Passer wrote:Concerning evolution, how does it explain the bug that changes itself to look like a leaf? Does it explain it the same way as other forms of life? I've heard tell of a butterfly or more probably a moth, I can't quite remember now, but it evolved into two different types. One type, because it spends its time mostly in rural areas, is white in colour, but the other type, because it spends most of its time in and around a dirty industrialised area, is more grey in its colouring.

But the bug resembling a leaf seems a bit of a stretch.

twistor59 wrote:When I read the title I just couldn't help thinking "tits like coconuts"

Passer wrote:Concerning evolution, how does it explain the bug that changes itself to look like a leaf? Does it explain it the same way as other forms of life? I've heard tell of a butterfly or more probably a moth, I can't quite remember now, but it evolved into two different types. One type, because it spends its time mostly in rural areas, is white in colour, but the other type, because it spends most of its time in and around a dirty industrialised area, is more grey in its colouring.

But the bug resembling a leaf seems a bit of a stretch.

susu.exp wrote:It´s worth noting that bugs are insects belonging to the Hemiptera, whereas leaf insects belong to a group called Euphasmida. They are distantly related, but their most recent common ancestor was at the base of the Neoptera. Butterflies and Beetles have a closer relationship than that. It bugs me (no pun intended) sometimes, that people don´t check these things with insects first. Imagine somebody writing a thread called "huge bat swimming the ocean feeding on krill", asking how evolution allowed a bat to swim through the ocean feeding on krill and meaning blue whales. They aren´t bats of course, but both bats and whales are mammals. Calling Phasmids bugs isn´t that different (it´s just a group that we aren´t as much involved as as mammals, but making up most of metazoan diversity should count for something).

Development of the animal body plan is controlled by large gene regulatory networks (GRNs), and hence evolution of body plans must depend upon change in the architecture of developmental GRNs. However, these networks are composed of diverse components that evolve at different rates and in different ways. Because of the hierarchical organization of developmental GRNs, some kinds of change affect terminal properties of the body plan such as occur in speciation, whereas others affect major aspects of body plan morphology. A notable feature of the paleontological record of animal evolution is the establishment by the Early “Cambrian of virtually all phylum-level body plans. We identify a class of GRN component, the kernels” of the network, which, because of their developmental role and their particular internal structure, are most impervious to change. Conservation of phyletic body plans may have been due to the retention since pre-Cambrian time of GRN kernels, which underlie development of major body parts.

Male dung beetles (Onthophagus taurus) facultatively produce a pair of horns that extend from the base of the head: males growing larger than a threshold body size develop long horns, whereas males that do not achieve this size grow only rudimentary horns or no horns at all. Here we characterize the postembryonic development of these beetles, and begin to explore the hormonal regulation of horn growth. Using radioimmune assays to compare the ecdysteroid titers of horned males, hornless males, and females, we identify a small pulse of ecdysteroid which is present in both hornless males and females, but not in horned males. In addition, we identify a brief period near the end of the final (third) larval instar when topical applications of the juvenile hormone analog methoprene can switch the morphology of developing males. Small, normally hornless, males receiving methoprene during this sensitive period were induced to produce horns in 80% of the cases. We summarize this information in two models for the hormonal control of male dimorphism in horn length.

Polymorphism may play an important role in speciation because new species could originate from the distinctive morphs observed in polymorphic populations. However, much remains to be understood about the process by which morphs found new species. To detail the steps of this mode of speciation, we studied the geographic variation and evolutionary history of a throat color polymorphism that distinguishes the “rock-paper-scissors” mating strategies of the side-blotched lizard, Uta stansburiana. We found that the polymorphism is geographically widespread and has been maintained for millions of years. However, there are many populations with reduced numbers of throat color morphs. Phylogenetic reconstruction showed that the polymorphism is ancestral, but it has been independently lost eight times, often giving rise to morphologically distinct subspecies/species. Changes to the polymorphism likely involved selection because the allele for one particular male strategy, the “sneaker” morph, has been lost in all cases. Polymorphism loss was associated with accelerated evolution of male size, female size, and sexual dimorphism, which suggests that polymorphism loss can promote rapid divergence among populations and aid species formation.

Insect pigmentation is a premier model system in evolutionary and developmental biology. It has been at the heart of classical studies as well as recent breakthroughs. In insects, pigments are produced by epidermal cells through a developmental process that includes pigment patterning and synthesis. Many aspects of this process also impact other phenotypes, including behavior and immunity. This review discusses recent work on the development and evolution of insect pigmentation, with a focus on pleiotropy and its effects on color pattern diversification.

Background: Saltational evolution in which a particular lineage undergoes relatively rapid, significant, and unparalleled change as compared with its closest relatives is rarely invoked as an alternative model to the dominant paradigm of gradualistic evolution. Identifying saltational events is an important first-step in assessing the importance of this discontinuous model in generating evolutionary novelty. We offer evidence for three independent instances of saltational evolution in a charismatic moth genus with only eight species.Methodology/Principal FindingsMaximum parsimony, maximum likelihood and Bayesian search criteria offered congruent, well supported phylogenies based on 1,965 base pairs of DNA sequence using the mitochondrial gene <italic>cytochrome oxidase subunit I, and the nuclear genes <italic>elongation factor-1 alpha</italic> and <italic>wingless</italic>. Using a comparative methods approach, we examined three taxa exhibiting novelty in the form of Batesian mimicry, host plant shift, and dramatic physiological differences in light of the phylogenetic data. All three traits appear to have evolved relatively rapidly and independently in three different species of <italic>Proserpinus. Each saltational species exhibits a markedly different and discrete example of discontinuous trait evolution while remaining canalized for other typical traits shared by the rest of the genus. All three saltational taxa show insignificantly different levels of overall genetic change as compared with their congeners, implying that their divergence is targeted to particular traits and not genome-wide.Conclusions/Significance Such rapid evolution of novel traits in individual species suggests that the pace of evolution can be quick, dramatic, and isolated—even on the species level. These results may be applicable to other groups in which specific taxa have generated pronounced evolutionary novelty. Genetic mechanisms and methods for assessing such relatively rapid changes are postulated.

Delvo wrote:Just because some silly entomologist at some point in the past decided to insist on pretending that the word "bug" has such an absurdly narrow definition, and somehow got other pretentious entomologists to go along with that obvious pretense, does not mean that that insistence has anything to do with the actual, and much wider, meaning of the word "bug" in the real world.

Sityl wrote:

Passer wrote:Concerning evolution, how does it explain the bug that changes itself to look like a leaf? Does it explain it the same way as other forms of life? I've heard tell of a butterfly or more probably a moth, I can't quite remember now, but it evolved into two different types. One type, because it spends its time mostly in rural areas, is white in colour, but the other type, because it spends most of its time in and around a dirty industrialised area, is more grey in its colouring.

But the bug resembling a leaf seems a bit of a stretch.

This is a good question, Passer, and I don't think anyone could do as good of a job at explaining it than Carl Sagan. Please watch this video, it's short but spot on.

[youtube]http://www.youtube.com/watch?v=dIeYPHCJ1B8[/youtube]

bug (n.)

"insect," 1620s (earliest reference is to bedbugs), probably from M.E. bugge "something frightening, scarecrow" (late 14c.), a meaning obsolete except in bugbear (1570s) and bugaboo (q.v.); probably connected with Scot. bogill "goblin, bugbear," or obsolete Welsh bwg "ghost, goblin" (cf. Welsh bwgwl "threat," earlier "fear"). Cf. also bogey (1) and Ger. bögge, böggel-mann "goblin." Perhaps influenced in meaning by O.E. -budda used in compounds for "beetle" (cf. Low Ger. budde "louse, grub," M.L.G. buddech "thick, swollen"). Meaning "defect in a machine" (1889) may have been coined c.1878 by Thomas Edison (perhaps with the notion of an insect getting into the works). Meaning "person obsessed by an idea" (e.g. firebug) is from 1841. Sense of "microbe, germ" is from 1919. Bugs "crazy" is from c.1900.

Passer wrote:But the bug resembling a leaf seems a bit of a stretch.