Genetic differentiation among populations ofBaetis rhodani(Ephemeroptera, Baetidae) in three Italian streams

Abstract

Seven microsatellite loci were recently described for the mayfly Baetis rhodani, but, at present, no data are available on the population structure of this species using these loci. We used four of these microsatellite loci for a preliminary analysis of the genetic differentiation of the mayfly B. rhodani in six populations from three Italian streams belonging to the same or different, but geographically distant, drainage basins. From these data, genetic polymorphism was observed between the sampled populations and clear differences were identified between pairs of populations; however, no specific population pattern was observed. The high F ST values suggest a limited dispersal of the species across the sampling sites. On the whole, the results obtained with microsatellite loci, characterized by marked heterozygosity deficiency, confirm the hypothesis of the patchy recruitment from a small number of matings and limited in-stream dispersal, as previously pointed out for some other baetid mayflies by genetic analyses using allozymes and mtDNA. This is the first contribution to a knowledge of the genetic structure of Italian Baetis rhodani populations.

Fine-scale dispersal in a stream caddisfly inferred from spatial autocorrelation of microsatellite markers

“…Dispersal and spatial autocorrelation Highly polymorphic markers are widely used to infer genetic variance within and among a priori populations of stream insects to provide a broad overview of gene flow over multiple generations (e.g., Wilcock et al 2003, Rebora et al 2005, Alp et al 2012 and to study local effects of bottlenecks (e.g., Shama et al 2011). We applied a traditional fixation-index approach and alternative methods that used the same data (microsatellite genotypes) but estimated gene flow on smaller spatial and temporal scales (SA) and relaxed the need to define populations a priori (clustering).…”

Geographical and seasonal evidence of cryptic diversity in the Baetis rhodani complex (Ephemeroptera, Baetidae) revealed by means of DNA taxonomy

“…The analysis of nuclear DNA sequences could support the identification of the cryptic species here suggested. In fact, a previous attempt to analyse the dispersal and the gene flow of this species complex in Italy by means of microsatellite markers (Rebora et al, 2005) could not shed light on this topic, probably for the presence of (then) unknown cryptic species, confounding the scenario for the analyses.…”

Evolutionary divergence in freshwater insects with contrasting dispersal capacity across a sea of desert

“…However, more commonly, mayfly species show evidence of restricted gene flow between different streams or catchments, as seen in Baetis rhodani in Italy (Rebora et al, 2005), Bungona narilla in Australia McLean et al, 2008) and F I G U R E 4 Spatial distribution of known and putative mayfly species sampled in this study. Pies represent proportions of individuals sampled at each site belonging to each species/putative species.…”

“…For example, widespread species Cloeon smaeleni of sub‐Saharan Africa and southern Arabia shows evidence of frequent dispersal across the ocean to Madagascar (Monaghan et al., ). However, more commonly, mayfly species show evidence of restricted gene flow between different streams or catchments, as seen in Baetis rhodani in Italy (Rebora et al., ), Bungona narilla in Australia (Hughes, Hillyer, et al., ; McLean et al., ) and Baetis bicaudatus in USA (Hughes, Mather, et al., ). The most widespread species found in the current study are also the only formally recognised species: C. fluviatile and T. arcuata have both been sampled across the Australian continent in mesic and arid climates (Alba‐Tercedor & Suter, ; Webb & Suter, ).…”

“…Due to an extremely short adult life stage and weak flying ability, dispersal in mayflies can be disrupted by small extents of cleared agricultural land, dams and even bridges (Málnás et al., ; McLean, Schmidt, & Hughes, ; Monaghan, Spaak, Robinson, & Ward, ). Individual mayflies do not often travel far from their place of birth and this can lead to low genetic exchange among populations, and strong genetic structure and divergence at multiple spatial scales (Hughes, Hillyer, & Bunn, ; Hughes, Mather, Hillyer, Cleary, & Peckarsky, ; Rebora, Lucentini, Palomba, Panara, & Gaino, ; Watanabe, Monaghan, Takemon, & Omura, ). Aquatic insects with high dispersal potential, such as dragonflies (Order Odonata), are less spatially restricted than mayflies, and are capable of flying substantial distances between aquatic habitats.…”