|Paternity and alopaternity in territorial fishes: behavioural and genetic studies|
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Reference no: PBICT/BIA/2055/95
Period: 1995 till 1998
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- University of the Azores; Department of Oceanography and Fisheries (DOP), more, co-ordinator
- University of Algarve; Faculty of Marine and Environmental Sciences; Centre of Marine Sciences (CCMAR), more
|In teleost fishes with parental care, paternal care is the dominant form. This sharply contrasts with birds and mammals. This mode of reproduction is present in many benthic species of the rocky shore. It is characterized by male territoriality, generaly centered in a rock cavity, where they receive and take care of eggs that are laid by females. In spite of the fact that this constitutes the basic reproduction system of these species, various intraspecific variations are known. This means that within a same population there are individuals acting in different ways, for instance parasiting the parental effort of territorial males. The evolution of parental care strategies in fishes and the evolutionary stability of different alternative strategies (or multiple adaptive solutions) led to various hypothesis that have inspired several experimental works of behavioural ecology. Since the reproductive success of a male is evaluated by the frequency with which his genes are represented in the genetic pool of the species, the paternity of the eggs he cares for constitutes a central factor of the system. Some studies revealed the occurrence of allopaternity in paternal males. Allopaternity appears not only associated with the "stealing" of fertilizations, made by subordinated males (sattelites and sneackers), but also through the addoption of clutchs of eggs from males with low quality territories. Both territoriality and the epigamic value of eggs guarded by a parental male seem to have determinant functions within these processes. The role of females, through male selection, is another key factor to be analysed. With the present project, we intend to study the following hypothesis: i) In Nature, females prefer to lay in nests that already have some eggs; ii) In the first spawnings of the year, females tend to lay fewer eggs than in those that follow; iii) When spawnings are laid in empty nests females lay less eggs than in nests that already have eggs; iv) Parental effort of males increases with the number of eggs in the nest; v) The percentage of survival of the eggs is positively correlated with the number of eggs guarded by the male; vi) The parental effort of the male is positively correlated with the degree of paternity of these eggs; vii) The percentage of paternity in relation to the embryos guarded by the parental male is higher in this male than for each one of the parasitic males; viii) The paternity percentage in relation to the embryos guarded by the parental male is higher is those species that make their nests in small shelters, than those nidifying in exposed surfaces or in multiple entrance shelters. This project is interdisciplinary and will associate experimental studies of behavioural ecology with a pilot study of molecular genetics. This part will involve the use of molecular DNA techniques, namely cloningg followed by microsatellite analysis by PCR (polimerasis chain reaction), with the goal of establishing parenthood (parental male/ embryos guarded) in several species of territorial fishes. A partial archive of the genoma of each species will be implemented.
Field: Life and Marine Sciences.