[MARMAM] New publication on the role of morphology and body size in heat conservation and dissipation

Stephanie Adamczak sadamcza at ucsc.edu
Tue Feb 4 12:39:29 PST 2020


Dear MARMAM,

My colleagues and I are excited to announce our new publication assessing
the role that body and appendage morphology plays in heat dissipation and
conservation in pilot whales and implications for ecogeographic roles. The
article has been published in the Journal of Biogeography, available here
https://onlinelibrary.wiley.com/doi/10.1111/jbi.13796.

Please feel free to contact me at sadamcza at ucsc.edu if you have any
questions.

Abstract
Aim
The aim of this study was to determine if marine mammals follow
ecogeographic rules. We examined Bergmann's rule and Allen's rule in two
pilot whale species with contrasting latitudinal distributions.

Location
Northwest Atlantic Ocean.

Taxon
*Globicephala *spp.

Methods
We analysed morphometric data collected from strandings of short‐ and
long‐finned pilot whales in the Northwest Atlantic Ocean to assess
intraspecific and interspecific variation in surface area to volume ratios
(SA:V) of the body core and appendage surface area relative to body core SA
(normalized appendage SA) using a novel 3D modelling method.

Results
Our results suggest that ecogeographic variation in morphometrics between
the two pilot whale species is consistent with morphological adaptations
required to balance heat conservation and heat dissipation. Interspecific
differences in morphology supported Bergmann's rule for fully grown
individuals: the more temperate long‐finned pilot whale had a larger body
size and lower body core SA:V than the short‐finned pilot whale, which has
a more tropical distribution. Allen's rule was not supported; when all
appendages were considered together, long‐finned pilot whales had larger
normalized SA than short‐finned pilot whales. However, the pectoral
flippers were the primary driver of this relationship; while long‐finned
pilot whales had proportionally larger pectoral flippers, short‐finned
pilot whales had proportionally larger dorsal fins and flukes. In addition,
larger long‐finned pilot whales (i.e. males and mature individuals) had
proportionally larger pectoral flippers than smaller long‐finned pilot
whales.

Main Conclusions
Pilot whales follow Bergmann's rule but do not follow Allen's rule when
fully mature. Thinly insulated appendages in marine mammals can be used to
dissipate heat as the core warms, and larger and better insulated marine
mammals may require relatively larger appendages in order to offload heat
and thermoregulate effectively. Our results provide novel insight into
ecogeographic rules and suggest that species in higher latitude climates
towards the poles will demonstrate tradeoffs between core body heat
conservation and appendage heat dissipation.
-- 
_______________________
Stephanie K. Adamczak, M.S.
Ph.D. Student, Department of  Ecology and Evolutionary Biology
University of California Santa Cruz
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