Intraspecific Phenotypic Plasticity Research Articles

Morpho-anatomical and molecular characterization indicates overlooked taxonomic diversity in the Antarctic genus Hymenocladiopsis (Rhodymeniales, Rhodophyta)

ABSTRACT Wide morphological variation has been described in the Antarctic macroalga Hymenocladiopsis prolifera, suggesting that there could be overlooked taxonomic diversity in the genus Hymenocladiopsis, which is currently considered to be monotypic. To clarify the taxonomy of the genus, morpho-anatomical and reproductive characters of specimens of Hymenocladiopsis were evaluated and genetic analyses were performed using the molecular markers COI-5P and rbcL. Our results indicate the presence of two groups within the Hymenocladiopsis samples, clearly differentiated both genetically and anatomically, which correspond to two distinct but closely related species. We described the main morpho-anatomical differences between these two species, and we recognized a name for each of them: H. prolifera (Reinsch) M.J. Wynne and H. crustigena R.L. Moe. Our results also indicate the occurrence of two morphotypes within H. crustigena specimens that are genetically identical but morphologically different, this variability being allegedly explained by a wide range of intraspecific phenotypic plasticity.

De novo transcriptome assembly for two color types of the marine sponge Mycale (Carmia) cecilia.

Despite the ecological importance and the potential pharmacological application of the sponge Mycale (Carmia) cecilia, it is uncertain whether the body-color variation, even in individuals coexisting in the same area, is due to intraspecific phenotypic plasticity or corresponds to taxonomic divergence. This uncertainty is relatively common in several Porifera groups, which lack the resolution of morphological diagnostic characters and slow-evolving mitochondrial genomes as occurs in early splitting lineages. We sequenced the RNA of six individuals with two different body-color (green-morphotype and red-morphotype) collected at the same time side by side. High-throughput sequencing of cDNA libraries produced ~ 129 million reads with a length of 150bp. Each morphotype was assembled separately owing to the low overlapping in the global assembly. Metatranscriptome de novo assembly of the trimmed and normalized reads produced 461 thousand transcripts for the green-morphotype and 342 thousand for the red-morphotype (respectively). Over 30% of the transcripts contained Open Reading Frames (ORFs) with functional significance. BUSCO analysis of the ORFs of putative poriferan origin (31.3% green or 30.4% red) indicated that our assemblies are 60% complete. This is the first attempt to evaluate the morphological diversity in the species M. (C.) cecilia and the phylum Porifera at the transcriptomic level. Due to the minimum overlap of the assembly and that, the red-morphotype diverged significantly from the green-morphotype (original color of M. (C.) cecilia). Therefore, we suggest that the red-morphotype should undergo a complete taxonomic investigation and its taxonomic status be reviewed. We expect that the transcriptome assembly metrics can be useful for comparing other transcriptome assemblies of non-model organisms.

Interspecific and intraspecific phenotypic diversity for drought adaptation in bioenergy Arundo species.

Biomass crops are commonly grown in low‐grade land and selection of drought‐tolerant accessions is of major importance to sustain productivity. In this work, we assess phenotypic variation under different environmental scenarios in a series of accessions of Arundo donax, and contrast it with two closely related species, Arundo donaciformis and Arundo plinii. Gas‐exchange and stomatal anatomy analysis showed an elevated photosynthetic capacity in A. plinii compared to A. donax and A. donaciformis with a significant intraspecific variation in A. donax. The three species showed significantly contrasting behaviour of transpiration under developing water stress and increasing vapour pressure deficit (VPD), with A. donax being the most conservative while A. plinii showed an elevated degree of insensitivity to environmental cues. Under optimal conditions, A. donax had the highest estimated leaf area (projected leaf area) and plant dry weight although a significant reduction under water stress was observed for A. donax and A. donaciformis accessions while no differences were recorded for A. plinii between optimal growing conditions (well‐watered [WW]) and reduced soil water availability (water‐stressed [WS]). A. donax displayed a markedly conservative water use behaviour but elevated sensitivity of biomass accumulation under stress conditions. By contrast, in A. plinii, biomass and transpiration were largely insensitive to WS and increasing VPD, though biomass dry weight under optimal conditions was significantly lower than A. donax. We provide evidence of interspecific phenotypic variation within the Arundo genus while the intraspecific phenotypic plasticity may be exploited for further selection of superior clones under disadvantageous environmental conditions. The extensive trade‐off between water use and biomass accumulation present in the three species under stress conditions provides a series of novel traits to be exploited in the selection of superior clones adapted to different environmental scenarios. Non‐destructive approaches are provided to screen large populations for water‐stress‐tolerant A. donax clones.

Intraspecific differences of Asian/Australian Phragmites australis subgroups reveal no potentially invasive traits

Phragmites australis is a cosmopolitan plant species with high intraspecific diversity and phenotypic plasticity. Due to its variability and large ecological niche breadth, subgroups of P. australis have become invasive in North America, and this invasion has been recognized late. While this cryptic invasion on the American continent has received much attention, little is known about the potential invasiveness of other subgroups, especially within Asian/Australian P. australis. We therefore compared the performance of three subgroups within the Asian/Australian group: a freshwater (CN) and an estuarine (YRD) subgroup collected in China and a genetically closely related subgroup collected from Australia (FEAU), grown in two common gardens in China. Our results showed that the FEAU subgroup had no strong invasive potential, as its total biomass, height, shoot number, specific leaf area, and stomatal conductance were lower than that of the two native subgroups. All three subgroups responded similarly with most traits to the different climates of the gardens, albeit with different response strength, expressed as phenotypic plasticity indices. The potential cryptic invasion risk of the FEAU subgroup in China seems to be low, since its functional traits showed low competitiveness and most traits with the lowest plasticity occurred in FEAU. However, caution is still advised, because other invasive mechanisms, such as enemy release or the performance under extreme environmental conditions were not tested in our study.

Intraspecific Phenotypic Variation in Nearly Threatened Mottled Nandus, Nandus nandus (Hamilton, 1822)

Understanding intraspecific phenotypic plasticity is a prerequisite of stock identification, evolutionary studies, sustainable utilization, and fishery conservation. In this study, intraspecific phenotypic plasticity was assessed in terms of the external features (i.e. meristic, morphometric, and truss-based morphometrics) of the wild Nandus populations from four freshwater sources in Southwestern Bangladesh. Fish samples were collected from Arial Kha River, Madaripur (AKRM, n=26); Nabaganga River, Jhenaidah (NRJ, n=22); Bohnni Baor, Gopalganj (BBG, n=26); and Dhakuria Beel, Jashore (DBJ, n=22). Meristic, morphometric, and truss network data were subjected to one-way ANOVA followed by post hoc (Tukey-HSD) test. The meristic counts of all the samples demonstrated significant differences only in one of the six characters. By contrast, significant differences were observed in 8 morphometric characters and 31 truss network data from 16 morphometric characters and 35 truss network data, respectively. Principal component (PCA) and canonical variate analyses (CVA) were also performed on morphometric and truss-based network data. Meristic and morphometric results from PCA and CVA showed that populations were completely intermingled, forming a compact cluster within intrapopulation levels, while truss morphometric characters formed a separate cluster. Three dendrograms independently based on phenotypic relationships among the individuals of the four populations also confirmed the absence of phenotypic differentiation among the population due to clustering of different groups. The baseline information resulting from the current study would be useful for genetic studies and further in situ conservation of Nandus populations in Bangladesh.

Differentiation of intraspecific phenotypic plasticity of elongate glassy perchlet, Chanda nama: Insights into landmark-based truss morphometric and meristic variations.

Objective:Understanding intraspecific phenotypic plasticity is a prerequisite to fish stock identification and sustainable fisheries management. In this study, we assessed intraspecific phenotypic plasticity in terms of meristic and morphometric characters of wild populations of elongate glassy perchlet, Chanda nama from two different rivers, namely Madhumati River – Narail (MRN) and Tulshiganga River – Jaypurhat (TRJ), and an ox-bow lake, Jhapa Baor – Jashore (JBJ) in Bangladesh.Materials and Methods:In this study, six meristics, 15 conventional morphometrics, and 23-truss-based morphometrics were subjected to a one-way analysis of variance (ANOVA), followed by the Tukey-HSD test. The mean values of three meristic counts and nine conventional and 12 truss-based morphometrics demonstrated significant differences in the ANOVA test. Furthermore, principal component analysis (PCA) and discrimination function analysis (DFA) were performed separately using conventional and truss-based morphometric data.Results:In PCA analysis, four principal components were extracted and cumulatively demonstrated 51.848%. On the contrary, two discriminant functions (DF1, 63.5%; DF2, 36.5%) resulted from DFA analysis. In the bi-plot alignment from the discriminant space, all individuals were exceedingly separated among the three inhabitants. A dendrogram developed using conventional and truss morphometric characters confirmed that two clusters were formed among three populations. The TRJ population formed a distinct cluster, and the JBJ population formed a different cluster with a subcluster of MRN. In the discriminant function analysis, precise classification outcomes displayed 82% of individuals into their unique populations, whereas 66.9% of individuals were categorized as a cross-validated assemblage.Conclusion:The baseline information resulting from the current study would be useful for environmental studies and further conservation of glassy perchlet populations in Bangladesh.

Salt Stress Induces Increase in Starch Accumulation in Duckweed (Lemna aequinoctialis, Lemnaceae): Biochemical and Physiological Aspects

In this study, antioxidant processes were searched for in macrophyte duckweed to investigate tolerance mechanisms in this species against oxidative damage caused by salinity stress. Biochemical and histological analyses were performed on four Lemna aequinoctialis clones grown in Schenk-Hildebrandt medium, 0.5 × SH, supplemented with 1% sucrose liquid medium containing or not containing NaCl in different NaCl concentrations (0, 25 and 50 mM). For most clones, the salt stress effects caused growth inhibition and antioxidant responses at 50 mM NaCl. Also, starch and reducing sugar accumulations were increased with salt, whereas the photosynthetic pigment content was reduced in clone L. aequinoctialis 5569. The plant growth inhibition reflects the oxidative stress shown by the significant increase in malondialdehyde (MDA) and hydrogen peroxide (H2O2) content. In the L. aequinoctialis 5568 clone, with the highest MDA levels, no antioxidant enzymatic activity was observed. The L. aequinoctialis 5570 clone presented higher ascorbate peroxidase and catalase activities in parallel, indicating that the efficiency of the defence mechanism relies on synchrony between such enzyme activities toward successive elimination of reactive oxygen species and resulting in the assurance of some level of protection of the metabolism from oxidative damage. Considering the moderate salt stress (25 mM), the maintenance of MDA content and small growth inhibition associated with the high starch production suggested the acclimation efficiency of L. aequinoctialis 5570 and 5567 clones, indicating that they may be suitable for cultivation under moderate saline conditions, serving as biofuel feedstock. In addition, this study demonstrates great intraspecific phenotypic plasticity of duckweed, L. aequinoctialis, from closely related clones.

Arbuscular mycorrhizal fungi: intraspecific diversity and pangenomes.

Contents Summary 1129 I. Introduction 1129 II. Intraspecific phenotypic variation and the plant host 1130 III. High inter-isolate genetic diversity in model AMF 1130 IV. Genome diversity within the model AM fungus Rhizophagus irregularis 1131 V. Pangenomes and the future of AMF ecological genomics 1131 Acknowledgements 1133 References 1133 SUMMARY: Arbuscular mycorrhizal fungi (AMF) are ubiquitous plant symbionts with an intriguing population biology. Conspecific AMF strains can vary substantially at the genetic and phenotypic levels, leading to direct and quantifiable variation in plant growth. Recent studies have shown that high intraspecific diversity is very common in AMF, and not only found in model species. Studies have also revealed how the phenotype of conspecific isolates varies depending on the plant host, highlighting the functional relevance of intraspecific phenotypic plasticity for the AMF ecology and mycorrhizal symbiosis. Recent work has also demonstrated that conspecific isolates of the model AMF Rhizophagus irregularis harbor large and highly variable pangenomes, highlighting the potential role of intraspecific genome diversity for the ecological adaptation of these symbionts.

Be cool: A review of hydro-physical changes and fish responses in winter in hydropower-regulated northern streams

Winter is an ecologically challenging season for ectothermic cold-water fish in natural streams because of reduced flow and freezing. Hydropower regulation in many northern rivers increase winter stream flow and temperatures, and reduce ice formation and surface ice cover. From a background review of knowledge about e.g. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) winter survival strategies, we explore responses to hydropower impacts as a basis for adaptive management, mitigating strategies, and future research. Winter intensity and duration, hydrologic conditions and channel characteristics drive complex ice processes which become more complex and pervasive in smaller, high-gradient streams. Stream ice formation may be divided into the dynamic period ‘freeze-up’ in early winter with sub-surface ice, more stable ‘mid-winter’ with surface ice, and the ecologically challenging ‘ice break-up’ in winter-spring with potential mechanical ice runs and scouring. The characteristics of periods vary depending on climate and hydropower regulation. In reaches downstream of power-plant outlets water temperature may increase and reduce surface ice formation. The mid-winter period destabilize or become absent. In bypass reaches flows decrease and facilitate freezing and ice production. Knowledge about longitudinal water temperature changes is limited. Hydro-peaked systems may aggravate high-low flow effects. A basic winter survival strategy in salmon and trout is energy storage, but also reduced metabolism, tolerance and starvation effected by quiescence. Energy storage may depend on local conditions, but there is little indication of adaptation to local thermal climates. Intraspecific phenotypic plasticity is important. The main behavioural strategy is risk-reducing sheltering in the substratum or deep areas, and nocturnal activity. Local movements between daytime refuges and nighttime slow-current activity areas are usually limited to meters. Larger fish may move more and aggregate in restricted suitable deep-slow refuge habitats such as pools and deep glides. Fish cope with ordinary thermal ice phenomena, and do not appear to become trapped in ice. Surface ice may reduce fish metabolism, but other factors, e.g. availability of substrate shelter, may override this effect. Mechanical ice break-ups and less surface ice may reduce survival. An adaptive mitigating strategy may be higher regulated flows in winter which increase rearing and/or resting habitat and survival, but studies are few and knowledge is limited. However, higher regulated flows also affect temperature regime. Low flows increase ice formation, reduce and fragment available habitat, and may reduce egg and fish survival. Influx of ground water may mitigate these impacts, as will stabilize minimum flows. Sudden drops in regulated water discharge should be avoided. Fish may strand, in particular at low temperatures in the daytime when fish are less mobile and seek shelter. The challenging winter season is understudied, and important management considerations and future research areas for better adaptive management are suggested.

Inter- and intraspecific phenotypic plasticity of three phytoplankton species in response to ocean acidification.

Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification on inter- and intraspecific reaction norms of three globally important phytoplankton species (Emiliania huxleyi, Gephyrocapsa oceanica and Chaetoceros affinis). Despite significant differences in growth rates between the species, they all showed a high potential for phenotypic buffering (similar growth rates between ambient and high CO2 conditions). Only three coccolithophore genotypes showed a reduced growth in high CO2. Diverging responses to high CO2 of single coccolithophore genotypes compared with the respective mean species responses, however, raise the question of whether an extrapolation to the population level is possible from single-genotype experiments. We therefore compared the mean response of all tested genotypes with a total species response comprising the same genotypes, which was not significantly different in the coccolithophores. Assessing species reaction norms to different environmental conditions on short time scale in a genotype-mix could thus reduce sampling effort while increasing predictive power.

Anterior sensory organs in Sabellariidae (Annelida)

AbstractSensory organs in Annelida are very diverse and may be useful for assessments of morphological adaptation and character evolution. We used several methods to provide new insights into processes underlying the evolutionary radiation of anterior sensory organs in Sabellariidae. The presence and morphological diversity of the median organ (MO) found in the group was reviewed in order to test its phylogenetic significance and possible relationships to the distribution and ecological traits of the lineages. To test the intraspecific phenotypic plasticity of the MO, molecular analyses were conducted that focused on mitochondrial and nuclear genes from populations of Idanthyrsus australiensis exhibiting variation in the morphology of the MO. We used an integrative microscopical study of the ontogeny of Sabellaria alveolata to describe the anterior sensory structures present in the larvae and the morphological changes occurring before, during, and after settlement. In larval stages, the palps and the dorsal hump (DH) exhibit distinct innervation. The larval DH organ, which is likely to play a major role in chemoreception for settlement, is interpreted as being the incipient form of the adult MO. These results suggest that annelid sensory organs including the MO may be useful for phylogenetic and developmental investigations.

Diploid Ruppia cirrhosa populations from a southern Mediterranean shallow system

This paper focuses on the morphology and karyology of representative Ruppia populations from a southern Mediterranean shallow system. The cosmopolitan genus Ruppia L. generally inhabits shallow waters such as coastal lagoons and brackish habitats. Ruppia species are characterised by a simplified morphology and high intraspecific phenotypic plasticity. The chromosome number of Sicilian Ruppia populations is reported here for the first time. The analysed populations showed morphological and reproductive characters of Ruppia cirrhosa (Petagna) Grande but a diploid cytotype (2n=20). A low fruit production was also observed, suggesting that vegetative reproduction is the main reproductive strategy adopted by the plant. This study did not resolve conclusively the taxonomic identity of these Ruppia populations and it also raises some open questions, needing further investigations.

Adaptive evolution and phenotypic plasticity during naturalization and spread of invasive species: implications for tree invasion biology

Although the genetic aspects of biological invasions are receiving more attention in the scientific literature, analyses of phenotypic plasticity and genotype-by-environment interactions are still seldom considered in tree invasion biology. Previous studies have shown that invasions of tree species can be affected by intraspecific phenotypic plasticity, pre-adaptation, and post-introduction evolution, and we suggest there are opportunities for new developments in this field. Here, we present a description of the use of quantitative and molecular genetics in tree invasion biology, and propose an approach based on common garden experiments, quantitative and molecular genetic methods to investigate the role of adaptive evolution, phenotypic plasticity, and genotype-by-environment interactions in tree invasions, particularly at the infraspecific level. We illustrate the utility of this approach using examples from quantitative genetic studies of Pinus and an example from a classical reciprocal common garden experiment with Acer species. By using this approach, researchers can test hypotheses about the role and strength of genetic and environmental effects on population-level invasiveness and gain insights into evolutionary processes that occur during biological invasions. Moreover, knowledge of phenotypic plasticity and local adaption of tree populations may help researchers improve assessments of invasion risk.

Cryptic diversity, intraspecific phenetic plasticity and recent geographical translocations inBranchiomma(Sabellidae, Annelida)

The importance of identifying biological diversity accurately and efficiently is becoming more evident. It is therefore critical to determine the species boundaries between closely related taxa and to establish diagnostic characters that allow us to define species. This is not an easy task when species exhibit high intraspecific phenotypic plasticity or when distinct evolutionary lineages with an unusually large amount of genetic distinctiveness show no apparent morphological diversity (cryptic species). These phenomena appear to be common in the genus of fan wormsBranchiomma(Sabellidae, Annelida), and consequently, taxonomic errors are widespread in the group. Moreover, someBranchiommaspecies have been unintentionally translocated outside the area where natural range extension is expected, increasing the taxonomic problems. We have performed a range of analytical methods including genetic distances, Bayesian inference, maximum likelihood, maximum parsimony, statistical parsimony analyses and general mixed Yule coalescent model to clarify the taxonomic status and assess the species boundaries ofBranchiommain Australia. This study shows that the traditional diagnostic morphological features are greatly homoplastic. Results also indicate that the diversity ofBranchiommain Australia is higher than previously reported and evidence some cases of high phenetic plasticity (in features previously considered as stable within species), high intraspecific genetic variability, cryptic species and several unexpected cases of translocations.

Morphological differences in the ovary of Libellulidae (Odonata)

All female Odonata have been assumed to produce oocytes continuously during their mature life span. However, a recent study of ovariole orientation and development led to the suggestion that Libellulidae are divided into two groups of species, one with continuous, the other with stepwise oocyte production. To find more evidence of this division, we compared the size variation and growth within the vitellarium of the ovary, studying oocytes, and follicle cells. We found that morphological characters discriminate between the two ovary types in eight of the 10 investigated species. In both types we found an increase in all measurements from the anterior to the posterior end of the vitellarium. The increase in oocyte width and follicle cell length was significantly higher in species with a continuous oocyte production. We also noted that follicle cells may have more than one nucleus and that their number can vary during vitellogenesis. Our study confirmed the hypotheses that two different ovary types exist in Libellulidae. The two species not fitting into this grouping could be an artefact of small sample size due to intraspecific phenotypic plasticity, or else there might be more than two ovary groups, or even a continuum. We could not offer an explanation as to how the process of stepwise oocyte production differs from continuous based production on morphological characters.

Variation in Morphology vs Conservation of a Mitochondrial Gene in Montastraea cavernosa (Cnidaria, Scleractinia)

Skeletal morphology of many scleractinian corals may be influenced by environmental factors and may thus result in substantial intraspecific phenotypic plasticity and, possibly, in overlapping morphologies between species. Environmentally induced variation can also mask phenotypic variation that is genetically based. Morphological analyses and DNA sequence analyses were performed on Montastraea cavernosa from the Flower Garden Banks, Texas, and from the Florida Keys in order to assess variation within and between geographic regions. Skeletal characters, including corallite diameter, columella width, theca thickness, nearest-neighbor distance, length of first septa cycle, and width of first septa cycle, varied within colonies, among colonies, and between the Flower Garden Banks and the Florida Keys. Morphological variation may be controlled by environmental and genetic influences at different levels. If phenotype is under genetic control, it is not influenced by the mitochondrial cytochrome oxidase subunit I gene, because analysis of a 708 base pair fragment revealed identical sequences of M. cavernosa from these geographic regions. This high level of nucleotide sequence similarity may result from functional constraints, efficient DNA repair mechanisms, or other processes. This gene was not found to exhibit any variation in association with that observed in the morphology, and we suggest that it is an inappropriate genetic marker to use to assess intraspecific variation within this species and possibly other scleractinian species as well. Analysis via other molecular techniques will be necessary in order to assess the factors that influence morphological variation and that distinguish populations within this species.