Abstract
Eurema elathea adults were census weekly (1992-1994) in six night-roosts around a forest fragment on a farm, and in two roosts in the urban area of Uberlândia, Minas Gerais, Brazil. Males were grouped in six phenotypic classes. These were based on a range between having a conspicuous wide black bar at the dorsal forewing inner margin (wet season dark morphs) and the absence of that bar (dry season light morphs). The body mass and wing area of co-occurring morphs were compared: differents morphs showed similar means. The abundance of butterflies and morph frequencies varied in close relation to humidity (rainfall). Individuals were infrequent and monomorphically dark in the wet season while light morphs predominated in dry periods when population peaked. A lower fraction of recaptured individuals and higher recruitment were recorded compared to other night-roosting butterflies. Dispersal potential was similar between the sexes and varied seasonally with a more sedentary population in dry periods. The maximum residence time recorded was 91 days for a female and 84 days for a male. The fraction of individuals that moved from one roosting site to another was similar in both sexes and male morphs, but significantly higher on the farm than in the urban area. Also, a significantly higher fraction (21.3%) of marked butterflies was recaptured in the urban area than on the farm (15.6%), suggesting a behavioral modification for sedentariness in the urban individuals. The selective forces shaping a gregarious roosting habit in E. elathea and other butterflies are discussed and a protocooperational strategy for saving energy is proposed.
Highlights
Shapiro (1976) defined seasonal polyphenism as “an annually repeating pattern of changing phenotypic ratios in successive generations, under some kind of environmental control”
In this paper we investigate morphometrical, phenological, and behavioral differences within male seasonal phenotypes of Eurema elathea
Owen (1971) noted that seasonal morphs of Precis octavia in Africa were larger in the dry season than in the wet season
Summary
Shapiro (1976) defined seasonal polyphenism as “an annually repeating pattern of changing phenotypic ratios in successive generations, under some kind of environmental control”. He later reviewed the subject and discussed its relation to theories of speciation (Shapiro, 1984a). West-Eberhard, in her excellent 1989 review, treats polyphenism as an example of phenotypic plasticity which she defines as “the ability of a single genotype to produce more than one alternative form of morphology, physiological state, and/or behavior in response to environmental conditions”. Summer light morphs tend to be less active and may theoretically decrease predation pressure via crypsis optimization in a dry background (Brakefield & Larsen, 1984)
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Schedule a callMore From: Brazilian journal of biology = Revista brasleira de biologia
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