Migration is more common among extinct hoofed mammals
Migratory behavior was more common among extinct hoofed mammals than among living species in a new evolutionary comparison. Researchers reconstructed the behavior of 51 extinct species and compared them with 207 living relatives. Models including fossils associate migration with faster extinction and speciation, although estimates change when extinct species are excluded.
Science··Morning
Seasonal routes and extinction
Following fresh vegetation lets hoofed mammals escape seasonal food shortages. Roads and fences can interrupt those journeys, while shifting resource timing can make them less dependable. A peer-reviewed evolutionary study published on November 5 asks how migration relates to extinction over much longer periods. Its comparison combines living species with animals lost during the late Quaternary, rather than treating today's surviving species as the entire history of these movements.[1]
Reconstructing vanished journeys
Migration rarely leaves an unambiguous fossil trace. Researchers therefore estimated migratory capacity from body mass, the share of grass in the diet and latitude, using relationships among living species. Across alternative evolutionary trees, the median estimate classified 41 of 51 extinct species as capable of migration, compared with documented migration in 95 of 207 living species. The definition includes a species when a seasonal return journey has been observed in at least one population, including historical populations; it does not assign the same behavior to every population.[1]
Fossils change the rate estimates
Models including extinct species associated migratory lineages with faster extinction and speciation. Restricting the analysis to living animals gave contrasting extinction estimates. The authors place more weight on whether the pattern persists and which way it points than on the exact numerical rates reconstructed by the models. Fossil sampling and the indirect reconstruction of behavior add uncertainty. This comparative analysis identifies an evolutionary association; it does not establish a universal explanation for extinction or make the loss of each surviving migratory population inevitable.[1]
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