Biology subjects

Lefevre, B. M.

Publications and source records attributed to Lefevre, B. M..

3 recordsLinked to original sources

bioRxiv2022

A novel mechanism for left-right asymmetry establishment involving tissue remodeling and MyoID

Left-right asymmetries have repeatedly evolved in diverse animals and affect the position, shape or size of specific organs. How novel left-right asymmetries arise remains unknown. Here, we examined Drosophila pachea, where males have evolved unique asymmetric genitalia lobes and a right-sided copulation posture in the past 3-6 million years. We found that male asymmetric lobes grow in pupae during a 360{degrees} clockwise genitalia rotation, a conserved and widespread developmental process in flies. Using two complementary approaches, drug application and a CRISPR-induced MyoID mutant, we altered genitalia rotation and found that asymmetric lobe sizes depend on genitalia rotation completion, while the sidedness of lobe asymmetry is determined by the rotation direction. We then investigated the impact of genital asymmetry on copulation posture. Males with reversed genital asymmetry still mate in the typical right-sided posture, indicating that right-sided behavior is not determined by asymmetric male genitalia. Our study reveals that a novel genitalia asymmetry has evolved through the co-option of a pre-existing tissue remodeling process. Tissue rotation represents a new mechanism, through which a bilateral organ can acquire a left-right size asymmetry. Summary statementHow asymmetric shapes evolve from symmetry is an important question in developmental biology. Using a juvenile hormone derivative, transgenics and CRISPR mutants in the non model species Drosophila pachea, we uncover that the developmental process of male genitalia rotation got co-opted during evolution of D. pachea to determine the extent and direction of a novel genital left-right asymmetry.

evolutionary biology↗

bioRxiv2021

Developmental timing of Drosophila pachea pupae is robust to temperature changes

Rearing temperature is correlated with the timing and speed of development in a wide range of poikiloterm animals that do not regulate their body temperature. However, exceptions exist, especially in species that live in environments with high temperature extremes or oscillations. Drosophila pachea is endemic to the Sonoran desert in Mexico, in which temperatures and temperature variations are extreme. We wondered if the developmental timing in D. pachea may be sensitive to differing rearing temperatures or if it remains constant. We determined the overall timing of the Drosophila pachea life-cycle at different temperatures. The duration of pupal development was similar at 25{degrees}C, 29{degrees}C and 32{degrees}C, although the relative progress differed at particular stages. Thus, D. pachea may have evolved mechanisms to buffer temperature effects on developmental speed, potentially to ensure proper development and individuals fitness in desert climate conditions.

developmental biology↗

bioRxiv2019

A primary sexual trait involved in courtship in insects: Male genital lobe morphology affects the chance to copulate in Drosophila pachea

IntroductionMale genitalia are thought to ensure transfer of sperm through direct physical contact with female during copulation. However, little attention has been given to their pre-copulatory role with respect to sexual selection and sexual conflict. Males of the fruitfly Drosophila pachea have a pair of asymmetric external genital lobes, which are primary sexual structures and stabilize the copulatory complex of female and male genitalia. We wondered if genital lobes in D. pachea may have a role before or at the onset of copulation, before genitalia contacts are made. ResultsWe tested this hypothesis with a D. pachea stock where males have variable lobe lengths. In 92 mate competition trials with a single female and two males, females preferentially engaged into a first copulation with males that had a longer left lobe and that displayed increased courtship vigor. In 53 additional trials with both males having partially amputated left lobes of different lengths, we observed a weaker and non-significant effect of left lobe length on copulation success. Courtship durations significantly increased with female age and when two males courted the female simultaneously, compared to trials with only one courting male. In addition, lobe length did not affect sperm transfer once copulation was established. ConclusionLeft lobe length affects the chance of a male to engage into copulation. The morphology of this primary sexual trait may affect reproductive success by mediating courtship signals or by facilitating the establishment of genital contacts at the onset of copulation.

evolutionary biology↗