Adult Sex Ratio in the Parnassius Mnemosyne Butterfly: Effects of Survival, Migration, And weather

Abstract

Sex ratio biases in animal populations influence the genetically effective population size, and thus are of interest in conservation. A butterfly group in which many authors report biases towards males is the genus Parnassius Latreille, 1804 (Papilionidae). Using a vulnerable woodland species, P. mnemosyne, we carried out a detailed marking campaign designed to eliminate biases towards individual sexes on marking. We then estimated the numbers of males and females using constrained linear models (CLMs) (Cormack-Jolly-Seber and Jolly-Seber in MARK); compared details of mobility between males and females using the Virtual Migration (VM) model; and built CLMs containing weather variables in order to directly assess weather effects on survival. The estimated population size was 4000 adults, with a male : female sex ratio of 1.5-1.6. Both daily and average catchability were higher for males, while the residence values (i.e., survival) were higher for females. Migration parameters were similar for the sexes, with slightly lower male survival within patches and slightly higher male emigration. CLMs with weather substituted for or added to marking days performed worse than models with mere marking days, and although weather affected the sexes differently, males still retained lower survival. The surplus of adult males in the studied population of P. mnemosyne was real, not caused by increased male survival or a difference in mobility. Therefore, the bias toward males must appear prior to adult emergence, probably during the larval period.

Demography of adults of the Marsh fritillary butterfly, Euphydryas aurinia (Lepidoptera: Nymphalidae) in the Czech Republic: Patterns across sites and seasons

“…A higher male catchability is frequently recorded in butterfly MRR studies (Schtickzelle et al, 2002;Baguette & Schtickzelle, 2003;Zimmermann et al, 2009;Kadlec et al, 2010), including those on E. aurinia (Schtickzelle et al, 2005;Junker & Schmitt, 2010;Junker et al, 2010), probably due to their more conspicuous activity, whereas the factorial response of catchability to time is due to variation in weather and marking effort (Schtickzelle et al, 2002;Vlasanek et al, 2009). In any case, if averaged across all years and systems, 16% of the males and 10% of the females were captured (mean of p's in Table 4).…”

Intraseasonal asynchrony as a factor boosting isolation within a metapopulation: The case of the clouded apollo

“…Based on CMR data worked up using Cox's proportional hazard model, the numbers of butterflies present in both metapopulation centers on consecutive days of the season were calculated (Fieberg & DelGiudice, 2009). Because of the well-known difference in survival parameters between males and females (Vlašánek et al, 2009;Zimmermann et al, 2009), as well as interseasonal fluctuations in population abundance, the model's parameters were calculated separately for each sex and season.…”

“…To begin with, it is worth mentioning that determining the habitat patch and subpopulation of the clouded apollo is not a trivial matter, owing to the differences in habitat requirements between caterpillars and adults. The crucial factor for the caterpillars is the presence of the food plants-Corydalis cava and C. solida (Konvička & Kuras, 1999;Välimäki & Itämies, 2003;Vlašánek et al, 2009). In the Pieniny Mts.…”

“…Based on the results of studies carried out in central Europe, however, it seems more appropriate to assume that single meadows represent a habitat patch if Corydalis sp. is/are present on their borders (Konvička & Kuras, 1999;Vlašánek et al, 2009). This important role of the ecotone is especially apparent in mountain areas (Adamski, 2013).…”

Dispersing maleParnassius smintheusbutterflies are more strongly affected by forest matrix than are females

“…Several studies have compared the dispersal of male and female butterflies within spatial population networks using the VM model (Petit et al, 2001;Wahlberg et al, 2002;Wang et al, 2004;Cizek & Konvicka, 2005;Rabasa et al, 2007;Vlasanek et al, 2009;Fric et al, 2010;Nowicki & Vrabec, 2011;Bonelli et al, 2013). These studies of 22 species/landscape combinations (15 different species), provide the most direct comparison to the present study.…”