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Evolution and Ecology of Fish Reproduction


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Multiple male traits and female choice.
In most species, females base their mate choice on sets of male secondary sexual traits, rather than on single cues. Male secondary sexual characters are usually considered as signals conveying information about the phenotypic and genetic quality of the signaller to females. However, the relationship between the degree of male ornamentation and female benefits is not necessarily always straightforward and attractiveness may be traded-off against different male traits such as male fertility, parental care, or immune function, all of which can have profound effects on female fitness. Our current ongoing projects on this issue regards:

  1. the expression of  multiple pre-copulatory sexual traits and male mating success in the peacock blenny Salaria pavo,
  2. the expression of multiple pre-copulatory sexual traits and male quality (in terms of fertility, immune response and parental care) in the peacock blenny and in the guppy, Poecilia reticulata (checking male fertility and immune response), in collaboration with Andrea Pilastro


Antimicrobial production and male parental care.
The embryonic and larval/juvenile stages of development are critical periods in fish life cycle because of the high mortality caused by predators and microbial infections. Whilst the morphological and behavioural traits which have been selected to reduce the effects of egg predation are rather well known, information on the anti-microbial defence mechanisms are limited. In fact, notwithstanding the fact that substances involved in the innate immune response have been isolated in different animal taxa, only preliminary and ill-defined indications on the existence of anti-microbial agents acting in the protection of fish eggs are available. Using male gobies and blennies as models, we are carrying on projects on:

  1. the efficacy of male antimicrobials in enhancing hatching success,
  2. activity spectrum of male antimicrobials (with Laura Marri and Daniela Marchini, University of Siena),
  3. intra-specific variability in antimicrobial production and female choice.

Eva Giacomello first started the study on antimicrobials in blenny males as a part of her PhD research. She is actually a post-doc at the University of Azores but we still consider her a full member of the “antimicrobial team”.


Fertilization dynamics and the influence of sperm competition in gobies.
Gobiids are bentonic fishes showing external fertilization and male parental care. They release sperm in the form of mucous trails, spawned both before and during egg deposition by females. Such trails dissolve gradually in water, releasing for hours active sperm. Mucins present in sperm trails are secreted by male accessory organs, the sperm duct glands. Species where alternative male reproductive tactics (nesting males and sneaker males) occur show a significant variety in investment in primary and secondary sexual characters. We are interested in study how this variety entails functional polymorphism in ejaculates (in terms of sperm number and quality and mucin content).


Nest choice and egg characteristics in demersal spawners.
To maximize their reproductive success, demersal spawners are expected to exert an accurate choice of breeding sites, given that factors, such as fluctuating temperature, oxygen availability, desiccation risk, and predator abundance, influence egg development and survival. Such factors constitute also selective pressures on egg characteristics like size, shape, chorion structure, and yolk content. This research is aimed to understand how breeding habitats influence nest choice and egg adaptations in demersal spawners in which males perform parental care. Using blennies and gobies as models, we intend to compare species breeding in different habitats (subtidal vs intertidal, sandy vs muddy bottom) with respect to nest selectivity and egg characteristics.