Specifically, we ask whether nuclear gene genealogies reveal arthemis and astyanax to be exclusive groups or reveal genealogical structure inconsistent with a scenario of primary differentiation in wing pattern.
Problems encountered in the move to land These early land animals had to solve the same problems that plants faced when they moved to the land: Mullen Show more https: Thus far we have collected data for mtDNA from two transects across the hybrid zone.
Preservation of soft-bodied organisms is rare, and in this case seems to have occurred when the animals were rapidly buried in a mudslide down into deep, anaerobic waters, where there was little bacterial decay. This is because the egg is dependent on diffusion alone for gas exchange, and means that the embryo must develop rapidly into a food-seeking larval form rather than undergo prolonged development within the egg.
Once thought to be extinct, the coelacanth is a living representative of this group.
Juvenile animals could avoid predation by the land-based adults by living in shallow water. For example, no a priori association between genealogical groups and geographic populations is predicted for genealogies of gene regions not linked to genes influencing wing color pattern. Many animals remain inconspicuous until threatened, then suddenly employ warning signals, such as startling eyespotsbright colours on their undersides or loud vocalizations.
However, once model and mimic have become closely similar, some degree of mutual protection becomes likely. The appearance of modern mammal groups The Ediacaran animals Between and million years ago during the Vendian Period relatively large, complex, soft-bodied multicellular animals appear in the fossil record for the first time.
Note that the marsupial and placental mammals provide some excellent examples of convergent evolutionwhere organisms that are not particularly closely related have evolved similar body forms in response to similar environmental pressures.
However, despite the fact that the mammals had what many people regard as "advanced" features, they were still only minor players on the world stage. The development of a key mammalian trait, the presence of only a single bone in the lower jaw compared to several in reptiles can be traced in the fossil history of this group.
Turtles and tortoises belong in a third group of amniotes, the Anapsida. Previous article in issue. At the same time some groups of plants and animals took a major step as they colonised the land for the first time. It includes Europe, Asia north of the Himalaya, northern Africa, and the northern and central parts of the Arabian Peninsula.
GO TO TOP Early reptiles and the amniotic egg One of the greatest evolutionary innovations of the Carboniferous period - million years ago was the amniotic eggwhich allowed early reptiles to move away from waterside habitats and colonise dry regions.
The mechanism was proposed by the entomologist F. This is only likely to work, however, when a trait is governed by a single gene, and many coloration patterns are certainly controlled by multiple genes. Like plants, animals evolved waterproof external layers, internal gas exchange systems, ways of reproducing that did not involve water, and strong support systems endoskeletons and exoskeletons that allowed them to move about on land.
The cause of the proliferation of animal forms in the Cambrian is a matter of considerable debate among scientists. Limenitis Author links open overlay panel Sean P. Many forms seen in the fossil record of the Cambrian disappeared without trace.
Lobe-finned fish also peaked in numbers during the Devonian. They contain familiar animals such as trilobites, molluscs and echinoderms, but also the first appearance of brachiopods, and some odd animals, e.
In the Devonian seas, brachiopods had become a dominant invertebrate group, while the fish continued to evolve, with sharks becoming the dominant marine vertebrates.
Arthropods, which had ventured temporarily onto land million years earlier, were the first animals to become more permanent colonists.
Many of their characteristic features are well suited for this habitat: These strategies may also be employed differentially throughout development.Indeed, the evolution of wing pattern diversity in butterflies has emerged as an important model system for studies of speciation, mimicry, and (most recently) the interface between evolution and development (McMillan et al.,Reed and Serfas, ).
HYBRIDIZATION AMONG ADMIRAL BUTTERFLIES Figure 1. Wing pattern diversity in the Limenitis arthemis species complex.
Specimens in the left-most column are nonmimetic L. a. arthemis, specimens on the far right are mimetic L. a. astyanax, and intermediate individuals representing the range of variation observed in hybrid.
Wing pattern evolution and the origins of mimicry among North American admiral butterflies Mullen, Sean P. The evolution of wing pattern diversity in butterflies has emerged as a model system for understanding the origins and maintenance of adaptive phenotypic novelty.
Wing pattern evolution and the origins of mimicry among North American admiral butterflies (Nymphalidae: Limenitis). Molecular Phylogenetics and Evolution. In press. Indeed, the evolution of wing pattern diver- sity in butterXies has emerged as an important model sys- Phylogenetic studies of taxa that exhibit adaptive pheno- tem for studies of speciation, mimicry, and (most recently) typic variation provide valuable insights into the evolution- the interface between evolution and development (McMil- ary.
Wing Pattern Evolution and the Origins of Mimicry of North American Admirals. Admiral butterflies (genus Limenitis) are a particularly appealing system to address questions regarding wing pattern evolution and speciation.Download