Heterogeneity within a population enhances its long-term survival. A fundamental method of maintaining population heterogeneity is the retention of rare or uncommon phenotypes by selective mating strategies. Employing two color morphs, red tuxedo and red, of the guppy (Poecilia reticulata, Poeciliidae), this study was designed to investigate whether P. reticulata females would preferentially seek out heterogeneous groupings of males exhibiting two color morphs. Adult female guppies were exposed simultaneously to two groups of males (n=10); one comprised of only the tuxedo color morph (n=5) and the other of both color morphs (n=5). For the latter group, the ratio of males exhibiting the two colorations was changed incrementally over multiple trials, beginning and ending with homogeneous groupings (5:0, 4:1, 3:2, 2:3, 1:4, 0:5). Experiments were conducted employing a 76 L aquarium partitioned at both ends to house the male groups. Individual females were placed into an acclimation, holding column located in the center compartment of the experimental aquarium. Subsequent to a five minute acclimation period in the holding column, each female was released. Courting behaviors and population affinities (i.e. female location relative to the male compartments) were recorded every five seconds over a five minute observation period. Females did not show a preference for male groupings exhibiting either the 4:1 or 1:4 color ratios. However, females clearly showed affinity for the male groupings of 3:2 and 2:3 (p <0.05). This investigation on female mate choice in P. reticulata clearly reveals that a mating strategy is occurring in this species and that it is frequency-dependent.

Numerous concerns have been raised about the sustainability of the biomedical research enterprise in the United States. Improving the postdoctoral training experience is seen as a priority in addressing these concerns, but even identifying who the postdocs are is made difficult by the multitude of different job titles they can carry. Here, we summarize the detrimental effects that current employment structures have on training, compensation and benefits for postdocs, and argue that academic research institutions should standardize the categorization and treatment of postdocs. We also present brief case studies of two institutions that have addressed these challenges and can provide models for other institutions attempting to enhance their postdoctoral workforces and improve the sustainability of the biomedical research enterprise.

Numerous concerns have been raised about the sustainability of the biomedical research enterprise in the United States. Improving the postdoctoral training experience is seen as a priority in addressing these concerns, but even identifying who the postdocs are is made difficult by the multitude of different job titles they can carry. Here, we summarize the detrimental effects that current employment structures have on training, compensation and benefits for postdocs, and argue that academic research institutions should standardize the categorization and treatment of postdocs. We also present brief case studies of two institutions that have addressed these challenges and can provide models for other institutions attempting to enhance their postdoctoral workforces and improve the sustainability of the biomedical research enterprise.

Numerous concerns have been raised about the sustainability of the biomedical research enterprise in the United States. Improving the postdoctoral training experience is seen as a priority in addressing these concerns, but even identifying who the postdocs are is made difficult by the multitude of different job titles they can carry. Here, we summarize the detrimental effects that current employment structures have on training, compensation and benefits for postdocs, and argue that academic research institutions should standardize the categorization and treatment of postdocs. We also present brief case studies of two institutions that have addressed these challenges and can provide models for other institutions attempting to enhance their postdoctoral workforces and improve the sustainability of the biomedical research enterprise.

Genetic imprinting: the parent of origin?specific biased expression of alleles is an important type of epigenetic gene regulation in flowering plants and mammals. All imprinted genes show either maternal ? or paternal?specific mono?allelic expression. Considering that plants and mammals shared a common ancestor more than one billion years ago, significant overlap and potentially equally significant differences in the genomic imprinting mechanisms in these two taxa are emerging. In plants, the imprinted genes are primarily imprinted in the ephemeral endosperm tissues of the seeds which do not contribute any genome to future generations, while in mammals, the imprinted genes are located in embryo, placenta, and the adult body. Though both kingdoms silence imprinted genes using DNA methylation, imprinted alleles in mammals are targeted for silencing while in plants preexisting methylation is specifically removed from the allele destined to be active in maternally expressed genes in the endosperm. It is now accepted that imprinting evolved in both taxa due to competition between parental genomes over resource allocation to offspring. Moreover, the distinct life cycle stages between the taxa may account for the different strategies used by plants and mammals to regulate parent?specific gene expression. The elucidation of the genetic basis and molecular mechanisms responsible for genetic imprinting have provided answers to various crucial questions arising in biological sciencesPlant Tissue Cult. & Biotech. 26(2): 267-284, 2016 (December)

The croaking gourami (Trichopsis vittatus) exhibits two phenotypes associated with humeral spotting. Fish possess a prominent, dark humeral patch or spot located behind the operculum or lack this spotting pattern. Segregation patterns observed from the progenies of eleven different crosses support the hypothesis that the inheritance of humeral spotting in T. vittatus is controlled by the action of a single autosomal locus, with complete dominance of the allele controlling the spotted phenotype.