Fred Ruhe
Well-known member
Saupe, E. E., Farnsworth, A., Lunt, D. J., Sagoo, N., Pham, K. V., & Field, D., 2019
Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic
Proceedings of the National Academy of Sciences of the United States of America 116. doi:10.1073/pnas.1903866116
Significance:
The fossil record reveals evidence of dramatic distributional shifts through time for many groups of organisms. One striking example is the early fossil record of modern birds, which shows that many bird groups currently restricted to the tropics were formerly found at high latitudes in North America and Europe.
Tracking potentially suitable habitat for these clades over the last 56 million years reveals that cooling trends throughout this period may have largely dictated the geographic distributions of these “tropical” groups, complicating our understanding of where on Earth many of these lineages originated.
https://www.pnas.org/content/early/2019/06/04/1903866116
Abstract: https://www.repository.cam.ac.uk/handle/1810/292621
Many higher-level avian clades are restricted to Earth’s lower latitudes, leading to historical biogeographic reconstructions favoring a Gondwanan origin of crown birds and numerous deep subclades. However, several such ‘tropical-restricted’ clades (TRCs) are represented by stem-lineage fossils well outside the ranges of their closest living relatives, often on northern continents. To assess the drivers of these geographic disjunctions, we combine ecological niche modeling, paleoclimate models, and the early Cenozoic fossil record to examine the influence of climatic change on avian geographic distributions over the last ~56 million years. By modeling the distribution of suitable habitable area through time, we illustrate that most Paleogene fossil-bearing localities would have been suitable for occupancy by extant TRC representatives when their stem-lineage fossils were deposited. Potentially-suitable habitat for these TRCs is inferred to have become progressively restricted towards the tropics throughout the Cenozoic, culminating in relatively narrow circumtropical distributions in the present day. Our results are consistent with coarse-scale niche conservatism at the clade level, and support a scenario whereby climate change over geological timescales has largely dictated the geographic distributions of many major avian clades. The distinctive modern bias towards high avian diversity at tropical latitudes for most hierarchical taxonomic levels may therefore represent a relatively recent phenomenon, overprinting a complex biogeographic history of dramatic geographic range shifts driven by Earth’s changing climate, variable persistence, and intercontinental dispersal. Earth’s current climatic trajectory portends a return to a megathermal state, which may dramatically influence the geographic distributions of many range-restricted extant clades.
Enjoy
Fred
Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic
Proceedings of the National Academy of Sciences of the United States of America 116. doi:10.1073/pnas.1903866116
Significance:
The fossil record reveals evidence of dramatic distributional shifts through time for many groups of organisms. One striking example is the early fossil record of modern birds, which shows that many bird groups currently restricted to the tropics were formerly found at high latitudes in North America and Europe.
Tracking potentially suitable habitat for these clades over the last 56 million years reveals that cooling trends throughout this period may have largely dictated the geographic distributions of these “tropical” groups, complicating our understanding of where on Earth many of these lineages originated.
https://www.pnas.org/content/early/2019/06/04/1903866116
Abstract: https://www.repository.cam.ac.uk/handle/1810/292621
Many higher-level avian clades are restricted to Earth’s lower latitudes, leading to historical biogeographic reconstructions favoring a Gondwanan origin of crown birds and numerous deep subclades. However, several such ‘tropical-restricted’ clades (TRCs) are represented by stem-lineage fossils well outside the ranges of their closest living relatives, often on northern continents. To assess the drivers of these geographic disjunctions, we combine ecological niche modeling, paleoclimate models, and the early Cenozoic fossil record to examine the influence of climatic change on avian geographic distributions over the last ~56 million years. By modeling the distribution of suitable habitable area through time, we illustrate that most Paleogene fossil-bearing localities would have been suitable for occupancy by extant TRC representatives when their stem-lineage fossils were deposited. Potentially-suitable habitat for these TRCs is inferred to have become progressively restricted towards the tropics throughout the Cenozoic, culminating in relatively narrow circumtropical distributions in the present day. Our results are consistent with coarse-scale niche conservatism at the clade level, and support a scenario whereby climate change over geological timescales has largely dictated the geographic distributions of many major avian clades. The distinctive modern bias towards high avian diversity at tropical latitudes for most hierarchical taxonomic levels may therefore represent a relatively recent phenomenon, overprinting a complex biogeographic history of dramatic geographic range shifts driven by Earth’s changing climate, variable persistence, and intercontinental dispersal. Earth’s current climatic trajectory portends a return to a megathermal state, which may dramatically influence the geographic distributions of many range-restricted extant clades.
Enjoy
Fred
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