JABES Highlights
Pecky Rice and Mango Trees Studied
P
ecky rice, mango trees, distribution is the sequential bro- potential ancestors
bears, and spiders—just ken-stick model. Surprisingly, the and their offspring.
some of the subjects under observed number of species and The quality of infer-
study with sophisticated statisti- the observed number of species ences is affected by
cal methods in the June issue of represented by a single individ- the relationship (par-
JABES, available at http://pubs. ual is a reasonable set of sum- ents or grandparents)
amstat.org/loi/jabes. mary statistics on which to base of the closest ances-
A pair of papers considers estimation. They estimate the tors. They apply the
two methods for estimating ani- number of spider species in an methods to a data set
mal or species abundance. Line Appalachian forest. of maize SSR marker
transect studies are traditionally Two papers look at the genet- profiles where the
conducted in straight lines across ics of plants. Tadeusz Caliński, results indicate a low
a region of interest to estimate Stanisław Czajka, Zygmunt error rate.
animal density and abundance. Kaczmarek, Paweł Krajewski, What is pecky
However, in mountainous ter- and Wiesław Pilarczyk, in rice, and why is this
rain, some animals (such as bears) “Analyzing the Genotype-by- of interest? Various species of
live in a restricted elevation zone Environment Interactions Under rice bugs suck the rice grains,
for part of the year. E. F. Becker a Randomization-Derived Mixed generating pecky rice grains. The
and P. X. Quang, in “A Gamma- Model,” describe novel proce- existence of pecky rice grains
Shaped Detection Function for dures for studying parameters results in a substantial decrease
Line-Transect Surveys with Mark- connected with a genotype-by- in the market price of rice, even
Recapture and Covariate Data,” environment interactions from if their proportion is quite small.
develop a procedure for estimat- large-scale varietals trial. They It is therefore important to esti-
ing bear abundance from aerial develop procedures to estimate mate accurately the proportion of
survey data where transects fol- these parameters and mean- pecky rice. Kohji Yamamura and
low elevation contours in moun- ingful functions thereof. This Masuhiro Ishimoto, in “Optimal
tainous terrain. To account for is illustrated by an analysis of Sample Size for Composite
animals not seen on the transect the results of a series of trials of Sampling with Subsampling,
line, a dual observer protocol is 16 pea varieties conducted in When Estimating the Proportion
overlaid. Covariates also are used resolvable incomplete blocks of Pecky Rice Grains in a Field,”
to account for heterogeneity in over nine locations with mul- develop a composite sampling
sighting rates. tiple replicates of each variety scheme with subsampling and
Rather than the abundance at each trial. At a more funda- determine the optimal sample
of a species, the number of spe- mental level, Hongmei Zhang size. These plans also account for
cies present in a survey area and Hal Stern, in “Inferences spatial heterogeneity in the pro-
is often of interest. Andrew for Genotyping Error Rate in portion of defective grains.
R. Solow and Woollcott K. Ancestry Identification from Mark R. T. Dale and
Smith, in “Estimating Species Simple Sequence Repeat Marker Marie–Josée Fortin, in “Spatial
Number Under an Inconvenient Profiles,” estimate genotyping Autocorrelation and Statistical
Abundance Model,” propose to error rates in ancestry identifica- Tests: Some Solutions,” examine
estimate species numbers using tion from simple sequence repeat the problem of spatial depen-
a mark-recapture framework, marker profiles. Contrary to pre- dence or spatial autocorrelation
but where the assumption that vious work, it is not necessary to that often occurs in ecological
relative abundances follow a assume a known ancestry for the data and how this causes serious
symmetric Dirichlet distribution subjects. This approach is based problems in analysis, affecting the
is relaxed. Ecologists have found on the rules for transmission of significance rates of statistical tests,
that a more realistic abundance genetic information between making them too liberal when the
JULY 2009 AMSTAT NEWS 25
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