Mitochondrial DNA variation and population structure of the island endemic Azorean bat (Nyctalus azoreum)

Abstract

The Azorean bat Nyctalus azoreum is the only endemic mammal native to the remote archipelago of the Azores. It evolved from a continental ancestor related to the Leisler's bat Nyctalus leisleri and is considered threatened because of its restricted and highly fragmented distribution. We studied the genetic variability in 159 individuals from 14 colonies sampled throughout the archipelago. Sequences of the D-loop region revealed moderate but highly structured genetic variability. Half of the 15 distinct haplotypes were restricted to a single island, but the most common was found throughout the archipelago, suggesting a single colonization event followed by limited interisland female gene flow. All N. azoreum haplotypes were closely related and formed a star-like structure typical of expanded populations. The inferred age of demographic expansions was consistent with the arrival of founder animals during the Holocene, well before the first humans inhabited the Azores. Comparisons with a population of N. leisleri from continental Portugal confirmed not only that all N. azoreum lineages were unique to the archipelago, but also that the current levels of genetic diversity were surprisingly high for an insular species. Our data imply that the Azorean bat has a high conservation value. We argue that geographical patterns of genetic structuring indicate the existence of two management units.

New insights on postglacial colonization in western Europe: the phylogeography of the Leisler's bat (Nyctalus leisleri)

“…These haplotypes were defined by 64 variable sites, of which 48 were transitions, seven transversions and nine indels. The 22 bp indel found in N. azoreum [27] was absent in all N. leisleri sequences examined in this study.…”

“…We used a range of mutation rates for the control region proposed by Petit et al [41] for the congeneric N. noctula, with a generation time of 2 years, a lower rate of 6.3%, a higher rate of 25.2%, with an average of 20% Myr 21 . The latter value was used in several other studies, including Salgueiro et al [27] and Chen et al [42]. The approximate Bayesian computation (ABC) approach, implemented in the DIYABC software [43], was also used to test for alternative scenarios for the colonization of Britain and Ireland by N. leisleri following the LGM using both microsatellite and mtDNA data (details of this analysis are provided in the electronic supplementary material).…”

“…Resulting sequences were imported into BIOEDIT [33], and aligned using CLUSTALW [34]. In order to combine our novel mtDNA dataset with existing lineages based on previous studies by Salgueiro et al [27,28], 46 European N. leisleri were sequenced for the mtDNA control region, resulting in 13 haplotypes (accession nos. DQ887597-DQ887608 and AY756613-AY756615).…”

Patterns of genic diversity and structure in a species undergoing rapid chromosomal radiation: an allozyme analysis of house mice from the Madeira archipelago

“…The proportion of endemic species in particular has been shown to be strongly related to island size and topographical complexity due to the increased opportunity for intra-island allopatric speciation (Emerson and Kolm, 2005). Recently, such approaches have been successfully applied to various plant and animal species diversifications in the Macaronesian islands (Jordal and Hewitt, 2004;Salgueiro et al, 2004;Silvertown, 2004).…”

Phylogeography of the Malagasy ring-tailed mongoose,Galidia elegans, from mtDNA sequence analysis

“…Typically, each gap is treated as a singe nucleotide change that occurs over time; however, an indel, composed of a series of contiguous bases or gaps, most likely arose once as a single event (Simmons and Ochoterena 2000), and steps should be taken to avoid the pseudoreplication of gaps within the indel so as to adequately reflect the occurrence of a single event. Recent studies suggest that indels comprise a part of the potential phylogenetic information available and should not be ignored (Simmons and Ochoterena 2000;Hamilton et al 2003;Salgueriro et al 2004). In light of this, a variety of strategies have been proposed for coding and analyzing indels to preserve such information (e.g.…”