Local Interactions Affect Spread of Resource in a Consumer-resource System With Group Defense

Integrodifference equations are a discrete time spatially explicit model that describes dispersal of ecological populations through space. This framework is useful to study spread dynamics of organisms and how ecological interactions can affect their spread. When studying interactions such as consumption, dispersal rates might vary with life cycle stage, such as cases with dispersive juveniles and sessile adults. In the non-dispersive stage, resources may engage in group defense to protect themselves from consumption. These local nondispersive interactions may limit the number of dispersing recruits that are produced and therefore affect how fast populations can spread. We present a spatial consumer-resource system using an integrodifference framework with limited movement of their adult stages and group defense mechanisms in the resource population. We model group defense using a Type IV Holling functional response, which limits survival of adult resource population and enhances juvenile consumers production. We find that high mortality levels for sessile adults can destabilize resource at carrying capacity. Furthermore, we find that at high resource densities, group defense leads to a slower local growth of resource in newly invaded regions due to intraspecific competition outweighing the effect of consumption on resource growth.

Species extinction at the various environmental forcing in a stochastic ecosystem model

This paper considers a stochastic multi-species single resource population model. The stochastic model is obtained from perturbing the supply of resource by a time dependent force. We use analytical investigations and numerical simulations to study the dynamics of our model under chaotic and periodic environmental oscillations, and show that the stochastic dynamics of our model exhibits a strong dependence on initial parameters.

Computational Study on the Dynamics of a Consumer-Resource Model: The Influence of the Growth Law in the Resource

The dynamics of a specific consumer-resource model for Daphnia magna is studied from a numerical point of view. In this study, Malthusian, chemostatic, and Gompertz growth laws for the evolution of the resource population are considered, and the resulting global dynamics of the model are compared as different parameters involved in the model change. In the case of Gompertz growth law, a new complex dynamic is found as the carrying capacity for the resource population increases. The numerical study is carried out with a second-order scheme that approximates the size-dependent density function for individuals in the consumer population. The numerical method is well adapted to the situation in which the growth rate for the consumer individuals is allowed to change the sign and, therefore, individuals in the consumer population can shrink in size as time evolves. The numerical simulations confirm that the shortage of the resource has, as a biological consequence, the effective shrink in size of individuals of the consumer population. Moreover, the choice of the growth law for the resource population can be selected by how the dynamics of the populations match with the qualitative behaviour of the data.

Identification of Point Mutation in Exon 3 of Leptin Gene in Munjal Sheep

Background: Leptin is a varied hormone which plays vital role in body development by regulating the balance between food intake and energy expenditure by signaling to the brain. Leptin has diverse effect on controlling appetite, energy metabolism, growth, reproduction, body composition and immunity. The present study was aimed to screen candidate point mutation (g.332G greater than A) in the targeted genomic region of leptin gene in Munjal sheep. Methods: A total of 50 Munjal sheep were selected and genomic DNA was isolated in Automated Maxell RSC DNA/ RNA purification system by using Maxwell RSC whole blood DNA kit. Reported set of primers was used to amplify 463bp fragment encompassing targeted region (exon 3) of leptin gene. PCR-RFLP was performed to genotype targeted point mutation in our resource population. PCR products were digested by Cail 1 restriction enzyme to genotype g.332G greater than A (at 332th nucleotide of exon 3 leptin gene) non-synonymous mutation (Arg to Gln). Result: All studied samples resolved into monomorphic banding pattern, revealed only AA (463bp single band bp) genotype. The absence of candidate mutation in our resource population might be due to small sample size.

Identification and Genetic Analysis of Major Gene ST3GAL4 Related to Serum Alkaline Phosphatase in Chickens

Background: An increasing number of studies have explored disease and growth traits through quantitative trait locus (QTLs) in chickens. Nevertheless, the pathogenic genes underlying the QTL effects remain poorly understood. Alkaline phosphatase (ALP) is a marker of osteoblast maturation and an important indicator of bone metabolism. The change of ALP can reflect the bone metabolism and growth traits of animals to a certain extent. Results: In this study, we identified a SNP site at ST3GAL4 that found by genome-wide association studies (GWAS) in previous studies, and found another 8 SNPs by DNA sequencing. Interestingly, there are 4 SNPs rs475471G>A, rs475533C>T, rs475621A>G, rs475647C>A were completely linked by haplotype analysis, and selected a tag SNP rs475471G>A to analyze the correlation between this SNP and ALP level in Hubbard leg disease population and an F2 chicken resource population produced by Anka and Gushi chickens, and carried out population genetic analysis in 18 chicken breeds. Association analysis showed that this QTL within ST3GAL4 were highly correlated with ALP level, the mutant individuals with genotype AA had the highest ALP level, followed by GA and GG genotypes. The mutant individuals with genotype AA and GA genotype had higher values for body weight (BW), chest width (CW), body slanting length (BSL), pelvis width (PW) at 4-week, the semi-evisceration weight (SEW), evisceration weight (EW) and Leg weight (LW) of AA and GA genotype also higher. The amplification and typing of 4,852 DNA samples from 18 different breeds and the result shown GG genotype mainly existed in egg-type chickens and dual-type chickens, while AA genotype mainly distributed in commercial broilers and F2 resource population. The individuals of AA genotype had the highest ALP and showed better growth performance. This is the first time to report the causal variant of ST3GAL4 gene that located at chromosome 24 related to chicken serum ALP level. Besides, tissue expression analysis used Cobb broiler showed that there were significant differences between different genotypes in spleen and duodenum.Conclusions: This study the first time to determine 9 SNPs within ST3GAL4 were related to ALP in chickens, 4 of them were complete linkage sequence variants, which provide useful information on the mutation of ST3GAL4 and could predict the serum ALP level of chicken early and effectively as a potential molecular breeding marker.

Picking Sequences and Monotonicity in Weighted Fair Division

We study the problem of fairly allocating indivisible items to agents with different entitlements, which captures, for example, the distribution of ministries among political parties in a coalition government. Our focus is on picking sequences derived from common apportionment methods, including five traditional divisor methods and the quota method. We paint a complete picture of these methods in relation to known envy-freeness and proportionality relaxations for indivisible items as well as monotonicity properties with respect to the resource, population, and weights. In addition, we provide characterizations of picking sequences satisfying each of the fairness notions, and show that the well-studied maximum Nash welfare solution fails resource- and population-monotonicity even in the unweighted setting. Our results serve as an argument in favor of using picking sequences in weighted fair division problems.

Analysis of four complete linkage sequence variants within a novel lncRNA located in a growth QTL on chromosome 1 related to growth traits in chickens

An increasing number of studies have shown that quantitative trait loci (QTLs) at the end of chromosome 1 identified in different chicken breeds and populations exert significant effects on growth traits in chickens. Nevertheless, the causal genes underlying the QTL effect remain poorly understood. Using an updated gene database, a novel lncRNA (named LncFAM) was found at the end of chromosome 1 and located in a growth and digestion QTL. This study showed that the expression level of LncFAM in pancreas tissues with a high weight was significantly higher than that in pancreas tissues with a low weight, which indicates that the expression level of LncFAM was positively correlated with various growth phenotype indexes, such as growth speed and body weight. A polymorphism screening identified four polymorphisms with strong linkage disequilibrium in LncFAM: a 5-bp indel in the second exon, an A/G base mutation, and 7-bp and 97-bp indels in the second intron. A study of a 97-bp insertion in the second intron using an F2 chicken resource population produced by Anka and Gushi chickens showed that the mutant individuals with genotype II had the highest values for body weight (BW) at 0 days and 2, 4, 6, 8, 10 and 12 weeks, shank girth (SG) at 4, 8 and 12 weeks, chest width (CW) at 4, 8 and 12 weeks, body slant length (BSL) at 8 and 12 weeks, and pelvic width (PW) at 4, 8 and 12 weeks, followed by ID and DD genotypes. The amplification and typing of 2,716 chickens from ten different breeds, namely, the F2 chicken resource population, dual-type chickens, including Xichuan black-bone chickens, Lushi green-shell layers, Dongxiang green-shell layers, Changshun green-shell layers, and Gushi chickens, and commercial broilers, including Ross 308, AA, Cobb and Hubbard broilers, revealed that II was the dominant genotype. Interestingly, only genotype II existed among the tested populations of commercial broilers. Moreover, the expression level in the pancreas tissue of Ross 308 chickens was significantly higher than that in the pancreas tissue of Gushi chickens (P < 0.001), which might be related to the conversion rates among different chickens. The prediction and verification of the target gene of LncFAM showed that LncFAM might regulate the expression of its target gene FAM48A through cis-expression. Our results provide useful information on the mutation of LncFAM, which can be used as a potential molecular breeding marker.

Detection of CNV in the SH3RF2 gene and its effects on growth and carcass traits in chickens

Background: The SH3RF2 gene is a protein-coding gene located in a quantitative trait locus associated with body weight, and its deletion has been shown to be positively associated with body weight in chickens. Results: In the present study, CNV in the SH3RF2 gene was detected in 4,079 individuals from 17 populations, including the “Gushi ×Anka” F2 resource population and populations of Chinese native chickens, commercial layers, and commercial broilers. The F2 resource population was then used to investigate the genetic effects of the chicken SH3RF2 gene. The results showed that the local chickens and commercial layers were all homozygous for the wild-type allele. Deletion mutation individuals were detected in all of the commercial broiler breeds except Hubbard broiler. A total of, 798 individuals in the F2 resource group were used to analyze the effects of genotype (DD/ID/II) on chicken production traits. The results showed that CNV was associated with 2-, 6-, 10-, and 12-week body weight ( P = 0.026, 0.042, 0.021 and 0.039 respectively) and significantly associated with 8-week breast bone length ( P = 0.045). The mutation was significantly associated with 8-week body weight ( P = 0.007) and 4-week breast bone length ( P = 0.010). CNV was significantly associated with evisceration weight, leg muscle weight, carcass weight, breast muscle weight and gizzard weight ( P = 0.032, 0.033, 0.045, 0.004 and 0.000, respectively). Conclusions: CNV of the SH3RF2 gene contributed to variation in the growth and weight gain of chickens.