Ben Creisler
Avian-related papers:
Free pdf:
Robert S. de Moya, Julie M. Allen, Andrew D. Sweet, Kimberly K. O. Walden, Ricardo L. Palma, Vincent S. Smith, Stephen L. Cameron, Michel P. Valim, Terry D. Galloway, Jason D. Weckstein & Kevin P. Johnson (2019)
Extensive host-switching of avian feather lice following the Cretaceous-Paleogene mass extinction event.
Communications Biology Â2, Article number: 445
doi:
https://doi.org/10.1038/s42003-019-0689-7 https://www.nature.com/articles/s42003-019-0689-7Free pdf:
https://www.nature.com/articles/s42003-019-0689-7.pdfNearly all lineages of birds host parasitic feather lice. Based on recent phylogenomic studies, the three major lineages of modern birds diverged from each other before the Cretaceous-Paleogene (K-Pg) mass extinction event. In contrast, studies of the phylogeny of feather lice on birds, indicate that these parasites diversified largely after this event. However, these studies were unable to reconstruct the ancestral avian host lineage for feather lice. Here we use genome sequences of a broad diversity of lice to reconstruct a phylogeny based on 1,075 genes. By comparing this louse evolutionary tree to the avian host tree, we show that feather lice began diversifying on the common ancestor of waterfowl and landfowl, then radiated onto other avian lineages by extensive host-switching. Dating analyses and cophylogenetic comparisons revealed that two of three lineages of birds that diverged before the K-Pg boundary acquired their feather lice after this event via host-switching.
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We examined correlated evolution between nest and egg characteristics in birds.
The ancestral state of nests was semi-open with nest sites becoming more open.
Open nests with variable clutch sizes were ancestral and clutch sizes have declined.
Eggs have evolved to be smaller and lighter in open, but not closed, nesting species.
There is a notable level of correlated evolution between nest and egg characteristics.
Abstract
Correlational selection is defined as selection for adaptive character combinations, and it therefore favours combinations of coevolved traits via phenotypic integration. Whereas the evolution of avian nest-building and egg-laying characteristics are well understood, their correlated dynamics remain overlooked. Here, we examined patterns of correlated evolution between nest, egg and clutch characteristics in 855 species of birds from 90 families, representing nearly 9% and 33% of avian species- and family-level diversity. We show that the ancestral state of birdsâ nests was semi-open with nest sites having since become progressively more open over time. Furthermore, nest characteristics appear to have influenced egg-laying patterns in that while semi-open nests with variable clutch sizes were probably ancestral, clutch sizes have declined over evolutionary time in both open and closed nests. Ancestrally, avian eggs were also large, heavy and either elliptic or round, and there have been high transition rates from elliptic to round eggs in open nests and vice versa in closed nests. Ancestrally, both unpigmented (white) and pigmented (blueâbrown) eggs were laid in open nests, although blueâbrown eggs have transitioned more to white over time in open and closed nests, independently. We conclude that there has been a remarkable level of correlated evolution between the nest and egg characteristics of birds, which supports scenarios of correlational selection on both of these extended avian phenotypes.