Par Apply and Analyze Newly studied parasite-host relationships have demonstrate
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Par Apply and Analyze Newly studied parasite-host relationships have demonstrated the influence of and preference for sexual reproduction in antagonistic coevolving species. Evaluate the following study to answer the questions further below COEVOLUTION HT Hi EVOLUTION HP Frozen stocks Time Figure 3. Parasite-host interaction in nematodes Credit: From Brockhurst M.A. 2011. Sex, death and the Red Queen. Science 336039): 166-167. Reprinted with permimion from AAAS In a study by Brockhurst (2011) researchers designed an experiment to evaluate how a parasite, capable of both asexual and sexual reproduction, may adapt to its host over a period of time. Using a Nematode worm host (H) and its cor- responding parasite (p), they devised two tests. First, they allowed the two species to co-evolve over numerous genera tions of both host (H', H, H, H') and parasite (P, P,P,P'). Then, using frozen stocks of parasite (PP, P, P, P they infected a new generation of the host (Ho, H,H',H') to examine the one-sided evolutionary progression of the host only. The rate of sexual reproduction of the parasite was graphed for both scenarios and compared to a control Questions 7. Compare the rate of sexual reproduction for the coevolving scenario as compared to the evolution scenario. What was the preferred adaptive strategy of the parasite species for coevolution? For evolution? WhyExplanation / Answer
7) In this experiment the organism C.elegans was exposed to attack by a pathogen species of a parasite. These parasite species attack and infect this nematode leading to activation of mechanisms for survival of these species. These species of nematodes start out-breeding leading to the development of new species which can survive in the changing environmental conditions and wil be resistant to the attack by these parasitic organisms. These species with new traits in nematodes will not be formed if there is inbreeding as the traits of resistance of this nematode will not be evident in the inbreeding progeny due to lack of genetic diversity in these nematode species. The process of co-evolution of nematode takes place due to outbreeding as compared to evolution which takes place during in-breeding with less genetic diversity and resistance against the pathogen attack. Thus it is an adpative strategy for survival against the infecting pathogenic parasitic species as described in the text.
8) The evolution of the nematode species due to inbreeding and parasitic infection caused the death of these species leading to the decline in the growth curve as depicted in the graph. Red -queen hypothesis signifies that parasites infect these nematodes during inbreeding among the similar species of worms causing the death of these nematodes. The nematode species become resistant and develop into co-evolution due to out-breeding among the different species leading to development of resistance and formation of new species of nematode C.elegans as evident by an increase in their population evident from the increase in the growth curve as given in the graph. The factors which were studied include host adaptation,parasite adaptation, fitness loss and deteriorating environmental conditions. The process of self-fertilization and asexual reproduction causes less genetic diversity as compared to the generation of diversity in outcrossing after sexual reproduction.
This scenario is not evident when the species of nematodes were infected with the frozen samples of parasite and there was not much significant change in the population number of the nematodes after infection. There was outcrossing among different species and self-fertilization among same species leading to an increase in the population of the nematode species.
9)Sexual reproduction is an adaptive strategy in mutualistic relationships in distinct species of termites which form a symbiotic mutualism or mutualistic symbiosis relationships with the species of the fungus Termitomyces which promotes the crop productivity. Sexual reproduction is not an adaptive strategy in antagonistic coevolving interactions with the species Pseudoxylaria species of fungus involved in a relationship with fungus growing termite species Odontotermes Obesus species of termite which does not cause an increase in crop productivity and nutrition.
References:
1)Sex and diversity: The mutualistic and parasitic fungi of a fungus growing termite differ in genetic diversity and reproductive strategy Lakshya Katariya, Priya B. Ramesh, Thejashwini GopalapFungal Ecology 26 (2017) 20e27.Renee M. Borges* Center for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India--Fungal Ecology 26 (2017) 20e27.
2)Running with the Red Queen: Host-parasite coevolution selects for biparental sex Levi T. Morran1,* , Olivia G. Schmidt1, Ian A. Gelarden1, Raymond C. Parrish II1, and Curtis M. Lively1 1Department of Biology, Indiana University, 1001 E. Third St., Bloomington, IN 47405 , Science. 2011 July 8; 333(6039): 216–218. doi:10.1126/science.1206360.
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