Rapid evolution of parasite life history traits on an expanding range-edge.
Parasites of invading species undergoing range advance may be exposed to powerful new selective forces. Low host density in range-edge populations hampers parasite transmission, requiring the parasite to survive longer periods in the external environment before encountering a potential host. These conditions should favour evolutionary shifts in offspring size to maximise parasite transmission. We conducted a common-garden experiment to compare life history traits among seven populations of the nematode lungworm (Rhabdias pseudosphaerocephala) spanning from the parasite population core to the expanding range-edge in invasive cane toads (Rhinella marina) in tropical Australia. Compared to conspecifics from the population core, nematodes from the range-edge exhibited larger eggs, larger free-living adults and larger infective larvae, and reduced age at maturity in parasitic adults. These results support a priori predictions regarding adaptive changes in offspring size as a function of invasion history, and suggest that parasite life history traits can evolve rapidly in response to the selective forces exerted by a biological invasion.
School of Biological Sciences, A08, University of Sydney, Sydney, NSW 2006, Australia.
Crystal
C
Kelehear
School of Biological Sciences, A08, University of Sydney, Sydney, NSW 2006, Australia.
Gregory P
GP
Brown
School of Biological Sciences, A08, University of Sydney, Sydney, NSW 2006, Australia.
Richard
R
Shine
D000818:Animals; D001315:Australia; D005075:Biological Evolution; D049628:Body Size; D002024:Bufo marinus / Q000469:parasitology*; D005260:Female; D005298:Fertility; D006790:Host-Parasite Interactions; D058865:Introduced Species; D007814:Larva; D008018:Life Cycle Stages; D010063:Ovum; D011156:Population Density; D017172:Rhabditoidea / Q000502:physiology*