Male reproductive traits of full-sibs of different age classes in three-spined sticklebacks (Gasterosteus aculeatus)

The process of ageing is associated with negative effects of mutations acting late in life, which range from those affecting cells to those affecting the whole organism. In many animal taxa, the deterioration of the phenotype with age also affects traits such as males’ primary and secondary sexual characteristics. In three-spined sticklebacks (Gasterosteus aculeatus), males usually reproduce at one or two years of age. To see whether sexual selection has the potential to differ between young and old males, full-sib brothers of different age classes were compared, which were bred and raised under standardised laboratory conditions. During two simulated, successive breeding seasons males were allowed to build their nest in single tanks either in the first (“young males”) or in the second (“old males”) breeding season. A comparison of reproductively active brothers of the first and second breeding season showed that older males produce more but smaller sperm, which might be of lower quality. The fact that older males stored more sperm is size dependent as the results show that larger males possess a greater absolute testis mass, which is inextricably linked to sperm number. However, independent of body size, old males had a lower intensity of red/orange and UV breeding coloration as well as a reduced testis melanisation, which might have consequences in female mate choice and sperm competition

Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?

<p>Abstract</p> <p>Background</p> <p>The use of ultraviolet (UV) signals for communication tasks is widespread in vertebrates. For instance, there is a UV component to mate choice in several species. Nevertheless, it remains unclear how the signal value of the UV wave band compares to that of other regions of the animal's visible spectrum. We investigated the relative importance of UV signals compared with signals of longer wavelengths in the threespine stickleback (<it>Gasterosteus aculeatus</it>), a species using UV wavelengths in female and male mate choice as well as in shoaling behavior. In a choice experiment, female sticklebacks were simultaneously presented with four male visual appearances manipulated by optical filters. Each male lacked one wavelength range of the stickleback's visible spectrum corresponding to the spectral sensitivities of the four cone types. The resulting male appearances thus had no UV (UV-), no short-wave (SW-), no medium-wave (MW-) or no long-wave (LW-) body reflectance.</p> <p>Results</p> <p>Males without UV wavelengths and long wavelengths ("red") were least preferred. In contrast, the removal of medium and most notably short wavelengths left male attractiveness to females rather unaffected. Using color metrics, the effects of the four optical filters on stickleback perception of three male body regions were illustrated as quantal catches calculated for the four single cones.</p> <p>Conclusion</p> <p>The removal of UV light (UV-) considerably reduced visual attractiveness of courting males to female three-spined sticklebacks particularly in comparison to the removal of short-wave light (SW-). We thus report first experimental evidence that the UV wave band clearly outranks at least one other part of an animal's visible spectrum (SW-) in the context of communication. In addition, females were also less attracted to males presented without long wavelengths (LW-) which supports the traditionally considered strong influence of the red color component on stickleback mate choice. Overall, the removal of medium wavelengths (MW-) and especially short (SW-) left male attractiveness for females rather unaffected. Our work suggests that, in addition to long wavelengths ("red"), the UV wave band contains important information for visual mate choice in sticklebacks. Hence, the previously suggested exclusive role of the characteristic red nuptial coloration in visual interactions between reproductively active stickleback conspecifics may be overestimated with UV wavelengths playing a more important role than previously suggested.</p

Male mate choice scales female ornament allometry in a cichlid fish

<p>Abstract</p> <p>Background</p> <p>Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in <it>Pelvicachromis taeniatus</it>, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males.</p> <p>Results</p> <p>We show that allometry of the female pelvic fin is scaled more positively in comparison to other fins. The pelvic fin exhibits isometry, whereas the other fins (except the caudal fin) show negative allometry. The size of the pelvic fin might be exaggerated by male choice because males prefer female stimuli that show a larger extension of the trait. Female pelvic fin size is correlated with individual condition, suggesting that males can assess direct and indirect benefits.</p> <p>Conclusions</p> <p>The absence of positive ornament allometry might be a result of sexual selection constricted by natural selection: fins are related to locomotion and thus may be subject to viability selection. Our study provides evidence that male mate choice might scale the expression of a female sexual ornament, and therefore has implications for the understanding of the relationship of female sexual traits with body size in species with conventional sex-roles.</p

Slow fertilization of stickleback eggs: the result of sexual conflict?

BACKGROUND: The fertilization success in sperm competition in externally fertilizing fish depends on number and quality of sperm. The time delay between sequential ejaculations may further influence the outcome of sperm competition. Such a time interval can load the raffle over fertilization if fertilization takes place very fast. Short fertilization times are generally assumed for externally fertilizing fish such as the three-spined stickleback (Gasterosteus aculeatus). In this pair-spawning fish, territorial males often try to steal fertilizations in nests of neighbouring males. This sneaking behaviour causes sperm competition. Sneakers will only get a share of paternity when eggs are not fertilized immediately after sperm release. Contrary to males, females may be interested in multiple paternity of their clutch of eggs. There thus may be a sexual conflict over the speed of fertilization. RESULTS: In this study we used two different in vitro fertilization experiments to assess how fast eggs are fertilized in sticklebacks. We show that complete fertilization takes more than 5 min which is atypically long for externally fertilizing fishes. CONCLUSION: This result suggests that the time difference does not imply high costs to the second stickleback male to ejaculate. Slow fertilization (and concomitant prolonged longevity of sperm) may be the result of sexual conflict in which females aimed at complete fertilization and/or multiple paternity

No evidence for UV-based nest-site selection in sticklebacks

BACKGROUND: Nests are built in various animal taxa including fish. In systems with exclusive male parental care, the choice of a nest site may be an important component of male fitness. The nest site may influence male attractiveness as a mate, and male, embryo, and juvenile survival probabilities. Reproductively active three-spined stickleback males establish and defend a territory in which they build a nest. Territories can differ remarkably in qualities that influence male and female reproductive success like predation risk or abiotic factors such as dissolved oxygen concentration or lighting conditions. The latter may be important because in sticklebacks the extended visual capability into the ultraviolet (UV) wave range plays a role in female mate choice. Males are thus expected to be choosy about the habitat in which they will build their nest. RESULTS: We tested nest-site choice in male three-spined sticklebacks with respect to different UV lighting conditions. Reproductively active males were given the simultaneous choice to build their nest either in an UV-rich (UV+) or an UV-lacking (UV-) environment. Males exhibited no significant nest-site preferences with respect to UV+ or UV-. However, larger males and also heavier ones completed their nests earlier. CONCLUSION: We found that UV radiation as well as differences in luminance had no influence on nest-site choice in three-spined sticklebacks. Males that built in the UV-rich environment were not different in any trait (body traits and UV reflection traits) from males that built in the UV-poor environment. There was a significant effect of standard length and body mass on the time elapsed until nest completion in the UV experiment. The larger and heavier a male, the faster he completed his nest. In the brightness control experiment there was a significant effect only of body mass on the duration of nest completion. Whether nest building preferences with respect to UV lighting conditions are context dependent needs to be tested for instance by nest-site choice experiment under increased predation risk

A hybrid BAC physical map of potato: a framework for sequencing a heterozygous genome

<p>Abstract</p> <p>Background</p> <p>Potato is the world's third most important food crop, yet cultivar improvement and genomic research in general remain difficult because of the heterozygous and tetraploid nature of its genome. The development of physical map resources that can facilitate genomic analyses in potato has so far been very limited. Here we present the methods of construction and the general statistics of the first two genome-wide BAC physical maps of potato, which were made from the heterozygous diploid clone RH89-039-16 (RH).</p> <p>Results</p> <p>First, a gel electrophoresis-based physical map was made by AFLP fingerprinting of 64478 BAC clones, which were aligned into 4150 contigs with an estimated total length of 1361 Mb. Screening of BAC pools, followed by the KeyMaps <it>in silico </it>anchoring procedure, identified 1725 AFLP markers in the physical map, and 1252 BAC contigs were anchored the ultradense potato genetic map. A second, sequence-tag-based physical map was constructed from 65919 whole genome profiling (WGP) BAC fingerprints and these were aligned into 3601 BAC contigs spanning 1396 Mb. The 39733 BAC clones that overlap between both physical maps provided anchors to 1127 contigs in the WGP physical map, and reduced the number of contigs to around 2800 in each map separately. Both physical maps were 1.64 times longer than the 850 Mb potato genome. Genome heterozygosity and incomplete merging of BAC contigs are two factors that can explain this map inflation. The contig information of both physical maps was united in a single table that describes hybrid potato physical map.</p> <p>Conclusions</p> <p>The AFLP physical map has already been used by the Potato Genome Sequencing Consortium for sequencing 10% of the heterozygous genome of clone RH on a BAC-by-BAC basis. By layering a new WGP physical map on top of the AFLP physical map, a genetically anchored genome-wide framework of 322434 sequence tags has been created. This reference framework can be used for anchoring and ordering of genomic sequences of clone RH (and other potato genotypes), and opens the possibility to finish sequencing of the RH genome in a more efficient way via high throughput next generation approaches.</p

Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?-0

F males under the ultraviolet-blocking (UV-), short-wave-blocking (SW-), medium-wave-blocking (MW-) and long-wave-blocking (LW-) treatment filters during the 10 min test phase of the stimulus experiment. (B) Mean relative time ± SEM spent by eight females within the preference zones in front of empty tanks under the UV-, SW-, MW- and LW- treatment filters during the 10 min test phase of the control experiment.<p><b>Copyright information:</b></p><p>Taken from "Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?"</p><p>http://www.biomedcentral.com/1471-2148/8/189</p><p>BMC Evolutionary Biology 2008;8():189-189.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2453139.</p><p></p

Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?-1

A) the ventral spine of male sticklebacks. (B-B) Relative quantal catches calculated for the four stickleback cone classes (UV, S, M, L) affected by the reflectance of the experimental background and each male body region under fullspectrum illumination (Natural) and under the four treatment filters (UV-, SW-, MW-, LW-). Quantal catches are calculated relative to the excitation of the four cone types by the stimulus background under unfiltered light (C) Relative irradiance (log quantal flux) of the True Light tubes used in the experiment and visual modelling. Irradiance was measured with an Avantes AVS-USB2000 connected to an Avantes CC-UV/VIS cosine corrector located in the stimulus tank centre with filters removed. Irradiance calibration was performed versus an Avantes NIST traceable irradiance application standard.<p><b>Copyright information:</b></p><p>Taken from "Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?"</p><p>http://www.biomedcentral.com/1471-2148/8/189</p><p>BMC Evolutionary Biology 2008;8():189-189.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2453139.</p><p></p

Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?-2

F males under the ultraviolet-blocking (UV-), short-wave-blocking (SW-), medium-wave-blocking (MW-) and long-wave-blocking (LW-) treatment filters during the 10 min test phase of the stimulus experiment. (B) Mean relative time ± SEM spent by eight females within the preference zones in front of empty tanks under the UV-, SW-, MW- and LW- treatment filters during the 10 min test phase of the control experiment.<p><b>Copyright information:</b></p><p>Taken from "Color signaling in conspicuous red sticklebacks: do ultraviolet signals surpass others?"</p><p>http://www.biomedcentral.com/1471-2148/8/189</p><p>BMC Evolutionary Biology 2008;8():189-189.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2453139.</p><p></p