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Passerine evolution likely began in Australia

November 11, 2021

[Posted by Chuck Almdale]

The typical passerine: House Sparrow – Passer domesticus

The following study, now several years old but years in the making, presents evidence for Australia as the origin of all Passerine birds.

A few highlights of the paper:

  • Increases in Cenozoic (66 Million years ago to now) global temperature or colonization of new continents were not the primary forces driving passerine diversification.
  • Analyzed DNA data from 4,060 nuclear loci, 221 individual birds representing all 137 passerine families and major subgroups.
  • Suggests that passerines originated on the Australian landmass ∼47 Ma.
  • Subsequent dispersal and diversification of passerines affected by a number of climatological and geological events, such as Oligocene glaciation and inundation of the New Zealand landmass.
  • Previously, due to lack of reliably vetted fossils, the age of crown passerines had been calibrated based on the geological separation of New Zealand from the rest of Gondwana in late Cretaceous ∼82 Ma.
  • Split between oscines and suboscines ∼44 Ma, occurs well before the appearance of ephemeral ice sheets in Antarctica during Late Eocene, which would have made the trans-Antarctic route implausible.
  • Specific ecological, geological, and climatological events proposed to be associated with the diversification and global distribution of Neornithes:
    • Opening of ecological niches following the Cretaceous-Paleogene (K-Pg ~66 Ma) mass extinction event (that dinosaur-killing meteor).
    • Establishment of dispersal corridors linking the geographic origin of modern birds to other landmasses during the Paleogene.
    • Rapid continental drift and island formation in Wallacea allowing the dispersal of songbirds out of Australia.
    • Fragmentation of tropical habitats during cooling events of the Late Cretaceous and Cenozoic.
    • Expansion of temperate habitats and retreat of glaciers during the Miocene.

The following will help you in reading the paper:

Crown Passerines: In phylogenetics, the crown group or crown assemblage is a collection of species, composed of the living representatives of the collection, plus the most recent common ancestor of the collection, plus all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants.

Oscine Passerines: Suborder Passeri, 5126 species. The half of the world’s birds with a fully developed syrinx, that can sing nicely and learn new songs.

Suboscine Passerines: Passerines with different syrinx structure, poorer singing, and can’t learn new songs. The 1348 suboscine species are classified in Suborder Tyranni, in three infraorders: Tyrannida – Tyrant Flycatchers & allies 10 families; Furnariida – Ovenbirds & allies, 9 families; Eurylaimides – Broadbills & allies, 5 families.

Acanthisitti: New Zealand Wrens, which are neither oscine nor suboscine. 1 family 2 species. They are not “wrens” as are those in the Americas and Europe.

This links to a useful cladogram which includes English names of families.

ScreenShot of small section of cladogram with English names

This links to a Wikipedia list of Passerine families (with links) with a nice cladogram.

The figures below are from the paper and are as large as I could fit onto this blog. You can download free jpeg files of the originals from the paper, linked below. The big star at the top of Figure 2 connects to the star at the bottom of Figure 1. All horizontal lines are time-lines; geological eras are at the bottom. The charts are data-rich, you can spend hours looking at them. The quote below is merely the introduction to the paper, it’s not even the abstract. There is much more.

Earth history and the passerine superradiation
PNAS | Carl H. Olveros & 31 others | 1 Apr 2019
Proceedings of the National Academy of Sciences of the United States of America

Our understanding of the factors that affected the diversification of passerines, the most diverse and widespread bird order (Passeriformes), is limited. Here, we reconstruct passerine evolutionary history and produce the most comprehensive time-calibrated phylogenetic hypothesis of the group using extensive sampling of the genome, complete sampling of all passerine families, and a number of vetted fossil calibration points. Our phylogenetic results refine our knowledge of passerine diversity and yield divergence dates that are consistent with the fossil record, and our macroevolutionary analyses suggest that singular events in Earth history, such as increases in Cenozoic global temperature or the colonization of new continents, were not the primary forces driving passerine diversification.

Figure 1. Family-level phylogenetic relationships in passerines reconciled from concatenation and coalescent analyses (connects to top of Fig. 2 at the circled star). Maximum likelihood bootstrap support (BS) values are indicated by boxes (BS > 70) or circles (BS < 70) at nodes. Node ages were estimated using 13 fossil calibrations in BEAST on nodes indicated by empty blue circles; 95% credible intervals are shown with orange bars. Ancestral areas were estimated under the DEC + j model using BioGeoBEARS from the distribution of clades represented by each tip [shown by boxes at tips coded according to the map (Inset)]. Light blue and pink bars indicate Oligocene glaciation and warming events, respectively. The estimate of Cenozoic global surface temperatures (red curve) was taken from ref. 99. Branches with the strongest support for diversification rate shifts are indicated by pink arrows in their descendant node for internal branches or at the base of the branch for terminal branches. Geological and climatic events are indicated above the timeline with descriptions provided in the key (Inset). Plei., Pleistocene; Plio., Pliocene.

Fig. 2. Family-level phylogenetic relationships in passerines reconciled from concatenation and coalescent analyses (connects to bottom of Fig. 1 at the circled star). Biogeographic reconstruction including fossil taxa (Inset, tree) yields identical ancestral areas for crown lineages of passerines, suboscines, and oscines (also SI Appendix, Fig. S8). Plei., Pleistocene; Plio., Pliocene.
Fig. 2 snipshot closeup. Biogeographic reconstruction including fossil taxa (Inset, tree) yields identical ancestral areas for crown lineages of passerines, suboscines, and oscines (also SI Appendix, Fig. S8). Plei., Pleistocene; Plio., Pliocene.

That’s all. Have fun.

  1. Jeanne almdale permalink
    November 13, 2021 9:40 am





    • Chukar permalink*
      November 16, 2021 4:31 pm

      Poo? Poo!
      This has been a matter of great debate for over 150 years.
      We’re closing in on what really happened over the past 100 million years.
      These things take time. That’s not poo.


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