Insects : their life-histories and habits . he only openings for profit-able selection. From time to time varieties arise that areglaringly unlike the ancestral type. Great and suddenjumps, as it were, are taken by Nature. Moreover, itis noticeable that certain species are especially liable tovary in this extreme degree, and that the same kinds ofvarieties (mutations as they are called) are produced overand over again. In all such cases interbreeding amongsimilar varieties must occur; and some naturalists (whofollow Professor De Vries of Amsterdam) assert that allspecies pass through these per
Insects : their life-histories and habits . he only openings for profit-able selection. From time to time varieties arise that areglaringly unlike the ancestral type. Great and suddenjumps, as it were, are taken by Nature. Moreover, itis noticeable that certain species are especially liable tovary in this extreme degree, and that the same kinds ofvarieties (mutations as they are called) are produced overand over again. In all such cases interbreeding amongsimilar varieties must occur; and some naturalists (whofollow Professor De Vries of Amsterdam) assert that allspecies pass through these periods of instability in thecourse of their history—periods when swarms of incipientspecies arise suddenly from the old stock. On this as-sumption the profound modification of an existing species,or the making of new ones, might be a comparativelyrapid process; for while many of the mutations are des-tined to fall before the ordeal of natural selection, a fewmay pass muster and transmit their distinctive charactersto posterity. Plate XXIII. Convergent Mimicry: The figures (from above downward) represent Metinaea imitata (sub-family J/fiowmna ,Heliconiu8 telchinia sub-family Heliconiince), Dismorphia praxinoe,female and male (family Pieridce). South America WARNING COLOURS AND MIMICRY 155 The case of DismorpMa praadnoe is by no meansisolated. Examples of mimicry among butterflies arenow known by hundreds, not only in South America, butin all the warmer regions of the globe. In some instancesas many as a dozen weaklings, including day-flying moths,are attached mimetically to a single dominant distastefultype. Yet we must not assume that the mere fact of oneinsects resemblance to another necessarily constitutes acase of mimicry. Uniformity of habit and environmentmay, on occasion, lead to uniformity of are instances on record of insects indigenous tocountries extremely remote which might well be put for-ward as examples of mimicry if a likeness in form andcolour w
Size: 1144px × 2184px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsects, bookyear1913
