Countergradient vs. cogradient variation in growth and diapause in a lichen‐feeding moth, Eilema depressum (Lepidoptera: Arctiidae)

Abstract

Separating genetic and environmental causes of the latitudinal differences among populations is crucial when evaluating the potential for microevolutionary responses to the changing environment. We studied among‐population and environmental components of variation in several life‐history traits of a lichen‐feeding moth Eilema depressum when offspring of replicate Swiss and Finnish females were reared in a common‐garden factorial experiment. A partial second generation was produced only among Swiss larvae, more likely so at higher temperature regime and higher host quality, and more frequently among the offspring of particular females. Growth rates of larvae that chose the diapause development were higher in northern individuals. Our results thus reveal adaptive differences between latitudinal populations in studied life‐history traits, allowing to expect rapid adaptation of the species to further environmental changes. In contrast, invariable responses of the growth rates of the larvae to temperature and host quality support the idea that some basic parameters of insect growth show a high degree of evolutionary conservatism.

Latitudinal cogradient variation of development time and growth rate and a negative latitudinal body weight cline in a widely distributed cabbage beetle

“…In most studies, the evolutionary response to a gradient is the opposite of the ecological response (countergradient variation) [6,8,11,14]. In the present study, C .…”

“…For example, larval development times consistently decreased with an increasing latitudinal gradient in four species of geometrid moths, Cabera exanthemata , Cabera pusaria , Chiasmia clathrata and Lomaspilis marginata [6]. The lichen-feeding moth, Eilema depressum , from a high latitudinal (60° N) population had a higher growth rate than those from a low latitudinal population (46–47° N) [14], and in the generalist grasshopper, Melanoplus femurrubrum , northern populations develop more rapidly and show higher growth rates than southern populations [8]. …”

“…The fruit fly, Drosophila melanogaster , has CnGV variation in a physiological trait coupled with CoGV in a morphological trait [11]. In recent years, 6 species have shown conclusive evidence of CnGV in physiological traits [6,8,14]; thus, CnGV is apparently a more widespread phenomenon than CoGV in insects. An understanding of the evolution of CoGV and CnGV should help predict the consequences of climate change [15].…”

Variation in two phases of post‐winter development of a butterfly

“…Intraspecific clines in life cycle traits often follow environmental gradients, such as temperature gradients along latitude (Bradford & Roff, ; Masaki, ; Gaston et al ., ). The degree to which genes and environments, and their interaction, contribute to the geographic phenological pattern influences how species and populations respond to short‐term environmental fluctuations and long‐term ecological changes (Blanckenhorn & Fairbairn, ; Gienapp et al ., ; Phillimore et al ., ; Pöykkö & Tammaru, ).…”

Response of the lichen-eating moth Cleorodes lichenaria larvae to varying amounts of usnic acid in the lichens

“…For many lichen metabolites, including usnic acid, toxicity and insecticidal activity have been described (e.g. Emmerich et al 1993;Ingólfsdóttir 2002;Pöykkö et al 2005;Pöykkö and Tammaru 2010). In feeding experiments with lichenivorous Lepidoptera, these authors demonstrated that usnic acid caused high mortality, growth retardation, and prolonged larval periods.…”