Extreme ecological and phenotypic differences in the tropical tree chicozapote (Manilkara zapota (L.) P. Royen) are not matched by genetic divergence: a random amplified polymorphic DNA (RAPD) analysis

Abstract

The chicozapote (Manilkara zapota) is a tropical fruit tree that occurs in two morphologically distinct populations in the Yucatan peninsula of Mexico. Forest populations consist of tall, straight trees, while swamp populations have a short, shrub‐like growth form. Swamp populations also have smaller leaves, fruit and seeds. We performed a random amplified polymorphic DNA (RAPD) analysis on four different populations of chicozapote to test if there was a genetic component to this variation. The populations differed in respect to habitat type (swamp vs. forest) and geographical location (east vs. west). We surveyed 80 random primers, nine of which revealed interpopulation band differences (28 band differences in total). Unweighted pair group method analysis (UPGMA) and neighbour‐joining dendrograms showed no separation of individuals between the different populations. Analysis of the RAPD data showed no significant differences between swamp and forest populations (P > 0.1). The lack of genetic differentiation suggests a failure to find a correlation between the RAPD loci and adaptive traits. The observed morphological differences between the swamp and forest populations of chicozapote may either be that gene flow has prevented a build‐up of neutral marker differences or a plastic response to differences in habitat.

Exploring local knowledge and preferences for shea (Vitellaria paradoxa) ethnovarieties in Southwest Burkina Faso through a gender and ethnic lens

“…Gwali et al (2012Gwali et al ( , 2014 find that local classification systems for shea in Uganda capture variations in fruit and nut traits, but that the distinct shea types recognized by farmers reflect different phenotypic expressions of actually similar genotypes. Other studies of tropical and temperate trees corroborate that phenotypic traits are not necessarily correlated to genetic variation, but rather constitute a plastic response to different environmental conditions and climatic changes (Kramer 1995;Heaton et al 1999;Assogbadjo et al 2009). Whether or not this is the case for 'small shea fruit' and 'big shea fruit' should be explored.…”

Genetic, morphological and spatial characterization of two populations of Mabea fistulifera Mart. (Euphorbiaceae), in different successional stages

“…The studied populations showed similar genetic variation levels, suggesting that selective forces did not increase with succession or that the effect of directional selection could be neutralized by gene flow among populations of distinct successional stages. It could also be possible that genetic differences between M. fistulifera populations were not due to natural selection, since RAPD markers have been generally reported to be neutral (Brunell and Whitkus, 1997;Heaton et al, 1999), and in this case, differences among populations would be caused by genetic drift. …”

Contrasting genetic diversity and differentiation of populations of two successional stages in a Neotropical pioneer tree (Eremanthus erythropappus, Asteraceae)

“…RAPD markers have been generally reported to be neutral markers (Brunell and Whitkus, 1997;Heaton et al, 1999), and here we did not analyze genetic differences in relation to morphological characters among the two successional stages. The morphological differences can be due to genetic differences and/or phenotypic plasticity.…”