Happy Easter, Everyone! Since we all know that chocolate (delicious, delicious chocolate) rots your teeth, I got you something else for Easter: Parasite Papers! MMMMM!
Remember when I talked about the dilution effect recently? I said that having hosts species with low competency would reduce disease transmission because low competency hosts reduce encounter rates between infectious agents and high competency hosts. ‘Decoy hosts’ (aka ‘dead end hosts’) are resistant ‘hosts’; they have a competency of 0, or close to it. So, they should be sucking up parasites without transmitting them, and therefore they should reduce the parasite population. But wait… what if parasites don’t die when they try to infect a decoy host? What if they get a second chance to find a susceptible host? Dun, dun, dun! (Ecology and Evolution is open access. You could read this paper RIGHT NOW, if you want. I’m sure the suspense is killing you.)
King, K.C., S.K.J.R. Auld, P.J. Wilson, T. James, and T.J. Little. 2013. The bacterial parasite Pasteuria ramosa is not killed if it fails to infect: implications for coevolution. Ecology and Evolution 3(2): 197-203.
Protective Symbionts Come at a Cost:
This is one of my favorite disease ecology topics: symbionts that reduce infection! But are disease-reducing symbioses free? Not in this aphid disease system! (Again, this is open access.)
Vorburger, C., P. Ganesanandamoorthy, and M. Kwiatkowski. 2013. Comparing constitutive and induced costs of symbiont-conferred resistance to parasitoids in aphids. Ecology and Evolution 3(3): 706-713.
Potassium Increases Disease Epidemics:
How about some abiotic factors? Potassium increases Daphnia and fungus populations, thereby increasing epidemics in this aquatic system. I like this paper because its very thorough. They did field work, modelling, and lab and mesocosm experiments.
Civitello, D.J., R.M. Penczykowski, J.L. Hite, M.A. Duffy, and S.R. Hall. 2013. Potassium stimulates fungal epidemics in Daphnia by increasing host and parasite reproduction. Ecology 94:380–388.
Paired Papers: Cane Toad Invasion!
Cane toads are still spreading throughout Australia. Last year, I read a cool paper about how there is some “enemy release” at the cane toad range edge, because lung worm parasite infections lag behind the invasion front by roughly two years. The Ecology Letters papers used a common garden experiment to demonstrate selection for better parasite transmission at the range edge. This year, their JAE paper explores the evolution of the toads; the rate of range expansion is increasing, and toads at the range edge are bigger and grow faster than non-edge toads.
Kelehear, C., G. P. Brown, and R. Shine. 2012. Rapid evolution of parasite life history traits on
an expanding range-edge. Ecology Letters 15: 329–337.
Brown, G.P., C. Kelehear, and R. Shine. 2013. The early toad gets the worm: cane toads at an invasion front benefit from higher prey availability. Journal of Animal Ecology.
Dilution Effect: a Meta-Analysis
Back to the dilution effect. Does host biodiversity broadly reduce infection? This paper says no, its more about community composition.
Daniel J Salkeld, D.J., K.A. Padgett, and J.H. Jones. 2013. A meta-analysis suggesting that the relationship between biodiversity and risk of zoonotic pathogen transmission is idiosyncratic. Ecology Letters.
Paper 1: I have to get some parasite manipulation stuff in here. So, here’s a neat paper about parasites making brine shrimp aggregate more than if they were uninfected. “EAT US ALL; WE’RE INFECTED.”
Paper 2: Oh, there’s more. Cestode-infected brine shrimp hang out at the surface of the water more than uninfected brine shrimp. Infected hosts alter their resource use, too. (Sadly, they don’t switch to eating brains.) That altered resource use changes the isotopic signature of the host, which could in turn effect energy flow in food webs. NEAT!
Nicolas O. Rode, N.O., E.J.P. Lievens, E. Flaven, A. Segard, R. Jabbour-Zahab, M.I. Sanchez, T. Lenormand. 2013. Why join groups? Lessons from parasite-manipulated Artemia. Ecology Letters 16(4): 493-501.
Sanchez, M.I., N. Varo, C. Matesanz, C. Ramo, J.A. Amat, and A.I. Green. 2013. Cestodes change the isotopic signature of brine shrimp, Artemia, hosts: Implications for aquatic food webs. International Journal of Parasitology 43(1): 73-80. (PDF LINK)
Which paper (or pair of papers) are you most interested in?