10.5061/DRYAD.S448N5D
Svagelj, Walter S.
National University of Mar del Plata
Laich, Agustina Gómez
National Scientific and Technical Research Council
Quintana, Flavio
National Scientific and Technical Research Council
Data from: Richards’s equation and nonlinear mixed models applied to avian
growth: why use them?
Dryad
dataset
2018
random effects
Phalacrocorax atriceps
grouped data
females
maximum growth rate
Growth models
nonlinear mixed models
growth data
asymptotic size
2018-11-15T15:47:11Z
2018-11-15T15:47:11Z
en
https://doi.org/10.1111/jav.01864
19747 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Postnatal growth is an important life-history trait that varies widely
across avian species, and several equations with a sigmoidal shape have
been used to model it. Classical three-parameter models have an inflection
point fixed at a percentage of the upper asymptote which could be an
unrealistic assumption generating biased fits. The Richards model emerged
as an interesting alternative because it includes an extra parameter that
determines the location of the inflection point which can move freely
along the growth curve. Recently, nonlinear mixed models (NLMM) have been
used in modeling avian growth because these models can deal with a lack of
independence among data as typically occurs with multiple measurements on
the same individual or on groups of related individuals. Here, we
evaluated the usefulness of von Bertalanffy, Gompertz, logistic, U4 and
Richards’s equations modeling chick growth in the Imperial Shag
(Phalacrocorax atriceps). We modelled growth in commonly used
morphological traits, including body mass, bill length, head length and
tarsus length, and compared the performance of models by using NLMM.
Estimated adult size, age at maximum growth and maximum growth rates
markedly differed across models. Overall, the most consistent performance
in estimated adult size was obtained by the Richards model that showed
deviations from mean adult size within 5%. Based on AICc values, the
Richards equation was the best model for all traits analyzed. For tarsus
length, both Richards and U4 models provided indistinguishable fits
because the relative inflection value estimated from the Richards model
was very close to that assumed by the U4 model. Our results highlight the
bias incurred by three-parameter models when the assumed inflection
placement deviates from that derived from data. Thus, the application of
the Richards equation using the NLMM framework represents a flexible and
powerful tool for the analysis of avian growth.
Morphological measurements of female chicks of the Imperial
ShagMorphological measurements of female chicks of the Imperial Shag
collected at Punta León (43º05´S, 64º30´W), Chubut, Argentina, from
November to December 2015. ID: chick identity, BillLength: bill length
(mm), HeadLength: head length (mm), TarsusLength: tarsus length (mm),
BodyMass: body mass (g), and t: age of the female chicks when measured (in
days).RGM_data.xlsx
Argentina
Punta León
43º05´S64º30´W
Patagonia