Genetic erosion in the snail littoraria subvittata (reid, 1986) due to mangrove deforestation
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Date
2016
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Journal of molluscan studies
Abstract
In tropical coastal ecosystems mangrove forests are important as feeding, spawning, breeding and nursery
grounds for many marine species. High human population pressure in coastal areas has led to the loss and
deterioration of mangrove habitats. Solar salt production can affect these habitats along the East African
coast. Littorinid snails live on mangrove trees, forming an important component of the mangrove ecosys-
tem and have been used as bioindicators of environmental health and community stress. Littoraria subvittata
is the most abundant littorinid species in mangroves along the East African coast. Partial mitochondrial
cytochrome oxidase subunit 1 (COI) gene sequences of 298 individuals were used to assess the impact of
mangrove deforestation at salt ponds on the genetic diversity and structuring of L. subvittata populations, as
well as to infer the demographic history of the species. Nucleotide and haplotype diversities were found to
be lower in samples from mangroves at salt ponds than in samples from natural mangroves. The mean
nucleotide diversity was 0.049 ± 0.036% and 0.115 ± 0.068% in mangroves at salt ponds and natural
mangroves, respectively. The mean haplotype diversity was 0.23 ± 0.14 and 0.50 ± 0.14 in mangroves at
salt ponds and natural mangroves, respectively. Analysis of molecular variance (AMOVA) detected a sig-
nificant population structure (Ф st = 0.049; P < 0.0001) for the combined populations. Hierarchical
AMOVA detected a significant population genetic structure only between populations from mangroves at
salt ponds and natural mangroves (Φ ct = 0.022; P < 0.05), but not between any other groupings.
Populations from natural mangrove sites showed a significant genetic structure (Ф st = 0.054, P < 0.0001),
while populations from sites at salt ponds could not be differentiated (Ф st = −0.0026, P = 0.64). Reduced
effective population size was observed in most samples from mangrove sites at salt ponds compared with
natural mangrove. The direction of migrants was mostly from salt ponds to natural mangroves. These
results show that salt ponds have a negative impact on the genetic diversity of L. subvittata populations and
modify the population’s genetic structure.
Description
Journal Article
Keywords
Genetic erosion, Mangrove deforestation, Snail Littoraria subvittata