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A meta-analysis of local adaptation in plants.

Leimu R, Fischer M - PLoS ONE (2008)

Bottom Line: We show that, overall, local plants performed significantly better than foreign plants at their site of origin: this was found to be the case in 71.0% of the studied sites.Furthermore, we found local adaptation much more common for large plant populations (>1000 flowering individuals) than for small populations (<1000 flowering individuals) for which local adaptation was very rare.Our results suggest that local adaptation is less common in plant populations than generally assumed.

View Article: PubMed Central - PubMed

Affiliation: Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany. roosa.leimu@plants.ox.ac.uk

ABSTRACT
Local adaptation is of fundamental importance in evolutionary, population, conservation, and global-change biology. The generality of local adaptation in plants and whether and how it is influenced by specific species, population and habitat characteristics have, however, not been quantitatively reviewed. Therefore, we examined published data on the outcomes of reciprocal transplant experiments using two approaches. We conducted a meta-analysis to compare the performance of local and foreign plants at all transplant sites. In addition, we analysed frequencies of pairs of plant origin to examine whether local plants perform better than foreign plants at both compared transplant sites. In both approaches, we also examined the effects of population size, and of the habitat and species characteristics that are predicted to affect local adaptation. We show that, overall, local plants performed significantly better than foreign plants at their site of origin: this was found to be the case in 71.0% of the studied sites. However, local plants performed better than foreign plants at both sites of a pair-wise comparison (strict definition of local adaption) only in 45.3% of the 1032 compared population pairs. Furthermore, we found local adaptation much more common for large plant populations (>1000 flowering individuals) than for small populations (<1000 flowering individuals) for which local adaptation was very rare. The degree of local adaptation was independent of plant life history, spatial or temporal habitat heterogeneity, and geographic scale. Our results suggest that local adaptation is less common in plant populations than generally assumed. Moreover, our findings reinforce the fundamental importance of population size for evolutionary theory. The clear role of population size for the ability to evolve local adaptation raises considerable doubt on the ability of small plant populations to cope with changing environments.

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Relationship of plant population size and local adaptation.A) The better performance of local plants compared to foreign plants is significantly greater for large (N = 24) than for small (N = 8) populations. The bars denote bias-corrected 95% confidence limits. B) The frequencies of cases where reaction norms for fitness cross (POS-POS, see Fig. 1) indicating selection for locally adapted specialists, cases where the reaction norms do not cross (POS-NEG), and cases where effect sizes are negative at both sites indicating maladaptation (NEG-NEG). White bars denote large populations and grey bars denote small populations.
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pone-0004010-g002: Relationship of plant population size and local adaptation.A) The better performance of local plants compared to foreign plants is significantly greater for large (N = 24) than for small (N = 8) populations. The bars denote bias-corrected 95% confidence limits. B) The frequencies of cases where reaction norms for fitness cross (POS-POS, see Fig. 1) indicating selection for locally adapted specialists, cases where the reaction norms do not cross (POS-NEG), and cases where effect sizes are negative at both sites indicating maladaptation (NEG-NEG). White bars denote large populations and grey bars denote small populations.

Mentions: Local plants performed better than foreign plants in a given environment only in large plant populations as indicated by a significant positive overall effect size, whereas in small populations there was no significant difference in plant performance between plant origins (Fig. 2a; test for difference between large and small populations: Qb = 5.50, df = 1, N = 32, P = 0.0026; this is smaller than the Bonferroni adjusted alpha level 0.0071). In addition, the frequencies of crossing and non-crossing reaction norms for fitness indicate that in large populations divergent selection and local adaptation sensu Kawecki and Ebert [12] (“POS-POS” case) occurred in 52.3% of the cases (Fig. 2b) whereas in small populations this was much rarer (9.3%, Fig. 2b). Furthermore, almost all maladapted pairs of populations were small (“NEG-NEG” case; Fig. 2b). These frequencies differed significantly between large and small populations (χ2 = 25. 5, N = 212, P = 0.0001). These results suggest that small populations lack the potential to adapt to local environments.


A meta-analysis of local adaptation in plants.

Leimu R, Fischer M - PLoS ONE (2008)

Relationship of plant population size and local adaptation.A) The better performance of local plants compared to foreign plants is significantly greater for large (N = 24) than for small (N = 8) populations. The bars denote bias-corrected 95% confidence limits. B) The frequencies of cases where reaction norms for fitness cross (POS-POS, see Fig. 1) indicating selection for locally adapted specialists, cases where the reaction norms do not cross (POS-NEG), and cases where effect sizes are negative at both sites indicating maladaptation (NEG-NEG). White bars denote large populations and grey bars denote small populations.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2602971&req=5

pone-0004010-g002: Relationship of plant population size and local adaptation.A) The better performance of local plants compared to foreign plants is significantly greater for large (N = 24) than for small (N = 8) populations. The bars denote bias-corrected 95% confidence limits. B) The frequencies of cases where reaction norms for fitness cross (POS-POS, see Fig. 1) indicating selection for locally adapted specialists, cases where the reaction norms do not cross (POS-NEG), and cases where effect sizes are negative at both sites indicating maladaptation (NEG-NEG). White bars denote large populations and grey bars denote small populations.
Mentions: Local plants performed better than foreign plants in a given environment only in large plant populations as indicated by a significant positive overall effect size, whereas in small populations there was no significant difference in plant performance between plant origins (Fig. 2a; test for difference between large and small populations: Qb = 5.50, df = 1, N = 32, P = 0.0026; this is smaller than the Bonferroni adjusted alpha level 0.0071). In addition, the frequencies of crossing and non-crossing reaction norms for fitness indicate that in large populations divergent selection and local adaptation sensu Kawecki and Ebert [12] (“POS-POS” case) occurred in 52.3% of the cases (Fig. 2b) whereas in small populations this was much rarer (9.3%, Fig. 2b). Furthermore, almost all maladapted pairs of populations were small (“NEG-NEG” case; Fig. 2b). These frequencies differed significantly between large and small populations (χ2 = 25. 5, N = 212, P = 0.0001). These results suggest that small populations lack the potential to adapt to local environments.

Bottom Line: We show that, overall, local plants performed significantly better than foreign plants at their site of origin: this was found to be the case in 71.0% of the studied sites.Furthermore, we found local adaptation much more common for large plant populations (>1000 flowering individuals) than for small populations (<1000 flowering individuals) for which local adaptation was very rare.Our results suggest that local adaptation is less common in plant populations than generally assumed.

View Article: PubMed Central - PubMed

Affiliation: Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany. roosa.leimu@plants.ox.ac.uk

ABSTRACT
Local adaptation is of fundamental importance in evolutionary, population, conservation, and global-change biology. The generality of local adaptation in plants and whether and how it is influenced by specific species, population and habitat characteristics have, however, not been quantitatively reviewed. Therefore, we examined published data on the outcomes of reciprocal transplant experiments using two approaches. We conducted a meta-analysis to compare the performance of local and foreign plants at all transplant sites. In addition, we analysed frequencies of pairs of plant origin to examine whether local plants perform better than foreign plants at both compared transplant sites. In both approaches, we also examined the effects of population size, and of the habitat and species characteristics that are predicted to affect local adaptation. We show that, overall, local plants performed significantly better than foreign plants at their site of origin: this was found to be the case in 71.0% of the studied sites. However, local plants performed better than foreign plants at both sites of a pair-wise comparison (strict definition of local adaption) only in 45.3% of the 1032 compared population pairs. Furthermore, we found local adaptation much more common for large plant populations (>1000 flowering individuals) than for small populations (<1000 flowering individuals) for which local adaptation was very rare. The degree of local adaptation was independent of plant life history, spatial or temporal habitat heterogeneity, and geographic scale. Our results suggest that local adaptation is less common in plant populations than generally assumed. Moreover, our findings reinforce the fundamental importance of population size for evolutionary theory. The clear role of population size for the ability to evolve local adaptation raises considerable doubt on the ability of small plant populations to cope with changing environments.

Show MeSH