Mode Of Reproduction Research Articles

The Dialectical Sociology of Michel Freitag and the Critique of Communication Society

Michel Freitag developed a ground-breaking sociological theory synthesizing the thought of sociology’s founders into the form of a dialectical sociology that conceives of the symbolic as ontological to social reality. After outlining his conceptualization of the historical evolution of society through its ‘modes of reproduction’, we will see how his analysis of contemporary societal transformations rests on a critical theory of communication and technology that, while entering a dialogue with the works of the Frankfurt school, especially those of Habermas, seeks to overcome their inherent contradictions. According to Freitag, the development of capitalist globalization alters the very substance of society as it tends to morph itself into a self-regulating cybernetic system. His sociology allows us to apprehend phenomena tied to the development of contemporary digital technologies such as the drive towards a new form of algorithmic governmentality fueled by digital oligopolies that increasingly dominate globalized capitalism, the rise of fake news in the era of post-truth and the transformation of subjectivity. Finally, his critique enables potent reflection on the dialectical possibilities of overcoming the dynamics of contemporary alienation.

Population Genomics of the Mostly Thelytokous Diplolepis rosae (Linnaeus, 1758) (Hymenoptera: Cynipidae) Reveals Population-specific Selection for Sex.

In Hymenoptera, arrhenotokous parthenogenesis (arrhenotoky) is a common reproductive mode. Thelytokous parthenogenesis (thelytoky), when virgin females produce only females, is less common and is found in several taxa. In our study, we assessed the efficacy of recombination and the effect of thelytoky on the genome structure of Diplolepis rosae, a gall wasp-producing bedeguars in dog roses. We assembled a high-quality reference genome using Oxford Nanopore long-read technology and sequenced 17 samples collected in France with high-coverage Illumina reads. We found two D. rosae peripatric lineages that differed in the level of recombination and homozygosity. One of the D. rosae lineages showed a recombination rate that was 13.2 times higher and per-individual heterozygosity that was 1.6 times higher. In the more recombining lineage, the genes enriched in functions related to male traits ('sperm competition", "insemination", and "copulation" gene ontology terms) showed signals of purifying selection, whereas in the less recombining lineage, the same genes showed traces pointing towards balancing or relaxed selection. Thus, although D. rosae reproduces mainly by thelytoky, selection may act to maintain sexual reproduction.

The biphasic life cycle of the non-spinose planktonic foraminifera is characterised by an aberrant coiling signature

The complete lifecycle of the planktonic foraminifera has continued to remain obscure. Benthic foraminifera exhibit an obligate alternation of generations between haploid gamonts and diploid agamonts, yet despite years of observation, the fusion of gametes to form a zygote, gamont or agamont has never been observed in the planktonic groups. Recent evidence from Neogloboquadrina pachyderma culture confirms that they do have a biphasic reproductive cycle and the agamonts may exhibit dimorphism in coiling direction. In this study we examine the morphology of normal and aberrant coiling tests of both N. pachyderma and N. incompta from three Arctic and North Atlantic water masses, to explore whether aberrant coiling is an indicator of a biphasic life cycle in the non-spinose planktonic foraminifera group as a whole. Using a Nano-Computed Tomography scanning approach, we morphologically compared the proloculus and growth trajectories of aberrant and normal coiling tests. Aberrant coiling tests were found to have a slightly larger proloculus and test size, consistent with a left coiling N. pachyderma agamont in the literature. This degree of dimorphism is insufficient to discriminate agamonts in the wild population and coiling direction remains their only distinguishable feature without further morphological investigation. The constant low-level aberrant coiling signature in a range of non-spinose planktonic foraminiferal genera implies that a biphasic life cycle is the principal mode of reproduction in the non-spinose planktonic group.

Fungal pathogen infection intensity associated with reproductive mode and elevation in an afrotropical anuran community

The effects of host ecology and environmental conditions on infection dynamics of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) have been documented in several tropical and montane regions across the globe. These interactions are often complex and unique at local scales. Data on the historical and current chytridiomycosis-amphibian system is largely lacking in Africa, especially central Africa. We conducted the first survey of Bd in continental Equatorial Guinea in 2019, and extensively sampled the land-bridge island, Bioko, in 2011 and 2019. Our results provide novel information on the distribution and prevalence of Bd in Equatorial Guinea and demonstrate the effects of host developmental mode and elevation on Bd infections. We found that Bd infection loads are positively linked with elevation and that direct-developing species have higher average Bd loads than aquatic breeding species at all elevations. These patterns corroborate previous findings in afrotropical amphibian assemblages. Additionally, our study confirms the presence of Bd in continental Equatorial Guinea, providing updated information on the distribution of Bd in central Africa, and confirming the need for careful monitoring of this biodiverse region. Keywords: Bioko, Equatorial Guinea, Bd infection load, amphibian conservation Los efectos de la ecología del huésped y las condiciones ambientales en la dinámica de infección del hongo quítrido anfibio Batrachochytrium dendrobatidis (Bd) se han documentado en varias regiones tropicales y montañosas de todo el mundo. Estas interacciones suelen ser complejas y únicas a escala local. Los datos sobre el sistema quitridiomicosis-anfibios histórico y actual faltan en gran medida en África, especialmente en África central. Realizamos la primera encuesta de Bd en Guinea Ecuatorial continental en 2019, y un muestreo extenso de la isla Bioko en 2011 y 2019. Nuestros resultados brindan información novedosa sobre la distribución y prevalencia de Bd en Guinea Ecuatorial y demuestran el efecto del modo de desarrollo del huésped y la elevación de las infecciones por Bd. Descubrimos que las cargas de infección por Bd están relacionadas positivamente con la elevación y que las especies en desarrollo directo tienen cargas promedio de Bd más altas que las especies acuáticas reproductoras a lo largo de la elevación. Estos patrones corroboran hallazgos previos en conjuntos de anfibios afrotropicales. Además, nuestro estudio confirma la presencia de Bd en Guinea Ecuatorial continental, proporcionando información actualizada sobre la distribución de Bd en África Central y confirmando la necesidad de un seguimiento cuidadoso de esta región biodiversa.

The reproductive biology and fecundity of female Atlantic Menhaden

AbstractObjectiveAtlantic Menhaden Brevoortia tyrannus support fisheries that yield the largest landings by volume on the U.S. East Coast and fulfill a critical ecological role as a forage species. The spawning reference point of the stock assessment model that is routinely applied to this species requires information on total annual fecundity. The goal of this study was to generate a contemporary, histology‐based evaluation of the reproductive biology and fecundity of female Atlantic Menhaden.MethodsFemale Atlantic Menhaden (n = 559) were collected between Cape Cod, Massachusetts, and Cape Hatteras, North Carolina, from 2013 to 2019. Ovarian tissues were prepared using standard histological techniques which, when coupled with oocyte size‐frequency and count data, were used to classify reproductive mode and estimate batch fecundity, spawning frequency, and maturity. Monthly gonosomatic indices were combined with published female reproductive information and spatiotemporal patterns in larval and juvenile abundance to designate spawning seasonality.ResultHistological preparations and oocyte size‐frequency patterns of female Atlantic Menhaden ovaries were consistent with indeterminate batch spawning. Batch fecundity increased with fork length, while spawning seasonality extended from September 15 to April 15 with a spawn every 7.5 ± 2.3 days. Female maturity probabilities transitioned from 0.2 to 0.8 over fork lengths of 214.8–226.5 mm (approximately ages 2.0–2.3 years). Estimated mean per capita female annual fecundity varied from 465,757 to 3,250,135 oocytes for fish ranging from 215.8 to 284.8 mm fork length (ages 2–6 years), which represented a 614–2267% (mean = 1656%) increase in annual female reproductive output relative to previous estimates.ConclusionFemale Atlantic Menhaden exhibit indeterminant batch spawning while spawning seasonality and mean per capita female annual fecundity were appreciably greater than previously reported. This new reproductive information illuminates the robust reproductive productivity of this species and will aid routinely conducted stock assessments.

An evolutionary epigenetic clock in plants.

Molecular clocks are the basis for dating the divergence between lineages over macroevolutionary timescales (~105 to 108 years). However, classical DNA-based clocks tick too slowly to inform us about the recent past. Here, we demonstrate that stochastic DNA methylation changes at a subset of cytosines in plant genomes display a clocklike behavior. This "epimutation clock" is orders of magnitude faster than DNA-based clocks and enables phylogenetic explorations on a scale of years to centuries. We show experimentally that epimutation clocks recapitulate known topologies and branching times of intraspecies phylogenetic trees in the self-fertilizing plant Arabidopsis thaliana and the clonal seagrass Zostera marina, which represent two major modes of plant reproduction. This discovery will open new possibilities for high-resolution temporal studies of plant biodiversity.

Sperm-dependent asexual species and their role in ecology and evolution.

Sexual reproduction is the primary mode of reproduction in eukaryotes, but some organisms have evolved deviations from classical sex and switched to asexuality. These asexual lineages have sometimes been viewed as evolutionary dead ends, but recent research has revealed their importance in many areas of general biology. Our review explores the understudied, yet important mechanisms by which sperm-dependent asexuals that produce non-recombined gametes but rely on their fertilization, can have a significant impact on the evolution of coexisting sexual species and ecosystems. These impacts are concentrated around three major fields. Firstly, sperm-dependent asexuals can potentially impact the gene pool of coexisting sexual species by either restricting their population sizes or by providing bridges for interspecific gene flow whose type and consequences substantially differ from gene flow mechanisms expected under sexual reproduction. Secondly, they may impact on sexuals' diversification rates either directly, by serving as stepping-stones in speciation, or indirectly, by promoting the formation of pre- and postzygotic reproduction barriers among nascent species. Thirdly, they can potentially impact on spatial distribution of species, via direct or indirect (apparent) types of competition and Allee effects. For each such mechanism, we provide empirical examples of how natural sperm-dependent asexuals impact the evolution of their sexual counterparts. In particular, we highlight that these broad effects may last beyond the tenure of the individual asexual lineages causing them, which challenges the traditional perception that asexual lineages are short-lived evolutionary dead ends and minor sideshows. Our review also proposes new research directions to incorporate the aforementioned impacts of sperm-dependent asexuals. These research directions will ultimately enhance our understanding of the evolution of genomes and biological interactions in general.

Combined effects of temperature, photoperiod, and salinity on reproduction of the brine shrimp Artemia sinica (Crustacea: Anostraca).

Artemia sinica is a brine shrimp species distributed in hypersaline salt lakes in northern China and Siberia and a successful invasive species in some coastal salterns. Although it is a commercially harvested and cultured species, knowledge of its reproductive characteristics is limited, and existing studies are often contradictory. The combined effects of temperature, salinity, and photoperiod on reproduction characteristics are experimentally studied to better understand its reproductive features. There were 36 combinations of three environmental factors (3×3×4), each with three or four levels, namely temperature (16, 25, 30°C), photoperiod (6 L:18 D, 12 L:12D, 18 L:6D), and salinity (50, 100, 150, 200 PSU). In each treatment, 48 to 80 pairs of A. sinica from Yuncheng Salt Lake (Shanxi, China) were cultured. Females were observed daily for reproductive mode and the number of offspring produced. Temperature, photoperiod, salinity, and their interactions significantly affected the lifespan and reproduction of A. sinica. The reproductive period was the longest and accounted for the largest proportion of life span at moderate temperature (25°C). Total offspring, offspring per brood, and offspring per day increased as salinity decreased, and the number of broods per female was highest at 25°C. Temperature, photoperiod, and salinity significantly influenced reproductive modes, and interactions among these factors were identified. Artemia sinica primarily reproduces oviparously under low temperature and short daylight conditions, and ovoviviparously under high temperature and long daylight conditions, with the maximum oviparity ratio recorded in treatments of 16°C, 6L:18D, and 50 or 100 PSU. The maximum ovoviviparity ratio was recorded under 30°C, 12L:12D, and 100 PSU. Unlike that documented for other Artemia species or populations, the brood size of A. sinica kept increasing throughout the reproductive period. It did not decline even in the last two broods. For the same brood number, the sizes of oviparous and ovoviviparous broods were similar. The length of the oviparous interval was often greater than that of the ovoviviparous interval, suggesting that oviparous offspring might require additional energy and time to construct the multi-layered eggshell. Compared to other species and populations, the A.sinica from Yuncheng Salt Lake has a relatively shorter pre-reproductive development time, a preference for ovoviviparity, and relatively higher fecundity and population growth capacity, making it a suitable culture species for obtaining fresh biomass.

Considering both sexual and clonal reproduction could help loosen the conflict of use over Robinia pseudoacacia

Black locust (Robinia pseudocacacia) is a widely planted tree for wood production; however, it is a very problematic invasive species through Europe. At local scale, this tree is able to invades adjacent ecosystems owing to its strong ability of asexual reproduction through root suckers. Due to this phenomenon, the role of sexual reproduction has been quite neglected at local scale. Here, we propose a double approach (i) to evaluate the ability of the species to develop under forest cover using French national forest inventory data (ii) to quantify the role of sexual and asexual reproduction at local scale using a simple visual assessment method. We evidenced that juvenile black locust regenerates in broadleaved forests where R. pseudoacacia did not contribute to the adult canopy; moreover, a significant higher presence in riparian forests relatively to non-riparian ones was demonstrated using national forest inventory data. Regeneration from sexual reproduction mode significantly contributes to local scale invasion (38% of the up-rooted juvenile plants) with a significantly higher ratio of sexual reproduction within oak dominated forests compared to pine dominated ones. We conclude that black locust forestry should consider that both reproduction modes contribute to the species natural regeneration and that both modes can occur under both coniferous and broadleaved forest cover. Thus, we propose to set up safety buffers around sensitive ecosystems such as natural reserves or riparian areas, to maintain black locust cultivation while minimising undesired invasions in natural areas.

The duality of drought: Pelagic‐ and benthic‐spawning stream fishes show opposing responses to drought in the southern Great Plains

AbstractObjectiveStreamflow is a primary determinant of fish assemblage structure in riverine systems, but alteration of natural flow regimes can result in fish assemblage shifts through the process of environmental filtering. Because natural drought conditions reduce and homogenize streamflow in a manner comparable to projections for climate change in some regions, drought could serve as a proxy for expected future flow conditions.MethodsWe investigated the effects of drought as a temporally dynamic environmental filter of the occurrence of two guilds of fishes, benthic spawners that deposit adhesive ova along the benthic zone of rivers and pelagic spawners that release semibuoyant, nonadhesive ova into the pelagic zone of rivers. We developed species‐specific random forest models to estimate annual probability of occurrence for three benthic‐spawning and four pelagic‐spawning minnow species at three sites in the upper Brazos River, Texas, for the period 1950–2018. We then used a generalized additive mixed‐effects model to assess the relationship between drought intensity and likelihood of occurrence to test whether reproductive modes differed in response to drought (hypothesis 1) and whether response to drought was spatially (hypothesis 2) or temporally (hypothesis 3) variable.ResultWe found support for hypothesis 1 as two of four pelagic‐spawning species (Shoal Chub Macrhybopsis hyostoma, Smalleye Shiner Notropis buccula) declined and two of three benthic‐spawning species increased as drought intensified, support for hypothesis 2 as responses to drought varied by gauge location, and no support for hypothesis 3 as drought response was consistent for periods 1950–1979 and 1980–2018.ConclusionThese findings offer insight into the future of riverine fish assemblages as climate change is expected to exacerbate regional drought conditions. Management of pelagic‐spawning fishes during extreme drought in the southern Great Plains may require strategies such as (1) rescues of fish from drying reaches, (2) captive holding and propagation, and (3) assisted recolonization following subsidence of drought conditions.

Contrasting Evolutionary Patterns Between Sexual and Asexual Lineages in a Genomic Region Linked to Reproductive Mode Variation in the pea aphid.

Although asexual lineages evolved from sexual lineages in many different taxa, the genetics of sex loss remains poorly understood. We addressed this issue in the pea aphid Acyrthosiphon pisum, whose natural populations encompass lineages performing cyclical parthenogenesis (CP) and producing one sexual generation per year, as well as obligate parthenogenetic (OP) lineages that can no longer produce sexual females but can still produce males. An SNP-based, whole-genome scan of CP and OP populations sequenced in pools (103 individuals from 6 populations) revealed that an X-linked region is associated with the variation in reproductive mode. This 840-kb region is highly divergent between CP and OP populations (FST = 34.9%), with >2,000 SNPs or short Indels showing a high degree of association with the phenotypic trait. In OP populations specifically, this region also shows reduced diversity and Tajima's D, consistent with the OP phenotype being a derived trait in aphids. Interestingly, the low genetic differentiation between CP and OP populations at the rest of the genome (FST = 2.5%) suggests gene flow between them. Males from OP lineages thus likely transmit their op allele to new genomic backgrounds. These genetic exchanges, combined with the selection of the OP and CP reproductive modes under different climates, probably contribute to the long-term persistence of the cp and op alleles.

Common lizard microhabitat selection varies by sex, parity mode, and colouration

BackgroundAnimals select and interact with their environment in various ways, including to ensure their physiology is at its optimal capacity, access to prey is possible, and predators can be avoided. Often conflicting, the balance of choices made may vary depending on an individual’s life-history and condition. The common lizard (Zootoca vivipara) has egg-laying and live-bearing lineages and displays a variety of dorsal patterns and colouration. How colouration and reproductive mode affect habitat selection decisions on the landscape is not known. In this study, we first tested if co-occurring male and female viviparous and oviparous common lizards differ in their microhabitat selection. Second, we tested if the dorsal colouration of an individual lizard matched its basking site choice within the microhabitat where it was encountered, which could be related to camouflage and crypsis.ResultsWe found that site use differed from the habitat otherwise available, suggesting lizards actively choose the composition and structure of their microhabitat. Females were found in areas with more wood and less bare ground compared to males; we speculate that this may be for better camouflage and reducing predation risk during pregnancy, when females are less mobile. Microhabitat use also differed by parity mode: viviparous lizards were found in areas with more density of flowering plants, while oviparous lizards were found in areas that were wetter and had more moss. This may relate to differing habitat preferences of viviparous vs. oviparous for clutch lay sites. We found that an individual’s dorsal colouration matched that of the substrate of its basking site. This could indicate that individuals may choose their basking site to optimise camouflage within microhabitat. Further, all individuals were found basking in areas close to cover, which we expect could be used to escape predation.ConclusionsOur study suggests that common lizards may actively choose their microhabitat and basking site, balancing physiological requirements, escape response and camouflage as a tactic for predator avoidance. This varies for parity modes, sexes, and dorsal colourations, suggesting that individual optimisation strategies are influenced by inter-individual variation within populations as well as determined by evolutionary differences associated with life history.

Fruits, seeds and leaves of guabijuzeiro (Myrcianthes pungens (O. Berg) D. Legrand): characteristics, uses and health benefits.

Native fruit trees have potential for use in the food and pharmaceutical industries, which is widely used in folk medicine. Guabiju, known as guabijuzeiro (Myrcianthes pungens (O. Berg) D. Legrand) is a perennial tree that belongs to the family Myrtaceae, occurring in Brazil from São Paulo to Rio Grande do Sul, and other countries like Uruguay, Bolivia, Paraguay and Argentina. This species demonstrates great commercial potential regarding the consumption of its fresh fruit or industrialized. Due to its importance is necessary to develop studies aimed at characterization (phenotypic, propagative, reproductive, chemical and nutritional), uses and applications. However, the available information has never been systematized and in this sense the objective of this review is to compile information about the species to guide further research. Regarding morphology, the guabijuzeiro is a semi-deciduous tree species, with propagation is carried out mainly through seeds and vegetative. Regarding reproductive aspects, there is a lack of studies that assess the mode of reproduction. The fruit can be consumed fresh or processed as ice cream, juice, freeze-dried or dehydrated. It is sweet and slightly acidic, low in calories, high in carbohydrates, essential fatty acids, calcium and potassium. Both the fruit, the seed and the leaves have high levels of bioactive compounds and high antioxidant capacity. The fruit pulp stands out for its carotenoids and phenolic compounds and the peel is rich in anthocyanins, especially in the mature phase, in addition to terpenoids. M. pungens has antimicrobial effects, gastroprotective activity and is promising in the prevention of neurodegenerative diseases and against the side effects of cisplatin, an anticancer agent. Finally, there is a need for further studies with this species, mainly in the characterization of the leaves, uses and applications of the fruit.

Genetic resources of macroalgae: Development of an efficient method using microsatellite markers in non-model organisms

Red and brown seaweeds are species with high ecological and economic importance. Here we report the feasibility of cost-effective molecular marker development in 6 species from different phyla. Microsatellite markers of two brown seaweed species Alaria esculenta and Pylaiella littoralis, and of four red seaweed species Calliblepharis jubata, Gracilaria gracilis, Gracilaria dura and Palmaria palmata were identified and characterized in genomic sequences obtained using Double-Digest Restriction site Associated DNA (ddRAD). A total of 64,623,186 reads were generated from two runs of multiplexed Illumina Miseq sequencing, from which 30,636 reads containing microsatellite motifs including 15,443 where primer pairs could be designed. Five hundred seventy-six primers pairs were selected for amplification trials to determine levels of polymorphism. Of these 576 loci, 338 could be amplified and 142 of the 338 loci were polymorphic. A total of 28 usable polymorphic markers were developed in A. esculenta, 18 in P. littoralis, 11 in C. jubata, 14 in G. gracilis, 21 in G. dura and 13 in P. palmata. The overall number of alleles per locus ranged from 2 to 22. These 105 new microsatellite markers will be useful for further studies of population genetics, breeding programs and conservation genetics of these species. Compared with traditional approaches, our study yielded thousands of microsatellite loci for six different species in a short time and with affordable costs. This study, based on the use of ddRADseq, provided preliminary data about the genetic structure and reproduction mode of these six non-model species based on a small number of individuals from two geographically-distant populations and on the genetic structure and reproduction mode of two non-model species, i.e. detection of clonality for two red algae, C. jubata and G. dura and detection of highly genetically divergent populations corresponding probably to different cryptic species under the name P. littoralis.

AoMedA has a complex regulatory relationship with AoBrlA, AoAbaA, and AoWetA in conidiation, trap formation, and secondary metabolism in the nematode-trapping fungus Arthrobotrys oligospora.

The asexual sporulation of filamentous fungi is an important mechanism for their reproduction, survival, and pathogenicity. In Aspergillus and several filamentous fungi, BrlA, AbaA, and WetA are the key elements of a central regulatory pathway controlling conidiation, and MedA is a developmental modifier that regulates temporal expression of central regulatory genes; however, their roles are largely unknown in nematode-trapping (NT) fungi. Arthrobotrys oligospora is a representative NT fungus, which can capture nematodes by producing adhesive networks (traps). Here, we characterized the function of AoMedA and three central developmental regulators (AoBrlA, AoAbaA, and AoWetA) in A. oligospora by gene disruption, phenotypic comparison, and multi-omics analyses, as these regulators are required for conidiation and play divergent roles in mycelial development, trap formation, lipid droplet accumulation, vacuole assembly, and secondary metabolism. A combined analysis of phenotypic traits and transcriptome showed that AoMedA and AoWetA are involved in the regulation of peroxisome, endocytosis, and autophagy. Moreover, yeast one-hybrid analysis showed that AoBrlA can regulate AoMedA, AoAbaA, and AoWetA, whereas AoMedA and AoAbaA can regulate AoWetA. Our results highlight the important roles of AoMedA, AoBrlA, AoAbaA, and AoWetA in conidiation, mycelia development, trap formation, and pathogenicity of A. oligospora and provide a basis for elucidating the relationship between conidiation and trap formation of NT fungi. IMPORTANCE Conidiation is the most common reproductive mode for many filamentous fungi and plays an essential role in the pathogenicity of fungal pathogens. Nematode-trapping (NT) fungi are a special group of filamentous fungi owing to their innate abilities to capture and digest nematodes by producing traps (trapping devices). Sporulation plays an important role in the growth and reproduction of NT fungi, and conidia are the basic components of biocontrol reagents for controlling diseases caused by plant-parasitic nematodes. Arthrobotrys oligospora is a well-known NT fungus and is a routinely used model fungus for probing the interaction between fungi and nematodes. In this study, the functions of four key regulators (AoMedA, AoBrlA, AoAbaA, and AoWetA) involved in conidiation were characterized in A. oligospora. A complex interaction between AoMedA and three central regulators was noted; these regulators are required for conidiation and trap formation and play a pleiotropic role in multiple intracellular activities. Our study first revealed the role of AoMedA and three central regulators in conidiation, trap formation, and pathogenicity of A. oligospora, which contributed to elucidating the regulatory mechanism of conidiation in NT fungi and helped in developing effective reagents for biocontrol of nematodes.

Reproductive biology: A genetic recipe for parthenogenesis

New work reveals differences in oogenic gene expression between parthenogenetic and sexually reproducing Drosophila mercatorum strains. Recapitulating those changes in D.melanogaster oocytes induced parthenogenesis in this normally sexually reproducing species, providing molecular insight into how these reproductive modes arise.

Effects of clearcutting on species composition and community renewal of Rhododendron shrubs in northwest Guizhou Province, China

Tree base sprouting is the main reproduction and expansion mode of Rhododendron plants. By leveraging the plot survey method, the species composition, community renewal, and species diversity in three Rhododendron shrub communities in control, and before and after clearcutting (CK, D3yr, and D6yr, respectively) were studied. Moreover, the dissimilarity of Rhododendron communities in CK, D3yr and D6yr were analyzed. The results showed that there were 26 plant species belonging to 14 families and 22 genera, in 3 communities in total, with 19 species of shrub plants and 7 species of herbaceous plants. The number of species increased from 13 in CK to 23 in D3yr and then decreased to 20 in D6yr. The height and coverage of D3yr and D6yr reached 39.3% and 58.9% of that of CK, respectively. The relative height of CK, D3yr, and D6yr was 43.79%, 65.4%, and 58.54%, respectively. The coverage of D3yr and D6yr reached 60.8% and 114.70% of that of CK, respectively. The relative coverage of CK, D3yr, and D6yr was 19.05%, 83.24%, and 77.32%, respectively. The important value of Rhododendron plants in the communities increased from 0.42 in CK to 0.74 in D3yr, and then decreased to 0.67 in D6yr. The α diversity in the shrub layer of D3yr and D6yr were generally lower than those of CK except Pielou evenness index. The β diversity indicates that the similarity between CK and D3yr was lower, that between CK and D6yr was moderate, and that between D3yr and D6yr was higher. The sprouting height and coverage of Rhododendron plants was significantly correlated with age and sprouting time. The sprouting ability of Rhododendron plants increased first and then decreased with age, while the sprouting ability of Rhododendron plants with age of 10–12 years was the strongest. Clearcutting measures can improve the dominance of Rhododendron plants in the communities, promote the sprouting and renewal of Rhododendron population, and accelerate the succession rate of communities.

Differential effects of parental and developmental temperatures on larval thermal adaptation in oviparous and viviparous model fish species

Phenotypic plasticity has been identified as a major mechanism of response to changing temperatures. Parental effects are potentially important drivers of ecological and evolutionary dynamics, while developmental plasticity also plays a key role in generating phenotypic variation. However, little is known of the interaction between parental effects and developmental plasticity on the thermal phenotypes of fishes with different reproductive modes (i.e. oviparous vs. viviparous). To understand the contributions of inter- and intra-generational plasticity of thermal phenotypes (preferred temperature, avoidance temperatures, critical thermal thresholds) in fishes with different reproductive modes, we carried out a factorial experiment in which both breeding parents and offspring were exposed to lower (22 °C) or higher (28 °C) temperatures, using zebrafish (Danio rerio) and guppies (Poecilia reticulata) as representative oviparous and viviparous species. We found that offspring thermal preference and avoidance of both species were significantly influenced by parental effects and developmental plasticity, with higher thermal preference and avoidance consistent with higher background (parental) temperature treatments. However, parental effects were only found to impose significant effect on the thermal tolerances of guppies. The findings suggest that phenotypic plasticity, both within and across generations, may be an important mechanism to adapt to rapid climate changes, and that future temperature fluctuations may impose more profound effects on viviparous fish species in general.

Population genetic differentiation of the ubiquitous brooding coral Pocillopora acuta along Phuket Island reefs in the Andaman Sea, Thailand

BackgroundThe widespread Indo-Pacific coral species Pocillopora acuta Lamarck, 1816 displays varying levels of asexual versus sexual reproduction, with strong repercussions on genetic diversity, connectivity and genetic structuring within and among populations. For many geographic regions, baseline information on genetic diversity is still lacking, particularly in the Andaman Sea. The region suffered a massive heat-induced bleaching event in 2010 with high coral cover loss of branching coral species such as P. acuta. A subsequent bleaching in 2016, however, revealed a mild bleaching response in pocilloporids compared to other coral taxa in the region, suggesting that rare, heat tolerant genotypes had been selected by the 2010 bleaching event. In order to test whether this potential ‘evolutionary rescue’ event has led to a low genetic diversity, we conducted a population genetic survey covering a total of nine different P. acuta populations (336 individuals) along a 50 km coastal stretch around Phuket Island, Thailand. We used six microsatellite markers to assess genotypic diversity and to determine the prevalent mode of reproduction (i.e. sexual or asexual recruitment).ResultsIn contrast to other Indian Ocean P. acuta populations, the majority of corals in this study adopted a sexual reproduction mode (75% across all populations). At the same time, substantial regional gene flow was observed around Phuket Island with strong genetic differentiation as indicated by three genetic clusters that were separated by only a few kilometers. Patterns of isolation by distance over 0.7 – 40 km suggest small-scale genetic barriers, such as changing currents throughout each monsoonal season, potentially contributing to locally restricted dispersal of P. acuta larvae.ConclusionsThe occurrence of distinct genetic clusters within short coastal stretches suggests that the 2010 bleaching event has not led to extreme genetic impoverishment. While more in-depth genomic analyses are necessary to investigate changes in genetic diversity following extreme bleaching events, our results will help guide conservation efforts to maintain genetic diversity of a coral species that likely will be dominant in future, warmer Andaman Sea reefs.

Variations in trophic niches of soil microarthropods with elevation in two distant mountain regions in Eurasia as indicated by stable isotopes (15N, 13C)

Knowledge on the trophic niche of animal species is important for understanding their coexistence and hence animal diversity. Trophic niches have been shown to vary with environmental conditions, but consequences of trophic niche shifts for food-web structure and functioning are little studied and this applies in particular for belowground communities. Here, using stable isotopes (15N, 13C), we investigated shifts in trophic niches of oribatid mites as model soil animal taxon along elevational gradients of two mountain ranges in Eurasia, the Alps in Austria and Changbai Mountain in China. The results showed pronounced differences in the use of basal resources (Δ13C values) and trophic positions (Δ15N values) between the two mountains due to the different parent rock with calcareous soils in the Alps and basalt bedrock on Changbai Mountain. Further, trophic positions changed with altitude, primarily related to changes in litter quality. Differences in trophic niches of oribatid mites between the two mountains were related to differences in functional traits such as body mass and reproductive mode. Generally, stable isotope values closely correlated with body mass underlining the importance of morphological characteristics as well as the parent rock for variations in trophic niches. Moreover, stable isotope values differed between parthenogenetic and sexual species, but this depended on mountain and parent rock, with higher trophic plasticity in parthenogenetic species on Changbai Mountain than in the Alps. Overall, our findings highlight the decisive role of parent rock in structuring montane soil food webs and provide novel insight into factors responsible for shifts in trophic niches in soil invertebrates.