User:Wesselkamper.1/sandbox

Evolution scientific paper topics:

Topic:  Convergent evolution of venom in various species. How has venom in different species evolved to resemble each other?

References:

Daltry, J. C., Wuester, W., & Thorpe, R. S. (1996). Diet and snake venom evolution. Nature, 379(6565), 537-540.

Hargreaves, A. D., Swain, M. T., Hegarty, M. J., Logan, D. W., & Mulley, J. F. (2014). Restriction and recruitment-gene duplication and the origin and evolution of snake venom toxins. bioRxiv.

Juárez, P., Comas, I., González-Candelas, F., & Calvete, J. J. (2008). Evolution of snake venom disintegrins by positive Darwinian selection. Molecular biology and evolution, 25(11), 2391-2407.

Whittington, C. M., Papenfuss, A. T., Bansal, P., Torres, A. M., Wong, E. S., Deakin, J. E., ... & Belov, K. (2008). Defensins and the convergent evolution of platypus and reptile venom genes. Genome research, 18(6), 986-994.

Wong, E. S., & Belov,K. (2012). Venom evolution through gene duplications.Gene, 496(1), 1-7. Web address of article I commented on and edited: https://en.wikipedia.org/wiki/Venom

Copy and pasted suggestions in talk page:

Evolution[edit source]
I think it would be useful to add a section that discusses the evolution of individual species evolution of venom and the convergent evolution of venom between species. Some snakes and lizards produce similar molecules in their venom to platypus venom. These components of both species' venom has evolved separately, suggesting convergent evolution. Source: http://genome.cshlp.org/content/18/6/986.full.pdf+html

[1]

Wesselkamper.1 (talk) 17:03, 29 September 2014 (UTC)Wesselkamper.1 Wesselkamper.1 (talk)

Snakes and Platypus[edit source]
We can include additional information to each of the sections or into a specific evolution section about the evolution of the specific glands that the venom is secreted from. It is known that the the snake venom glands evolved from what were originally their modified salivary glands while platypus venom glands evolved from their modified sweat glands. [2]Wesselkamper.1 (talk) 17:22, 29 September 2014 (UTC)Wesselkamper.1

FIN

Additional Information for Snake Venom[edit source]
Studies found that the composition of snake venom within species varies with geological location. The study showed evidence that the variation was not due to gene flow or phylogenetic relationships, but rather with differences in diet. [3]

Wesselkamper.1 (talk) 17:36, 29 September 2014 (UTC)Wesselkamper.1
 * 1) Jump up^ http://genome.cshlp.org/content/18/6/986.full.pdf+html
 * 2) Jump up^ http://genome.cshlp.org/content/18/6/986.full.pdf+html
 * 3) Jump up^ http://pages.bangor.ac.uk/~bss166/Publications/!Daltry_Callo_Nature.pdf

1 sentence and citation added:

The composition of snake venom can vary within a species due to diet variation, which is caused by differences in geological location. [6]

Daltry, Jennifer C., Wolfgang Wuester, and Roger S. Thorpe. "Diet and snake venom evolution." Nature 379.6565 (1996): 537-540.

 FINAL DRAFT STARTS HERE 

Affects of Various Processes on the Evolution of Venom

Venom (or toxin) is a trait found in numerous species across at least seven different metazoan phyla (Kordis and Gubensek, 2000). Snakes, spiders and scorpions are the most comprehensively studied of all venomous animals, but this characteristic established itself within mammals (shrews and platypuses), lizards, fish, insects, centipedes, echinoderms, sea snails, jellyfish, cephalopods and sea anemone. Primarily made up of peptides and proteins, toxins also include other molecules such as neurotransmitters, salts, amino acids, and polyamines. Accumulated together, these collection of molecules create venoms, which provide animals with a variety of functions such as defense against predators or competitors and the immobilization, paralysis, death or pre-digestion of prey. The toxins in venom target main tissues and physiological pathways (e.g. cardiovascular and nervous systems) that can be reached through the bloodstream (Fry et al., 2009) by binding to enzymes, ion channels and receptors (Kordis and Gubensek, 2000). Not only have animals developed toxins that vary across families, genus, interspecifically and intraspecifically (Juarez et al., 2008), additionally, they evolved incredibly diverse methods of venom transfer (Fry et al., 2009). From snake fangs to the spurs on the hind legs of platypuses, the variation in morphology along with the diverse components of venoms themselves clearly show that different phylogenetic clades evolved venoms independently of one another (Wong and Belov, 2012). The knowledge of the history of the venomous trait not only helps us to understand the evolution of many species but also provides much insight into venoms’ biochemical and pharmacological roles around the world (Kordis and Gubensek, 2000). Multiple evolutionary forces lead to the origination of venom, along with adaptive, convergent and divergent evolution of its genetic makeup. A majority of research has been done primarily on snakes; as a result, much of the focus in this paper will revolve around snake venom. In spite of this, we can hypothesize that many conclusions made by experiments on snake venom can, to some extent, be similar to other species, especially those in the same phylum.

The first question in the evolution of venom is its origin: How did venom initially arise in to the genome of a species? Until recently, there was not much debate over how snake venom originated, but recent studies have data that disagrees with the standard conclusion. Researchers have primarily proposed that an incredibly rare gene duplication event produced and diversified snake venom. These duplicated genes were then hypothesized to have been recruited by a venom gland and subsequently acted on by natural selection. This process requires neofunctionalization, in which one of the duplicated genes exhibit an entirely different function than its ancestor (Fry et al., 2009). This idea of the origin of venom has been widely accepted for many years; however, new studies have suggested something different. Evolutionary biologists are calling for further examination of the previously unquestioned recruitment hypothesis. Furthermore, gene duplication and neofunctionalization are both exceptionally rare; therefore, both happening concurrently to create and diversify venom in multiple species is that much more infrequent. This makes the recruitment hypothesis quite improbable and advanced analysis of snake venom provides evidence that it might not be the basis of toxins in animals. The newest hypothesis is one that also begins with gene duplication, but of genes that had already been expressed in the body tissues of ancestors. Due to subfunctionalization, in which ancestral function(s) are split between the copied genes, one of the duplicates becomes limited to only the venom (salivary) gland and as a result, evolves in to the toxin producing gene. Data has shown that pre-existing proteins in the salivary glands were the origin of the toxins in snake venom. In less complicated terms, some researchers have come to see snake venom as just “a modified form of saliva,” instead of an entirely recruited set of proteins from various tissues throughout the body. This restriction hypothesis is the more parsimonious of the two because it requires less complicated mutations, and therefore may be the better theory (Hargreaves et al., 2014).

Nevertheless, the complexity of the origin of venom cannot be diminished mainly because it is a homoplastic trait that has emerged separately numerous times in many different species. The insectivore group possesses most of the venom carrying mammals (primarily shrews). Shrews are known to have venomous saliva and most likely evolved their trait similarly to snakes (Ligabue-Braun et al., 2012). However, extensive research on male platypuses (female platypuses do not produce venom) confirm that unlike snakes and insectivores, modified sweat glands are what evolved into their venom glands (Whittington et al., 2008). In addition, although platypus toxin was initially formed from gene duplication (similar to snakes), data provides evidence that the further evolution of platypus venom does not rely as much on gene duplication as once was thought (Wong and Belov, 2012). It is important that research continues on how venoms, especially from lesser studied species (e.g. sea anemone, insects, other mammals), were derived. This allows for the better understanding of toxin origination in all organisms, which in turn can provide valuable information on various venoms and their effects.

Utilization of venom across a large amount species demonstrates a classic example of convergent evolution and a homoplastic trait. It is difficult to conclude exactly how this trait came to be so intensely widespread and diversified. However, logistically we can compare it to flying, one of the most profound cases of convergent evolution. Bats and insects are clearly not closely related at all, but they both have the ability to fly. Similarly, snakes, platypuses and jellyfish are immensely far apart on the phylogenetic tree, but all contain species that have developed venom. We can attribute these trends to natural selection and adaptive evolution. These animals adapted to the need of a better, more efficient way to render prey helpless or ward off predators. When a mutation allowed for an animal to incapacitate its prey or predator, this specific animal was more likely to survive and pass on its newly founded venomous genes (Kordis and Gubensek, 2000). Different species have come to resemble each other, in the fact that they all produce venom, because of the need to fill similar, corresponding niches within each of their environments. Although it is proven that reptile and platypus venoms have independently evolved, it is thought that there are certain protein structures that are favored to evolve into toxic molecules. This provides more evidence as to why venom has become a homoplastic trait and why very different animals have convergently evolved (Whittington et al., 2008).

The role of natural selection also contributes to the divergent evolution of venoms within the same species. Variation between venoms of animals in the same species (as well as different species) is ubiquitous. More specifically, the multigene families that encode the toxins of venomous animals are actively selected on, creating more diverse toxins with specific functions. Venoms adapt to their environment and victims and accordingly evolve to become maximally efficient on a predator’s particular prey (particularly the precise ion channels within the prey). Consequently, venoms become specialized to an animal’s standard diet. For example, Conus snails are predators that feed on many types of prey and venom found in one Conus species is remarkably different in the types of peptides that occur in any other species of Conus. Even types of scorpion venom have become so selective that it can differentiate between the ion channels of mammals and insects (Kordis and Gubensek, 2000). Snakes within the same species in dissimilar geographical locations are well-known for having varying compositions of venom. Years ago researchers proposed that differences in diets were the cause of the toxin variation. The diet of local prey would impose natural selection on the venom in order to function most efficiently on that specific prey, and not as much on novel prey. As a result, the differentiation of toxin composition within the same species of snake could be explained (Daltry et al., 1996). When Daltry and his colleagues experimented, little evidence was found to support their theory, however, much more recent studies have provided strong evidence that venom variation is in fact caused by the adaptive evolution of different diets (Barlow et al., 2009). Divergence can also be a product of coevolutionary relationships between venomous animals and their prey. The variation in venoms may be due to an evolutionary arms race; predators use venom on prey that in turn become immune to the venom as a result of natural selection, thus selecting for predators with an improved toxin that can debilitate prey once again. This allows venomous snakes to adapt to an assortment of prey types that are subdued most proficiently by different toxin formulations (Juarez et al., 2008). Constant evolutionary divergence of predatory venom supplies a way for venomous animals to continuously contend with their prey. The strong forces of natural selection and adaptation allocated the best genes for each venomous animal in its specific environment. In turn, this initiated the intraspecific divergence of the genetic makeup of venom.

The study of venom and its evolution is incredibly important in today’s society. It can assist in making immense breakthroughs, not only in how to treat wounds injected with venoms, but also in biochemical and pharmaceutical areas. Multiple pharmaceutical drugs, including blood thinners and anti-angiogenics, have been derived from snake toxins. It is essential that lesser studied venomous species, such as fish, are examined for the potential benefits that they could provide. With new information suggesting that there are thousands of more venomous fish than was once thought, a goldmine of valuable information could be waiting to be discovered in their untapped venom sequences (Smith and Wheeler, 2006). Along with fish, platypus and all other species’ toxins contain significant potential for the development of new drugs and chemicals (Whittington et al., 2008).

References

Barlow, A., Pook, C. E., Harrison, R. A., & Wüster, W. (2009). Coevolution of diet and prey-specific venom activity supports the role of selection in snake venom evolution. Proceedings of the Royal Society B: Biological Sciences. Rspb.

Daltry, J. C., Wuester, W., & Thorpe, R. S. (1996). Diet and snake venom evolution. Nature 379:537-540.

Fry, B. G., Roelants, K., Champagne, D. E., Scheib, H., Tyndall, J. D., King, G. F., & de la Vega, R. C. R. (2009). The toxicogenomic multiverse: convergent recruitment of proteins into animal venoms. Annual review of genomics and human genetics 10:483-511.

Hargreaves, A. D., Swain, M. T., Hegarty, M. J., Logan, D. W., & Mulley, J. F. (2014). Restriction and recruitment-gene duplication and the origin and evolution of snake venom toxins. BioRxiv.

Juárez, P., Comas, I., González-Candelas, F., & Calvete, J. J. (2008). Evolution of snake venom disintegrins by positive Darwinian selection. Molecular biology and evolution 25:2391-2407.

Kordiš, D., & Gubenšek, F. (2000). Adaptive evolution of animal toxin multigene families. Gene 261:43-52.

Ligabue-Braun, R., Verli, H., & Carlini, C. R. (2012). Venomous mammals: a review. Toxicon 59:680-695.

Smith, W. L., & Wheeler, W. C. (2006). Venom evolution widespread in fishes: a phylogenetic road map for the bioprospecting of piscine venoms. Journal of Heredity 97:206-217.

Whittington, C. M., Papenfuss, A. T., Bansal, P., Torres, A. M., Wong, E. S., Deakin, J. E., & Belov, K. (2008). Defensins and the convergent evolution of platypus and reptile venom genes. Genome research 18:986-994.

Wong, E. S., & Belov, K. (2012). Venom evolution through gene duplications. Gene 496:1-7.

 WIKIPEDIA ARTICLE ADDITION STARTS HERE 

Utilization of venom across a large amount species demonstrates a classic example of convergent evolution and a homoplastic trait. It is difficult to conclude exactly how this trait came to be so intensely widespread and diversified. , the multigene families that encode the toxins of venomous animals are actively selected on, creating more diverse toxins with specific functions. Venoms adapt to their environment and victims and accordingly evolve to become maximally efficient on a predator’s particular prey (particularly the precise ion channels within the prey). Consequently, venoms become specialized to an animal’s standard diet (Kordis and Gubensek, 2000).

Scientists believe the origin of snake venom began with gene duplication of genes that had been expressed in the body tissues of ancestors. Due to subfunctionalization, in which an ancestral function is split between the copied genes, one of the duplicates becomes limited to only the venom (salivary) gland and as a result, evolves in to the toxin producing gene. Data has shown that pre-existing proteins in the salivary glands were the origin of the toxins in snake venom. Some researchers have come to see snake venom as just “a modified form of saliva,” instead of an entirely recruited set of proteins from various tissues throughout the body. (Hargreaves et al., 2014).

Shrews are known to have venomous saliva and most likely evolved their trait similarly to snakes. (Ligabue-Braun et al., 2012).

Extensive research on platypuses shoes that their toxin was initially formed from gene duplication, but data provides evidence that the further evolution of platypus venom does not rely as much on gene duplication as once was thought (Wong and Belov, 2012). Modified sweat glands are what evolved into platypus venom glands. Although it is proven that reptile and platypus venoms have independently evolved, it is thought that there are certain protein structures that are favored to evolve into toxic molecules. This provides more evidence as to why venom has become a homoplastic trait and why very different animals have convergently evolved (Whittington et al., 2008).