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Vol. 60, 2021
(update: 2021.03.03; 04.29)
Morphological and Genetic
Variation Among Populations of the Fiddler Crab Minuca burgersi (Holthuis, 1967)
(Crustacea: Brachyura: Ocypodidae) from Shores of the Caribbean Basin
and Western South Atlantic Ocean
C. L.
Thurman1, R. E. Alber1, M. J. Hopkins2,
and Hsi-Te Shih3,*
doi:10.6620/ZS.2021.60-19
1Department
of Biology, University of Northern Iowa, 1227 West 27th St., Cedar
Falls, IA 50614-0421, USA. E-mail: thurman@uni.edu (Thurman);
meierreid@gmail.com (Alber)
2Division of Paleontology, American Museum of Natural
History, Central Park West at 79th Street, New York, NY 10024-5192,
USA. E-mail: mhopkins@amnh.org (Hopkins)
3Department of Life Science and Research Center for
Global Change Biology, National Chung Hsing University, Taichung 402,
Taiwan. *Correspondence: E-mail: htshih@dragon.nchu.edu.tw (Shih)
Received 14 September 2020 / Accepted
10 February 2021
Communicated by Benny K.K. Chan
For this study, in addition to
museum vouchers, 1437 specimens of Minuca
burgersi
(Holthuis, 1967) were collected from crab colonies at 105 locations in
the western Atlantic Ocean to examine diversity in a species with a
large geographic range. Both allometric and geometric morphometry were
coupled with the molecular analysis of DNA to give a broader
perspective of intraspecific variability in this species. A total of
1153 specimens from the Caribbean Sea and the Atlantic coast of South
America demonstrated that M. burgersi
from both regions are very similar in their pattern of growth. The
average carapace width (CW) for Caribbean is larger than the average
for South American males and females. However, size distribution based
on CW is unimodal in Caribbean and bimodal in South American
populations. The carapace length-width ratio is about 0.68 in females
and 0.66 in males. South American males express asymmetric elongation
of the cheliped in smaller CW intervals than Caribbean males. In a
sample of 259 females, carapace shape is distinct between South
American and Caribbean populations. Caribbean populations have less
swelling in the branchial regions than South American populations. The
swelling correlates primarily with geographic region and to a lesser
degree with substrate and salinity. Molecular data from the 16S rDNA
and cytochrome c oxidase
subunit I (COI) reveal three
clades within Minuca burgersi.
Two clades are distributed in the Caribbean and the third in eastern
South America. The timing of divergence between Caribbean and South
American clades is coincident with an increased rate of water and
sediment outflow from the Amazon as inferred from the geologic record.
Current patterns and associated gene flow within the Caribbean were
subsequently influenced by the closing of the Isthmus of Panama. We
speculate that various populations may employ different larval
dispersion mechanisms resulting in genetic heterogeneity. Consequently,
there is considerable biological divergence among populations of M. burgersi in the Caribbean and
South America.
Key words: Fiddler crab, Biogeography,
Diversity, Morphology, Allometry, Geometric morphometrics, 16S rDNA,
Cytochrome c oxidase subunit
I (COI), Molecular phylogeny.
Citation:
Thurman CL, Alber RE, Hopkins MJ, Shih HT. 2021. Morphological and
genetic variation among populations of the fiddler crab Minuca burgersi
(Holthuis, 1967) (Crustacea: Brachyura: Ocypodidae) from shores of the
Caribbean Basin and western South Atlantic Ocean. Zool Stud 60:19. doi:10.6620/ZS.2021.60-19.
Supplementary
Materials: Fig.
S1
| Fig.
S1
| Table S1a | Table S1b | Table S2 | Table
S3 | Dataset S1
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