| 1. |
- Andersson, Malte, 1941, et al.
(författare)
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Female sociality and kin discrimination in brood parasitism: unrelated females fight over egg laying
- 2015
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 26:3, s. 755-762
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Tidskriftsartikel (refereegranskat)abstract
- In conspecific brood parasitism, some females ("parasites") lay eggs in nests of other females of the same species ("hosts"). This reproductive tactic is particularly common in waterfowl, in which studies suggest that parasites are often related to the host. Here, we test the hypothesis that hosts may discriminate and reject unrelated parasites. Based on observations and >4100 h of digital video film, we analyze behavioral interactions at 65 nests of High Arctic common eiders during the laying sequence. We also estimate parasitism and host-parasite relatedness by albumen fingerprinting of 975 eggs from 232 nests. Among the video-filmed nests in which interactions were recorded during the egg-laying period, 11 had eggs from 2 females. At 8 of these 11 nests, there was overt female aggression and significantly lower host-parasite relatedness (mean coefficient of relationship r = -0.40) than in the nests with tolerant or no interactions (r = 0.91). The results demonstrate active female kin discrimination in common eiders, used against nonrelatives that try to lay eggs in the nest. Other females trying to access the nest were often prevented from doing so: in 65% of 34 such attempts, the sitting female rejected the intruder. Brood "parasitism" in eiders and other waterfowl is complex, ranging from violent female conflict and parasitic exploitation of the host's parental care to nest takeover and potential kin selection favoring acceptance of related parasites. These and other aspects of female sociality in eiders are discussed; in some respects, they may resemble certain long-lived matriarchal mammals.
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| 2. |
- Arlt, Debora, et al.
(författare)
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Proximate causes of avian protandry differ between subspecies with contrasting migration challenges
- 2016
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 27, s. 321-331
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Tidskriftsartikel (refereegranskat)abstract
- In many migratory birds, males precede females during migration and arrival at the breeding sites. Three proximate mechanisms are proposed to explain this phenomenon of protandry: males 1) winter closer to breeding sites, 2) start spring migration earlier, and/or 3) migrate faster than females. So far, the relative contribution of these mechanisms to protandry is unknown. The present study investigated the importance of each of the 3 proximate mechanisms of protandry for a songbird migrant wintering in Africa, the northern wheatear (Oenanthe oenanthe). Two subspecies co-occur in Europe on migration, of which the leucorhoa northern wheatears breeding from Iceland to Canada have to cross the North Atlantic, whereas the nominate form breeding in Europe does not face any significant sea barrier. We show that the leucorhoa subspecies had a significantly higher degree of protandry at stopover sites across Europe than the oenanthe subspecies (-6 vs. -2 days). Leucorhoa northern wheatear's higher degree of protandry was associated with a larger age effect, in which old males preceded young males, and greater sex-specific differences in wing shape and refueling yielding higher migration speeds in males than females. In oenanthe northern wheatears, light-level geolocators revealed that males did not winter closer to the breeding sites or migrate faster than females, but initiated spring migration earlier. Our results demonstrate that the significance of the mechanisms causing protandry can differ between related taxa and highlight the importance of the advancement in male arrival date with age as a potential factor shaping the degree of protandry.
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| 3. |
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| 4. |
- Berglund, Anders, et al.
(författare)
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Baltic pipefish females need twice as many males as they get
- 2017
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 28:3, s. 827-832
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Tidskriftsartikel (refereegranskat)abstract
- Sex role reversal in 2 pipefish species, Syngnathus typhle and Nerophis ophidion, is potentially explained by females reproducing twice as fast as males. Moreover, in oceanic populations from the Swedish west coast, females compete for males with males pre- ferring to mate with larger females. However, in a brackish Baltic population of S. typhle, males do not prefer larger mates, whereas choosiness remains in the local N. ophidion population. We explore whether this absence of male choice in brackish S. typhle can be explained by males and females having more similar potential reproductive rates here, whereas the sex difference may remain in the local N. ophidion population. Contrary to our expectations, in both species, females out-reproduced males by a factor of more than 2, just as in the oceanic populations. We measured this experimentally as the number of males a female potentially could fill with eggs within the time span of 1 male pregnancy, in relation to males available in nature. Thus, we conclude that sexual selection on females is as strong in brackish as in oceanic populations of both species but that targets of selection via male choice are shifted to traits other than body size in S. typhle. Hence, costs and benefits of choice are probably more important than potential reproductive rates to understand mate choice. We suggest that it may be misleading to use targets of sexual selection, such as choice for large body size, as an indicator of the strength of sexual selection.
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| 5. |
- Bergman, Martin, et al.
(författare)
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Mate detection in a territorial butterfly-the effect of background and luminance contrast
- 2015
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 26:3, s. 851-860
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Tidskriftsartikel (refereegranskat)abstract
- Many animals search for potential mates or prey using a perch-and-sally strategy. The success of such a strategy will depend on factors that affect the observer's ability to detect a passing resource item. Intrinsic factors (e.g., eye structure and physiology) have received much recent attention, but less is known about effects on object detection in nature and extrinsic factors such as size, coloration, and speed of a passing object and the background against which the object is viewed. Here, we examine how background affects the detection of butterfly models by perched males of the butterfly Asterocampa leilia in the field. We test the hypothesis that male choice of perch site in nature will influence the contrast between the object and background against which it is viewed and that this will influence success in detecting the object. We also test the effect of contrast by manipulating the brightness of the object and presenting butterfly models of different reflectance (ranging from black to white). We found an effect of model luminance, with dark models being most likely to elicit a response regardless of background. Further, there was an effect of background type with models viewed against blue sky eliciting the highest response. Perceived luminance contrast correlates to behavior; highly contrasting objects are more frequently detected. This study expands our understanding of visual system performance and has implications for our understanding of the behavior and evolutionary ecology of perching species.
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| 6. |
- Cerritelli, Giulia, et al.
(författare)
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Assessing reliance on vector navigation in the long-distance oceanic migrations of green sea turtles
- 2019
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 30:1, s. 68-79
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Tidskriftsartikel (refereegranskat)abstract
- Vector navigation, i.e., maintaining a constant heading for a given amount of time, is hypothesized to provide a viable basis for the navigational feats of a number of long-distance animal migrants. Since animals following this strategy are subject to drift by wind or by ocean current, performing long migrations relying on vector navigation is particularly challenging. We tested whether vector navigation could be involved in the migrations of green turtles (Chelonia mydas) that migrate between the remote Ascension Island and Brazil. To this aim, a novel approach was followed using individual-based numerical models to simulate migratory trajectories of virtual turtles that were compared to actual routes reconstructed by satellite. Simulated postnesting migrations from Ascension revealed that weak currents enabled modeled turtles to reach the Brazilian coast, but only for a limited range of headings around due West. This conclusion was corroborated by comparing modeled trajectories with the actual routes of previously tracked turtles, with a beeline vector navigation strategy providing the best fit, although a true-navigation strategy directed to the landfall site produced similar results. Finally, we tested if a vector navigational strategy was feasible for the prebreeding migration from Brazil towards Ascension, but modeled routes mostly failed to reach the island or a larger area around it, with individuals drifting away under the influence of currents. We conclude that Ascension turtles can take advantage of vector navigation when migrating towards a wide target like the Brazilian coast, while the demanding prebreeding migration likely requires more complex navigational systems.
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| 7. |
- Favati, Anna, 1980-, et al.
(författare)
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Individual aggression, but not winner–loser effects, predicts social rank in male domestic fowl
- 2017
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 28:3, s. 874-882
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Tidskriftsartikel (refereegranskat)abstract
- Many factors can affect the probability for an individual to obtain a high social rank, including size, weaponry, and behavioral attributes such as aggression. Recent experiences of winning or losing can also affect the chances of winning future contests, commonly referred to as “winner–loser effects”. Individuals often differ in behavior in a consistent way, including in aggression, thereby showing differences in personality. However, the relative importance of recent experience and aspects of personality in determining rank, as well as the extent to which winning or losing affects aggression, has rarely been studied. Here, we investigate these questions using male domestic fowl. We matched males for body size, comb size, and aggression in pair-wise duels to: 1) study the effect of contest outcome on aggression and 2) compare the effect of individual aggression and contest experience on future social status in small groups. We found that aggression was a highly repeatable personality trait and that aggression increased after winning and decreased after losing. Nevertheless, such winner–loser effects were not enough to increase the odds of becoming dominant in a small group. Instead, aggressiveness measured prior to a contest experience best predicted future rank. Boldness and exploration did not predict rank and of the 2, only boldness was positively correlated with aggressiveness. We conclude that for male domestic fowl in contests among phenotypically matched contestants, aggressiveness is more important for obtaining high rank than winner–loser effects, or other aspects of personality.
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| 8. |
- Favati, Anna, et al.
(författare)
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Personality remains : no effect of 3-week social status experience on personality in male fowl
- 2018
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 29:2, s. 312-320
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Tidskriftsartikel (refereegranskat)abstract
- Behavioral responses of male fowl did not depend on social rank after 3 weeks in stable groups, but were consistent over time for an individual. Theory suggests that stable social states, for example, stable social hierarchies, may lead to consistent variation in behavior, that is, variation in personality. Our results suggest that variation in personality is not a consequence of variation in social status and that personality is more important than current social position in determining individual behavior in stable groups.Individuals often differ in behavior in a consistent way, that is, they show variation in personality. Understanding the processes explaining the emergence and maintenance of this variation is a current major topic in the field of animal behavioral research. Recent theoretical models predict that differences in various states can generate individual variation in behavior. Previous studies have mainly focused on endogenous states like metabolic rate or energy reserves, but theory also suggests that states based on social interactions could play important roles in shaping personality. We have earlier demonstrated short-term status-dependent variation in behavior in the domestic fowl (Gallus gallus domesticus), but whether such behavioral variation remains also after a longer period of time, is unknown. Therefore, we examine the influence of social status on variation in behavior, using experimental manipulation of social status in pairs of male domestic fowl. We scored males in 3 personality assays (novel arena test, novel object test, and aggression test) before and after 3 weeks in pairs as either dominant or subordinate. We observed individual consistency of behavior despite alteration of social status. We further found no support for social status acting as a state that generates variation in personality over the used time interval: social status had no significant effect on the change in behavioral responses between repeated personality tests. Our results suggest that personality is more important than current social situation for describing individual behavior in stable groups.
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| 9. |
- Favati, Anna, et al.
(författare)
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The ontogeny of personality traits in the redjunglefowl, Gallus gallus
- 2016
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Ingår i: Behavioral Ecology. - : Oxford University Press. - 1045-2249 .- 1465-7279. ; 27:2, s. 484-493
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Tidskriftsartikel (refereegranskat)abstract
- Consistent behavioral differences among individuals, that is, personality, are described in numerous species. Nevertheless, thedevelopment of behavioral consistency over ontogeny remains unclear, including whether the personality of individuals is consistentthroughout life, and if adult personality can be predicted already at young age. We investigated the ontogeny of personality in thered junglefowl (Gallus gallus) by scoring personality of hatchlings at 5 time points through adulthood, including before and after themajor developmental stages of becoming independent and sexual mature. We use the conceptual framework laid out by Stamps andGroothuis (2010a) to holistically investigate the observed changes in behavioral response over ontogeny. We demonstrate that meanvalues of behavioral responses changed across ontogeny and stabilized after independence. Rank-order consistencies of behavioralresponses were overall low across independence and sexual maturation. Only in 1 case could low rank-order consistencies potentiallybe explained by different phenotypes displaying different amounts of change in behavior; more explorative individuals decreased inexploration after independence, while less explorative individuals remained so. Correlations among behavior varied across ontogenyand weakened after sexual maturation. Our results demonstrate that both absolute values and consistency of behavioral traits maychange across ontogeny and that individual developmental trajectories and adult personality only to some extent can be predictedearly in life. These results have implications for future studies on personality, highlighting that the life stage at which individuals arescored affects the observed consistency of behavioral responses.
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| 10. |
- Friesen, C. R., et al.
(författare)
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The relationship of body condition, superoxide dismutase, and superoxide with sperm performance
- 2019
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 30:5, s. 1351-1363
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Tidskriftsartikel (refereegranskat)abstract
- Sperm competition theory predicts a negative correlation between somatic investment and traits that aid in pre- and postcopulatory sexual selection. Sperm performance is critical for postcopulatory success but sperm are susceptible to damage by free radicals such as superoxide radicals generated during mitochondrial respiration (mtSOx). Males can ameliorate damage to spermatozoa by investing in the production of antioxidants, like superoxide dismutase (SOD), which may act as a mechanistic link to pre- and postcopulatory trade-offs. Some male Australian, color-polymorphic painted dragon lizards (Ctenophorus pictus) possess a yellow throat patch (bib) that females prefer over nonbibbed males and are also more likely to win male-male contests indicating that males with bibs may be better at monopolizing females. We tested whether the sperm performance in nonbibbed males was superior to that of bibbed males. We show that overall sperm performance was not different between the bib-morphs, however, higher mtSOx levels were negatively correlated with sperm performance in bibbed males, but not of nonbibbed males. Blood cell mtSOx levels are negatively correlated with SOD activity in the plasma in all males early in the breeding season but SOD was lower in bibbed males. Nonbibbed males maintain a positive correlation between body condition and SOD activity over time while bibbed males do not. Together, these data suggest physiological associations between body condition, SOD activity, and sperm performance are linked to the expression of a yellow gular patch, which may be related to intrinsic differences in the metabolism of bibbed versus nonbibbed males.
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