Gunnhild Marthinsen

Atlantic salmon show capability for cardiac acclimation to warm temperatures

Increases in environmental temperature predicted to result from global warming have direct effects on performance of ectotherms. Moreover, cardiac function has been observed to limit the tolerance to high temperatures. Here we show that two wild populations of Atlantic salmon originating from northern and southern extremes of its European distribution have strikingly similar cardiac responses to acute warming when acclimated to common temperatures, despite different local environments. Although cardiac collapse starts at 21-23 °C with a maximum heart rate of ~150 beats per min (bpm) for 12 °C-acclimated fish, acclimation to 20 °C considerably raises this temperature (27.5 °C) and maximum heart rate (~200 bpm). Only minor population differences exist and these are consistent with the warmer habitat of the southern population. We demonstrate that the considerable cardiac plasticity discovered for Atlantic salmon is largely independent of natural habitat, and we propose that observed cardiac plasticity may aid salmon to cope with global warming.

Low support for separate species within the redpoll complex (Carduelis flammea–hornemanni–cabaret) from analyses of mtDNA and microsatellite markers

The redpoll complex, consisting of three currently recognized species (Carduelis flammea, C. hornemanni and C. cabaret), is polytypic in biometry, morphology, physiology and behaviour. However, previous genetic work has not revealed any indications of genetic differentiation. We analysed sequence variation in the mtDNA control region, and allele frequencies of supposedly faster evolving microsatellites (n=10), in an attempt to detect molecular genetic support for the three species, as well as two subspecies of C. flammea (ssp. flammea and rostrata), within this complex. We used samples from two subspecies of the twite (Carduelis flavirostris, ssp. flavirostris and rufostrigata) as outgroup. We found no structure among redpoll individuals in mtDNA haplotypes or microsatellite allele frequencies, and only marginal differences between redpoll taxa in analyses of molecular variance (AMOVAs) of predefined groups. In contrast, the two twite subspecies constituted two well-supported monophyletic groups. Our study thus strengthens previous indications of low genetic support for current redpoll taxa. Two major alternative interpretations exist. Either redpolls form a single gene pool with geographical polymorphisms possibly explained by Bergmanns and Glogers rules, or there are separate gene pools of recent origin but with too little time elapsed for genetic differentiation to have evolved in the investigated markers. Future studies should therefore examine whether reproductive isolation mechanisms and barriers to gene flow exist in areas with sympatric breeding.

Male extraterritorial forays, age and paternity in the socially monogamous reed bunting (Emberiza schoeniclus)

Genetic studies have shown that extra-pair paternity is widespread among socially monogamous bird species. Yet, the role of males and females and their behavior leading to this mixed reproductive strategy is poorly understood. Here, we analyze paternity in relation to male age and mating behavior in the socially monogamous reed bunting (Emberiza schoeniclus). We report a positive relation between male extraterritorial forays and success in obtaining extra-pair fertilizations. Extraterritorial forays tended to increase in frequency with male age and older males sired a larger number of extra-pair offspring than young males. Identified extra-pair sires were old in nine out of ten cases. The likelihood of being cuckolded was not affected by male age. Although based on correlative data, our results highlight age-dependent explorative male behavior as a key determinant for the understanding of extra-pair mating in the reed bunting. We do, however, emphasize the need for further studies to reveal the role of females in extra-pair copulations and fertilizations.

Improved DNA fragment length estimation in capillary electrophoresis

In CE the charged DNA strands are fractionated according to fragment lengths as they migrate through the capillary, since shorter DNA fragments pass through the sieving matrix faster. Multiplexed internal size standards are used to estimate the size of unknown DNA fragments. In the literature there are statements about migration abnormalities for the 250 and 340 bp fragments in the GeneScan‐500 (GS500) internal size standards. Such anomalous migration of size standards could obviously introduce errors in the estimation of unknown fragments. Therefore, a number of analysis programs simply exclude some of these fragments. In the present work we first evaluate the effect of excluding each of the fragments in the internal size standards used in CE. Next, a method which is based on estimating the true values of the anomalous fragments is presented. The results obtained by the new method indicate a significant improvement compared to results obtained when one (or both) of the anomalous fragments in GS500 is (are) excluded or included when estimating the size of unknown DNA fragments. In the higher‐molecular‐weight region, the average error is reduced from 1.91 bp in ABI GeneMapper (excluding 250 bp) to 0.15 bp in the new method (using the estimated values for 250 and 340 bp). In the lower‐molecular‐weight region, excluding both fragments will improve the results by an average of 0.74 bp compared to ABI GeneMapper.

Identification of Blood Parasites in Old World Warbler Species from the Danube River Delta

Abstract Warbler species of the families Sylviidae and Acrocephalidae occurring in the Danube river delta are frequently exposed to blood-sucking arthropods that transmit avian blood parasites. We investigated infections by three genera of hemosporidian parasites in blood samples from six warbler species. Altogether in 17 (32.6%) of 52 blood samples, a PCR product was amplified. The great reed warbler (Acrocephalus arundinaceus) had the highest prevalence, with 63.6% (7/11) infected individuals, whereas no infection was detected in marsh warbler (Acrocephalus palustris). The most common parasite genus was Haemoproteus, which was found in 15.4% (8/52) of individuals. Seven known parasite lineages (five Haemoproteus and two Plasmodium) and two new lineages were recorded (one Leucocytozoon and one Plasmodium).

Sperm performance in conspecific and heterospecific female fluid

Abstract Divergent sexual selection within allopatric populations may result in divergent sexual phenotypes, which can act as reproductive barriers between populations upon secondary contact. This hypothesis has been most tested on traits involved in precopulatory sexual selection, with less work focusing on traits that act after copulation and before fertilization (i.e., postcopulatory prezygotic traits), particularly in internally fertilizing vertebrates. However, postcopulatory sexual selection within species can also drive trait divergence, resulting in reduced performance of heterospecific sperm within the female reproductive tract. Such incompatibilities, arising as a by‐product of divergent postcopulatory sexual selection in allopatry, can represent reproductive barriers, analogous to species‐assortative mating preferences. Here, we tested for postcopulatory prezygotic reproductive barriers between three pairs of taxa with diverged sperm phenotypes and moderate‐to‐high opportunity for postcopulatory sexual selection (barn swallows Hirundo rustica versus sand martins Riparia riparia, two subspecies of bluethroats, Luscinia svecica svecica versus L. s. namnetum, and great tits Parus major versus blue tits Cyanistes caeruleus). We tested sperm swimming performance in fluid from the outer reproductive tract of females, because the greatest reduction in sperm number in birds occurs as sperm swim across the vagina. Contrary to our expectations, sperm swam equally well in fluid from conspecific and heterospecific females, suggesting that postcopulatory prezygotic barriers do not act between these taxon pairs, at this stage between copulation and fertilization. We therefore suggest that divergence in sperm phenotypes in allopatry is insufficient to cause widespread postcopulatory prezygotic barriers in the form of impaired sperm swimming performance in passerine birds.

Sex differences in body size and body condition in breeding Temminck’s Stints Calidris temminckii

There have been very few reports of body size measurements of live Temminck’s Stints, but earlier studies have shown sex differences in body mass and tarsus length. Here we use molecular techniques to determine the sex of Temminck’s Stints from a Norwegian breeding population. In total, we report measurements of body weight, wing length, tarsus length, bill length, skull length and keel length from 17 males and 30 females. We found significant sex differences in all of these variables, with the exception of tarsus length. The differences in skull length disappeared after the bill lengths had been subtracted from the measurements. A discriminant function analysis based on wing length and bill length correctly classified 86% of the cases (12/16 males, 25/27 females). Female Temminck’s Stints are known to regularly lay more than one clutch of eggs per season and could therefore be expected to be physiologically deprived of bodily energy stores. Nevertheless, we found females to be in better body condition than males.

Reduced genetic diversity and sperm motility in the endangered Gran Canaria Blue Chaffinch Fringilla teydea polatzeki

AbstractThe Blue Chaffinch (Fringilla teydea) is endemic to the Canary Islands and restricted to the pine forests on Tenerife (ssp. teydea) and Gran Canaria (ssp. polatzeki). While the teydea population is large and stable, the polatzeki population underwent a dramatic decline in the twentieth century and currently numbers less than 200 individuals. Here, we show that microsatellite allelic diversity is lower in polatzeki than in teydea, consistent with a genetic bottleneck scenario. Our genotyped polatzeki individuals, which were wild-caught but currently used in a captive breeding programme, have the same allelic diversity as free-ranging birds. However, the captive polatzeki males seem to have reduced sperm motility as compared with captive teydea males, which could be an effect of reduced genetic diversity. Because polatzeki and teydea are phylogenetically distinct, they should be recognized as Evolutionarily Significant Units by conservation authorities. We also recommend maintaining the captive polatzeki population as a pre-emptive measure against extinction in the wild.ZusammenfassungEingeschränkte genetische Vielfalt und Spermienbeweglichkeit beim vom Aussterben bedrohten Teide-Blaufinken (Fringilla teydea polatzeki) auf Gran Canaria Der Teide-Blaufink (Fringilla teydea polatzeki) ist auf den Kanarischen Inseln endemisch und lebt ausschließlich in den Pinienwäldern auf Teneriffa (ssp. teydea) und Gran Canaria (ssp. polatzeki). Während die Population auf Teneriffa groß und stabil ist, erfuhr die Population auf Gran Canaria im 20. Jahrhundert einen dramatischen Rückgang und umfasst zur Zeit weniger als 200 Individuen. In dieser Arbeit zeigen wir, dass die allelische Vielfalt der Mikrosatelliten bei Polatzeki geringer als bei Teydea ist, was im Einklang mit einem genetischen „Engpass-Szenario“steht. Unsere genotypisch eindeutig identifizierten Polatzeki-Individuen, die Wildfänge waren und jetzt in Gefangenschaft in einem Brutprogramm eingesetzt werden, zeigten die gleiche allelische Vielfalt wie die Tiere im Freiland. Aber die gefangenen Polatzeki-Männchen scheinen gegenüber den Teydea-Männchen eine reduzierte Spermienbeweglichkeit zu haben, was an einer geringeren genetischen Vielfalt liegen könnte. Weil Polatzeki und Teydea phylogenetisch unterschiedlich sind, sollten sie vom Naturschutz offiziell als Evolutionary Significant Units (ESU) anerkannt werden. Wir empfehlen außerdem, die derzeit in Gefangenschaft gehaltene Polatzeki-Population weiterzuführen als Vorsichtsmaßnahme gegen die mögliche Ausrottung im Freiland.

Phylogeographic origin and genetic diversity of dunlin Calidris alpina in Svalbard

We investigated the genetic structure of the presumably small (10–100 pairs) and isolated dunlin (Calidris alpina) population breeding in Svalbard, and compared it with similar data recently published from several dunlin populations in the western Palearctic and East Greenland. Using mitochondrial and nuclear DNA markers, as well as data on bill lengths, we sought to infer the phylogeographic origin of Svalbard dunlins and assess their within-population level of genetic diversity. Only dunlins with haplotypes of the European mtDNA clade (EUR) were found in Svalbard, indicating a close resemblance to dunlin populations in East Greenland and Iceland. Microsatellite data for Svalbard dunlins, as well as their short bills, also supported a western origin. The Svalbard population did not show signs of inbreeding or reduced levels of genetic diversity compared to other investigated populations, which suggests that the population was recently founded or is currently subject to considerable gene flow.