The study of spatial distribution of the population of Lima bean in the Central Valley of Costa Rica showed that for any given population, the mean distance to the nearest population is 1768.7 m (n=497 populations). The range for the distance to the nearest population was between 165 and 3697 m. The occurrence of local population extinction was common in wild populations of Lima bean. A total of 91 episodes of local extinction was recorded, of which, only 19 resulted in permanent loss of the population indicating that about 79% of the sites that experience extinction were recolonized during the study period. Results also revealed that small populations were most likely to experience local extinction. Not all the populations were equally likely to produce seeds. Nearly one-fifth of the populations in the study area failed to produce flowers every year indicating that populations differ in their ability to maintain a seed reservoir in the soil. Populations that produce seeds in a given year have a high probability of producing seeds in future years while those that become extinct also have a greater probability of staying extinct.
Plant populations may experience local extinction and at the same time new populations may appear in nearby suitable locations. Species may also colonize the same site on multiple occasions. Here, we examined the impact of local extinction and recolonization on the genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central valley of Costa Rica. We compared genetic diversity from the samples taken from the populations before and after extinction at 13 locations using microsatellite markers. Locations were classified according to the occurrence of extinction episodes during the previous five years into three groups: 1) populations that experienced extinction for more than one year, and were later recolonized (recolonized), 2) populations that did not experience local extinction (control), and 3) populations that did not experience local extinction during the study, but were cut to experimentally simulate extinction (experimental). Our data did not show a clear tendency in variation in allele frequencies, expected heterozygosity, and effective number of alleles within and between groups of populations. However, we found that the level of genetic differentiation between samples collected at different times at the same location was different in the three groups of populations. Recolonized locations showed the highest level of genetic differentiation (mean Fst = 0.2769), followed by control locations (mean F st = 0.0576) and experimental locations (mean F st = 0.0189). Similar findings were observed for Nei ' s genetic distance between samples (d i,j = 0.1786, 0.0400, and 0.0037, respectively). Our results indicate that genetic change in lima beans depends on the duration and frequency of local extinction episodes. These findings also showed that control populations are not in equilibrium. Implications of these results for the establishment of conservation strategies of genetic resources of lima beans are discussed.
Let G = An, a finite alternating group. We study the commuting graph of G and establish, for all possible values of n barring 13, 14, 17, and 19 whether or not the independence number is equal to the cliquecovering number.
A routine check-up was performed on a captive 14-year-old female margay (Leopardus wiedii), a cutaneous mass was detected on the ventral thorax. The mass was surgically removed and sent for histopathological analysis. Histologically, the mass was a poorly-demarcated, highly cellular, infiltrative and unencapsulated mesenchymal neoplasm. Immunohistochemical labeling for smooth muscle actin and vimentin were positive, while desmin and cytokeratin were negative which is consistent with a myofibroblastic fibrosarcoma. This type of tumor has been diagnosed in wild felines, however this seems to be the first report of its occurrence in this L. wiedii. Wildlife oncology studies should be performed to promote our understanding of cancer in a species.
Let G = An, a finite alternating group. We study the commuting graph of G and establish, for all possible values of n barring 13, 14, 17 and 19, whether or not the independence number is equal to the clique-covering number.
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