User:Hudson.336/sandbox

Paul Hudson TA: Paul Larson Tues @ 3

Annotated Bibliography

"Unisexual Salamander Reproduction"

I plan on writing about unisexual salamander reproduction -- known as kleptogenesis, this form of reproduction is entirely unique to 5 salamander species found in the United States and Canada. Kleptogenesis has allowed for an all female lineage of salamanders that, upon mating with a male, is able to incorporate half the genome of the male into that of its offspring. This results in elevated ploidy levels and individuals with the genetic information of up to 4 different salamander species! There is very little written about this subject on Wikipedia -- kleptogenesis does not even have its own entry, and I would love to expand on it.

Bi, K., Bogart, J., & Fu, J. (2009). An examination of intergenomic exchanges in A. laterale-dependent unisexual salamanders in the genus Ambystoma. Cytogenetic and Genome Research124, 44-50. doi:10.1159/000200087

---> This article provides a perfect graphic that describes unisexual salamanders' unique form of reproduction exceptionally well. A quick glance can help a reader to really understand kleptogenesis, and I think it would be perfect for Wikipedia or my research paper. The research also expands on unisexual reproduction by delving deeper into how different species reproduce in comparison to one another.

Bogart, J. P., Ke, B., Jinzong, F., Noble, D. A., & Niedzwiecki, J. (2007). Unisexual salamanders (genus Ambystoma) present a new reproductive mode for eukaryotes. Genome, 50(2), 119-136. doi:10.1139/G06-152

---> This is the go-to article for a description of unisexual salamander reproduction. I will definitely need to cite it in order to define kleptogenesis and describe its origins in ancient salamander lineages. I will most likely get a lot of foundational information here and then expand on it through further research.

Brodman, R., & Krouse, H. D. (2007). HOW BLUE-SPOTTED AND SMALL-MOUTHED SALAMANDER LARVAE COEXIST WITH THEIR UNISEXUAL COUNTERPARTS. Herpetologica, 63(2), 135-143.

---> This is another article that presents research on unisexual salamander life history and behavior in comparison to sexual individuals. One of its most interesting findings is that unisexual larvae are often completely superior to certain sexual species -- however, sexual species survive by adapting to different niches and utilizing refuge strategies. This could possibly explain why unisexual and sexual species are able to coexist and maintain their populations.

NOËL, S., LABONTÉ, P., & LAPOINTE, F. (2011). Genomotype Frequencies and Genetic Diversity in Urban and Protected Populations of Blue-spotted Salamanders (Ambystoma laterale) and Related Unisexuals. Journal Of Herpetology, 45(3), 294-299.

---> I really like this article because it represents contemporary research on unisexual salamanders and their life history (instead of just genetic research). It helps to demonstrate how unisexual and sexual salamander individuals are better suited to different environments, and provides further support to the investigation of why unisexual salamanders evolved and thrived (but didn't dominate) through time.

Ramsden, C. C., Bériault, K. K., & Bogart, J. P. (2006). A nonlethal method of identification of Ambystoma laterale, A. jeffersonianum and sympatric unisexuals. Molecular Ecology Notes, 6(1), 261-264. doi:10.1111/j.1471-8286.2005.01164.x

---> This is a short and simple article, but I think it is very important in protecting threatened salamander species, and would be something that is very useful to readers just doing some quick research on Wikipedia. It also has some basic information on kleptogenesis and salamander genealogy that I could definitely cite in my writing.

-Paul Hudson TA: Paul Larson Tues @ 3

Editing Project

https://en.wikipedia.org/wiki/Klepton

--Suggestion --

This article is pretty short, and I feel that there is a lot of information that could be added to make it more informative for readers. Specific information that could be added includes but is not limited to:

1.) Kleptogenesis is entirely unique to 5 salamander species of the genus Ambystoma, all of which are native to the United States and Canada.

2 Kleptogenesis results in elevated ploidy levels and, in salamanders, individuals with the genetic information of up to 5 different salamander species.

3.) Kleptogenesis has allowed the 5 Ambystoma species to evolve a unisexual lineage of all female individuals.

--Edit--

"Kleptogenesis is a form of reproduction in which a female organism is able to incorporate half the genome of a male into her offspring after mating. She is also able to mate with the male and produce clones that do not incorporate any of the male's genome."

Bogart, J (2009), "An examination of intergenomic exchanges in A. laterale-dependent unisexual salamanders in the genus Ambystoma", Cytogenetic and Genome Research 124 (04): 44–50, doi:10.1159/000200087, ISSN 1800-427X

-RESEARCH PAPER FINAL DRAFT

An Analysis of Kleptogenesis in the Ambystoma Genus of Salamanders

Paul Hudson

TA: Paul Larson

Recitation: Tuesday, 3 PM

November 14th, 2014

Sexual reproduction, for the most part, is predominant among aquatic and terrestrial vertebrates. The benefits of meiosis are powerful in the natural world -- recombination contributes to genetic diversity and, therefore, allows for a relatively rapid response to a variable environment in comparison to asexual reproduction (Lodé 2012). To compound on this point, there is strong evidence for the extinction of asexual lineages throughout history, as well as for the recent (in terms of evolution) differentiation of current asexual lineages (Bogart et al. 2007). Asexual reproduction, however, does confer pros of its own: in an all-female population, every individual can reproduce as well as contribute twice as much genetic material as sexual organisms to the next generation (Bogart & Bi 2013). It is clear, then, that either mode of reproduction has the potential to be successful -- a blend of the two strategies would seem to be highly advantageous, and it is when found in nature. An all female, unisexual complex of mole salamanders in the genus Ambystoma serve as a perfect example of organisms that have employed this meld of sex and cloning. These salamanders participate in a unique mode of reproduction known as kleptogenesis, in which mating with a male is absolutely necessary for the production of offspring, but incorporation of his genome is optional and occurs quite differently than in sexual reproduction (Bogart et al. 2007). Kleptogenic reproduction results in three potential outcomes. The female may simply activate cell division in the egg through the presence of a male's sperm without incorporating any of his genetic material -- this results in the production of clonal offspring. The female may also incorporate the male's sperm into her egg, but can do so without excising any of her genetic material. This results in increased ploidy levels that range from triploid to pentaploid in wild-caught individuals. Finally, the female also has the option of replacing some of her genetic material with that of the male's, resulting in a "hybrid" of sorts without increasing ploidy (Bogart & Bi 2013). In total, five species of Ambystoma salamanders contribute to this unisexual complex: A. tigrinum, A. barbouri, A. texanum, A. jeffersonium, and A. laterale. Over twenty genomic combinations have been found in nature, ranging from "LLJ" individuals (two A. laterale and an A. jeffersonium genome) to "LJTi" individuals (an A. laterale, A. jeffersonium, and an A. tigrinum genome) (Bogart & Bi 2013). Every combination, however, contains the genetic information from the A. laterale species, and analysis of mitochondrial DNA has indicated that these unisexual species most likely diverged from an A. barbouri individual some 5 million years ago (Bogart et al. 2007), making them the oldest unisexual vertebrate species on Earth (Bi & Bogart 2010). The fact that these salamanders have persisted for so long is remarkable, as it contradicts the notion that a majority of asexual lineages arise when the conditions are right and quickly disappear (Lodé 2012). It has been argued that this persistence is very much due to the aforementioned "genome replacement" strategy that accompanies kleptogenic reproduction -- replacing a portion of the maternal genome with paternal DNA in offspring has allowed unisexual individuals to "refresh" their genetic material through time. This facet of kleptogenesis was recently ascertained from genetic research that indicates there is no ancestral A. laterale genome that is maintained from one unisexual to the next, and that there is not a specific "L" genome that is found more often than others. "L" genetic material found in these salamanders has also not evolved to be substantially unique from sexual genomes (Bi et al. 2009). Because all members of the unisexual Ambystoma complex require an "L" genome but do not share a particular one in common, than it could potentially be argued that the presence of A. laterale genetic material is critical to unisexual reproduction and success. Perhaps the "L" genome is, in effect, being used to keep unisexual species up to date with the environment around them without strictly reproducing sexually. In other words, to prevent the accumulation of deleterious mutations, these salamanders could replace an "L" genome that has begun to demonstrate low fitness with the genome of a fit A. laterale individual while still maintaining another 2-4 genomes for the next generation. They could, in effect, circumnavigate "Muller's Ratchet" (Bi et al. 2009). With such noteworthy success throughout history, one would expect these unisexual individuals to have completely overrun and replaced strictly sexual species. This, however, is not the case, and the reasons behind this phenomenon are being studied extensively to better understand the evolution of these persistent amphibians. There is no doubt that unisexual and sexual salamander species coexist; unisexual species require a sexual male to reproduce, even clonally (Brodman & Krouse 2007). For example, A. laterale and A. texanum larvae persist in ponds that contain unisexual larvae, even though unisexual larvae have been proven to be better overall competitors than the A. laterale larvae at this life stage -- they are often larger and better hunters, even capable of consuming larvae of the sexual species. How, then, can the three species coexist (Brodman & Krouse 2007)? There is strong evidence for a change in sexual salamander species' behavior. The larvae of A. laterale, who suffer from weakened growth and lower rates of survival in the presence of unisexual larvae, were found to be "hiding" at significantly higher rates when exposed to this competition. They were found under leaf litter and other vegetation a majority of the time, while unisexual larvae could be found hiding or actively hunting in equal amounts. Behavior such as this is indicative of niche partitioning; the sexual species must change their mode of resource acquisition (sneaking vs. open hunting) in order to reduce competition and encourage coexistence (Brodman & Krouse 2007). The persistence of sexual Ambystoma species in the face of high competition from unisexual individuals can also be analyzed through an alternative lens. The reproductive interactions between the two salamander complexes are, in effect, a form of parasitism. Because there is the potential for none of a sexual male's genetic material to be passed on to the next generation, there is a fitness deficit associated with mating with a unisexual female. If unisexual females play the role of a parasite, then it is critical to their success that their host (the sexual male) is not killed or extirpated. This interplay between organisms helps to explain the coexistence of both species -- by what mechanisms, however, is this maintained? Research conducted by Dawley and Dawley (1986) has indicated that sexual males are able to differentiate between sexual and unisexual females, which are otherwise morphologically quite similar. It was shown that this differentiation is conducted via a chemical pathway -- in the study, sexually active males were given the choice of traversing a path that ended in a sexually active unisexual female or another path that ended in a sexually active conspecific female. Males were found to have preferentially chosen conspecifics over unisexuals a majority of the time (Dawley & Dawley 1986). How, then, are unisexual females able to persist in the face of chemical detection and avoidance by sexual males? During salamander mating rituals, the male produces spermatophores (capsules filled with sperm) that the female is then able to latch onto if she finds her mate's display to be satisfactory. As it is possible for sexual males to release over 40 spermatophores during just one mating ritual, it would not be out of the question for nearby unisexual females to obtain sperm from these extra spermatophores. There is also the potential for "desperate" males, who are surrounded by exclusively unisexual females, to purposefully mate with them (Dawley & Dawley 1986). The knowledge gained from this study further explains the concurrence of asexual and sexual individuals in light of the Red Queen Hypothesis. The Red Queen Hypothesis states that living organisms are in a constant evolutionary arms race with one another, simply in order to survive. This suits the case of unisexual and sexual salamanders quite well -- the two species have coevolved. Sexual lineages have persisted throughout history because they are able to avoid reproducing with unisexuals and mate with conspecifics, and the unisexual lineage has persisted because the species complex often exhibits competitive advantages and is able to parasitize sexual individuals. The derived traits of both lineages have prevented one from overtaking the other. The contemporaneousness of both lineages can also be explained in the context of limiting resources. Phosphorous is a nutrient critical to life on Earth, as it plays an integral role in DNA structure. Because polyploid individuals can potentially have over twice the amount of DNA than diploid individuals, they would need to acquire over twice as much phosphorous in their diet. When resources are low and it is difficult to find food rich in phosphorous, than sexual salamander species would have a fitness advantage over unisexual salamanders, who would struggle to grow and produce offspring (Neiman et al. 2013). In the end, the polyploid unisexual complex of Ambystoma salamanders is an evolutionary powerhouse that has walked the Earth longer than any other unisexual vertebrate in history. Their distinct form of reproduction, kleptogenesis, has conferred on them multiple fitness advantages over their sexual counterparts, who they may utilize as activators of asexual reproduction or as a source for new, additive genetic material. Coevolutionary competition between the two lineages, however, has resulted in their coexistence across North America. Hopefully, future research can further elucidate the exact mechanisms by which kleptogenesis occurs, and why it occurs in just a select few salamanders species.

References

Bi, K., Bogart, J., & Fu, J. (2009). An examination of intergenomic exchanges in A. laterale-dependent unisexual salamanders in the genus Ambystoma. Cytogenetic and Genome Research, 124, 44-50. doi:10.1159/000200087

Bi, K., Bogart, J. (2010). Time and Time again: unisexual salamanders (genus Ambystoma) are the oldest unisexual vertebrates. BMC Evolutionary Biology, 10(1), 1-14.

Bogart, J. P., & Bi, K. (2013). Genetic and genomic interactions of animals with different ploidy levels. Cytogenetic and genome research, 140(2-4), 117-136.

Bogart, J. P., Ke, B., Jinzong, F., Noble, D. A., & Niedzwiecki, J. (2007). Unisexual salamanders (genus Ambystoma) present a new reproductive mode for eukaryotes. Genome, 50(2), 119-136. doi:10.1139/G06-152

Brodman, R., & Krouse, H. D. (2007). How Blue-spotted and Small-mouthed salamanders larvae coexist with their unisexual counterparts. Herpetologica, 63(2), 135-143.

Dawley, E., & Dawley, R. (1986). Species Discrimination by Chemical Cues in a Unisexual-Bisexual Complex of Salamanders. Journal of Herpetology, 20(1), 114-116.

Lodé, T. (2012). Adaptive Significance and Long-Term Survival of Asexual Lineages. Evolutionary Biology. Published online: http://link.springer.com.proxy.lib.ohio-state.edu/article/10.1007/s11692-012-9219-y/fulltext.html

Neiman, M., Kay, A., & Krist, A. (2013). Can resource costs of polyploidy provide an advantage to sex?. Heredity, 110(2), 152-159. doi:10.1038/hdy.2012.78

Changes to the Klepton Page

Kleptogenic reproduction results in three potential outcomes. A unisexual female may simply activate cell division in the egg through the presence of a male's sperm without incorporating any of his genetic material -- this results in the production of clonal offspring. The female may also incorporate the male's sperm into her egg, but can do so without excising any of her genetic material. This results in increased ploidy levels that range from triploid to pentaploid in wild-caught individuals. Finally, the female also has the option of replacing some of her genetic material with that of the male's, resulting in a "hybrid" of sorts without increasing ploidy.[4].

In the wild, five species of Ambystoma salamanders contribute to a unisexual complex that reproduces via kleptogenesis: A. tigrinum, A. barbouri, A. texanum, A. jeffersonium, and A. laterale. Over twenty genomic combinations have been found in nature, ranging from "LLJ" individuals (two A. laterale and an A. jeffersonium genome) to "LJTi" individuals (an A. laterale, A. jeffersonium, and an A. tigrinum genome)[4]. Every combination, however, contains the genetic information from the A. laterale species, and analysis of mitochondrial DNA has indicated that these unisexual species most likely diverged from an A. barbouri individual some 5 million years ago[5], making them the oldest unisexual vertebrate species on Earth[6]

The fact that these salamanders have persisted for so long is remarkable, as it contradicts the notion that a majority of asexual lineages arise when the conditions are right and quickly disappear [7]. It has been argued that this persistence is very much due to the aforementioned "genome replacement" strategy that accompanies kleptogenic reproduction -- replacing a portion of the maternal genome with paternal DNA in offspring has allowed unisexual individuals to "refresh" their genetic material through time. This facet of kleptogenesis was recently ascertained from genetic research that indicates there is no ancestral A. laterale genome that is maintained from one unisexual to the next, and that there is not a specific "L" genome that is found more often than others. "L" genetic material found in these salamanders has also not evolved to be substantially unique from sexual genomes.[4]

-->I also removed the changes I made earlier in the semester because I went into more detail here. The information directly from my paper flowed pretty smoothly with the article, but I made a few changes to make it sound a bit more like an encyclopedia entry.