McGill2003a
Référence
McGill, B.J. (2003) Does Mother Nature really prefer rare species or are log-left-skewed SADs a sampling artefact? Ecology Letters, 6(8):766-773
Résumé
Intensively sampled species abundance distributions (SADs) show left-skew on a log scale. That is, there are too many rare species to fit a lognormal distribution. I propose that this log-left-skew might be a sampling artefact. Monte Carlo simulations show that taking progressively larger samples from a log-unskewed distribution (such as the lognormal) causes log-skew to decrease asymptotically (move towards -infinity) until it reaches the level of the underlying distribution (zero in this case). In contrast, accumulating certain types of repeated small samples results in a log-skew that becomes progressively more log-left-skewed to a level well beyond the underlying distribution. These repeated samples correspond to samples from the same site over many years or from many sites in 1 year. Data from empirical datasets show that log-skew generally goes from positive (right-skewed) to negative (left-skewed) as the number of temporally or spatially replicated samples increases. This suggests caution when interpreting log-left-skew as a pattern that needs biological interpretation.
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@ARTICLE { McGill2003a,
AUTHOR = { McGill, B.J. },
TITLE = { Does Mother Nature really prefer rare species or are log-left-skewed SADs a sampling artefact? },
JOURNAL = { Ecology Letters },
YEAR = { 2003 },
VOLUME = { 6 },
PAGES = { 766-773 },
NUMBER = { 8 },
MONTH = { aug },
ABSTRACT = { Intensively sampled species abundance distributions (SADs) show left-skew on a log scale. That is, there are too many rare species to fit a lognormal distribution. I propose that this log-left-skew might be a sampling artefact. Monte Carlo simulations show that taking progressively larger samples from a log-unskewed distribution (such as the lognormal) causes log-skew to decrease asymptotically (move towards -infinity) until it reaches the level of the underlying distribution (zero in this case). In contrast, accumulating certain types of repeated small samples results in a log-skew that becomes progressively more log-left-skewed to a level well beyond the underlying distribution. These repeated samples correspond to samples from the same site over many years or from many sites in 1 year. Data from empirical datasets show that log-skew generally goes from positive (right-skewed) to negative (left-skewed) as the number of temporally or spatially replicated samples increases. This suggests caution when interpreting log-left-skew as a pattern that needs biological interpretation. },
OWNER = { brugerolles },
TIMESTAMP = { 2007.12.18 },
}
