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- Raia, P., et al.
(författare)
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Progress to extinction: increased specialisation causes the demise of animal clades
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Animal clades tend to follow a predictable path of waxing and waning during their existence, regardless of their total species richness or geographic coverage. Clades begin small and undifferentiated, then expand to a peak in diversity and range, only to shift into a rarely broken decline towards extinction. While this trajectory is now well documented and broadly recognised, the reasons underlying it remain obscure. In particular, it is unknown why clade extinction is universal and occurs with such surprising regularity. Current explanations for paleontological extinctions call on the growing costs of biological interactions, geological accidents, evolutionary traps, and mass extinctions. While these are effective causes of extinction, they mainly apply to species, not clades. Although mass extinctions is the undeniable cause for the demise of a sizeable number of major taxa, we show here that clades escaping them go extinct because of the widespread tendency of evolution to produce increasingly specialised, sympatric, and geographically restricted species over time.
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| 2. |
- Silvestro, Daniele, et al.
(författare)
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A 450 million years long latitudinal gradient in age-dependent extinction
- 2020
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 23:3, s. 439-446
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Tidskriftsartikel (refereegranskat)abstract
- Leigh Van Valen famously stated that under constant conditions extinction probability is independent of species age. To test this 'law of constant extinction', we developed a new method using deep learning to infer age-dependent extinction and analysed 450 myr of marine life across 21 invertebrate clades. We show that extinction rate significantly decreases with age in > 90% of the cases, indicating that most species died out soon after their appearance while those which survived experienced ever decreasing extinction risk. This age-dependent extinction pattern is stronger towards the Equator and holds true when the potential effects of mass extinctions and taxonomic inflation are accounted for. These results suggest that the effect of biological interactions on agedependent extinction rate is more intense towards the tropics. We propose that the latitudinal diversity gradient and selection at the species level account for this exceptional, yet little recognised, macroevolutionary and macroecological pattern.
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| 3. |
- Piras, P., et al.
(författare)
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Evolution of the sabertooth mandible: A deadly ecomorphological specialization
- 2018
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Ingår i: Palaeogeography Palaeoclimatology Palaeoecology. - : Elsevier BV. - 0031-0182. ; 496, s. 166-174
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Tidskriftsartikel (refereegranskat)abstract
- Saber-toothed cats were armed with formidable weapons. They evolved a number of highly derived morphological features, most notably a pair of extremely long upper canines, which makes them unique within the felid family. Although the sabertooth character evolved several times among carnivorous mammals, sabertooth clades mostly had disjunctive occurrences both in space and time, and no sabertooth is alive today. We studied the rates of phenotypic and taxonomic diversification in the mandible of sabertooths, as compared to the rates calculated for both extinct and extant conical toothed cats. We found that the mandible's shape and physical properties in sabertooth clades evolved at distinctly higher rates than the rest of the felid tree. In addition, sabertooths had similar speciation rate to conical toothed cats, but statistically higher extinction rate. The wealth of morphological specializations required to be a sabertooth, and their tendency to focus on large-sized species as prey, was likely responsible for such high extinction rate, and for the peculiar, disjunctive patterns of sabertooth Glade occurrence in the fossil record.
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