Table 1 Regression coefficient estimates for the age of an LTR-RT as response and various genomic factors as predictors
PredictoraRegressionb coefficientSEt-valueP-value
Intercept0.2520.0435.7960.000
Chr20.0240.0112.2070.027
Chr30.0090.0110.7650.444
Chr40.0220.0121.8760.061
Chr50.0110.0110.9990.318
Chr60.0230.0121.9040.057
Chr70.0420.0113.7410.000
HR−0.0210.007−3.0620.002
Near 5′ end−0.0120.006−1.9710.049
Near colinear gene−0.0500.006−8.3350.000
Log distance to a gene0.0700.00325.4340.000
Gypsy superfamily0.0940.0452.0890.037
  • Chr, chromosome; HR, homologous recombination.

  • a The following predictors are considered: chromosome membership (Chr2–7, with Chr1 as baseline), adjacent HR rate, proximity to the 5′ end of a gene (with proximity to the 3′ end as baseline), colinearity of the closest gene with the homologous gene on a homeologous pseudomolecule in wild emmer (Dvorak et al. 2018) (with baseline that the gene is next to a noncolinear gene), log distance (bp) to the nearest gene, and long terminal repeat-retrotransposon superfamily membership (with Copia as baseline).

  • b The regression coefficients for the various predictors correspond to: for Chr2, the difference between the mean age on Chr2 and that on Chr1; analogously for Chr3–7; for “Near 5′ end,” the difference between the mean age of long terminal repeat-retrotransposons (LTR-RTs) near the 5′ end of a gene and those near the 3′ end; for “Near colinear gene,” the difference between the mean age of LTR-RTs next to colinear genes and those next to noncolinear genes; for Gypsy superfamily, the difference in mean age between Gypsy and Copia elements; and for “Intercept,” the mean age in the reference level, consisting of Copia elements on Chr1 closest to a noncolinear gene and its 3′ end.