| 1. |
- Lissaker, Maria, et al.
(författare)
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Cannibalize or care? The role of perceived paternity in the sand goby, Pomatoschistus minutus
- 2008
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 62, s. 1467-1475
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Tidskriftsartikel (refereegranskat)abstract
- Parental care is a costly part of reproduction. Hence, natural selection should favor males which avoid caring for unrelated young. However, the decision to abandon or reduce care requires cues which are evaluated to give information on potential reproductive value of the offspring. The prediction that male sand gobies, Pomatoschistus minutus, care for foreign eggs as long as they were spawned in their own nest and at least some of such cues are fulfilled was tested. Egg-guarding males that had recently taken part in a spawning event were given a clutch of eggs that was sired either by themselves or another male, in either their own or another male's aquarium. Males that had not taken part in a spawning event were used as controls and were given eggs sired by another male. We measured the amount of filial cannibalism and nest building. Control group males did not care for eggs and ate them all before rebuilding the nest. In the other treatments, there were no significant effects of paternity, though males moved to another male's aquarium increased their clutch area threshold and completely consumed larger clutches than males that were not moved. There was no intermediate response in any treatment in the form of increased partial filial cannibalism or less well-constructed nests. Our results suggest that egg-guarding males cannot distinguish between eggs sired by themselves and those sired by other males but are able to react to cues indicating paternity state. Males do not adopt eggs to attract females in P. minutus.
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| 2. |
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| 3. |
- Nyman, A., et al.
(författare)
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The capacity for additional matings does not affect male mating competition in the sand goby
- 2006
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 71, s. 865-870
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Tidskriftsartikel (refereegranskat)abstract
- Models of sexual selection predict that mating competition within a population will increase with a biased operational sex ratio (OSR). However, these models do not consider any influence of the individuals' capacity for additional matings. Using the sand goby, Pomatoschistus minutus, we tested whether intensity of mating competition (measured as the fraction of time spent displaying) is influenced by a male's imminent capacity for additional matings (nest capacity, i.e. additional space available for egg laying in the nest). We manipulated nest size and number of females (zero to three) allowed to spawn in each male's nest, and then used display rate to estimate the male's intensity of mating competition. The nests were never filled completely, but always had room for eggs from at least one more mating. We found no significant difference in display rate between males with large or small nests, whether nest size was measured as nest capacity or area already covered by eggs. In fact, males with many eggs in their nests displayed as much as males with empty nests. However, male display decreased significantly with time. As male display behaviour was not influenced by whether the nest was empty or was partially filled, the number of males and females ready to mate (i.e. the OSR) provides a good estimate of the intensity of male mating competition. Nevertheless, many other species may adjust mating competition to their capacity for additional matings, which may thus influence the accuracy of OSR-based estimates of mating competition and sexual selection. (c) 2006 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.
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| 4. |
- Olsson, Karin H., 1979, et al.
(författare)
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Relative costs of courtship behaviours in nest-building sand gobies
- 2009
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 77, s. 541-546
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Tidskriftsartikel (refereegranskat)abstract
- Courting males often use multiple signals to advertise their quality to females. Assuming that courtship traits are energetically costly, one would expect a limit to the overall courtship effort of an individual and that a high courtship effort takes its toll on individual condition. We tested this experimentally using a small marine fish, the sand goby, Pomatoschistus minutus, whose males attract females through courtship displays and well-built nests (mussel shells covered with sand). At the end of a 5-day period of supplemental food, or repeatedly induced courtship or construction of nests (or none of these, as a control), we tested whether male display intensity, nest quality (nest cover and nest opening size) and body condition were affected. Males provided with food in excess were in significantly better condition and had significantly higher nest quality than control males. Display rate, however, was not significantly affected by feeding regime. Fish that had been manipulated to perform increased courtship or nest building did not suffer in terms of reduced condition, display rate or nest quality. However, individual fish that displayed intensely after treatment also built better-covered nests. Both of these traits are important in female choice. Moreover, fish that displayed intensely before the treatment continued to do so after treatment, a result that is compatible with signalling of genetic or phenotypic quality. Our results suggest that (1) nest cover is an honest signal of male condition, although we found no cost of nest building per se and (2) courtship display does not signal male condition.
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| 5. |
- Singer, A., et al.
(författare)
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Genetic mating patterns studied in pools with manipulated nest site availability in two populations of Pomatoschistus minutus
- 2006
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 19:5, s. 1641-1650
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Tidskriftsartikel (refereegranskat)abstract
- Pomatoschistus minutus show paternal care in a resource defence mating system. We investigated the effect of nest-site availability on parasitic spawning. Each experimental pool contained four potentially nest-building males, four females and nests-sites in shortage (2) or excess (6). Both treatments were conducted in two populations; one with natural nest-sites in excess, one with a nest-site shortage. Microsatellite-DNA revealed that all nest-holders had fertilized most of the eggs they tended. Yet, 35% of the nests contained eggs fertilized by another male and 14.4% of the males had performed parasitic spawning. There was no site or treatment effect. Several females spawned in two nests, which coincided with parasitic spawnings, suggesting a cost to the nest-holder in terms of lost mating success. Nest-holders with and without eggs and non-nesting males all spawned parasitically, generating a significantly lower opportunity for sexual selection compared to if there had been no parasitic spawning.
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| 6. |
- Svensson, Ola, 1971
(författare)
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Freshwater Fishes of México
- 2008
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Ingår i: Ciklidbladet. ; 4
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Recension (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Svensson, Ola, 1971, et al.
(författare)
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Parasitic spawning in sand gobies: an experimental assessment of nest-opening size, sneaker male cues, paternity, and filial cannibalism
- 2007
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 18, s. 410-419
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Tidskriftsartikel (refereegranskat)abstract
- Sneaking is common in nest-building fish with paternal care, but the role of nest-opening size in protecting against entry by sneaker males has never been tested before. Using the sand goby (Pomatoschistus minutus), a fish with exclusive paternal care, experimental manipulations of nest openings provided no support for the hypothesis that nest openings serve as physical or visual defense or that sneaker males prefer to parasitize nests with wide openings. Female mating preference was also not influenced by nest-opening size. However, female courtship behavior and visibility were important cues for sneaker males. Most sneak entries occurred when the nest holder was occupied with courtship, chasing another sneaker male or nest building. In half the cases of observed sneak entry, the sneaker male fertilized eggs, also when sneaking only occurred before spawning. Sneak entry and its duration were good estimates of stolen paternity, but neither sneak entries nor degree of fertilizations were correlated with filial cannibalistic behavior. Testes size did not explain parasitic spawning success in replicates with genetically determined sneaking. However, all sneaker males without breeding coloration had huge testes and small sperm duct glands, whereas nest-holding males had small testes and large sperm duct glands, and sneaker males with breeding coloration were intermediate.
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| 8. |
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| 9. |
- Svensson, Ola, 1971, et al.
(författare)
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The importance of sperm competition risk and nest appearance for male behaviour and female choice in Pomatoschistus minutus.
- 2005
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 16:6, s. 1042-1048
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Tidskriftsartikel (refereegranskat)abstract
- To test if an increased sperm competition risk affects male behavior and mating decisions of both sexes, we performed two experiments using the sand goby, Pomatoschistus minutus, a nest-building fish with exclusive paternal care. In our first experiment, a nest-holding male, with a confined female, was sequentially exposed to a vial with a sneaker male or an empty vial. While male courtship, nest building, displacement fanning, and time outside the nest were unaffected, individual males showed a higher mucus preparation effort inside the nest in the presence of a sneaker male than when alone. We found such mucus to contain sperm, thus clearly suggesting an importance in sperm competition. In our second experiment, a female was free to spawn with two different males, one of which was exposed to a confined sneaker male. Male mating success was not affected by the presence of a sneaker male. However, the volume of sand the male had put on his nest was positively associated with female spawning decision, while nest-opening width was not. In a partial correlation of five traits thought to attract females (nest-opening width, sand volume, male courtship display, displacement fanning, and male size), males that fanned well were found to also build large nests or display intensely, but not both. This indicates that rather than being jacks-of-all-trades, individual males focus on a subset of traits for attracting females.
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