The appendages of the adult fruit fly and other insects and Arthropods develop from secondary embryonic fields that form after the primary anterior/posterior and dorsal/ventral axes of the embryo have been determined. In Drosophila, the position and fate of the different fields formed within each segment are determined by genes acting along both embryonic axes, within individual segments, and within specific fields. Since the major architectural differences between most Arthropod classes and orders involve variations in the number, type and morphology (...) of body appendages, the elucidation of the embryology and molecular genetics of the origin and patterning of insect limb fields may help to facilitate an understanding of both the mechanism of appendage formation and some of the major steps in the morphological evolution of the Arthropods. In this review, we will discuss recent studies that have advanced our understanding of both the origin and patterning of Drosophila leg and wing secondary fields. These results provide fresh insights into potentially general mechanisms of how body parts develop and evolve. (shrink)

Evolutionary changes in traits that affect both ecological divergence and mating signals could lead to reproductive isolation and the formation of new species. Insect cuticular hydrocarbons (CHCs) are potential examples of such dual traits. They form a waxy layer on the cuticle of the insect to maintain water balance and prevent desiccation, while also acting as signaling molecules in mate recognition and chemical communication. Because the synthesis of these hydrocarbons in insect oenocytes occurs through a common biochemical pathway, natural or (...) sexual selection on one role may affect the other. In this review, we explore how ecological divergence in insect CHCs can lead to divergence in mating signals and reproductive isolation. We suggest that the evolution of insect CHCs may be ripe models for understanding ecological speciation. (shrink)

An award-wining biologist takes us on the dramatic expeditions that unearthed the history of life on our planet. Just 150 years ago,most of our world was an unexplored wilderness.Our sense of how old it was? Vague and vastly off the mark. And our sense of our own species’ history? A set of fantastic myths and fairy tales. Fossils had been known for millennia, but they were seen as the bones of dragons and other imagined creatures. In the tradition of The (...) Microbe Hunters and Gods, Graves, and Scholars, Sean Carroll’s Remarkable Creatures celebrates the pioneers who replaced our fancies with the even more amazing true story of how our world evolved. Carroll recounts the most important discoveries in two centuries of national history — from Darwin’s trip around the world to CharlesWalcott’s discovery of pre-Cambrian life in the Grand Canyon; from Louis and Mary Leakey’s investigation of our deepest past in East Africa to the trailblazers in modern laboratories who have located a time clock in our DNA. Join him in a rousing voyage of discovery, from the epic journeys of pioneering naturalists to the breakthroughs making headlines today. (shrink)