Genetic analysis of the dry forest timber tree Sideroxylon capiri in Costa Rica using AFLP

Sideroxylon capiri (“Tempisque”) is a threatened and economically important timber species in the dry forest of Costa Rica. To assess the extent of the genetic diversity between and within populations of this species, 86 samples were obtained from four sites in the northwestern part of the country from protected and non-protected areas. They were analyzed by amplified fragment length polymorphism. Five primers were used to generate 254 polymorphic bands. Molecular variance indicated a 92 % within locations with a PhiPT (φ st) of 0.083 and a He from 0.204 to 0.249. PCoA analysis showed two different groups: one formed by Palo Verde and La Cruz samples, and another group with Nicoya and Barra Honda samples. The dendrogram arranged the samples in three groups: individuals from Palo Verde and La Cruz divided in two groups, and a more compact group from Barra Honda and Nicoya. A positive correlation between pairwise linearized geographical distance and genetic differentiation among populations was detected by Mantel test (R 2 = 0.76241, P = 0.04). Results are discussed in terms of fragmentation of the continuous forests and geographical barriers. Despite these results, it is evident that a great genetic diversity exists for this species and the results can be used for conservation purposes.Universidad de Costa Rica/[]/UCR/Costa RicaConsejo Nacional para Investigaciones Científicas y Tecnológicas/[]/CONICIT/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de QuímicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Diapause in a tropical oil-collecting bee: molecular basis unveiled by RNA-Seq

Abstract Background Diapause is a natural phenomenon characterized by an arrest in development that ensures the survival of organisms under extreme environmental conditions. The process has been well documented in arthropods. However, its molecular basis has been mainly studied in species from temperate zones, leaving a knowledge gap of this phenomenon in tropical species. In the present study, the Neotropical and solitary bee Tetrapedia diversipes was employed as a model for investigating diapause in species from tropical zones. Being a bivoltine insect, Tetrapedia diversipes produce two generations of offspring per year. The first generation, normally born during the wet season, develops faster than individuals from the second generation, born after the dry season. Furthermore, it has been shown that the development of the progeny, of the second generation, is halted at the 5th larval instar, and remains in larval diapause during the dry season. Towards the goal of gaining a better understanding of the diapause phenomenon we compared the global gene expression pattern, in larvae, from both reproductive generations and during diapause. The results demonstrate that there are similarities in the observed gene expression patterns to those already described for temperate climate models, and also identify diapause-related genes that have not been previously reported in the literature. Results The RNA-Seq analysis identified 2275 differentially expressed transcripts, of which 1167 were annotated. Of these genes, during diapause, 352 were upregulated and 815 were downregulated. According to their biological functions, these genes were categorized into the following groups: cellular detoxification, cytoskeleton, cuticle, sterol and lipid metabolism, cell cycle, heat shock proteins, immune response, circadian clock, and epigenetic control. Conclusion Many of the identified genes have already been described as being related to diapause; however, new genes were discovered, for the first time, in this study. Among those, we highlight: Niemann-Pick type C1, NPC2 and Acyl-CoA binding protein homolog (all involved in ecdysteroid synthesis); RhoBTB2 and SASH1 (associated with cell cycle regulation) and Histone acetyltransferase KAT7 (related to epigenetic transcriptional regulation). The results presented here add important findings to the understanding of diapause in tropical species, thus increasing the comprehension of diapause-related molecular mechanisms