High genetic diversity vs. low genetic and morphological differentiation ofArgiope trifasciata(Araneae, Araneidae) in Tunisia

High genetic diversity of spider species in a mosaic montane grassland landscape

“…Subsequent analyses based on the COI gene indicated that the majority of the investigated spider species harbour high haplotype diversity among the sampled shrubland localities of the GGHNP, alongside moderate to low nucleotide diversity. Similar occurrences were reported in analyses of spider species from other countries [10,[96][97], albeit on a larger geographical scale. Unfortunately, few reports on the genetic diversity of South African araneid populations are available for comparison with our study (e.g.…”

“…[98]). While genetic diversity was relatively high among our investigated taxa, genetic differentiation was moderate to low, implying the possibility of such diversity being maintained by gene flow [10]. Additionally, the current reported genetic variability experienced by the populations of the five investigated taxa may be the result of unequal gene flow transfer between the selected localities [99][100].…”

“…A total of two million generations were run for each species to ensure appropriate phylogenetic inference, with the exception of P. browningi, which was run for four million generations due to the increased number of base pairs. Four MCMC chains were run (3 hot, 1 cold), and sampling was performed every 1000 generations, with an adequate burn-in of 10% of the number of generations, determined from likelihood scores and convergence of posterior probabilities [10], for each species. All trees sampled in the burn-in phase were discarded.…”

“…Habitat fragmentation, giving rise to remnant woody vegetation patches in a grassland matrix, produces variable and unique challenges to faunal lifestyles [4][5]. Dispersal between such fragmented habitats is often dependent upon the distance of individual habitats in relation to native vegetation [6], with connectivity in and among populations being a direct consequence of taxon dispersal ability [7][8][9][10].…”

“…Limitations to population homogeneity, in the form of incomplete or fragmented phenotypic and genetic variability, can occur due to physical and/or behavioural barriers [25][26]. Those species with an aerial dispersal ability often possess a more homogenous genetic structure over a large geographical range compared to their substrate-bound counterparts, particularly spiders [10,[27][28][29]. While large numbers of spider species possess conserved morphological characteristics, highly conserved morphology in cryptic species is often associated with strong genetic differentiation [30].…”