Limits...
How specificity and epidemiology drive the coevolution of static trait diversity in hosts and parasites.

Boots M, White A, Best A, Bowers R - Evolution (2014)

Bottom Line: We examine theoretically how epidemiological feedbacks and the characteristics of the interaction between host types and parasites strains determine the coevolution of host-parasite diversity.The interactions include continuous characterizations of the key phenotypic features of classic gene-for-gene and matching allele models.We emphasize that although the high specificity is well known to promote temporal "Red Queen" diversity, it is costs and combinations of hosts and parasites that cannot infect that will promote static trait diversity.

View Article: PubMed Central - PubMed

Affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom. m.boots@exeter.ac.uk.

Show MeSH

Related in: MedlinePlus

Transmission functional forms and evolutionary simulations with costs to host resistance or parasite transmission showing multiple branching. Subpanels A(i)–D(i) indicate the transmission coefficient, , for susceptible host type h against 11 representative parasite strains () from the continuous distribution of the parasite with strain  indicated in red and other types progressing in order from this type. A(ii)–D(ii) display “heat” diagrams where is shown for a continuous combination of susceptible host types h against parasite strains p. A(iii)–D(iii) show the relationships between host type and reproduction (solid line) and parasite strain and either maximum transmission or virulence (dotted line). Simulations of the model represented by equations 1–2 with the respective transmission functions are shown for the host in A(iv)–D(iv) and for the parasite in A(v)–D(v). The specific functions are for (A) ,  and ; (B) ,  and ; (C) ,  and ; (D) ,  and . Other parameters and simulation methods are as in Figure1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4257575&req=5

fig03: Transmission functional forms and evolutionary simulations with costs to host resistance or parasite transmission showing multiple branching. Subpanels A(i)–D(i) indicate the transmission coefficient, , for susceptible host type h against 11 representative parasite strains () from the continuous distribution of the parasite with strain indicated in red and other types progressing in order from this type. A(ii)–D(ii) display “heat” diagrams where is shown for a continuous combination of susceptible host types h against parasite strains p. A(iii)–D(iii) show the relationships between host type and reproduction (solid line) and parasite strain and either maximum transmission or virulence (dotted line). Simulations of the model represented by equations 1–2 with the respective transmission functions are shown for the host in A(iv)–D(iv) and for the parasite in A(v)–D(v). The specific functions are for (A) , and ; (B) , and ; (C) , and ; (D) , and . Other parameters and simulation methods are as in Figure1.

Mentions: Figure3 shows infection matrices with specificity and variation in infectivity and susceptibility range that do lead to the generation of polymorphism through multiple branching (in all cases, costs are imposed on host resistance and parasite transmission as indicated by Figure3, column iii). The CD analysis is undertaken on the general model (equations 1 and 2) and indicates that there is no limit to the level of diversity that can occur (details are shown in the Supporting Information). However, the CD analysis indicates that host–parasite coexistence is only possible when the number of host strains and parasite strains is equal or the host strains exceed the parasite strains by 1. This therefore permits “any” level of diversity, but imposes the restriction that if it is to occur through a process of evolutionary branching, then it requires a strict, repeating, pattern in which a host branching event is followed by a parasite branching event. AD analysis and simulations confirm the CD findings and show that for a suitable choice of trade-offs, polymorphism will evolve through a repeating process of an evolutionary branching event in the host followed by evolutionary branching event in the parasite (Fig.3, see Supporting Information for more detail and Best et al. (2010) for a discussion on the shape of trade-offs that lead to branching for the model shown in Fig.3A). This process is further highlighted in Figure4 in which simulation results of Figure3A are enhanced to indicate the position of the host and parasite branching points and to include local pairwise invadability plots for each of the current residents strains at the branching points. As predicted from the CD and AD analyses, branching occurs in a strict order of host, then parasite (Fig.4).


How specificity and epidemiology drive the coevolution of static trait diversity in hosts and parasites.

Boots M, White A, Best A, Bowers R - Evolution (2014)

Transmission functional forms and evolutionary simulations with costs to host resistance or parasite transmission showing multiple branching. Subpanels A(i)–D(i) indicate the transmission coefficient, , for susceptible host type h against 11 representative parasite strains () from the continuous distribution of the parasite with strain  indicated in red and other types progressing in order from this type. A(ii)–D(ii) display “heat” diagrams where is shown for a continuous combination of susceptible host types h against parasite strains p. A(iii)–D(iii) show the relationships between host type and reproduction (solid line) and parasite strain and either maximum transmission or virulence (dotted line). Simulations of the model represented by equations 1–2 with the respective transmission functions are shown for the host in A(iv)–D(iv) and for the parasite in A(v)–D(v). The specific functions are for (A) ,  and ; (B) ,  and ; (C) ,  and ; (D) ,  and . Other parameters and simulation methods are as in Figure1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257575&req=5

fig03: Transmission functional forms and evolutionary simulations with costs to host resistance or parasite transmission showing multiple branching. Subpanels A(i)–D(i) indicate the transmission coefficient, , for susceptible host type h against 11 representative parasite strains () from the continuous distribution of the parasite with strain indicated in red and other types progressing in order from this type. A(ii)–D(ii) display “heat” diagrams where is shown for a continuous combination of susceptible host types h against parasite strains p. A(iii)–D(iii) show the relationships between host type and reproduction (solid line) and parasite strain and either maximum transmission or virulence (dotted line). Simulations of the model represented by equations 1–2 with the respective transmission functions are shown for the host in A(iv)–D(iv) and for the parasite in A(v)–D(v). The specific functions are for (A) , and ; (B) , and ; (C) , and ; (D) , and . Other parameters and simulation methods are as in Figure1.
Mentions: Figure3 shows infection matrices with specificity and variation in infectivity and susceptibility range that do lead to the generation of polymorphism through multiple branching (in all cases, costs are imposed on host resistance and parasite transmission as indicated by Figure3, column iii). The CD analysis is undertaken on the general model (equations 1 and 2) and indicates that there is no limit to the level of diversity that can occur (details are shown in the Supporting Information). However, the CD analysis indicates that host–parasite coexistence is only possible when the number of host strains and parasite strains is equal or the host strains exceed the parasite strains by 1. This therefore permits “any” level of diversity, but imposes the restriction that if it is to occur through a process of evolutionary branching, then it requires a strict, repeating, pattern in which a host branching event is followed by a parasite branching event. AD analysis and simulations confirm the CD findings and show that for a suitable choice of trade-offs, polymorphism will evolve through a repeating process of an evolutionary branching event in the host followed by evolutionary branching event in the parasite (Fig.3, see Supporting Information for more detail and Best et al. (2010) for a discussion on the shape of trade-offs that lead to branching for the model shown in Fig.3A). This process is further highlighted in Figure4 in which simulation results of Figure3A are enhanced to indicate the position of the host and parasite branching points and to include local pairwise invadability plots for each of the current residents strains at the branching points. As predicted from the CD and AD analyses, branching occurs in a strict order of host, then parasite (Fig.4).

Bottom Line: We examine theoretically how epidemiological feedbacks and the characteristics of the interaction between host types and parasites strains determine the coevolution of host-parasite diversity.The interactions include continuous characterizations of the key phenotypic features of classic gene-for-gene and matching allele models.We emphasize that although the high specificity is well known to promote temporal "Red Queen" diversity, it is costs and combinations of hosts and parasites that cannot infect that will promote static trait diversity.

View Article: PubMed Central - PubMed

Affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom. m.boots@exeter.ac.uk.

Show MeSH
Related in: MedlinePlus