Browsing by Author "Miranda, Jason"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Male mating success in the Azorean rock-pool blenny: The effects of body size, male behaviour and nest characteristicsPublication . Oliveira, Rui Filipe; Miranda, Jason; Carvalho, Natacha; Gonçalves, Emanuel João; Grober, Matthew S.; Santos, Ricardo Serrãofemale visits, were courted more often by females and received more spawnings. Larger males also received a higher number of male intrusions, attacked more conspecifics and defended larger territories. Larger males showed more nest cleaning behaviour and a marginally non-significant trend for higher egg fanning rate. Male courtship, male attack rate against conspecifics and parental behaviour were all correlated with the frequency of female spawnings received by each male even when controlling for male size, suggesting that these behaviour patterns influence male mating success. On the other hand, a positive partial correlation was found between female courtship and the frequency of female spawnings, controlling for the number of female visits, which suggests a role for female mate choice on male mating success. Finally, males nesting in chambers in the bottom of pools received more spawnings than males nesting either in crevices or under boulders. However, nest opening area was associated significantly negatively with male mating success, when controlling for male size. Thus, the present data suggest strongly that male characteristics overrule nest characteristics in determining male mating success in the Azorean rock-pool blenny.
- Neurochemical correlates of male polymorphism and alternative reproductive tactics in the Azorean rock-pool blenny, Parablennius parvicornisPublication . Miranda, Jason; Oliveira, Rui Filipe; Carneiro, Luís Alberto; Santos, Ricardo Serrão; Grober, Matthew S.In the common Azorean rock-pool blenny, Parablennius parvicornis, males exhibit alternative reproductive morphologies: (1) larger males defend nest sites, provide parental care, have anal glands (involved in pheromone release), testicular glands, and low gonad:body weight ratio (GSI) and (2) smaller, younger, males do not defend nests, have reduced glands and high GSI. These smaller non-nesting males behave as satellites (associated with nests) or sneakers (moving among nests), attempting to achieve parasitic fertilizations via sperm competition. In non-mammals, arginine vasotocin (AVT) is a key hypothalamic peptide involved in the control of reproductive behavior and physiology, and several fish species that exhibit alternative male reproductive morphs show polymorphism in AVT brain chemistry. We conducted an immunocytochemical study to generate comparative data on this intertidal blenny. Our analysis showed no difference in AVT-immunoreactive cell number or size between the male morphs, which is consistent with studies on other fish, including blennies. The number of AVT cells was positively correlated to fish body mass, while cell size showed no such relation. If corrected for body mass, the smaller non-nesting males have significantly more cells than the large nesting males. Our data suggest that the size and number of forebrain AVT cells develops initially to allow for reproduction in the young non-nesting males and this pattern does not appear to change when males take on the nesting morphotype later in life. This result appears to be consistent in many fishes with alternative male morphotypes.
- The relationship between the presence of satellite males and nest-holders' mating success in the azorean rock-pool blenny Parablennius sanguinolentus parvicornisPublication . Oliveira, Rui Filipe; Carvalho, Natacha; Miranda, Jason; Gonçalves, Emanuel JoãoIn the Azorean rock-pool blenny, sexually active males may adopt alternative reproductive tactics. In the present paper the relationship between the presence of satellite males and the reproductive success of nest-holders was investigated by comparing nests with and without an associated satellite male. Males with an associated satellite male suffered more conspeci®c intrusions but they did not display a higher frequency of attacks towards conspeci®cs. Nest-holder males were more aggressive towards other conspeci®cs than towards satellites and the tolerance of nest-holders towards satellites was inversely correlated with the time spent by the satellites in the breeding territory, which suggests control by the nest- holder male of the satellite investment in shared territorial defence. Nest-holders with an associated satellite male had higher condition factors and received more female visits and more spawnings. These results bear two possible interpretations. (1) Nest-holders bene®t from the presence of a satellite male by increased attractiveness of their nests to females; satellite males are mutualists helping to defend the nest-owner's territory and to attract females, which is why they are tolerated. (2) Satellite males associate preferentially with more successful nest- holder males which have higher condition factors, and by doing so have more opportunities to achieve parasitic fertilizations. Only experiments will allow these two hypotheses to be distinguished.