Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across...Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across Australia and New Zealand.Our dataset spanned 35°of latitude,and included over 1 million observations,making it the larg-est empirical study ever conducted for a single physical defence trait.A weighted logistic regression was applied first within Australia and New Zealand separately,and then across the com-bined dataset.Important Findings There was no significant latitudinal gradient in the proportion of spe-cies with spinescence in Australia or New Zealand,or in the overall dataset.That is,plant species are no more likely to be defended by spines at low latitudes than at high latitudes.This finding is counter to the idea that plant defences increase with latitude due to increased selective pressure from higher levels of herbivory.We suggest that future studies should investigate the relationship between herbivory and defence directly,without using latitude as a proxy.展开更多
Aims Organisms on islands are thought to escape biotic pressure and lose defensive capabilities.However,broadscale,evidence-based tests of this idea are rare.In this study,we asked:(i)whether the proportion of spinesc...Aims Organisms on islands are thought to escape biotic pressure and lose defensive capabilities.However,broadscale,evidence-based tests of this idea are rare.In this study,we asked:(i)whether the proportion of spinescent plant species differed between islands and mainlands and(ii)whether the proportion of spinescent species increased with increasing island area and with decreasing island distance to mainland.Methods We compiled species lists for 18 island–mainland pairs around Australia.We classified 1129 plant species as spinescent or nonspinescent using published species descriptions.Important Findings There was no significant difference between the proportion of spinescent species found on islands and on mainlands.Proportions of spinescent species were not significantly related to island area or distance to mainland.Our results suggest that spinescence is just as important to island plants as it is to mainland plants,even for plants inhabiting small or distal islands.This is unexpected,given prevailing thought and previous work on island–mainland comparisons.Our study demonstrates the importance of testing well-accepted yet untested ideas.展开更多
基金Australian Research Council(DP 0984222 and DP140102861)to A.T.M.
文摘Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across Australia and New Zealand.Our dataset spanned 35°of latitude,and included over 1 million observations,making it the larg-est empirical study ever conducted for a single physical defence trait.A weighted logistic regression was applied first within Australia and New Zealand separately,and then across the com-bined dataset.Important Findings There was no significant latitudinal gradient in the proportion of spe-cies with spinescence in Australia or New Zealand,or in the overall dataset.That is,plant species are no more likely to be defended by spines at low latitudes than at high latitudes.This finding is counter to the idea that plant defences increase with latitude due to increased selective pressure from higher levels of herbivory.We suggest that future studies should investigate the relationship between herbivory and defence directly,without using latitude as a proxy.
基金Australian Research Council Discovery Project(DP140102861 to A.T.M.).
文摘Aims Organisms on islands are thought to escape biotic pressure and lose defensive capabilities.However,broadscale,evidence-based tests of this idea are rare.In this study,we asked:(i)whether the proportion of spinescent plant species differed between islands and mainlands and(ii)whether the proportion of spinescent species increased with increasing island area and with decreasing island distance to mainland.Methods We compiled species lists for 18 island–mainland pairs around Australia.We classified 1129 plant species as spinescent or nonspinescent using published species descriptions.Important Findings There was no significant difference between the proportion of spinescent species found on islands and on mainlands.Proportions of spinescent species were not significantly related to island area or distance to mainland.Our results suggest that spinescence is just as important to island plants as it is to mainland plants,even for plants inhabiting small or distal islands.This is unexpected,given prevailing thought and previous work on island–mainland comparisons.Our study demonstrates the importance of testing well-accepted yet untested ideas.
