Nelson Toro-Perea

Genetic structure of the red mangrove ( Rhizophora mangle L.) on the Colombian Pacific detected by microsatellite molecular markers

AbstractRhizophora mangle, one of the five species of the genus Rhizophora, is found widely distributed along the American and West African coasts. This species is one of the principal constituents of the mangrove ecosystem in Colombia and is also found within the most important economic activities for the communities that inhabit the littoral. In order to assess the degree of genetic diversity of R. mangle in five populations of the Colombian Pacific, nuclear microsatellite molecular markers were used. In 92 individuals sampled, it was found that 100% of the loci were polymorphic

Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus

(\overline H _0 = 0.494)

Evidence for adaptive divergence of thermal responses among Bemisia tabaci populations from tropical Colombia following a recent invasion.

, and no private alleles were detected. The population structure of R. mangle in the Colombian Pacific, was highly significant (P < 0.001); however, the greatest differentiation was detected at the within-population level (94.62%). For the populations of La Plata, Virudó and Charambirá, the tendency toward panmixia could be the cause of the low differentiation among these three locations. Within populations, the genetic diversity revealed a deviation from Hardy–Weinberg equilibrium with high significance in Virudó and Tumaco, where it appears the intense anthropogenic activity has exercised strong pressure on the red mangrove, resulting in the possible fragmentation of the local landscape and therefore an increase in the rate of endogamy within these populations. Despite this situation, our study―one of the first developed in genetics of the red mangrove in Colombia―did not show evidence of recent bottleneck effects or deterioration in its genetic composition, which could be exploited to propose management and restoration programs for the zones where the forests of this species are degraded.

Barcoding, population structure, and demographic history of Prodiplosis longifila associated with the Andes

Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life-history traits on diversification of unrelated but co-distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present-day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life-history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid-Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life-history traits of mangrove species, which should have had a strong influence on seed dispersal capability and, thus, population connectivity, we found that vicariant events, climate fluctuations and marine currents have shaped the distribution of genetic diversity in strikingly similar ways.

Jumping a geographic barrier: diversification of the mangrove species Pelliciera rhizophorae (Tetrameristaceae) across the Central American Isthmus

There is an increasing evidence that populations of ectotherms can diverge genetically in response to different climatic conditions, both within their native range and (in the case of invasive species) in their new range. Here, we test for such divergence in invasive whitefly Bemisia tabaci populations in tropical Colombia, by considering heritable variation within and between populations in survival and fecundity under temperature stress, and by comparing population differences with patterns established from putatively neutral microsatellite markers. We detected significant differences among populations linked to mean temperature (for survival) and temperature variation (for fecundity) in local environments. A QST − FST analysis indicated that phenotypic divergence was often larger than neutral expectations (QST > FST). Particularly, for survival after a sublethal heat shock, this divergence remained linked to the local mean temperature after controlling for neutral divergence. These findings point to rapid adaptation in invasive whitefly likely to contribute to its success as a pest species. Ongoing evolutionary divergence also provides challenges in predicting the likely impact of Bemisia in invaded regions.

Thermal reaction norms between populations with climatic differences of the invader silverleaf whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) MEAM 1 clade in Colombia

Prodiplosis longifila Gagné (Diptera: Cecidomyiidae) is an insect pest that attacks various types of crops, including tomato, Solanum lycopersicum L. (Solanaceae), a vegetable with substantial economic significance worldwide. Prodiplosis longifila is a widely distributed pest in Colombia, Ecuador, and Peru, countries characterized by the presence of significant geographic barriers like the Andes Mountains. It has been reported that geographic barriers affect the dynamics and genetic differentiation of insect populations. Therefore, the aim of this study was to assess the diversity, genetic structure, and demographic history of P. longifila through the analysis of sequences within the mitochondrial region of cytochrome oxidase I (COI) and rDNA‐ITS2 in 27 populations located in Colombia and Ecuador. Analyses were performed on populations distributed in three geographic groups separated by the presence of the Andes Mountains. A total of 11 haplotypes were identified with the COI gene and only one haplotype in the rDNA‐ITS2 was found. Analyses of population structure and demographic history revealed that there is a structure associated with the Andes, which is reflected in an uneven distribution of the haplotype frequencies between regions, but even so, gene flow between populations was detected which produces low genetic differentiation. Because P. longifila has a short‐range dispersion that determines its territorial nature, it would be expected that other factors are producing the genetic exchange between populations. We suggest that the anthropogenic effect produced by farming practices, such as the use of seedlings as seed, which may carry P. longifila larvae, cause passive dispersal of pest throughout the Andes, particularly in Colombia.

Genetic diversity and population structure of Anastrepha obliqua in southwestern Colombia

The Central American Isthmus (CAI) is an important geographic barrier in the Neotropics. Its role in the diversification of marine and coastal species has been detected in fishes, turtles, sea urchins, and mangroves. We evaluated the CAI’s influence on the diversification of the most ancient neotropical mangrove species Pelliciera rhizophorae across populations from the Caribbean and Pacific coasts, based on the analysis of ten nuclear microsatellite loci and two noncoding chloroplast DNA regions. The two molecular markers showed concordant patterns of diversification in this mangrove species. Contrary to our expectations, this study did not reveal significant genetic structure among populations separated by the CAI. Two major genetic variants (cluster I and cluster II) were found on both coasts, but the two were not found intermixed in the same population. Within each coastal region, breaking of gene flow among populations was found at two points in the Pacific Basin and one point in the Caribbean Basin, separating the Colombian and Panamanian populations. Our study revealed a transisthmian connection among populations of P. rhizophorae. This result, together with the reduced genetic diversity in the Caribbean reported in our previous study, suggests the recent origin of these populations, probably due to reintroduction of P. rhizophorae from the Pacific coast. Taking into account that these introductions are random events, this study raises a new question: Why are genetic variants not intermixed within the Caribbean populations? Our hypotheses suggest the influence of environmental factors and/or anthropogenic impact on the establishment of these Caribbean patches.

The bud midge Prodiplosis floricola in citrus crops in Colombia

Insect species can respond adaptively to stress temperature conditions including both thermal limits and reaction norms. In this study, we considered two populations of the whitefly Bemisia tabaci (Gennadius), in which adaptive differentiation was detected for tolerance to upper thermal limits. These two populations are found in two regions of Colombia with climatic differences: the Caribbean region with high environmental temperatures and the Southwest region with lower temperature regimens. We assessed the thermal responses to a range of 1 h heat shocks (37, 39, 41, 43 and 44 °C) performed below the thermal limits for this species. Thermal responses were measured using three life-history traits involved in fitness: survival, fecundity and viability of the offspring after heat shocks. Survival or fecundity as a response to heat shocks did not differ among populations; however, there were significantly different responses for viability between populations. The Southwestern population showed higher viability responses to low heat shocks than the Caribbean population. This relationship suggests a potential trade-off, which appears to be associated with climatic regions. In addition, these results suggest that adaptation under thermal limits does not necessarily involve similar responses throughout the reaction norm. A potential ongoing evolutionary response is taking place through the thermal reaction norms for viability after the invasion by this pest in Colombia.

Karyotype of the Neotropical mangrove species Pelliciera Rhizophorae Triana and Planchon (Tetrameristaceae)

The West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), is a quarantine pest in Colombia that infests economically important plants, although little is known about its population dynamics. In this study, cytochrome oxidase subunit I (COI) and NADH dehydrogenase subunit 6 (ND6) mitochondrial genes were concatenated to characterise the genetic diversity and population structure of A. obliqua, associated with two factors: (1) ecosystem differences in two geographical regions of southwestern Colombia (the inter‐Andean valley of the Cauca River and the mountain region), and (2) the host plants present in the area. Additionally, a first approach was made at understanding the species demographic history. Seven haplotypes were found with Kimura 2‐parameter (K2P) genetic distances between 0.1 and 4%. Haplotype genealogies and demographic analyses suggest that the population of A. obliqua in southwestern Colombia is the result of introductory events of multiple populations of A. obliqua. However, the data indicate that the population genetic structure could be related to the ecological differences of the two regions being studied. Significant differences were also found among the distribution of haplotype frequencies of A. obliqua with regard to the diversity of host plants. This study is the first to provide an understanding of the population dynamics of A. obliqua in Colombia, which may ultimately contribute to strategies, such as sterile insect technique (SIT), for the management of the pest.

Molecular analysis of the expression of a crtB transgene and the endogenous psy 2- y 1 and psy 2- y 2 genes of cassava and their effect on root carotenoid content

Sampling performed in flower buds of citrus in Colombia allowed the detection of the presence of Prodiplosis longifila Gagné and Prodiplosis floricola Felt (Diptera: Cecidomyiidae). The polyphagous P. longifila is a pest of Solanaceae, but whether both species cause economic losses in citrus is unknown. These congeneric species are indistinguishable in the larval stage, and their morphological identification, which is complex, is performed on adult males. This study comprises a morphological description and characterization of the damage generated by P. floricola larvae feeding on the flowers of key lime, Citrus × aurantiifolia (Christm.) Swingle (pro. sp.), and Tahiti lime, Citrus × latifolia Tanaka ex Q. Jiménez (Rutaceae), as well as a population genetical analysis of the insect. Prodiplosis floricola was found in the localities of Támesis (Antioquia), Garzón (Huila), and Palmira and Zarzal (Valle del Cauca). These populations were characterized by COI and ITS2 molecular markers, with a moderate genetic structure found that cannot be explained by the geographic distance between the populations. The haplotype distribution pattern indicates that the populations are composed of highly differentiated haplotypes of equivalent frequencies, which suggests that the Colombian populations of P. floricola are products of multiple introductions and that their dispersion between populations is attributable to anthropic transport. Citrus in Colombia constitutes a new host for P. floricola and increases the known geographical range of the insect, as it has only been previously reported in Brazil and the USA. The molecular markers used in the present study are useful for early diagnosis of P. floricola in the larval stage and for future research on the population dynamics in citrus.