Phylogeography and molecular phylogeny of Macaronesian island Tarphius (Coleoptera: Zopheridae): why are there so few species in the Azores?

Abstract

Aim We used a phylogenetic framework to examine island colonization and predictions pertaining to differentiation within Macaronesian Tarphius (Insecta, Coleoptera, Zopheridae), and explain the paucity of endemics in the Azores compared with other Macaronesian archipelagos. Specifically, we test whether low diversity in the Azores could be due to recent colonization (phylogenetic lineage youth), cryptic speciation (distinct phylogenetic entities within species) or the young geological age of the archipelago.Location Macaronesian archipelagos (Azores, Madeira and the Canary Islands), northern Portugal and Morocco.Methods Phylogenetic analyses of mitochondrial and nuclear genes of Tarphius beetles of the Azores, other Macaronesian islands and neighbouring continental areas were used to investigate the origin of island biodiversity and to compare patterns of colonization and differentiation. A comparative nucleotide substitution rate test was used to select the appropriate substitution rate to infer clade divergence times.Results Madeiran and Canarian Tarphius species were found to be more closely related to each other, while Azorean taxa grouped separately. Azorean taxa showed concordance between species and phylogenetic clades, except for species that occur on multiple islands, which segregated by island of origin. Divergence time estimates revealed that Azorean Tarphius are an old group and that the most recent intra-island speciation event on Santa Maria, the oldest island, occurred between 3.7 and 6.1 Ma.Main conclusions Our phylogenetic approach provides new evidence to understand the impoverishment of Azorean endemics: (1) Tarphius have had a long evolutionary history within the Azores, which does not support the hypothesis of fewer radiation events due to recent colonization; (2) the current taxonomy of Azorean Tarphius does not reflect common ancestry and cryptic speciation is responsible for the underestimation of endemics; (3) intra-island differentiation in the Azores was found only in the oldest island, supporting the idea that young geological age of the archipelago limits the number of endemics; and (4) the lack of evidence for recent intra-island diversification in Santa Maria could also explain the paucity of Azorean endemics. Phylogenetic reconstructions of other species-rich taxa that occur on multiple Macaronesian archipelagos will reveal whether our conclusions are taxon specific, or of a more general nature.

Modeling directional spatio‐temporal processes in island biogeography

“…The colonization pattern can be less evident in archipelagos with a more complex geological history, such as the Azores (Amorim et al. ), Canaries (Sanmartín et al. ), Cape Verde (Carranza et al.…”

Comparative phylogeography of oceanic archipelagos: Hotspots for inferences of evolutionary process

“…However, the islands are located over a complex microplate rather than a single hotspot. Nevertheless, there is some evidence for a directional mode of dispersal from older to younger islands [plants (80,81); arthropods (82,83)], although a simple progression rule is not common [yet Van Riel (84) presents intriguing evidence from gastropods]. Much of the current evidence consists of age estimates of haplotypes/alleles rather than robustly structured cladogenetic branching between islands.…”

A new species of Tarphius Erichson, 1845 (Coleoptera: Zopheridae) from North Africa and notes on an Iberian species

“…This study, together with the recent findings of Machado (2012) and Amorim et al (2012), highlights the necessity of additional work to adequately inventory Tarphius species richness in North Africa and Macaronesia. S.A.…”

“…In spite of this, two species were recently described from Deserta Grande (Madeira archipelago) and Fuerteventura (Canary Islands) (Machado 2012), and additional cryptic species are currently being described from the Azores (Borges et al in prep.; see also Amorim et al 2012). In addition, a large effort to collect Tarphius in several locations throughout mainland Portugal, Morocco, Azores and Madeira archipelagos resulted in the discovery and description of a new species from North Africa (Tarphius isabelae n.sp.)…”

“…The genus Tarphius Erichson, 1845 is represented in the Palaearctic region by 69 species (Franz 1967;Dajoz 1977;Borges et al 2008Borges et al , 2010 Ś lipiński & Schuh 2008; Arechavaleta et al 2010;Amorim et al 2012;Machado 2012). Additionally, four species are known from other regions, including two from South America (Franz 1967) and two from the Himalayas (Ślipiński 1985) (see Appendix 1).…”