Andrew P. Krupa

Peacocks lek with relatives even in the absence of social and environmental cues

Lek mating systems are characterized by males displaying in groups. The main benefit from group display is thought to be an increase in the number of females arriving per male. However, when mating success is highly skewed it is not clear why unsuccessful males participate in group display. In theory, all males on leks could obtain indirect fitness benefits if displaying groups consisted of related individuals. Here we present two independent sets of data that show that peacocks (Pavo cristatus) display close to their kin. DNA fingerprinting showed that males at Whipsnade Park were more closely related to males within the same lek than to males at other leks. Separately, we found that after an experimental release of a mixed group of related and unrelated males, brothers (paternal sibs or half-sibs) established permanent display sites very close together. This result is unexpected, as the released birds could not become familiar with their brothers during their development. The released young were hatched from eggs that had been removed from their parents shortly after laying and mixed with the eggs of non-relatives. These data indicate that birds can evolve a means of kin association that does not involve learning the characteristics of relatives or the use of environmental cues. If social learning is not necessary for kin association then kin effects may be of more widespread importance in avian social interactions, and in particular in the evolution of lek mating, than previously appreciated.

New methods to identify conserved microsatellite loci and develop primer sets of high cross-species utility - as demonstrated for birds

We have developed a new approach to create microsatellite primer sets that have high utility across a wide range of species. The success of this method was demonstrated using birds. We selected 35 avian EST microsatellite loci that had a high degree of sequence homology between the zebra finch Taeniopygia guttata and the chicken Gallus gallus and designed primer sets in which the primer bind sites were identical in both species. For 33 conserved primer sets, on average, 100% of loci amplified in each of 17 passerine species and 99% of loci in five non‐passerine species. The genotyping of four individuals per species revealed that 24–76% (mean 48%) of loci were polymorphic in the passerines and 18–26% (mean 21%) in the non‐passerines. When at least 17 individuals were genotyped per species for four Fringillidae finch species, 71–85% of loci were polymorphic, observed heterozygosity was above 0.50 for most loci and no locus deviated significantly from Hardy–Weinberg proportions.

The annual number of breeding adults and the effective population size of syntopic newts (Triturus cristatus, T. marmoratus)

Pond‐breeding amphibians are deme‐structured organisms with a population genetic structure particularly susceptible to demographic threats. We estimated the effective number of breeding adults (Nb) and the effective population size (Ne) of the European urodele amphibians Triturus cristatus (the crested newt) and T. marmoratus (the marbled newt), using temporal shifts in microsatellite allele frequencies. Eight microsatellite loci isolated from a T. cristatus library were used, five of which proved polymorphic in T. marmoratus, albeit with high frequencies of null alleles at two loci. Three ponds in western France were sampled, situated 4–10 kilometres apart and inhabited by both species. Parent–offspring cohort comparisons were used to measure Nb; samples collected at time intervals of nine or 12 years, respectively, were used to measure Ne. The adult population census size (N) was determined by mark–recapture techniques. With one exception, genetic distances (FST) between temporal samples were lower than among populations. Nb ranged between 10.6 and 101.8 individuals, Ne ranged between 9.6 and 13.4 individuals. For the pond where both parameters were available, Nb/N (overall range: 0.10–0.19) was marginally larger than Ne/N (overall range: 0.09–0.16), which is reflected in the temporal stability of N. In line with the observed differences in reproductive life‐histories between the species, Nb/N ratios for newts were about one order of magnitude higher than for the anuran amphibian Bufo bufo. Despite of the colonization of the study area by T. cristatus only some decades ago, no significant genetic bottleneck could be detected. Our findings give rise to concerns about the long‐term demographic viability of amphibian populations in situations typical for European landscapes.

CUCKOO PARASITISM AND PRODUCTIVITY IN DIFFERENT MAGPIE SUBPOPULATIONS PREDICT FREQUENCIES OF THE 457bp ALLELE: A MOSAIC OF COEVOLUTION AT A SMALL GEOGRAPHIC SCALE

Abstract The level of defense against great spotted cuckoo (Clamator glandarius) parasitism in different European populations of magpie (Pica pica) depends on selection pressures due to parasitism and gene flow between populations, which suggests the existence of coevolutionary hot spots within a European metapopulation. A mosaic of coevolution is theoretically possible at small geographical scales and with strong gene flow, because, among other reasons, plots may differ in productivity (i.e., reproductive success of hosts in the absence of parasitism) and defensive genotypes theoretically should be more common in plots of high productivity. Here, we tested this prediction by exploring the relationship between parasitism rate, level of defense against parasitism (estimated as both rejection rate and the frequency of the 457bp microsatellite allele associated with foreign egg rejection in magpies), and some variables related to the productivity (average laying date, clutch size, and number of hatchlings per nest) of magpies breeding in different subpopulations. We found that both estimates of defensive ability (egg rejection rate and frequency of the 457bp allele) covaried significantly with between-plot differences in probability of parasitism, laying date, and number of hatchlings per nest. Moreover, the parasitism rate was larger in more productive plots. These results confirm the existence of a mosaic of coevolution at a very local geographical scale, and the association between laying date and number of hatchlings with variables related to defensive ability and the selection pressure arising from parasitism supports the prediction of coevolutionary gradients in relation to host productivity.

A quantitative trait locus for recognition of foreign eggs in the host of a brood parasite

Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter‐defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter‐defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus.

Microsatellite resources for Passeridae species: a predicted microsatellite map of the house sparrow Passer domesticus

We identified microsatellite sequences of potential utility in the house sparrow (Passer domesticus) and assigned their predicted genome locations. These sequences included newly isolated house sparrow loci, which we fully characterized. Many of the newly isolated loci were polymorphic in two other species of Passeridae: Berthelot’s pipit Anthus berthelotii and zebra finch Taeniopygia guttata. In total, we identified 179 microsatellite markers that were either isolated directly from, or are of known utility in, the house sparrow. Sixty‐seven of these markers were designed from unique sequences that we isolated from a house sparrow genomic library. These new markers were combined with 36 house sparrow markers isolated by other studies and 76 markers isolated from other passerine species but known to be polymorphic in the house sparrow. We utilized sequence homology to assign chromosomal locations for these loci in the assembled zebra finch genome. One hundred and thirty‐four loci were assigned to 25 different autosomes and eight loci to the Z chromosome. Examination of the genotypes of known‐sex house sparrows for 37 of the new loci revealed a W‐linked locus and an additional Z‐linked locus. Locus Pdoμ2, previously reported as autosomal, was found to be Z‐linked. These loci enable the creation of powerful and cost‐effective house sparrow multiplex primer sets for population and parentage studies. They can be used to create a house sparrow linkage map and will aid the identification of quantitative trait loci in passerine species.

Microsatellite loci in the crested newt (Triturus cristatus) and their utility in other newt taxa

A.P. Krupa1, R. Jehle1, D.A. Dawson1, L.K. Gentle1, M. Gibbs1, J.W. Arntzen2 & T. Burke1,∗ 1Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK; 2National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands, and Universidade do Porto, Unidade de Genetica Animal e Conservacao, Campus Agrario de Vairao, Rua de Monte, Crasto, 4480 Vila do Conde, Portugal (∗Corresponding author: E-mail: T.A.Burke@sheffield.ac.uk)

Genetic similarity and relationships of DNA fingerprints with performance and with heterosis in Japanese quail lines from two origins and under reciprocal recurrent or within-line selection for early egg production.

DNA fingerprints of Japanese quail male and female pure line breeders were obtained with probes 33.6, 33.15, and R18.1 and they yielded a total of 59 scoreable bands. Bandsharing (0 < BS < 1) was calculated within and between six quail lines of two origins, and under reciprocal recurrent (AA and BB), within-line (DD and EE) or no (PP and FF) selection. Twenty one pair types were compared. BS was 0.30 higher within line than between lines. BS with the control line was smaller for reciprocal recurrent selection lines than for lines under individual selection. Bandsharing between the two reciprocal recurrent selection lines was 0.19 lower than between lines under individual selection. These results indicate that the two selection methods had different effects on the genetic constitution of the lines, in agreement with previous observations made from the analysis of biochemical polymorphisms with the same set of birds. Egg production and weight traits of pure and crossbred progeny from fingerprinted quail were obtained and compared, and a linear relationship with the measure of bandsharing was estimated. No significant regression coefficient of performance on BS was found over all progeny genetic types. Heterosis from individual matings could also be estimated under the two selection methods since the same birds were parents of both pure and crossbred performance-tested quail. The association of heterosis with the difference between BS of parents of the purebreds and BS of parents of their half-sib crossbreds was favourable and significant for early production traits in lines DD and EE, but no relationship was found in lines AA and BB. These results indicate that the high level of heterosis obtained through reciprocal recurrent selection, and the heterosis observed under within-line selection may have, partly at least, a different genetic determinism. Therefore, the relationship of heterosis with BS may also depend on the past history of selection in the lines.