An extended dataset
We measured heterochiasmy as the log of the male/-to-female ratio (ρ) of autosomal recombination rate measured either with chiasma number or map length. We log-transformed the ratio to avoid bias due to measurement error in the denominator. Chiasma-count data for different species were compiled by Burt et al. [16], and we used their dataset, adding a few recent studies. We compiled genetic map data and linkage studies in animals and plants for which both a male and a female map were available. Only homologous fragments (i.e., between shared markers) in male and female maps were considered (especially in low-resolution maps). Heterochiasmy data were available for 107 species, with 46 sets of data based on genomic maps (Table 2).
Table 2  Dataset Pooled by Species with Levels of Phylogenetic Grouping Used in the Analysis
Note that references given in Burt et al. [17] were not repeated here
a K, kingdom. Numeric indicators in this column are: 1, Animalia; 2, Plantae
b P, phylum. Numeric indicators in this column are: 1, Arthropoda; 2, Chordata; 3, Embryophyta; 4, Platyhelminthes
c C, class. Numeric indicators in this column are: 1, Actinopterygii; 2, Amphibia; 3, Magnoliopsidae (subclass asterids); 4, Aves; 5, Coniferopsida; 6, Insecta; 7, Liliopsida; 8, Mammalia; 9, Magnoliopsidae (subclass rosids); 10, Trematoda; 11, Turbellaria
d Data refers to linkage map (LM) or chiasma count (CC)
e Male and female indicate the value for the chiasma count or map length for each sex
f Ratio refers to male/female recombination rate
g  Vsc refers to the presence or absence of sex chromosome (see Materials and Methods, “Sex chromosome effect”)
h Data were obtained from maps DBNordic2 and NIAIJapan (http://www.genome.iastate.edu/pig.html) [54,55]
ND, no data
Table 2  Continued