Robert Warren, Lisa Nagy, Jane Selegue, Julie Gates, and Sean Carroll produced this experiment that wanted to examine homeotic gene expression in butterflies. The hypothesis they tested was do homeotic genes have driven morphological change or do the homeotic genes provide a pre-existing plan where insects segment diversity evolved. The genes Antp, Scr, Abd-A, and Ubx were isolated from a cDNA library and were used to explore differences in limb and wing numbers between flies and butterflies. Where Ubx and Abd-A are expressed, the limb and wing numbers arose. They started to wonder if the expression of BX-C genes were different in butterflies (P.Coeni) and fruit flies (drosophila). When they did tests, they saw that conservation of BX-C and ANT-C homeotic gene expression are fundamentally similar and don’t explain the differences in appendages in each species. They looked into embryogenesis, and at 20% of the embryogenesis of butterflies, they saw Abd-A protein and RNA are expressed in the anterior and abdominal segments. High levels of Antp expression are seen in the thorax. Past the 20% mark of embryogenesis, the patterns seen of Abd-A, DII, and Antp expression differed extremely - no DII or Antp were expressed in the abdominal proleg.
After seeing this, they tested out if DII is responsible for the down regulation of Ubx/Abd-A. They used double-label experiments using antibodies against butterfly DII and Ubx/Abd-A antibodies and performed them. The activation of DII in the proleg trails repression for Ubx and Abd-A expression, which showed that repression of BX-C gene, is the initial event. When DII expression abdominal segments of drosophila embryo expression is repressed due Ubx and Abd-A, the abdominal limb formation in but...
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...nes to produce different kinds of structures patterned in the same position. In general, 0 changes the number, size, pattern of homologous structure, and body appendages, that involve changes in timing and spatial regulation of existing genes. In some cases, these are homeotic genes and in other cases they are downstream genes.
If I were to continue this line of research, I would test and see if there are different hox genes for different animals. I would expect to see duplication to occur in the lineages within each species. For example, if duplication were to occur at hox gene levels (in butterflies, fruit flies, earthworms, etcetera) I would expect to see different hox genes. But, since hox how genes are conserved, that would probably not end up happening. So this new test would prove that hox genes are conserved and every species should have the same hox genes.
The objective of this experiment is to determine what genes are responsible for the white-eye color in two strains of Drosophila melanogaster, known as the common fruit fly. Drosophila is used as the experimental organism for many reasons which include its small size, easy maintenance, short 10 day generation time, and a fully sequenced genome. The characteristics of the wild type, which is the most common phenotype found in nature, include brick red eyes, long wings, gray/tan body, and smooth bristles. Of course, there are mutations that occur that cause specific traits to deviate from the wild-type phenotype. These traits include wing length, bristle shape, body color, and eye color.
There is no doubt that arthropods are an extremely successful group of animals, with an estimated 5-10 million species worldwide[1], and this can be attributed to having an exoskeleton; it provides many benefits, such as protection from parasitism and other threats. However, one major disadvantage of having an exoskeleton is the limitations that an inelastic cuticle can place on growth. The exoskeleton provides protection, but when freshly moulted the animal is soft and vulnerable, as well as having limited mobility and use of appendages; many seek shelter before moulting[2]. There are similarities and differences between the moult cycles of all the arthropods, however only crustaceans and insects will be discussed here.
Eyesenkes theory provides an amicable solution. If we could assume that this information was genetically coded in to the cells at birth then this no longer becomes an issue and we can explain how’s and why the constructs are laid down to a loose genetic template i.
Shubin, N.H, Tabin, C., & Caroll, S. 2009. Deep homology and the origins of evolutionary novelty. Nature, 457: 818-823.
Drosophila is a small fruit fly, it is about 3mm long. This insect is a model organism most commonly used in developmental biology and genetics. The Drosophila fruit flies are especially suited in experiments because of their short life cycle which consist of two weeks; they easily reproduce many offspring, and are also cheap1. The drosophila contains four chromosomes that can easily be experimented on, which allows in-depth observation. In this experiment, Drosophila melanogaster were used to identify the properties of Mendelian inheritance. The Law of Segregation states that allele pairs separate during gamete formation and randomly unite during fertilization and is carried by every individual. The Law of Independent Assortment states that each parent randomly passes on alleles to their offspring. Although, the Law of Independent assortment does not take in account the patters of sex-linked inheritance.
The majority of scientific work in genetics and genomic sequencing has been done in the last 155 years. In 1859, Charles Darwin published On the Origin of Species where he proposed evolution by natural selection. Evolution is the change of inherited characteristics of biological populations over successive generations.Yet, the principals of genetics required to explain how characters are ...
Referring to the manipulability account, if scientists would change the heritable differences in physical characteristics of the organism in a population, there would be a visible change in their reproductive success (Millstein, 2006). For example, in a population of beetles with varying abilities to withstand different temperatures, a new beetle genotype is introduced that can withstand a greater range of temperatures, and we would expect that the relative reproductive success of the other genotypes would decrease (Millstein, 2006). Phylogenetic relationships among the four Radix species are inferred based on their genomes and nuclear loci (Feldmeyer, 2015). Three different tests to infer selection and changes in amino acid properties yielded a total of 134 genes with signatures of positive selection (Feldmeyer, 2015). The majority of these genes belong to functional genes including reproduction, genitalia, development, and growth rate (Feldmeyer, 2015).
McCall, Robert A., Sean Nee and Paul H. Harvey. "The role of wing length in the evolution." Evolutionary Ecology (1998): 569-580. Web.
Davis, Lloyd S. and John T Darby. Penguin Biology. San Diego: Academic Press, Inc., 1990.
A lot of butterflies have developed eye spots on their wings. These eye spots provide the butterfly the facade of a much bi...
Jeffery Turner and his team of bio-scientists at Nexia Biotechnologies; alongside Randolph Lewis, Ming Xu and Michael Hinman from the University of Wyoming; have taken the genes responsible for a spider’s silk produc...
sequence. Epigenetics in turn affects how cells read the genes. Epigenetic change is a regular and
Evolutionary developmental biology (evo-devo) was instituted in the early 1980s as a distinctive field of study to characterise the new synthesis of evolution hypothesis (Müller, 2007). Evo-devo is regarded as a new rule in evolutionary biology and a complement to neo-Darwinian theories. It has formed from the combination of molecular developmental biology and evolutionary molecular genetics; their integration has helped greatly to understand both of these fields. Evo-devo as a discipline has been exploring the role of the process of individual development and the changes in evolutionary phenotype, meaning the developmental procedure by which single-celled zygotes grow to be multicellular organisms. Alterations in the developmental program frequently cause differences in adult morphology.
One of the first reason why insects are so successful because they possess a tough exoskeleton that is covered with a waxy water repellant layer. The exoskeleton of insects also has helped them survive. An insect's external skeleton, or exoskeleton, is made of semi-rigid plates and tubes. In insects, these plates are made of a plastic like material called chitin along with a tough protein. A waterproof wax covers the plates and prevents the insect's internal tissues from drying out. Insect exoskeletons are highly effective as a body framework, but they have two drawbacks: they cannot grow once they have formed, and like a suit of armor, they become too heavy to move when they reach a certain size. Insects overcome the first problem by periodically molting their exoskeleton and growing a larger one in its place. Insects have not evolved ways to solve the problem of increasing weight, and this is one of the reasons why insects are relatively small. But compared to animals the Exoskeletons d...
J. Losos, K. Mason, S. Singer, based on the work of P. Raven, & G. Johnson, Biology, 8th ed., (McGraw-Hill Education (Asia), Singapore, 2008), pp. 994-995.