Phenotypic senescence and multilevel variation in different body sizes in a natural insect population
Pásztor, Kata; Kőrösi, Ádám; Gór, Ádám; Kis, János (2022), Phenotypic senescence and multilevel variation in different body sizes in a natural insect population, Dryad, Dataset, https://doi.org/10.5061/dryad.jq2bvq8bp
Senescence seems to be universal in living organisms and plays a major role in life-history strategies. Phenotypic senescence, decline of body condition and/or performance with age, is a largely understudied component of senescence in natural insect populations, although it would be important to understand how and why insects age under natural conditions.
We aimed a) to investigate how body mass and thorax width change with age in a natural population of the univoltine Clouded Apollo butterfly (Parnassius mnemosyne, Lepidoptera: Papilionidae) and b) to assess the distribution of body mass, thorax width, wing and proboscis length in the population within and between the flight periods.
We studied a population between 2014–2020 using mark-recapture during the whole flight period each year. Repeated measurements on body mass and thorax width and single measurements on wing and proboscis length were performed on marked individuals. We analysed body mass and thorax width change with age (days since marking) and initial body mass, thorax width, wing and proboscis length with time since the first day of the flight period.
Both body mass and thorax width declined significantly with age in all years. The rate of change was significantly different for sexes only in 2016 for body mass. Individuals appearing earlier in the season had significantly higher initial body mass and thorax width than those appeared later in almost every year. In 2015, 2016 and 2019, earlier individuals had longer proboscides, while wing length showed significant trend only in 2019. Initial body mass varied little among years, in contrast, initial thorax width showed high annual variation. In all years, the latter two were higher for females. Moderate annual variation and no sexual difference were found in wing and proboscis length.
Variation in body sizes can be highly influenced by the experienced environment which continuously changes because of global climate crisis; hence further long-term studies are necessary to unravel the drivers of phenotypic senescence in wild insect populations. As far as we know, this is the first study that detected phenotypic senescence in a wild butterfly population, using in situ measurements.