Variation in stickleback head morphology associated with parasite infection

Abstract

Dingemanse, N. J., Oosterhof, C., Van Der Plas, F., Barber, I. (2009). Variation in stickleback head morphology associated with parasite infection. Biological Journal of the Linnean Society, 96, (4), 759-768. Sponsorship: Netherlands Organization for Scientific Research; Research Council of Norway IMPF: 02.04 RONO: 00Parasites can affect host phenotypes, influencing their ecology and evolution. Host morphological changes occurring post-infection might result from pathological by-products of infection, or represent adaptations of hosts or parasites. We investigated the morphology of three-spined sticklebacks, Gasterosteus aculeatus, from a population naturally infected with Schistocephalus solidus, which grows to large sizes in their body cavity. We examined local effects of infection on trunk shape, which are imposed directly by the bulk of the growing parasite, and distant effects on head morphology. We show that trunk shape differed between infection classes, and was affected more severely in fish with heavier total parasite mass. We further show unexpected differences in head morphology. The heads of infected fish were reduced in size and differently shaped to those of non-infected fish, with infected fish having deeper heads. Importantly, both head size and shape were also affected more severely in fish with heavier total parasite mass. This latter result suggests that differences in morphology are caused by post-infection changes. Such changes may be incidental, evolutionarily neutral 'side effects' of infection. However, because head morphology affects foraging ecology, such changes are likely to have fitness consequences for hosts, and may constitute adaptations, either of hosts or of parasites. We discuss our finding in the context of the evolution of phenotypic plasticity, and suggest testable hypotheses examining the proximate mechanisms underlying these morphological effects and their potential evolutionary basis.Peer reviewe

Ant Societies Buffer Individual-Level Effects of Parasite Infections

“…Parasites often affect head size and shape, even when they do not reside in the head itself. Cestode-infected fish exhibit smaller heads, and head size further decreased with increasing parasitic load (Dingemanse et al 2009). This pattern of increased morphological change in response to increased parasitic load has been previously observed in various systems (Krist 2000).…”

“…Although host responses to infection are clearly common, it remains difficult to predict the direction they will take and the degree to which host and parasite will benefit from them (Dingemanse et al 2009). For example, body size can either increase or decrease in response to the parasite.…”

Summary and perspective on evolutionary ecology of fishes

“…Parasites can affect host phenotypes, for example by causing a reduction in size and shape of heads of threespined sticklebacks (Dingemanse et al 2009a). Furthermore, parasites can increase selection against migrants between diversifying populations because migrants encounter parasites to which they are poorly adapted (Maccoll and Chapman 2010).…”

Behavioral, physiological and morphological correlates of parasite intensity in the wild Cururu toad (Rhinella icterica)

“…The process of dynamic interactions between host and parasite can lead to host physiological and morphological changes (Johnson, 1999, Roberts et al., 1999, Tinsley et al., 2002, Kristan and Hammond, 2004, Dingemanse et al., 2009). Experimental studies with adult and young mice ( Mus musculus ) have shown that the intestinal nematode ( Heligmosomoides polygyrus ) decrease host body reserves (e.g.…”