Biology subjects

Gurka, R.

Publications and source records attributed to Gurka, R..

3 recordsLinked to original sources

bioRxiv2021

Males perceive honest information from female released sex pheromone in a moth

There is accumulating evidence that male insects advertise their quality to conspecific females through pheromones. However, most studies of female released sex pheromone assume information transfer regarding merely the species of the female and her mating status. We show that more and precise information is conveyed through the female sex pheromone, positioning it as an honest sexual trait. We demonstrate that females in bad physical conditions (small, starved or old) lay significantly fewer eggs than females in good conditions (large, fed or young). The ratio of the sex pheromone blend in gland extracts of female pink bollworm moths accurately describes the female phenotypic condition whereas the pheromone amount in the glands fails to provide an honest signal of quality. Moreover, males use the female released pheromone blend to choose their mates and approach females that signal higher reproductive potential. In addition, surrogating the female effect, using synthetic pheromone blend that represents that of higher quality females (0.6:0.4 ZZ:ZE) more males were attracted to this blend than to the blend representing the population mean (0.5:0.5 ZZ:ZE). Both, female advertisement for males and the male choosiness, suggest that pheromones have evolved as sexual traits under directional, sexual selection.

evolutionary biology↗

bioRxiv2019

Hydrodynamic regime drives flow reversals in suction feeding larval fishes during early ontogeny

Fish larvae are the smallest self-sustaining vertebrates. As such, they face multiple challenge that stem from their minute size, and from the hydrodynamic regime in which they dwell. This regime of intermediate Reynolds numbers (Re) was shown to affect the swimming of larval fish and impede their ability to capture prey. Numerical simulations indicate that the flow fields external to the mouth in younger larvae result in shallower spatial gradients, limiting the force exerted on the prey. However, observations on feeding larvae suggest that failures in prey capture can also occur during prey transport, although the mechanism causing these failures is unclear. We combine high-speed videography and numerical simulations to investigate the hydrodynamic mechanisms that impede prey transport in larval fishes. Detailed kinematics of the expanding mouth during prey capture by larval Sparus aurata were used to parameterize age-specific numerical models of the flows inside the mouth. These models reveal that, for small larvae that slowly expand their mouth, not all the fluid that enters the mouth cavity is expelled through the gills, resulting in flow reversal at the mouth orifice. This efflux at the mouth orifice was highest in the younger ages, but was also high (>8%) in slow strikes produced by larger fish. Our modeling explains the observations of \"in-and-out\" events in larval fish, where prey enters the mouth but is not swallowed. It further highlights the importance of prey transport as an integral part in determining suction feeding success.

zoology↗

bioRxiv2019

Open source computational simulation for a moth-inspired navigation algorithm

Olfactory navigation in insects, for instance when males search for mates, is a navigational problem of a self-propelled agent with limited sensor capabilities in a scalar field (odor) convected and diffused by turbulent wind. There are numerous navigation strategies proposed to explain the navigation paths of insects to food (flowers) or mating partners (females). In a search for a mate, the males use airborne pheromone puffs in turbulent environments around trees and vegetation. It is difficult to compare the various strategies because of a lack of a single simulation framework that can change a single parameter in time and test all the strategies against a controlled environment. This work aims at closing this gap, suggesting an open source, freely accessible simulation framework, abbreviated MothPy. We implement the simulation framework using another open source package (\"pompy\") that recreates a state-of-the-art puff-based odor plume model of Farrell et al. [1]. We add four different navigation strategies to the simulation framework based on and extending the previously published models [2, 3], and compare their performance with different wind and odor spread parameters. We test a sensitivity analysis of the navigation strategies to the plume meandering and to increased turbulence levels that are effectively expressed as the elevated puff spread rates. The simulations are compared statistically and provide an interesting view on the robustness and effectiveness of various strategies. This benchmarking-ready simulation framework could be useful for the biology-oriented, as well as engineering-oriented studies, assisting to deduce the evolutionary efficient strategies and improving self-propelled autonomous systems in complex environments.

animal behavior and cognition↗