| 1. |
- Bokma, Folmer, et al.
(författare)
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Unexpectedly many extinct hominins
- 2012
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Ingår i: Evolution. - Hoboken, NJ : Wiley-Blackwell. - 0014-3820 .- 1558-5646. ; 66:9, s. 2969-2974
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies indicate that Neanderthal and Denisova hominins may have been separate species, while debate continues on the status of Homo floresiensis. The decade-long debate between splitters, who recognize over 20 hominin species, and lumpers, who maintain that all these fossils belong to just a few lineages, illustrates that we do not know how many extinct hominin species to expect. Here, we present probability distributions for the number of speciation events and the number of contemporary species along a branch of a phylogeny. With estimates of hominin speciation and extincton rates, we then show that the expected total number of extinct hominin species is 8, but may be as high as 27. We also show that it is highly unlikely that three very recent species disappeared due to natural, background extinction. This may indicate that human-like remains are too easily considered distinct species. Otherwise, the evidence suggesting that Neanderthal and the Denisova hominin represent distinct species implies a recent wave of extinctions, ostensibly driven by the only survivor, H. sapiens.
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| 2. |
- van den Brink, Valentijn, et al.
(författare)
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Estimating population differentiation between isolated root vole (Microtus oeconomus) populations in the Netherlands using geometric morphometrics
- 2011
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Ingår i: Lutra. - : Zoogdiervereniging. - 0024-7634. ; 54:2, s. 111-121
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We investigated morphological differentiation in threatened populations of the root vole subspecies Microtus oeconomus arenicola, measured by using geometric morphometrics on skulls recovered from owl pellets. Using populations from Finland as a reference, we compared measures of morphological differentiation to levels of genetic differentiation reported in literature for the same populations. We found that the degree of morphometric population differentiation was generally lower than the degree of genetic differentiation, yet it revealed broadly similar patterns of geographic isolation. This suggests that skull shape is conserved in isolated root vole populations, and that geometric morphometric measurements from skeletal parts recovered from owl pellets may provide a cost-effective method to monitor population subdivision.
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| 3. |
- van den Brink, Valentijn, et al.
(författare)
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Morphometric shape analysis using learning vector quantization neural networks : an example distinguishing two microtine vole species
- 2011
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Ingår i: Annales Zoologici Fennici. - 0003-455X .- 1797-2450. ; 48:6, s. 359-364
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Tidskriftsartikel (refereegranskat)abstract
- Closely related species may be very difficult to distinguish morphologically, yet sometimes morphology is the only reasonable possibility for taxonomic classification. Here we present learning-vector-quantization artificial neural networks as a powerful tool to classify specimens on the basis of geometric morphometric shape measurements. As an example, we trained a neural network to distinguish between field and root voles from Procrustes transformed landmark coordinates on the dorsal side of the skull, which is so similar in these two species that the human eye cannot make this distinction. Properly trained neural networks misclassified only 3% of specimens. Therefore, we conclude that the capacity of learning vector quantization neural networks to analyse spatial coordinates is a powerful tool among the range of pattern recognition procedures that is available to employ the information content of geometric morphometrics.
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