Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons
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Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons. / Glaw, Frank; Köhler, Jörn; Hawlitschek, Oliver; Ratsoavina, Fanomezana M.; Rakotoarison, Andolalao; Scherz, Mark D.; Vences, Miguel.
I: Scientific Reports, Bind 11, 2522, 2021.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons
AU - Glaw, Frank
AU - Köhler, Jörn
AU - Hawlitschek, Oliver
AU - Ratsoavina, Fanomezana M.
AU - Rakotoarison, Andolalao
AU - Scherz, Mark D.
AU - Vences, Miguel
N1 - Funding Information: We are grateful to Angeluc Razafimanantsoa and Theo Rajoafiarison for their great help during our expedition as well as our local guides, cooks, and porters. We would also like to thank MICET and their drivers for logistic support. Field research in Madagascar was funded by the Mohamed bin Zayed Species Conservation Fund (project 11253064 to F.G. and O.H.) and BIOPAT. F.G. was supported by a Bavarian initiative for research (‘SNSB-innovativ’) and A.R. by a fellowship of the Deutscher Akademischer Austauschdienst. This work was carried out in collaboration with the Mention Zoologie et Biodiversité Animale, Université d’Anananarivo. Publisher Copyright: © 2021, The Author(s).
PY - 2021
Y1 - 2021
N2 - Evolutionary reduction of adult body size (miniaturization) has profound consequences for organismal biology and is an important subject of evolutionary research. Based on two individuals we describe a new, extremely miniaturized chameleon, which may be the world’s smallest reptile species. The male holotype of Brookesia nana sp. nov. has a snout–vent length of 13.5 mm (total length 21.6 mm) and has large, apparently fully developed hemipenes, making it apparently the smallest mature male amniote ever recorded. The female paratype measures 19.2 mm snout–vent length (total length 28.9 mm) and a micro-CT scan revealed developing eggs in the body cavity, likewise indicating sexual maturity. The new chameleon is only known from a degraded montane rainforest in northern Madagascar and might be threatened by extinction. Molecular phylogenetic analyses place it as sister to B. karchei, the largest species in the clade of miniaturized Brookesia species, for which we resurrect Evoluticauda Angel, 1942 as subgenus name. The genetic divergence of B. nana sp. nov. is rather strong (9.9‒14.9% to all other Evoluticauda species in the 16S rRNA gene). A comparative study of genital length in Malagasy chameleons revealed a tendency for the smallest chameleons to have the relatively largest hemipenes, which might be a consequence of a reversed sexual size dimorphism with males substantially smaller than females in the smallest species. The miniaturized males may need larger hemipenes to enable a better mechanical fit with female genitals during copulation. Comprehensive studies of female genitalia are needed to test this hypothesis and to better understand the evolution of genitalia in reptiles.
AB - Evolutionary reduction of adult body size (miniaturization) has profound consequences for organismal biology and is an important subject of evolutionary research. Based on two individuals we describe a new, extremely miniaturized chameleon, which may be the world’s smallest reptile species. The male holotype of Brookesia nana sp. nov. has a snout–vent length of 13.5 mm (total length 21.6 mm) and has large, apparently fully developed hemipenes, making it apparently the smallest mature male amniote ever recorded. The female paratype measures 19.2 mm snout–vent length (total length 28.9 mm) and a micro-CT scan revealed developing eggs in the body cavity, likewise indicating sexual maturity. The new chameleon is only known from a degraded montane rainforest in northern Madagascar and might be threatened by extinction. Molecular phylogenetic analyses place it as sister to B. karchei, the largest species in the clade of miniaturized Brookesia species, for which we resurrect Evoluticauda Angel, 1942 as subgenus name. The genetic divergence of B. nana sp. nov. is rather strong (9.9‒14.9% to all other Evoluticauda species in the 16S rRNA gene). A comparative study of genital length in Malagasy chameleons revealed a tendency for the smallest chameleons to have the relatively largest hemipenes, which might be a consequence of a reversed sexual size dimorphism with males substantially smaller than females in the smallest species. The miniaturized males may need larger hemipenes to enable a better mechanical fit with female genitals during copulation. Comprehensive studies of female genitalia are needed to test this hypothesis and to better understand the evolution of genitalia in reptiles.
U2 - 10.1038/s41598-020-80955-1
DO - 10.1038/s41598-020-80955-1
M3 - Journal article
C2 - 33510189
AN - SCOPUS:85100298417
VL - 11
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
M1 - 2522
ER -
ID: 284286165