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Increases in the mean and variability of thermal regimes result in differential phenotypic responses among genotypes during early ontogenetic stages of lake sturgeon (Acipenser fulvescens).

ABSTRACT: Climate change is affecting thermal conditions worldwide. Understanding organismal responses associated with predicted changes are essential for predicting population persistence. Few studies have examined the effects of both increased mean and variance in temperature on organismal traits, particularly during early life stages. Using lake sturgeon (Acipenser fulvescens) from Black Lake, MI, we tested whether phenotypic variation differed among families reared in two constant (10 and 18°C) and two fluctuating-temperature treatments (10-19°C) representing temperatures experienced in the river and a simulated anthropogenic disturbance. Body length, body area, and yolk-sac area were quantified at hatch. Family-by-treatment interactions explained up to 50% of the variance observed among families in offspring hatch traits. Families incubated in 18°C and the fluctuating anthropogenic treatment had 6-10 times higher variance in traits than those incubated at 10°C. Hatched larvae were placed in raceways with ambient river water. Emergence body length, emergence timing, and growth were quantified upon emergence. Families differed in time to emergence and growth with the greatest range observed in the 18°C treatment. Results demonstrate that differential responses among genotypes to changes in the mean and variability of thermal incubation regimes can affect traits at hatch as well as a subsequent ontogenetic stage.

SUBMITTER: Dammerman KJ

PROVIDER: S-EPMC5108217 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Increases in the mean and variability of thermal regimes result in differential phenotypic responses among genotypes during early ontogenetic stages of lake sturgeon (<i>Acipenser fulvescens</i>).

Dammerman Kari J KJ Steibel Juan P JP Scribner Kim T KT

Evolutionary applications 20160831 10

Climate change is affecting thermal conditions worldwide. Understanding organismal responses associated with predicted changes are essential for predicting population persistence. Few studies have examined the effects of both increased mean and variance in temperature on organismal traits, particularly during early life stages. Using lake sturgeon (<i>Acipenser fulvescens</i>) from Black Lake, MI, we tested whether phenotypic variation differed among families reared in two constant (10 and 18°C) ...[more]

PMID: 27877204

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Project description:Gastrointestinal (GI) or gut microbiotas play essential roles in host development and physiology. These roles are influenced partly by the microbial community composition. During early developmental stages, the ecological processes underlying the assembly and successional changes in host GI community composition are influenced by numerous factors, including dispersal from the surrounding environment, age-dependent changes in the gut environment, and changes in dietary regimes. However, the relative importance of these factors to the gut microbiota is not well understood. We examined the effects of environmental (diet and water sources) and host early ontogenetic development on the diversity of and the compositional changes in the gut microbiota of a primitive teleost fish, the lake sturgeon (Acipenser fulvescens), based on massively parallel sequencing of the 16S rRNA gene. Fish larvae were raised in environments that differed in water source (stream versus filtered groundwater) and diet (supplemented versus nonsupplemented Artemia fish). We quantified the gut microbial community structure at three stages (prefeeding and 1 and 2 weeks after exogenous feeding began). The diversity declined and the community composition differed significantly among stages; however, only modest differences associated with dietary or water source treatments were documented. Many taxa present in the gut were over- or underrepresented relative to neutral expectations in each sampling period. The findings indicate dynamic relationships between the gut microbiota composition and host gastrointestinal physiology, with comparatively smaller influences being associated with the rearing environments. Neutral models of community assembly could not be rejected, but selectivity associated with microbe-host GI tract interactions through early ontogenetic stages was evident. The results have implications for sturgeon conservation and aquaculture production specifically and applications of microbe-based management in teleost fish generally.IMPORTANCE We quantified the effects of environment (diet and water sources) and host early ontogenetic development on the diversity of and compositional changes in gut microbial communities based on massively parallel sequencing of the 16S rRNA genes from the GI tracts of larval lake sturgeon (Acipenser fulvescens). The gut microbial community diversity declined and the community composition differed significantly among ontogenetic stages; however, only modest differences associated with dietary or water source treatments were documented. Selectivity associated with microbe-host GI tract interactions through early ontogenetic stages was evident. The results have implications for lake sturgeon and early larval ecology and survival in their natural habitat and for conservation and aquaculture production specifically, as well as applications of microbe-based management in teleost fish generally.

Project description:In this study, the effects of different feeding frequencies on the growth and the expression of genes in the GH/IGF axis were assessed in juvenile Chinese sturgeon. The newly hatched Chinese sturgeons were bred for 38 days at three different feeding frequencies groups (feeding frequency of two times a day, TWD; three times a day, THD; and four times a day, FOD), and the expression levels of the GH/IGF axis responses to feeding frequency were determined by quantitative real-time PCR. In addition, the full-length of the Coding Sequences of IGF I and IGF II genes (489-bp and 660-bp, respectively), were cloned and analyzed from Chinese sturgeon the first time. Multiple sequence alignments of IGFs revealed that Chinese sturgeon are high sequence identity to IGFs from other species. The phylogenetic relationships based on the IGF I and IGF II amino acid sequences were consistent with the traditional classification. After 38 days of growth, the three different feeding frequencies groups of Chinese sturgeon had no significant difference of body length, body weight, specific growth rate, the survival rate, the rate of weight gain and the condition factor. However, the relative expression of Chinese sturgeon GH in the pituitary decreased with increasing feeding frequency. The relative expression of Chinese sturgeon GHR in liver and skeletal muscle was deceased with increasing feeding frequency, while the relative expression of GHR in stomach and intestines at THD group was significantly higher than that of at TWD group and FOD group (p?<?0.05). The relative expression of Chinese sturgeon IGF I in liver increased significantly with increasing feeding frequency (p?<?0.05). The relative expression of IGF I in stomach and skeletal muscle was similar at the three groups. The relative expression of IGF I in intestines was significantly higher at FOD group than at TWD group and THD group (p?<?0.05). The relative expression of Chinese sturgeon IGF II in liver at TWD group was significantly higher than that at THD group and FOD group (p?<?0.05). However, the relative expression of IGF II in stomach, intestines and skeletal muscle at THD group was higher than that at TWD group and FOD group. Based on these previous studies that liver IGF I is regarded as a biomarker of growth performance, this result suggested that the juvenile Chinese sturgeon is better for growth when feeding four times daily compared to twice and thrice daily.

Project description:BackgroundEvolution of sturgeons and paddlefishes (order Acipenseriformes) is inherently connected with polyploidization events which resulted in differentiation of ploidy levels and chromosome numbers of present acipenseriform species. Moreover, allopolyploidization as well as autopolyploidization seems to be an ongoing process in these fishes and individuals with abnormal ploidy levels were occasionally observed within sturgeon populations. Here, we reported occurrence of Siberian sturgeon (Acipenser baerii) male with abnormal ploidy level for this species, accessed its ploidy level and chromosome number and investigate its potential sterility or fertility in comparison with normal individuals of sterlet (A. ruthenus), Russian sturgeon (A. gueldenstaedtii) and Siberian sturgeon (A. baerii).ResultsAcipenser ruthenus possessed 120 chromosomes, exhibiting recent diploidy (2n), A. gueldenstaedtii and A. baerii had ~245 chromosomes representing recent tetraploidy (4n), and A. baerii male with abnormal ploidy level had ~ 368 chromosomes, indicating recent hexaploidy (6n). Genealogy assessed from the mtDNA control region did not reveal genome markers of other sturgeon species and this individual was supposed to originate from spontaneous 1.5 fold increment in number of chromosome sets with respect to the number most frequently found in nature for this species. Following hormone stimulation, the spontaneous hexaploid male produced normal sperm with ability for fertilization. Fertilization of A. baerii and A. gueldenstaedtii ova from normal 4n level females with sperm of the hexaploid male produced viable, non-malformed pentaploid (5n) progeny with a ploidy level intermediate to those of the parents.ConclusionThis study firstly described occurrence of hexaploid individual of A. baerii and confirmed its autopolyploid origin. In addition to that, the first detailed evidence about fertility of spontaneous hexaploid sturgeon was provided. If 1.5 fold increment in number of chromosome sets occurring in diploids, resulted triploids possess odd number of chromosome sets causing their sterility or subfertility due to interference of gametogenesis. In contrast, 1.5 fold increment in number of chromosome sets in naturally tetraploid A. baerii resulted in even number of chromosome sets and therefore in fertility of the hexaploid specimen under study.

Dataset Information

Increases in the mean and variability of thermal regimes result in differential phenotypic responses among genotypes during early ontogenetic stages of lake sturgeon (Acipenser fulvescens).

Publications

Increases in the mean and variability of thermal regimes result in differential phenotypic responses among genotypes during early ontogenetic stages of lake sturgeon (<i>Acipenser fulvescens</i>).

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