Anthropogenic impacts on the contextual morphological diversification and adaptation of Nile tilapia (Oreochromis niloticus, L. 1758) in East Africa
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Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
Environmental Biology of Fishes
Abstract
Nile tilapia occurs naturally in East Africa
where it’s an economically important species. Many of
the natural populations of Nile tilapia have been affected
by anthropogenic activities including translocations, associated
with programmes aimed at enhancing capture
fisheries and aquaculture productivity. Using geometric
morphometric analyses, we tested the hypothesis that
such anthropogenic activities have augmented admixture
among natural populations of Nile tilapia and
influenced the geographical distribution of morphological
variation within the species. Our expectation was
that Nile tilapia shape divergent might be consistent
with reportedly anthropogenic activities in nonnative
environments. To test this hypothesis, we analyzed the
shapes of 490 individuals from thirteen populations;
three farms, six natives and four nonnative natural populations.
Our analysis revealed that the most pronounced
shape diversification was observed in seven
populations; three nonnatives (Victoria, Kyoga and
Sindi farm) and four natives (Albert, River Nile, George
and Turkana). The features responsible for the observed
morphotypes were mainly related to the orientation of
the anterior region of the fish and may be due to diversifying
selection in response to new environmental pressures
(for nonnative populations), admixture or drift.
Shape change in the nonnative high-altitude populations
was unexpectedly conserved, suggesting recent introductions
which may have not resulted in admixture or
there was strong selection against change in the traits
measured. On the other hand, the recorded morphotypic
clusters explained the possible genetic link to their putative
ancestral home. Our results were partially consistent
with our prediction that the nonnative populations
exhibited divergent morphotypes. We recommend further
investigations with molecular genetics for followup
of these findings.
Description
Keywords
Nile tilapia, Geometric morphometrics, MorphoJ, Populations, Condition factor, Morphological diversification
Citation
Tibihika, P. D., Waidbacher, H., Masembe, C., Curto, M., Sabatino, S., Alemayehu, E., ... & Meimberg, H. (2018). Anthropogenic impacts on the contextual morphological diversification and adaptation of Nile tilapia (Oreochromis niloticus, L. 1758) in East Africa. Environmental Biology of Fishes, 101(3), 363-381. https://doi.org/10.1007/s10641-017-0704-0