The relationship between neutral genetic diversity and performance in wild arthropod populations

Larger effective populations (Ne) are characterised by higher genetic
diversity, which is expected to predict population performance (average
individual performance that influences fitness). Empirical studies of the
relationship between neutral diversity and performance mostly represent
species with small Ne, while there is limited data from the species-rich
and ecologically important arthropods that are assumed to have large Ne
but are threatened by massive declines. We performed a systematic
literature search and used meta-analytical models to test the prediction
of a positive association between neutral genetic diversity and
performance in wild arthropods. From 14 relevant studies of 286
populations, we detected a weak (r = 0.15) but non-significant positive
association both in the full data set (121 effect sizes) and a reduced
data set accounting for dependency (14 effect sizes). Theory predicts that
traits closely associated with fitness show relatively stronger
correlation with neutral diversity, this relationship was upheld for
longevity and marginally for reproduction. Our analyses point to major
knowledge gaps in our understanding of relationships between neutral
diversity and performance. Future studies using genome-wide data sets
across populations could guide more powerful designs to evaluate
relationships between adaptive, deleterious and neutral diversity and
performance.