Losses of female song with changes from tropical to temperate breeding in the New World blackbirds

Birds in which both sexes produce complex songs are thought to be more common in the tropics than in temperate areas, where typically only males sing. Yet the role of phylogeny in this apparent relationship between female song and latitude has never been examined. Here, we reconstruct evolutionary changes in female song and breeding latitude in the New World blackbirds (Icteridae), a family with both temperate and tropical representatives. We provide strong evidence that members of this group have moved repeatedly from tropical to temperate breeding ranges and, furthermore, that these range shifts were associated with losses of female song more often than expected by chance. This historical perspective suggests that male-biased song production in many temperate species is the result not of sexual selection for complex song in males but of selection against such songs in females. Our results provide new insights into the differences we see today between tropical and temperate songbirds, and suggest that the role of sexual selection in the evolution of bird song might not be as simple as we think.     

Phylogenetic position of the Hawaiian geraniums based on rbcL Sequences

The seven currently recognized species of Geranium endemic to the Hawaiian Islands are unusual in their shrubby or arborescent habit and unlobed, parallel-veined leaves rather than the palmately cleft or lobed leaves and herbaceous habit typical of the genus. Their placement within the genus and their biogeographic source have been obscured by this morphological distictiveness and the limited resolution of relationships on the basis of morphology in the very speciose subgenus Geranium. Phylogenetic analysis of rbcL gene sequences provides strong support for the monophyly of the Hawaiian group, and indicates that the Hawaiian clade is deeply nested within section Geranium rather than comprising a separate section. The continental relatives studied to date with the greatest similarity in sequence to the Hawaiian group are native to the Americas rather than Asia or the Pacific. The Hawaiian species are extremely similar to one another in rbcL sequence, while the tree topology obtained is consistent with a basal position for Geranium arboreum within the group.     

Contrasting ability of deep and shallow rooting rice genotypes to grow through plough pans containing simulated biopores and cracks

Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research...