Figure 1. Population genomic data and laboratory evolution experiments allow to uncover the effects of various factors on transposable element (TE) accumulation in hybrids.

Upon hybridization, the TE content of a hybrid is determined by equal contributions from the TE contents of its parents. Subsequent evolution can either leave the hybrid TE content unchanged, or drive it to increase or decrease. These changes can be driven by biases in transposition or excision rates or by variation in natural selection efficiency. Two complementary approaches can be used to investigate which factors drive TE dynamics in hybrids. First, genomic data from natural populations can be harnessed to understand how population structure, environmental pressures and natural selection efficiency shaped natural variation in TE content. Second, evolution experiments in laboratory controlled conditions (constant environment and relaxed natural selection) allow to test the effect of properties of artificial hybrid genotypes on TE accumulation, namely evolutionary divergence between parents and initial TE content.