%0 Journal Article
%A McGill, B.J.
%T Does Mother Nature really prefer rare species or are log-left-skewed SADs a sampling artefact?
%B Ecology Letters
%D 2003
%V 6
%P 766-773
%N 8
%8 aug
%X 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.
%# brugerolles
%Z timestamp=(2007.12.18)
%F McGill2003a
%3 BibTeX type = ARTICLE