Sex specificity of dispersal behaviour and flight morphology varies among tree hollow beetle species

Abstract

Background Flight performance and dispersal behaviour can differ between sexes, resulting in sex-biased dispersal. The primary sex ratio of populations may also explain dispersal bias between sexes, as this bias may evolve with the primary sex ratio to reduce intrasexual competition. Although dispersal bias between sexes is relevant to population dynamics, there are few studies on sex-biased dispersal in insects. We studied the flight performance and dispersal behaviour of seven saproxylic beetle species associated with tree hollows from a sex perspective. We also analysed the possible coevolution of flight performance with the primary sex ratio. Methods Wing loading and wing aspect ratio were used as measures of the flight performance of species and sexes. Dispersal behaviour was explored by analysing the frequency of each sex in interception traps versus the primary sex ratio obtained by tree hollow emergence traps using contingency tables and posthoc standardized residuals. A more active flight behaviour was expected for the sex with higher capture frequency in the interception traps. To explore the causes of flight performance bias between sexes, we searched for possible correlations between wing loading or wing aspect ratio and primary sex ratio using Pearson’s correlation coefficient. Results Wing loading and wing aspect ratio differed between species and sexes, with flight performance being higher in males than in females for four of the seven species analysed. Dispersal behaviour and flight performance matched in the case of Elater ferrugineus; males showed higher flight performance and were the most collected sex in the interception traps (more active flyers). In contrast, the higher flight activity of Cetonia carthami aurataeformis females was not correlated with a higher flight performance than that of males. Moreover, we found that a bias in the primary sex ratio towards females is often correlated with a decrease in female flight performance. Conclusions We stress that flight performance and dispersal behaviour of sexes do not always go hand in hand. Moreover, the relationship between the sex ratio and flight performance bias between sexes is not driven by competition within the most abundant sex. The inclusion of a sex perspective in insect dispersal studies would be useful to detect dispersal bias between sexes and its causes and would allow for further analysis of its effects on population dynamics.

Phylogeography and distribution modelling reveal the history and future of a saproxylic beetle of European conservation concern

“…This difference could be attributed to female philopatry, as shown for another saproxylic beetle in the genus Osmoderma (Hedin et al, 2008). This could be related to sex‐biased dispersal (Martínez‐Pérez et al, 2022), but is purely speculative as there are no studies on this topic for C. cinnaberinus .…”

Clinging to the top: natal dispersal tracks climate gradient in a trailing-edge population of a migratory songbird

“…Dispersal capacity can vary with age, sex and other individual traits [ 22 , 43 ]. Natal dispersal is typically greater than adult dispersal within vertebrates [ 17 , 22 , 50 ], suggesting that natal dispersal could be a key driver of climate-induced range shifts [ 10 , 22 , 49 ].…”

Flight Dispersal in Supratidal Rockpool Beetles

“…Although direct measures of flight dispersal can be achieved in the field (e.g., mark-release-recapture methods, see [ 13 , 14 ]), this method presents serious difficulties for small organisms and species travelling long distances. In such cases, indirect measurements based on wing morphology serve as reliable insights into flight performance [ 15 ]. Key wing characteristics, including length, width, and area, are closely linked to flight dispersal capacity [ 16 ].…”

“…Key wing characteristics, including length, width, and area, are closely linked to flight dispersal capacity [ 16 ]. Several studies on different insect orders have explored wing loading (body mass to wing area ratio) and wing aspect ratio (wing length to wing width ratio), e.g., [ 15 , 16 , 17 , 18 , 19 , 20 ]. Low wing loading correlates with superior flight capacity, as larger wings per unit of weight demand less energy for a given flight distance [ 15 , 21 , 22 ].…”

“…Several studies on different insect orders have explored wing loading (body mass to wing area ratio) and wing aspect ratio (wing length to wing width ratio), e.g., [ 15 , 16 , 17 , 18 , 19 , 20 ]. Low wing loading correlates with superior flight capacity, as larger wings per unit of weight demand less energy for a given flight distance [ 15 , 21 , 22 ]. Aspect ratio, reflecting wing shape, significantly influences speed and manoeuvrability, with longer and more slender wings associated with higher acceleration capacity [ 22 ] and faster flying, as seen in dipterans and odonatans [ 23 ].…”