Vol. 60, 2021
(update: 2021.01.06; 02.18)
Preliminary Study of
Temperature Effects on Size and Shape in the Modern Spinicaudatan Eulimnadia texana (Crustacea:
Branchiopoda)
Manja
Hethke1,*, Stephen C. Weeks2, Veronika Schöttle1,
and D. Christopher Rogers3
doi:10.6620/ZS.2021.60-02
1Institut
für Geologische Wissenschaften, Freie Universität Berlin,
Malteserstraße 74-100, D-12249 Berlin, Germany. *Correspondence:E-mai:
manja.hethke@fu-berlin.de (Hethke)
E-mail: schoettle@icloud.com (Schöttle)
2Department of Biology, The University of Akron,
Akron, Ohio, U.S.A., 44325-3908; E-mail: scw@uakron.edu (Weeks)
3Kansas Biological Survey, and The Biodiversity
Institute, The University of Kansas, Higuchi Hall, 2101 Constant
Avenue, Lawrence, KS 66047-3759 USA. E-mail: branchiopod@gmail.com
(Rogers)
Received 2 September 2020 / Accepted
14 December 2020
Communicated by Benny K.K. Chan
Studies
of temperature effects on morphology in Spinicaudata have focused on
length, with no data on shape. To fill this gap, size and shape
variability in response to temperature fluctuations was investigated by
rearing the modern spinicaudatan Eulimnadia
texana. Two days after
hydration, juvenile individuals were separated into four different
temperature treatments: 20°C, 23°C, 26°C, and 29°C. Hermaphrodite size
and shape were analysed by looking at linear combinations of size
variables and using Fourier shape analysis; methods that are also used
to describe fossil size and shape for better comparison. Size
differences were considerable, with reduced growth at low and high
temperatures and accelerated growth at the optimum temperature of 26°C,
revealing that the reaction of size to increasing temperature is
non-linear. The height of the dorsal margin, which is associated with
space for egg production in Eulimnadia
texana,
accounts for a high
amount of size variability in this species and, presumably, in most of
the Limnadiidae. Hermaphrodite shapes reared under temperatures of 20°C
and 29°C are statistically distinct, while intermediate temperatures
yield intermediate shapes. The rate of shape change along temperature
is comparatively low between 23°C and 26°C and accelerated at lower and
higher temperatures. With increasing temperature, the highest point of
the dorsal margin is shifted towards the anterior of the carapace,
while it assumes a median position at 20°C. Our result that temperature
has strong effects on carapace size and shape implies considerable
ecophenotypic variability in Spinicaudata.
Key words: Freshwater ecology,
Limnadiidae, Phenotypic plasticity, Spinicaudata, Temperature.
Citation: Hethke M, Weeks SC, Schöttle V,
Rogers DC. 2021. Preliminary study of temperature effects on size and
shape in the modern spinicaudatan Eulimnadia
texana (Crustacea: Branchiopoda). Zool Stud 60:2. doi:10.6620/ZS.2021.60-02.

Supplementary
Materials: Table S1
| Table S2
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