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The natural history of Nicrophorus nigrita, a Western Nearctic species (Coleoptera: Silphidae)

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Abstract

Nicrophorus nigrita Mannerheim is an atypical Nearctic burying beetle due to its lack of dorsal, elytral maculations. Aspects of this species' natural history were investigated and compared to those of Nearctic congeners. Adults from a central Californian coastal population were found to be crepuscular and active year-round, with minimal activity during winter. The sex ratio of wild-trapped N. nigrita was female-biased while laboratory-raised broods were slightly male-biased. Adult male pronotal width was greater than that of females (mean ± SD) (5.84 ± 0.74 vs. 5.67 ± 0.66). A minimum population size of 4565 individuals was calculated for Big Creek Canyon. Analysis of mouse carcass transect data indicated that N. nigrita adults located dead mice more successfully in moist, cool, redwood-forested canyons than in six other habitat-types. Vertebrate scavengers, flies and ants were the most common competitors of N. nigrita for mouse carcasses. The reproductive biology of this species differed only slightly from known Nicrophorus biology. Carcass mass strongly predicted the mean pronotal width of the offspring in a brood. Nicrophorus nigrita differs from Nearctic congeners in the lack of elytral maculations, the greater length of time required to complete development from larva to adult and an apparent lack of reproductive diapause. It only shares year-round activity with Nicrophorus mexicanus Matthews.
... Burying beetles, genus Nicrophorus, are broadly distributed in the northern hemisphere (Sikes andVenables 2013, Sikes et al. 2016). In many locations, multiple species cooccur (Peck and Kaulbars 1987, Lomolino et al. 1995, Dekeirsschieter et al. 2011) and compete for small vertebrate carcasses that all Nicro phorus species use for reproduction (Scott 1998). ...
... Thermal optimums vary depending on food availability and species' thermoregulatory capacity (Dreisig 1980). Within the genus Nicrophorus, different species exhibit varying environmental temperature tolerances (Wilson et al. 1984, Trumbo 1990, Sikes 1996, Scott 1998. Body sizes and morphological features of burying beetles play a significant role in their ability to thermoregulate (Merrick and Smith 2004). ...
... (www.r-project.org). Quinby, 2016) N. pustulatus (24 ∘ C; Robertson, 1992;Rauter & Moore, 2002) N. vespillo (20 ∘ C; Meierhofer et al., 1999) N. vespillo (15 ∘ C; Meierhofer et al., 1999) N. nigrita (13-20 ∘ C; Sikes, 1996) Setup-Oviposition ( ...
... More unexpected is the finding that N. sayi development is substantially slower than development of the congeners N. orbicollis Say and N. vespillo (Linnaeus) when the latter two were reared at 15 ∘ C, despite this apparently being a suboptimal temperature for these species (Meierhofer et al., 1999;Quinby, 2016). Furthermore, a second species, N. nigrita Mannerheim, that has peak activity in similar temperatures in late autumn at high elevation in California, displays remarkably similar total development time (Sikes, 1996). ...
Article
1. Burying beetles (Nicrophorus spp.) provide an excellent model system to test predictions about the relationships between environment, life‐history and behaviour. All species in the genus display similar natural histories, breeding on vertebrate carcasses and providing parental care to developing offspring. However, variations in other aspects of species' ecologies provide a rich framework to examine the evolution of parental behaviours and other traits. 2. One little‐studied species, N. sayi, breeds in substantially colder temperatures than its congeners, creating a potentially harsh environment for offspring. Here, we examined the timing of reproductive and developmental events in this species, and also investigated the effects of removing parents on offspring performance. 3. We find that development is not only extremely slow in this species, but it is also delayed even in comparison to other burying beetles reared at similar temperatures. However, the presence of parents reduces the time that offspring take to leave the carcass. This decrease in development time does not appear to result in a trade‐off with mortality or body size. 4. From these results, we suggest that very slow development may be advantageous when living in a particularly cold environment. Additionally, one role of extended parental care may be to assist offspring in dealing with these harsh conditions, and to mitigate the potentially negative consequences of adopting such a slow life‐history strategy.
... We captured more females than males of both Nicrophorus species. Across Nicrophorus 316 species, some studies have documented roughly equal sex ratios in the wild (Milne & Milne, 1976;317 Anderson, 1982;Otronen, 1988), while others have also noted higher captures rates of females 318 than males (Conley, 1982;Trumbo, 1990;Sikes, 1996). However, this is not necessarily indicative 319 of differences in secondary sex ratios. ...
Preprint
Burying beetles of the genus Nicrophorus have become a model for studying the evolution of complex parental care in a laboratory. Nicrophorus species depend on small vertebrate carcasses to breed, which they process and provision to their begging offspring. However, vertebrate carcasses are highly sought after by a wide variety of species and so competition is expected to be critical to the evolution of parental care. Despite this, the competitive environment for Nicrophorus is rarely characterized in the wild and remains a missing factor in laboratory studies. Here, we performed a systematic sampling of Nicrophorus orbicollis living near the southern extent of their range at Whitehall Forest in Clarke County, Georgia, USA. We determined the density of N. orbicollis and other necrophilous species that may affect the availability of this breeding resource through interference or exploitation competition. In addition, we characterize body size, a key trait involved in competitive ability, for all Nicrophorus species at Whitehall Forest throughout the season. Finally, we compare our findings to other published natural history data for Nicrophorines. We document a significantly longer active season than was observed twenty years previously at Whitehall Forest for both N. orbicollis and Nicrophorus tomentosus , potentially due to climate change. As expected, the adult body size of N. orbicollis was larger than N. tomentosus , the only other Nicrophorus species that was captured in 2022 at Whitehall Forest. The other most prevalent interspecific insects captured included species in the families Staphylinidae, Histeridae, Scarabaeidae, and Elateridae, which may act as competitors or predators of Nicrophorus eggs and larvae. Together, our results indicate significant variation in intra- and interspecific competition relative to populations within the N. orbicollis range. These findings suggest that the competitive environment varies extensively over space and time, which help to inform the role of ecology in the evolution of parental care in this species.
... The species has previously been observed in Europe (mostly on different Nicrophorus species; Hyatt, 1980;Korn, 1982), North America (N. investigator, N. nigrita;Grossman & Smith, 2008;Sikes, 1996) Wettlaufer et al., 2018). Nicrophorus pustulatus thus occupies a distinct ecological niche that may isolate the mites, and possibly select for adaptations specific to this niche. ...
Article
Coevolution is often considered a major driver of speciation, but evidence for this claim is not always found because diversity might be cryptic. When morphological divergence is low, molecular data are needed to uncover diversity. This is often the case in mites, which are known for their extensive and often cryptic diversity. We studied mites of the genus Poecilochirus that are phoretic on burying beetles (Silphidae: Nicrophorus). Poecilochirus taxonomy is poorly understood. Most studies on this genus focus on the evolutionary ecology of Poecilochirus carabi sensu lato, a complex of at least two biological species. Based on molecular data of 230 specimens from 43 locations worldwide, we identified 24 genetic clusters that may represent species. We estimate that these mites began to diversify during the Paleogene, when the clade containing P. subterraneus branched off and the remaining mites diverged into two further clades. One clade resembles P. monospinosus. The other clade contains 17 genetic clusters resembling P. carabi s.l.. Among these are P. carabi sensu stricto, P. necrophori, and potentially many additional cryptic species. Our analyses suggest that these clades were formed in the Miocene by large‐scale geographic separation. Diversification also seems to have happened on a smaller scale, potentially due to adaptation to specific hosts or local abiotic conditions, causing some clusters to specialize on certain beetle species. Our results suggest that biodiversity in this genus was generated by multiple interacting forces shaping the tangled webs of life.
... Further, previous studies that quantify daily activity in burying beetles through hourly trap checks, provide evidence for daily temporal niche partitioning Ohkawara et al. 1998;Bedick et al. 1999). Specifically, N. tomentosus has been documented as a diurnal species, while N. orbicollis, N. sayi, and N. americanus are documented as nocturnal Sikes 1996;Bedick et al. 1999). To this point, however, there has been no high-resolution, comprehensive examination of the daily activity of burying beetles and how they relate to space use in a speciose community. ...
Article
Full-text available
Resource niche partitioning mediates the coexistence of similar species by reducing the chance of competitive encounters. For co-occurring species that share an ephemeral resource, contrasting activity in space and time may facilitate their persistence. Burying beetles (Silphidae: Nicrophorus) depend entirely on small vertebrate carcasses to reproduce. Given the unpredictability of this resource, and its value to congeners and other scavenger species, burying beetles likely endure intense competition to secure a carcass. Here, contrasting spatial and temporal niche patterns are explored as resource allocation strategies among five sympatric species of burying beetles (N. americanus, N. marginatus, N. pustulatus, N. orbicollis, and N. tomentosus). Specifically, the space-use and daily activity patterns are measured, at a fine scale, across species pairs to extrapolate contrasting niche-use patterns within a nicrophorine-rich grassland community in North-Central Oklahoma, USA. The results of this study reveal an important interplay between space-use and daily temporal activity in mediating the scramble competition associated with carrion resources. Where spatial or temporal overlap between burying beetle species is high, direct competition is mediated along an alternative niche dimension. For instance, N. americanus and N. orbicollis, a species dyad thought to be in direct competition, do overlap temporally but were found to have segregated space-use patterns. Our findings provide key insights into the competitive interactions within a necrophilous community and further inform our broader understanding of the spatial and temporal resource dimensions that drive the ecological niche.
... The Silphidae is a small family of Coleoptera, commonly known as Carrion Beetles and is comprised of about 175 species arranged in 15 genera (Peck, 2001). The Australian fauna is poorly developed, with only three known species in two genera (Williams, 1981;Sikes, 1996;Peck, 2001). Froggatt (1907) had earlier noted that the family was poorly represented in Australia with 13 described species. ...
Article
Full-text available
The Australian burying beetle, Ptomaphila perlata Kraatz, 1876 (Coleoptera: Silphidae) is recorded feeding and breeding in the rotting carcass of the Swamp Wallaby, Wallabia bicolor (Mammalia: Macropodidae) in northern Sydney, New South Wales, Australia. The habitat of the beetle is also described and the literature on the species including biological observations is reviewed.
... Nicrophorus defodiens has been captured in (0). Nicrophorus nigrita has also been observed to have greater success at carcass burial in mesic coastal forests (Sikes 1996) . Cooler conifer forests in the region may be the preferred habitat of these species. ...
Article
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The bunchgrass prairies of the Palouse region in eastern Washington state and adjacent Idaho were almost completely converted to agriculture in the past century. Today, prairie habitat exists only on small remnants scattered across the landscape. The invertebrate fauna of these habitat remnants is poorly known, both in terms of species diversity and community composition. Pitfall traps baited with carrion were used to sample carrion beetles (Coleoptera: Silphidae) during June and July of 2003. Prairie remnants were selected based on size to test whether habitat area influenced the diversity of this important insect community. Three size classes were identified; greater than ten hectares, between ten and two hectares, and less than two hectares. Only remnants of high habitat quality based on previously established floristic criteria were included in the study. Eight species of carrion beetles were collected, most of which were in the genus Nicrophorus (the burying beetles). Species richness and Shannon-Wiener diversity were not significantly correlated with habitat area or perimeter to area ratio. Beetle abundance was strongly correlated with soil parent material. The potential significance of soil type was explored with multivariate analyses. Soil characteristics appear to exert a strong influence on carrion beetle communities.
... Further, previous studies that quantify daily activity in burying beetles through hourly trap checks, provide evidence for daily temporal niche partitioning Ohkawara et al. 1998;Bedick et al. 1999). Specifically, N. tomentosus has been documented as a diurnal species, while N. orbicollis, N. sayi, and N. americanus are documented as nocturnal Sikes 1996;Bedick et al. 1999). To this point, however, there has been no high-resolution, comprehensive examination of the daily activity of burying beetles and how they relate to space use in a speciose community. ...
Conference Paper
Circadian rhythms are endogenous mechanisms responsible for the onset and termination of many important physiological processes related to energy allocation, and are thought to evolve to maximize fitness in a particular biotic and abiotic context. These rhythms and the related daily activity regime of an organism are often the phenotypical expression of interspecific niche competition, and this expression is particularly interesting in species that compete for hyperephemeral resource such as carrion. Here we examine the daily activity and circadian patterns in a Nicrophorine burying beetle species, Nicrophorus marginatus, which is often found in sympatry with multiple congeners and is one of few in its clade that exhibits diurnality. We tested the hypothesis that this species would segregate activity to periods associated with lower risk of dessication and predation by avian predators, and that activity phenotype would be governed by circadian regulatory mechanisms rather than external cues. We recorded daily activity patterns in a 12:12 LD condition using a Trikinetics digital locomotion monitor, and found that N. marginatus exhibit a strongly crepuscular activity pattern, with females displaying greater overall activity than males during light but not dark cycles. We then recorded activity in dark-only conditions, and show that the crepuscular activity patterns persisted in the absence of external light cues, suggesting an endogenous mechanism of activity regulation. Crepuscular activity in the species may have evolved as a compromise between intrinsic physiological constraints associated with desiccation and extrinsic predation and competition risks.
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Chapter
Most nests of brood-caring insects are colonized by a rich community of mite species. Since these nests are ephemeral and scattered in space, phoresy is the principal mode of dispersal in mites specializing on insect nests. Often the mites will arrive on the nestfounding insect, reproduce in the nest, and their offspring disperse on the insect’s offspring. A literature review shows that mites reproducing in the underground brood chambers of burying beetles use alternative routes for dispersal. For example, the phoretic instars of Poecilochirus spp. (Mesostigmata: Parasitidae) disperse early by attaching to the parent beetles. Outside the brood chamber, the mites switch host at carcasses and pheromone-emitting male beetles, where juvenile and mature burying beetles of several species congregate. Because they preferably switch to beetles that are reproductively active and use all species of burying beetles within their ranges, they have a good chance to arrive in a new brood chamber. Other mite associates of burying beetles (Alliphis necrophilus and Uropodina) disperse from the brood chamber on the beetle offspring. We suggest that these mites forgo the possible time gain of dispersing early on the parent beetles because their mode of attachment precludes host switching. Their phoretic instars, once attached, have to stay on their host and so only dispersing on the beetle offspring guarantees that they are present on reproducing burying beetles of the next season. The mites associated with burying beetles provide an example of multiple solutions to one life-history problem — how to find a new brood chamber for reproduction. Mites that have mobile phoretic instars disperse on the parent beetles and try to arrive in the next brood chamber by host-switching. They are independent of the generation cycle of a single host and several generations of mites per host generation are possible. Mites that are constrained by their mode of attachment disperse on the beetle offspring and wait until their host becomes mature and reproduces. By this they synchronize their generation time with the generation time of their host species.
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Adult individuals of the burying beetle species Nicrophorus defodiens Mannerheim, N. guttula Motschulsky, and N. investigator Zetterstedt show extensive geographic variation in elytral colour patterns, from an orange and black banded pattern to one where maculations are extremely reduced. Individuals with slightly to extensively reduced maculations are generally confined to Pacific coastal localities but, as variation is continuous and extremes are often sympatric, do not warrant separate specific or subspecific status. Examination of the geographic distribution of the colour of the basal article of the antennal club of N. guttula individuals shows the colour of the article to be associated with variation in elytral colour. This confirms that N. hecate Bland, previously characterized by a red basal article of the antennal club, is a junior synonym of N. guttula Motschulsky, previously characterized by a black basal article. The possible roles of thermoregulation and mimicry accounting for the variation in elytral colour are briefly discussed.
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Size of breeding groups and resource quality (carcass mass) were varied independently in experiments using the burying beetle, Nicrophorus defodiens, to examine reproductive output of beetles using carcasses exposed to carrion competitors. Male-female pairs experienced the same rate of brood failure as groups of four beetles (two males and two females). Groups of four produced more total larvae and a greater brood mass than pairs on large but not small carcasses, whereas reproductive output per female was lower for groups. Carcasses prepared by groups of two males and two females attracted similar numbers of free-flying congeners as carcasses prepared by pairs. The ability of more than two individuals to produce a larger brood than that of pairs may decrease the costs of communal breeding on larger carcasses, but by itself, is not sufficient to explain the evolution of breeding associations consisting of multiple females.