Metapopulation dynamics of Lima bean ( Phaseolus lunatus L.) in the Central Valley of Costa Rica.

Abstract

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.

Restoration of genetic diversity in the dry forest treeSwietenia macrophylla(Meliaceae) after pasture abandonment in Costa Rica

“…Human activity also creates metapopulation scenarios, e.g. by intensive land use, changes in agricultural practices, and urban development that may result in fragmentation of the landscape and temporal degradation of suitable habitats (Rocha et al . 1997, 2002).…”

The impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica: consequences for the conservation of plant genetic resources

“…For each population, we collected a voucher specimen, fruit and seed samples, and described the site with parameters such as size of the population, topography, associated vegetation and geographical coordinates using a Garmin 48 GPS unit. Similar surveys were conducted again in 1993, 1994 and 1999. Previous studies revealed the occurrence of multiple extinction and recolonization events among wild populations of lima beans (Rocha et al 2002, Barrantes 2003. Monthly monitoring of 106 populations for six year (from November 1994 to December 2000) showed that 39 populations experienced local extinction that lasted for more than one year.…”

“…These findings suggest that multiple extinctions lead to more severe bottlenecks, hence resulting in more differentiation between samples taken form the same location. Moreover, the likelihood of extinction is also related to population size, as small populations are more likely to disappear (Rocha et al 2002, Barrantes 2003, which suggests that such populations may be more susceptible to genetic losses.…”

“…Wild and weedy relatives of cultigens are an extremely important source of genes for crop improvement, but these crucial genetic resources are coming under increasing pressure the world over, as wild habitats are altered and lost. Previous studies have revealed the occurrence of multiple extinction and recolonization events in lima beans (Rocha et al 2002, Barrantes 2003, but their consequences on genetic diversity have not been studied in detail.…”