The cost of reproduction hypothesis suggests that allocation into current reproduction constrains future reproduction. How organisms accrue reproductive costs may differ between species and with varying levels of resource quality. Burying beetles are model organisms for testing for the cost of reproduction because of their unique natural history; beetles utilize small vertebrate carcasses for reproduction and they and their offspring feed exclusively on these discrete resources. Burying beetles also can utilize a large range of carcass sizes for reproduction. We tested for the cost of reproduction in two species of burying beetles, Nicrophorus marginatus and Nicrophorus guttula found in Central Utah by breeding beetles on a range of carcass sizes (5g, 10g, 20g, 30g, 40g, and 50g carcasses). We also used a manipulation experiment to force beetles into over-allocating energy into reproduction to assess reproductive costs. For both species, reproduction was costly, with beetles suffering reduced lifespan and reduced lifetime fecundity with increased resource quality. Both species also showed clear signs of senescence, having reduced brood size and lower efficiency as individuals aged. Females did not show indications of terminal investment in terms of female mass change, unlike the previously studied Nicrophorus orbicollis, which gained less mass after each reproductive attempt as it aged. Nicrophorus marginatus consistently outperformed N. guttula in terms of total number of offspring produced for all carcass sizes. Nicrophorus guttula populations may continue to persist with N. marginatus by exploiting a less desirable but more abundant resource.



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Life Sciences; Biology



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burying beetles, cost of reproduction, terminal investment, resource allocation

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Biology Commons