Genetic consequences in plant populations: global and souther patterns

AGUILAR, R.; QUESADA, M.; ASHWORTH, L.

Congreso; VI Southern Connexion Congress; 2010

The   loss   and   fragmentation   of   habitats   by   human   activities   are   pervasive phenomena in terrestrial ecosystems and the main current driving forces behind biodiversity   loss.   Much   research   has   been   conducted   worldwide   to   evaluate fragmentation effects on plant population genetic parameters. We quantitatively reviewed the results of fragmentation studies to test the general hypothesis that fragmentation   affects   the   genetic   diversity   of   plant   populations.   We   also assessed whether fragmentation has differential effects depending on certain life history   and   ecological   traits   of   plants,   and   tested   whether   particular methodological   approaches   influence   the   ability   to   detect   genetic   erosion   in fragmentation studies. Overall, genetic diversity and outcrossing rates of plants decreased in fragmented habitats. Outcrossing and either common or recently rare plants showed strongest negative effects on their genetic diversity.  Higher inbreeding   coefficients   were   only   observed   in   studies  analyzing   progenies  in fragmented   habitats.   Finally,   the   time   elapsed   in   fragmentation   conditions significantly   influenced   the   magnitude   of   effects.   Results   suggest   that fragmentation is shifting mating patterns towards increased selfing. Remarkably, only   20%   of   the   studies   were   conducted   in   the   Southern   Hemisphere   (SH). Although main general response patterns remain similar within this set of studies, I   will   discuss   some   particular   trends   observed   in   species   from   the   SH   and compare them with global patterns.