith width, otolith thickness, the shape of the mesial and lateral surfaces, the shape of the sulcus acusticus, the presence or absence of ostio‐caudal differentiation, and the shape, size, and thickness of the rostrum.

DNA barcoding reveals larval fish diversity and distribution along the Cibareno River (West Java, Indonesia)

Context There is a global problem with ongoing riverine infrastructure projects where, despite knowledge of potential environmental impacts, there is rapid development, often without appropriate environmental safeguards. This results in fragmentation of riverine fish communities, especially diadromous species. Understanding freshwater fish larval ecology is critical to provide insight into the likely impacts of these projects. Aims To assess fish larval biodiversity on the basis of DNA barcoding, abundance and its distribution pattern in the Cibareno River. Methods Fish larvae were collected at six locations in the Cibareno River. The larvae were identified by DNA barcoding. Key results A notable disparity was seen in the distribution of larval abundance in different locations. The non-native species, Poecilia reticulata, was the most abundant larval species, with an intraspecific diversity of 0.003 (99.7% similarity). The upstream area exhibited a lower level of larval species diversity than did the downstream area. Conclusions Genetic identification can reliably identify fish larvae and determine their spatial riverside distribution in the Cibareno River. The conservation of connectivity maintains fish community integrity and diversity between upstream and downstream locations in the weir building plan. Implications This discovery emphasises the relevance of larval identification in fish biodiversity assessment and sustainable fisheries resource monitoring.