Summary1. Ecologists and evolutionary biologists often need to simultaneously evaluate the significance of multiple related hypotheses. Multiple comparisons need to be corrected to avoid inappropriately increasing the number of null hypotheses that are wrongly rejected. The traditional method of correction involves Bonferroni-type multiple comparison procedures which are highly conservative, tending to increase the number of wrong rejections of true hypotheses as the number of hypotheses being simultaneously tested increases. 2. Newer procedures which are based on False Discovery Rates and which do not suffer the same loss of power as traditional methods are described. Algorithms and spreadsheet-based software routines for three procedures which are especially useful in ecology and evolution are provided. 3. The strengths and potential pitfalls of FDR-based analysis and of presenting results as FDR-adjusted P-values are discussed with reference to traditional methods such as the sequential Bonferroni correction. 4. FDR-based multiple comparison procedures should be more widely adopted because they are often more appropriate than traditional methods for identifying truly significant results.
Insects provide examples of many cunning stratagems to cope with the challenges of living in a world dominated by surface forces. Despite being the current masters of the land environment, they are at constant risk of being entrapped in liquids, which they prevent by having waxy and hairy surfaces. The problem is particularly acute in an enclosed space, such as a plant gall. Using secreted wax to ef ciently parcel and transport their own excrement, aphids were able to solve this problem 200 Myr ago. Here, we report on the physical and physiological signi cance of this ingenious solution. The secreted powdery wax has three distinct roles: (i) it is hydrophobic, (ii) it creates a microscopically rough inner gall surface made of weakly compacted wax needles making the gall ultra-hydrophobic, and (iii) it coats the honeydew droplets converting them into liquid marbles, that can be rapidly and ef ciently moved.
Transgenerational effects of environmental conditions can have several important ecological and evolutionary implications. We conducted a fully factorial experiment manipulating food availability across three generations in the collembolan
Folsomia candida
, a springtail species that inhabits soil and leaf litter environments which vary in resource availability. Maternal and grandmaternal food availability influenced age at maturity and reproductive output. These effects appear to be cumulative rather than adaptive transgenerational life-history adjustments. Such cumulative effects can profoundly influence eco-evolutionary dynamics in both stable and fluctuating environments.
Despite its significance regarding the conservation and management of biological resources, the body of theory predicting that the correlation between successive environmental states can profoundly influence extinction has not been empirically validated. Identical clonal populations from a model experimental system based on the collembolan Folsomia candida were used in the present study to investigate the effect of environmental autocorrelation on time to extinction. Environmental variation was imposed by variable implementation (present/absent) of a culling procedure according to treatments that represented six patterns of environmental autocorrelation. The average number of culling events was held constant across treatments but, as environmental autocorrelation increased, longer runs of both favourable and unfavourable culling tended to occur. While no difference was found among the survival functions for the various treatments, the time taken for 50% of the component populations to become extinct decreased significantly with increasing environmental autocorrelation. Similarly, analysis of all extinct populations demonstrated that time to extinction was shortened as environmental autocorrelation increased. However, this acceleration of extinction can be fully offset if sequential introduction is used in place of simultaneous introduction when founding the populations.
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