The Evolutionary Significance of Body Size in Burying Beetles

• Main Author: Momcilovich, Ashlee Nichole
• Format: Others
• Published: BYU ScholarsArchive 2018
• Subjects: burying beetle; Nicrophorus; body size; evolution
• Online Access: https://scholarsarchive.byu.edu/etd/7327; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=8327&context=etd

Body size is one of the most commonly studied traits of an organism, which is largely due to its direct correlation with fitness, life history strategy, and physiology of the organism. Patterns of body size distribution are also often studied. The distribution of body size within species is looked at for suggestions of differential mating strategies or niche variation among ontogenetic development. Patterns are also examined among species to determine the effects of competition, environmental factors, and phylogenetic inertia. Finally, the distribution of body size across the geographic range of a species or group of closely related is looked at for indications of the effects of climate and resource availability on body size at different latitudes and altitudes. In this collection of research, I address the evolution and importance of body size in burying beetles (genus Nicrophorus). Body size is important to several aspects of burying beetle natural history, including competitive ability, fitness, parental care, climate tolerance, and locomotor activity. In Chapter 1, I use a large data set of body size measurements for seventy of the seventy-three Nicrophorus species to make inferences about the distribution of body size within the genus, across its geographic range, and the importance of body size in speciation. I found that the range of body sizes is not normally distributed, with an overrepresentation of small-sized species. I also found that expansion of the burying beetle range has been restricted by their inability to tolerate warm, dry climates, and therefore the majority of burying beetle diversity occurs in the temperature mid-latitudes of the northern hemisphere. Body size also seems to be important in speciation, as almost all sister taxa are significantly different in body size. In Chapter 2 I use common garden experiments to assess the importance of body size for males and females in competition, reproductive output, and starvation resistance. Body size is equally important for both sexes in starvation resistance, but it is more important for males in competitions for carcasses and for females in reproductive output. In Chapter 3 I test for fitness consequences of multigenerational effects of body size in offspring. I found that the larger offspring that are produced by larger mothers and on larger carcasses had higher fitness than small offspring. In Chapter 4 I test for the possibility of brood parasitism in two species of burying beetles, N. guttula and N. marginatus, which co-occur over part of their geographic ranges. I found that both species are able to detect and remove parasitic larvae. Finally, in Chapter 5 I compiled parent and offspring body sizes from seven species of burying beetles and use them to compare the heritability of body size among species using comparative techniques and a meta-analysis. I found that body size heritability is different between species, but is low for the genus as a whole. Together, these projects provide valuable information on the evolutionary significance of body size in Nicrophorus, and indicate compelling questions for future research into the evolution of body size in burying beetles.