Cranial and chromosomal geographic variation in manatees (Mammalia: Sirenia: Trichechidae) with the description of the Antillean manatee karyotype in Brazil
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- 作者：Helen M. D. do R. Barros ; Ana C. O. Meirelles ; Fá ; bia O. Luna ; Miriam Marmontel ; Pedro Cordeiro-Estrela ; Neide Santos and Diego Astú ; a
- 刊名：Journal of Zoological Systematics and Evolutionary Research
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：55
- 期：1
- 页码：73-87
- 全文大小：1542K
- ISSN：1439-0469
文摘
We employed landmark-based 3D geometric morphometrics to assess cranial size and shape diversification in m>Trichechus manatus m> and m>T. inunguis m> to compare it with patterns among all manatee taxa (m>T. manatus latirostris m>,m> T. m. manatus m>,m> T. inunguis m> and m>T. senegalensis m>), and to analyse geographic variation within American manatee populations, using a sample of 189 skulls. Chromosome G- and C-banding techniques were performed in m>T. m. manatus m> from Brazil. All taxa were statistically discriminated by skull shape. m>Trichechus m. manatus m> and m>T. m. latirostris m> have larger skulls than m>T. inunguis m>. A morphological discontinuity was noted within m>T. m. manatus m>, with the Brazilian population south of the Amazon discriminated from the m>T. m. manatus m> Caribbean and m>T. m. latirostris m>USA populations. Specimens from Suriname and Guyana had a skull shape more similar to the one from the Caribbean population. The Brazil Antillean manatee population exhibited morphological differences similar in magnitude to those found between the Amazonian and African species. Additionally, structural chromosome differences were detected between that population (chromosome pair 4 is metacentric and 10 is submetacentric) and manatees from Puerto Rico and Florida. Based on such morphological discontinuity and chromosomal divergence, we hypothesize that the Amazon River mouth may be acting as a reproductive barrier for the m>T. m. manatus m> population in Brazil, thus indicating that its taxonomic status and conservation strategies need an urgent reassessment.