Associations between aggressive behavior and yeast amount in the food in male fruit fly Drosophila melanogaster

Agresija ir svarīgs evolūcijas virzītājspēks. Dzīvnieki, kuri būs spējīgāki uzvarēt konfliktus varēs ar lielāku varbūtību nodot savus gēnus nākošajām paaudzēm. Tomēr kādi faktori ietekmē dzīvnieka varbūtību uzvarēt nav līdz galam noskaidrots. Teorētiskie modeļi un esošie pētījumi sniedz tikai virspusēju skatījumu. Dzīvnieki savas dzīves laikā būs pakļauti dažādiem vides faktoriem ar variējošu pakāpi, tomēr, ne visi būs vienlīdz nozīmīgi agresīvas uzvedības mainībā. Uzturs dzīvniekiem mainās dzīves laikā un attīstības sākumā optimālā barības vielu attiecība būs svarīga indivīda nākotnes izdzīvošanā un ģenētiskajā fitnesā, jo fiziskais fenotips visam mūžam veidojas tieši individuālās attīstības laikā. Šajā pētījumā laboratoriski tika pārbaudīta olbaltumvielu avota - rauga, saistība ar augļu mušu Drosophila melanogaster tēviņu agresivitāti. Tika iegūti un salīdzināt dati par laiku līdz pirmajai uzbrukuma reizei, kopējo kontaktu skaitu un cīņā pavadīto laiku. Augļu mušām ar lielāku olbaltumvielu avota pieejamību visi trīs parametri norādīja uz augstāku agresivitāti. Kopējais cīņā pavadītais laiks un kontaktu skaits bija lielāks nekā kontroles grupai, kā arī pirmo uzbrukumu veica ātrāk. Izskaidrojums ir meklējams masas, enerģijas rezervju, resursu uztveres atšķirībā un agresīvās uzvedības teorijā.Aggression is an important driving force in evolution. Animals, which are more capable to win a conflict will have more opportunities to pass on their genes. However, factors that could affect animal’s probability of winning are not fully determined. Theoretical framework and existing research only give an insight. Animals in their lifetime will be exposed to many varying environmental factors, however, not all of them will have an equal effect on the variability of aggressive behaviour. The diet of animals will change throughout their lifetime and early life optimal nutrient ratio has an important effect on animals’ future survivability and genetic fitness. In this study relationship between protein source - yeast, and aggression was put to the test for fruit fly Drosophila melanogaster males. Data for the latency of the first encounter, total time spent fighting and number of encounters was obtained and compared. All three parameters indicated that the fruit flies with more available protein sources were more aggressive. Total number of encounters and time spent fighting was larger compared to the control group, as well as time up to the first encounter was shorter. The explanation is to be found in body mass, energy reserve, perception of the resources differences, as well as in the theory of aggressive behaviour

Development under predation risk increases serotonin-signaling, variability of turning behavior and survival in adult fruit flies Drosophila melanogaster

The development of high-throughput behavioral assays, where numerous individual animals can be analyzed in various experimental conditions, has facilitated the study of animal personality. Previous research showed that isogenic Drosophila melanogaster flies exhibit striking individual non-heritable locomotor handedness. The variability of this trait, i.e., the predictability of left-right turn biases, varies across genotypes and under the influence of neural activity in specific circuits. This suggests that the brain can dynamically regulate the extent of animal personality. It has been recently shown that predators can induce changes in prey phenotypes via lethal or non-lethal effects affecting the serotonergic signaling system. In this study, we tested whether fruit flies grown with predators exhibit higher variability/lower predictability in their turning behavior and higher survival than those grown with no predators in their environment. We confirmed these predictions and found that both effects were blocked when flies were fed an inhibitor (αMW) of serotonin synthesis. The results of this study demonstrate a negative association between the unpredictability of turning behavior of fruit flies and the hunting success of their predators. We also show that the neurotransmitter serotonin controls predator-induced changes in the turning variability of fruit flies, regulating the dynamic control of behavioral predictability