Phylogeography of the endangered darkling beetle species of Pimelia endemic to Gran Canaria (Canary Islands)

Abstract

Phylogenetic and geographical nested clade analysis (NCA) methods were applied to mitochondrial DNA sequences of Pimelia darkling beetles (Coleoptera, Tenebrionidae) endemic to Gran Canaria, an island in the Canary archipelago. The three species P. granulicollis, P. estevezi and P. sparsa occur on the island, the latter with three recognized subspecies. Another species, P. fernandezlopezi (endemic to the island of La Gomera) is a close relative of P. granulicollis based on partial Cytochrome Oxidase I mtDNA sequences obtained in a previous study. Some of these beetles are endangered, so phylogeographical structure within species and populations can help to define conservation priorities. A total of about 700 bp of Cytochrome Oxidase II were examined in 18 populations and up to 75 individuals excluding outgroups. Among them, 22 haplotypes were exclusive to P. granulicollis and P. estevezi and 31 were from P. sparsa. Phylogenetic analysis points to the paraphyly of Gran Canarian Pimelia, as the La Gomera P. fernandezlopezi haplotypes are included in them, and reciprocal monophyly of two species groups: one constituted by P. granulicollis, P. estevezi and P. fernandezlopezi (subgenus Aphanaspis), and the other by P. sparsa'sensu lato'. The two species groups show a remarkably high mtDNA divergence. Within P. sparsa, different analyses all reveal a common result, i.e. conflict between current subspecific taxonomic designations and evolutionary units, while P. estevezi and P. fernandezlopezi are very close to P. granulicollis measured at the mtDNA level. Geographical NCA identifies several cases of nonrandom associations between haplotypes and geography that may be caused by allopatric fragmentation of populations with some cases of restriction of gene flow or range expansion. Analyses of molecular variance and geographical NCA allow definition of evolutionary units for conservation purposes in both species-groups and suggest scenarios in which vicariance caused by geological history of the island may have shaped the pattern of the mitochondrial genetic diversity of these beetles.

The dynamics of genetic and morphological variation on volcanic islands

“…Parallelism of phylogeographic patterns in unrelated taxa may provide support for the hypothesis of a common historical cause (Walker & Avise 1998). Phylogenetic studies of the beetle genus Pimelia on Gran Canaria suggest that this genus colonized the island before the Roque Nublo cycle (Contreras-Diaz et al 2003). Phylogeographic breaks in the distribution of mt haplotype clades in Pimelia sparsa (Contreras-Diaz et al (Pestano & Brown 1999).…”

A Preliminary Molecular Phylogeny of the Namib Desert Darkling Beetles (Tenebrionidae)

“…The dNTP concentration was 100 µM for CO II fragments and 200 µM for Cyt B, respectively. Primers for COII (TL-J-3037; 5'-TAATATG GCAGATTAGTGCATTGGA-3' and TK-N-3785; 5'-GAGACCATTACTTGCTTTCAGTCATCT-3') have been previously used by Contreras-Díaz et al (2003) in a study on the darkling beetle genus Pimelia on the Canary Islands. PCR started with an initial cycle of 4 min at 95°C followed by 35 cycles of: 30 sec denaturation at 95°C, 1 min annealing at 50°C and 2 min extension at 72°C.…”

“…; see also Sole et al 2005 and references therein). To overcome this problem we used sequence data of a group of six Pimelia (Tenebrionidae) species aged approximately 10 (9.3-10.7) Mya (Contreras-Díaz et al 2003), which are endemic to the 15 My old island Gran Canaria (Canary Islands; Table 1). Likelihood of the Bayesian tree (MRBAYES) for the combined data set was -log 7004.9 without, and -log 7020.9 with enforcement of a molecular clock, respectively.…”

Using statistical phylogeography to infer population history: Case studies on Pimelia darkling beetles from the Canary Islands

“…Recently, the ease in obtaining DNA sequence data, and the improvement of phylogenetic methods, have promoted their application to many different speciose endemic organisms from the Canary and other Macaronesian archipelagos, including vertebrate and arthropod groups (e.g. Juan et al, 1995Juan et al, , 1998Juan et al, , 2000Brown and Pestano, 1998;Emerson et al, 1999Emerson et al, , 2000aCarranza et al, 2001;Rees et al, 2001a, b;Contreras-Dı´az et al, 2003). The molecular phylogenies provide a hypothesis of relationships of taxa, that can be used for testing the mono-or polyphyly of a particular group of taxa on the islands, understanding colonization sequences, disentangling extinction, hybridization and lineage sorting effects, or even comparing island speciation rates with the corresponding continental relatives (Emerson, 2002).…”

“…The study of genetic diversity within darkling beetle species and populations can help not only to understand adaptive trends in these insects in relation to environmental factors, but also to give a historic perspective to the biogeography of these key organisms in arid/semi-arid environments. For example, in a previous study we analysed the phylogeography of the Pimelia endemic species of the island of Gran Canaria (Contreras-Dı´az et al, 2003) and the results helped to establish evolutionary units for conservation purposes.…”