Fig 1.
Simplified avian phylogenetic tree of avian groups with cytological crossover data.
Except for Palaeognathae, the graph includes the avian orders with crossover data for at least two species. *Data for the guinea fowl are presented here. The tree is based on Prum et al., Nature 526(7574). doi: 10.1038/nature15697 (2017).
Fig 2.
Immunolocalization of recombination events in chicken and guinea fowl oocytes.
Chicken (A) and guinea fowl (B) immunostained oocytes showing the complete sets of synaptonemal complexes. The number of bivalents, including the sex pair, is 39 in the chicken and 38 in the guinea fowl. The six largest synaptonemal complexes are labeled with a number next to the centromere signal (red bulging dots). In the guinea fowl, foci on macro-SCs are predominantly located towards the chromosome ends.
Table 1.
Average synaptonemal complex lengths and MLH1 foci in the chicken and the guinea fowl.
Fig 3.
Graphic representation of the macro-SCs.
Each bar represents a synaptonemal complex. The total height is the average SC length in micrometers. The short (p) and long (q) arms are shown in different colors to ease the comparison of the arm ratios.
Fig 4.
Comparative distribution of MLH1 foci in the six largest macrobivalents.
Each column represents the distribution of SCs with n foci as a fraction of the cells analyzed in each species. Colors indicate bivalents with 1 to 8 or >8 foci. The color code is shown below the graph.
Fig 5.
Distribution of MLH1 foci along individual macrobivalents of the chicken and the guinea fowl.
For each bivalent, the x-axis indicates the positions of the MLH1 foci in micrometers measured from the centromere (c). The bin width in each histogram is equivalent to 0.5 μm. The y-axis indicates the proportion of MLH1 focus number in each interval.
Fig 6.
Number of COs per cell in birds showing the heterogenous variations between orders.
Bars represent the average number of COs (vertical) and the standard deviation (horizontal) in each species. COs data are from MLH1 focus counts in all species except in the turkey that are from chiasmata in lampbrush chromosomes. Differences in CO numbers can be larger in species within the same order than across orders. Data source: chicken and guinea fowl, present study. American rhea, [27]; duck, [41]; Gray goose, [49]; turkey, [26]; common quail,[24]; zebra finch, [51]; white wagtail, [28].