Are parental care trade‐offs in shorebirds driven by parental investment or sexual selection?

Sexual selection, mating systems and parental behaviour are closely linked, although the exact nature of their relationship is controversial. The parental investment hypothesis (PIH) states that parental care disparity drives sexual selection intensity, because the sex providing less care competes for the sex that provides more. In contrast, the sexual selection hypothesis (SSH) asserts that more intense sexual selection on males leads to reduced male parental investment. We tested these hypotheses using directional phylogenetic comparative methods in shorebirds, which have an unusually diverse array of breeding systems. Changes in parental care and sexual selection intensity were tightly correlated, and we carried out three sets of analyses focusing on changes in male behaviour, female behaviour and in either sex. The results from the analyses were consistent with both PIH and SSH, although the patterns in male transition were sensitive to model values. We propose two explanations for these results. First, phylogenetic transitions may be idiosyncratic so that they depend on the ecological circumstances of individual species. Second, transitions in social traits, such as breeding systems, may be rapid and take place in ecological time, so directional phylogenetic methods that work through longer time scales may not infer accurately the timing and direction of all changes.     

Permo--Carboniferous Paleoecology and Morphotypic Series

The genera of primitive and synapsid reptiles which form theusual morphotypic series leading to cynodonts are not membersof a phyletic series. Ecological analyses show three developingevolutionary lines during the Permo-Carboniferous—onelowland, living on deltas and in swamps; a second somewhat moreupland; and a third distinctly upland. The members of thesethree lines are the source of the morphotypic genera, but mostof them come from deposits formed in lowlands where they cameby successive invasions from moreupland habitats. Evidence ofthe upland lines comes from these lowland sites, from invadinganimals, and from those introduced by mechanical transport fromtheir upland habitats. The brain cases and masticatory structures ofthe members ofthe morphotypic series—Hylonomus, Haptodus, Varanosaurus,Ophiacodon, Dimetrodon, Eotitanosuchus, Scymnognathus, Lycosuchus,Thrinaxodon—are examined in light of the ecological interpretations.Deformed coordinates applied to the lateral aspects of the skullsof the genera show clearly that the morphotypes do not providea coherent evolutionary series. The "trends" of evolutionarychange from Hylonomus to Thrinaxodon can best be seen if thesetwo and Haptodus are used as an evolutionary series, the stagesthat are missing interpolated, and the roles ofthe other generaevaluated on the basis of this more or less idealized, conceptualseries.     

Conserved flanking microsatellite sequences (ReFS) differentiate between Lepidoptera species,and provide insight into microsatellite evolution

High rates of mutation and homoplasy mean that microsatellites generally are not considered to be useful molecular markers for inferring systematic relationships between species. However, an earlier pilot study suggested that conserved flanking microsatellite sequences, also known as repetitive flanking sequences (ReFS), may form a basis for a dominant marker that can differentiate between species of Lepidoptera. We present data that demonstrate that ReFS are quick and easy to use, and generate highly repeatable banding patterns from a range of Lepidoptera species. Sequence data from a subset of ReFS‐amplified bands revealed microsatellite families with flanking sequences that are more conserved within than among species: this is probably attributable to recombination‐mediated events, transposition of mobile elements or a combination of the two. Our data support the use of ReFS as dominant interspecific molecular markers, and add to the growing literature on the evolution of microsatellites in Lepidoptera.