Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (<it>Coregonus </it>spp.)

Abstract Background Adaptive radiation within fishes of the Coregonus lavaretus complex has created numerous morphs, posing significant challenges for taxonomy and conservation priorities. The highly endangered North Sea houting (C. oxyrhynchus; abbreviated NSH) has been considered a separate species from European lake whitefish (C. lavaretus; abbreviated ELW) due to morphological divergence and adaptation to oceanic salinities. However, its evolutionary and taxonomic status is controversial. We analysed microsatellite DNA polymorphism in nine populations from the Jutland Peninsula and the Baltic Sea, representing NSH (three populations, two of which are reintroduced) and ELW (six populations). The objectives were to: 1) analyse postglacial recolonization of whitefish in the region; 2) assess the evolutionary distinctiveness of NSH, and 3) apply several approaches for defining conservation units towards setting conservation priorities for NSH. Results Bayesian cluster analyses of genetic differentiation identified four major groups, corresponding to NSH and three groups of ELW (Western Jutland, Central Jutland, Baltic Sea). Estimates of historical migration rates indicated recolonization in a north-eastern direction, suggesting that all except the Baltic Sea population predominantly represent postglacial recolonization via the ancient Elbe River. Contemporary gene flow has not occurred between NSH and ELW, with a divergence time within the last 4,000 years suggested from coalescence methods. NSH showed interbreeding with ELW when brought into contact by stocking. Thus, reproductive isolation of NSH was not absolute, although possible interbreeding beyond the F1 level could not be resolved. Conclusion Fishes of the C. lavaretus complex in the Jutland Peninsula originate from the same recolonization event. NSH has evolved recently and its species status may be questioned due to incomplete reproductive isolation from ELW, but it was shown to merit consideration as an independent conservation unit. Yet, application of several approaches for defining conservation units generated mixed outcomes regarding its conservation priority. Within the total species complex, it remains one among many recently evolved unique forms. Its uniqueness and high conservation priority is more evident at a local geographical scale, where conservation efforts will also benefit populations of a number of other endangered species.</p

Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

Admixture between wild and captive populations is an increasing concern in conservation biology. Understanding the extent of admixture and the processes involved requires identification of admixed and non-admixed individuals. This can be achieved by statistical methods employing Bayesian clustering, but resolution is low if genetic differentiation is weak. Here, we analyse stocked brown trout populations represented by historical (1943–1956) and contemporary (2000s) samples, where genetic differentiation between wild populations and stocked trout is weak (pairwise FST of 0.047 and 0.053). By analysing a high number of microsatellite DNA markers (50) and making use of linkage map information, we achieve clear identification of admixed and non-admixed trout. Moreover, despite strong population-level admixture by hatchery strain trout in one of the populations (70.8%), non-admixed individuals nevertheless persist (7 out of 53 individuals). These remnants of the indigenous population are characterized by later spawning time than the majority of the admixed individuals. We hypothesize that isolation by time mediated by spawning time differences between wild and hatchery strain trout is a major factor rescuing a part of the indigenous population from introgression

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)-5

<p><b>Copyright information:</b></p><p>Taken from "Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)"</p><p>http://www.biomedcentral.com/1471-2148/8/137</p><p>BMC Evolutionary Biology 2008;8():137-137.</p><p>Published online 9 May 2008</p><p>PMCID:PMC2396634.</p><p></p

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)-1

, measuring the steepness of increase of P(D) [53] (red line).<p><b>Copyright information:</b></p><p>Taken from "Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)"</p><p>http://www.biomedcentral.com/1471-2148/8/137</p><p>BMC Evolutionary Biology 2008;8():137-137.</p><p>Published online 9 May 2008</p><p>PMCID:PMC2396634.</p><p></p

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)-4

S. A value of 1 denotes a "pure" RIN individual, and conversely 0 denotes a "pure" VID individual. values were ranked from lowest to highest. The analyses were conducted using STRUCTURE 2.2 [51,52]. a) values in the VAR94 sample. b) values in the VAR04 sample.<p><b>Copyright information:</b></p><p>Taken from "Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)"</p><p>http://www.biomedcentral.com/1471-2148/8/137</p><p>BMC Evolutionary Biology 2008;8():137-137.</p><p>Published online 9 May 2008</p><p>PMCID:PMC2396634.</p><p></p

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)-3

Ndicated by arrows. Punctuated green arrows indicate 10 = < 15, blue arrows indicate 15 = < 20 and red arrows indicate = 20. Estimates of < 10 are not shown. See Additional file for an overview of all and values and their associated 95% confidence intervals. The analyses were conducted using the method and software MIGRATE 2.0.3 [58].<p><b>Copyright information:</b></p><p>Taken from "Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (spp.)"</p><p>http://www.biomedcentral.com/1471-2148/8/137</p><p>BMC Evolutionary Biology 2008;8():137-137.</p><p>Published online 9 May 2008</p><p>PMCID:PMC2396634.</p><p></p