Abstract

DE FREITAS ENCINAS DARDENGO, Juliana; BANDINI ROSSI, Ana Aparecida  and  LEMES VARELLA, Tatiane. The effects of fragmentation on the genetic structure of Theobroma speciosum (Malvaceae) populations in Mato Grosso, Brazil. Rev. biol. trop [online]. 2018, vol.66, n.1, pp.218-226. ISSN 0034-7744.  http://dx.doi.org/10.15517/rbt.v66i1.27904.

Native Theobroma species, such as cacauhy, are losing their habitat due to the intense forest fragmentation in the Amazon region, and preserving their genetic diversity has been the focus of many conservation programs. The aim of the present study is to assess whether fragmentation and habitat reduction affect its genetic structure and lead to genetic diversity losses in natural Theobroma speciosum populations. The study was conducted in two Mato Grosso State (Brazil) locations: Apiacás and Alta Floresta counties. Juruena National Park (JNP) in Apiacás County holds a natural T. speciosum population that has not suffered anthropic influences. A population composed of individuals from three anthropized urban forest parks (UF) in Alta Floresta County was analyzed for comparison. The leaves of 75 T. speciosum individuals distributed in the urban forest fragments and of 100 individuals found in the Juruena National Park were sampled. All nine microsatellite loci showed high polymorphism levels between categories (adults and sub-adults), in both populations. The sub-adult individuals of the fragmented area had a higher value (0.71), and the preserved population, the same value (0.69). The analysis of molecular variance showed 83 % genetic diversity within categories; 16 %, between populations; and only 1 %, between categories. Although the effects were small, a persistent fragmentation process can increase inbreeding and facilitate genetic drift, leading T. speciosum populations to inbreeding depression and loss of diversity. Rev. Biol. Trop. 66(1): 218-226. Epub 2018 March 01.

Keywords : genetic variability; cacauhy; inbreeding; Amazon; anthropic influence; microsatellite.

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