Kin discrimination in polyphenic salamander larvae: trade-offs between inclusive fitness and pathogen transmission

Abstract

Some larval amphibians can develop into two distinct morphological types: a small-headed Bnormal^morph and a rarer broad-headed morph with specialized adaptations to feed on the normal morph. Cannibalism confers nutritional benefits that accelerate development, essential for survival in transient environments, but incurs potential inclusive fitness costs. Selective cannibalism of non-kin thus should be favored. However, subjects may be more vulnerable to contracting disease from non-siblings to which they lack immunological defenses. We investigated kin discrimination and pathogen transmission among Korean salamander (Hynobius leechii) larvae. We placed broad-headed morph larvae into a circular arena together with two normal morph larvae, one their sibling and the other a non-sibling. To test for kin discrimination, we recorded all behavioral interactions among them. To study pathogen transmission, we fed broad-headed larvae either a sibling or non-sibling normal larva that we previously had infected with the bacterium Aeromonas hydrophila. Two days after ingestion, we determined whether the bacterium had systemically infected cannibals by quantitative PCR (qPCR). Broad-headed larvae discriminated between sibling and non-sibling normal larvae, directing aggressive behaviors mostly toward siblings. Infection loads varied more widely among broad-headed larvae that cannibalized non-siblings than those that cannibalized siblings, but the highest infection loads were recorded after ingestion of nonsiblings. Cannibalizing non-siblings thus may increase the risk of contracting disease. Broad-headed larvae discriminate most strongly between siblings and non-siblings late in development, when inclusive fitness costs of cannibalizing relatives diminish and vulnerability to novel pathogens transmitted by non-relatives rises.

Paternity and egg cannibalism in the ringlegged earwig Euborellia annulipes (Dermaptera: Anisolabididae)

“…; Widdig ), birds (Andersson et al . ), amphibians (Walls & Roudebush ; Pfennig et al .1993; but see Garza & Waldman ), fishes (Neff ,b; Edenbrow & Croft ) and insects (Dobler & Kölliker ; Parsons et al . ; Schultner et al .…”

“…Avoidance of aggression or cannibalism directed at kin has been noted in many different taxa, including mammals (Holmes & Sherman 1982;Blumstein et al 2002;Widdig 2007), birds (Andersson et al 2015), amphibians (Walls & Roudebush 1991;Pfennig et al1993; but see Garza & Waldman 2015), fishes (Neff 2003a,b;Edenbrow & Croft 2012) and insects (Dobler & Kölliker 2010;Parsons et al 2013;Schultner et al 2013;Bayoumy & Michaud 2015). However, the mechanisms by which individuals discriminate between kin and non-kin are not always known (Widdig 2007) and more than one mechanism could operate simultaneously (Holmes & Sherman 1983;Waldman 1988).…”

Parental Sex and Not Kinship Determines Egg Cannibalism in Arma custos Fallou (Hemiptera: Pentatomidae: Asopinae)

“…Kin-killing behavior is observed when the nutritional profits outweigh the costs of decreased inclusive fitness (Pfennig, 1997). Although strategies for avoiding cannibalism have been studied in many taxa (Samu et al, 1999;Siegel et al, 2007;Widdig, 2007;Edenbrow and Croft, 2012;Parsons et al, 2013;Bayoumy and Michaud, 2015;Garza and Waldman, 2015;Ringler et al, 2017), little is known about the mechanisms regulating the predatory behavior of hemipterans (Arbogast, 1979;Pajunen and Pajunen, 1991;Agarwala and Dixon, 1992). Most arthropods avoid consuming their own kin when given the choice Kölliker, 2010, 2011;Parsons et al, 2013).…”

Kin-Avoidance in Cannibalistic Homicide

“…Studies on tiger salamander larvae suggest cannibalistic kin-avoidance, but there is also evidence for a cannibalistic kin-preference at least at some ages. A study that tested the role of pathogens in kin cannibalism in tiger salamander larvae was conducted by Garza and Waldman (2015) and provided some evidence for differential effects of pathogens transmitted by kin‐ and non-kin predation. Finally, cannibalism has been observed in prehistory ( Villa, 2005 ), in 16th and 17th century Europe as medicinal cannibalism ( Sugg, 2015 ), and in chimpanzees and bonobos, our closest relatives in the animal kingdom ( Bygott, 1972 ; Goodall, 1977 ; Nishida and Kawanaka, 1985 ; Hamai et al, 1992 ; Fowler and Hohmann, 2010 ).…”