Hi Andrea, Thank you for the paper. Will be useful.
Kind regards, Helmi On Monday, March 1, 2021 at 11:49:51 PM UTC+8 [email protected] wrote: > Dear All, > this is out now: > https://link.springer.com/article/10.1007/s11692-021-09531-3 > > On the Misidentification of Species: Sampling Error in Primates and > Other Mammals Using Geometric Morphometrics in More Than 4000 Individuals > Andrea Cardini, Sarah Elton, Kris Kovarovic, Una Strand Viđarsdóttir & > P. David Polly - Evolutionary Biology (2021) > > The abstract is below. > For a couple of days, I'll leave a pdf copy at > https://tinyurl.com/speciesmisid > > The focus is morphospecies in living mammals but has potential > implications beyond that (especially in palaeo). > Cheers > > Andrea > > > On the Misidentification of Species: Sampling Error in Primates and > Other Mammals Using Geometric Morphometrics in More Than 4000 Individual > Abstract > An accurate classification is the basis for research in biology. > Morphometrics and morphospecies play an important role in modern > taxonomy, with geometric morphometrics increasingly applied as a > favourite analytical tool. Yet, really large samples are seldom > available for modern species and even less common in palaeontology, > where morphospecies are often identified, described and compared using > just one or a very few specimens. The impact of sampling error and how > large a sample must be to mitigate the inaccuracy are important > questions for morphometrics and taxonomy. Using more than 4000 crania of > adult mammals and taxa representing each of the four placental > superorders, we assess the impacts of sampling error on estimates of > species means, variances and covariances in Procrustes shape data using > resampling experiments. In each group of closely related species (mostly > congeneric), we found that a species can be identified fairly accurately > even when means are based on relatively small samples, although errors > are frequent with fewer specimens and primates more prone to > inaccuracies. A precise reconstruction of similarity relationships, in > contrast, sometimes requires very large samples (> 100), but this varies > widely depending on the study group. Medium-sized samples are necessary > to accurately estimate standard errors of mean shapes or intraspecific > variance covariance structure, but in this case minimum sample sizes are > broadly similar across all groups (≈ 20–50 individuals). Overall, thus, > the minimum sample sized required for a study varies across taxa and > depends on what is being assessed, but about 25–40 specimens (for each > sex, if a species is sexually dimorphic) may be on average an adequate > and attainable minimum sample size for estimating the most commonly used > shape parameters. As expected, the best predictor of the effects of > sampling error is the ratio of between- to within-species variation: the > larger the ratio, the smaller the sample size needed to obtain the same > level of accuracy. Even though ours is the largest study to date of the > uncertainties in estimates of means, variances and covariances in > geometric morphometrics, and despite its generally high congruence with > previous analyses, we feel it would be premature to generalize. Clearly, > there is no a priori answer for what minimum sample size is required for > a particular study and no universal recipe to control for sampling > error. Exploratory analyses using resampling experiments are thus > desirable, easy to perform and yield powerful preliminary clues about > the effect of sampling on parameter estimates in comparative studies of > morphospecies, and in a variety of other morphometric applications in > biology and medicine. Morphospecies descriptions are indeed a small > piece of provisional evidence in a much more complex evolutionary > puzzle. However, they are crucial in palaeontology, and provide > important complimentary evidence in modern integrative taxonomy. Thus, > if taxonomy provides the bricks for accurate research in biology, > understanding the robustness of these bricks is the first fundamental > step to build scientific knowledge on sound, stable and long-lasting > foundations. > > > > -- > Dr. Andrea Cardini > Researcher, Dipartimento di Scienze Chimiche e Geologiche, Università di > Modena e Reggio Emilia, Via Campi, 103 - 41125 Modena - Italy > tel. 0039 059 4223140 > > Adjunct Associate Professor, Centre for Forensic Anthropology, The > University of Western Australia, 35 Stirling Highway, Crawley WA 6009, > Australia > > E-mail address: [email protected], [email protected] > WEBPAGE: https://sites.google.com/view/alcardini2/ > or https://tinyurl.com/andreacardini > > FREE Yellow BOOK on Geometric Morphometrics: > https://tinyurl.com/yellowmorphobook > > ESTIMATE YOUR GLOBAL FOOTPRINT: > http://www.footprintnetwork.org/en/index.php/GFN/page/calculators/ > SUPPORT: secondwarning.org > -- You received this message because you are subscribed to the Google Groups "Morphmet" group. 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