Dear Colleagues: We may need to pay particular attention to this is we expect to monitor the North American bees associated with deciduous and conifer forests.Message 1 of 1 , Feb 20, 2009View SourceDear Colleagues:We may need to pay particular attention to this is we expect to monitor the North American bees associated with deciduous and conifer forests. I wonder if this system is found in the Megachile spp. associated with the pollination of woodland Cypripedium reginae?peter---------- Forwarded message ----------
From: Neal Smith <smithn@...>
Date: Fri, Feb 20, 2009 at 12:15 PM
Subject: Behavioural environments and niche construction: the evolution of dim-light foraging in bees. Biological Reviews
NOTA BENE: There were no photos or drawings in the paper so I added a fewBehavioural environments and niche construction: the evolution of dim-light foraging in beesWilliam T. Wcislo , Simon M. TierneyCorrespondence to * (E-mail: WcisloW@...).KEYWORDSforaging behavior • nocturnal • crepuscular • matinal • vespertine • evolution • niche shifts • niche construction • neurobiology of night vision • Apoidea
Most bees forage for floral resources during the day, but temporal patterns of foraging activity vary extensively, and foraging in dim-light environments has evolved repeatedly. Facultative dim-light foraging behaviour is known in five of nine families of bees, while obligate behaviour is known in four families and evolved independently at least 19 times. The light intensity under which bees forage varies by a factor of 108, and therefore the evolution of dim-light foraging represents the invasion of a new, extreme niche.
The repeated evolution of dim-light foraging behaviour in bees allows tests of the hypothesis that behaviour acts as an evolutionary pacemaker. With the exception of one species of Apis, facultative dim-light foragers show no external structural traits that are thought to enable visually mediated flight behaviour in low-light environments. By contrast, most obligate dim-light foragers show a suite of convergent optical traits such as enlarged ocelli and compound eyes. In one intensively studied species (Megalopta genalis) these optical changes are associated with neurobiological changes to enhance photon capture. The available ecological evidence suggests that an escape from competition for pollen and nectar resources and avoidance of natural enemies are driving factors in the evolution of obligate dim-light foraging.
DIGITAL OBJECT IDENTIFIER (DOI)10.1111/j.1469-185X.2008.00059.x About DOI
Bees are generally regarded as sun-loving creatures (Michener, 2007). Indeed, most bees fly under full sun but some have evolved an ability to fly in very dim light conditions—including moonlight and even starlight—and so bees of different species experience foraging environments in which average light intensity varies by a factor of more than 108 (i.e. the difference between sunlight and starlight; see Lythgoe, 1979; Warrant, 2004). Thus, for day-flying species the evolution of dim-light foraging represents the invasion of an extreme environment, and provides an opportunity to look at the relative roles of behavioural, physiological, and structural changes in facilitating these niche shifts.
Mayr (1960, p. 371) argued that the invasion of a new niche invariably establishes a new array of selection pressures, and that such shifts require "almost without exception" a change in behaviour. Changes in behaviour may then lead to subsequent evolutionary changes in other features favourable for life in the new environment, although they are not inevitable (e.g. Darwin, 1872; Mayr, 1958; Evans, 1966; Wcislo, 1989; Prum, 1998; Odling-Smee, Laland & Feldman, 2003; West-Eberhard, 2003). The hypothesis that behaviour shapes selective environments, and acts as a pacemaker of evolution, dates to Lamarck (1809) and subsequent Darwinian formulations by Baldwin (1902) and others (see reviews in Lewontin, 1983, 2000; Wcislo, 1989; West-Eberhard, 2003; Odling-Smee et al., 2003; Weber & Depew, 2003). Odling-Smee et al. (2003) review methods to test for the relative importance of organism-induced modifications of their selective environment, which they termed "niche construction" (following Lewontin, 2000). One test involves comparative methods: if facultative behaviour takes the lead in initiating evolutionary change, then the distribution of character states across a phylogeny should reveal that traits associated with the new environment are concentrated in those branches of the tree where the novel (niche constructing) behaviour is obligatory (cf. Fig. 1 of Wcislo, 1989).Here we first review the phyletic distribution of dim-light foraging in bees, both facultative and obligate, as well as the phenotypic traits that enable such activity. We then use these comparative data to test the relative importance of temporal niche construction in shaping the evolution of foraging patterns of bees, and the structural and physiological traits associated with the novel behaviour.