Papers by Gabrielle Nevitt
Genetics, Oct 4, 2021
Procellariiform seabirds rely on their sense of smell for foraging and homing. Both genomes and t... more Procellariiform seabirds rely on their sense of smell for foraging and homing. Both genomes and transcriptomes yield important clues about how olfactory receptor (OR) subgenomes are shaped by natural and sexual selection, yet no transcriptomes have been made of any olfactory epithelium of any bird species thus far. Here, we assembled a high-quality genome and nasal epithelium transcriptome of the Leach’s storm-petrel (Oceanodroma leucorhoa) to extensively characterize their OR repertoire. Using a depth-of-coverage-assisted counting method, we estimated over 160 intact OR genes (∼500 including OR fragments). This method reveals the highest number of intact OR genes and the lowest proportion of pseudogenes compared to other waterbirds studied, and suggests that rates of OR gene duplication vary between major clades of birds, with particularly high rates in passerines. OR expression patterns reveal two OR genes (OR6-6 and OR5-11) highly expressed in adults, and four OR genes (OR14-14, OR14-12, OR10-2, and OR14-9) differentially expressed between age classes of storm-petrels. All four genes differentially expressed between age classes were more highly expressed in chicks compared to adults, suggesting that OR genes may exhibit ontogenetic specializations. Three highly differentially expressed OR genes also had high copy number ratios, suggesting that expression variation may be linked to copy number in the genome. We provide better estimates of OR gene number by using a copy number-assisted counting method, and document ontogenetic changes in OR gene expression that may be linked to olfactory specialization. These results provide valuable insight into the expression, development, and macroevolution of olfaction in seabirds.
The American Naturalist, Jun 1, 2021
Inbreeding depression is often found in small, inbred populations, but whether it can be detected... more Inbreeding depression is often found in small, inbred populations, but whether it can be detected in and have evolutionary consequences for large, wide-ranging populations is poorly known. Here, we investigate the possibility of inbreeding in a large population to determine whether mild levels of inbreeding can still have genetic and phenotypic consequences and how genomically widespread these effects can be. We apply genome-wide methods to investigate whether individual and parental heterozygosity is related to morphological, growth, or life-history traits in a pelagic seabird, Leach's storm-petrel (Oceanodroma leucorhoa). Examining 560 individuals as part of a multiyear study, we found a substantial effect of maternal heterozygosity on chick traits: chicks from less heterozygous (relatively inbred) mothers were significantly smaller than chicks from more heterozygous (noninbred) mothers. We show that these heterozygosity-fitness correlations were due to general genome-wide effects and demonstrate a correlation between heterozygosity and inbreeding, suggesting inbreeding depression. We used population genetic models to further show that the variance in inbreeding was probably due to past demographic events rather than the current mating system and ongoing mate choice. Our findings demonstrate that inbreeding depression can be observed in large populations and illustrate how the integration of genomic techniques and fieldwork can elucidate its underlying causes.
Brain Behavior and Evolution, Dec 7, 2017
week after hatching lack even the most basic visually guided behaviours and are probably blind. T... more week after hatching lack even the most basic visually guided behaviours and are probably blind. Thus, vision in Leach's storm petrel chicks starts to function sometime around the 3rd week after hatching, well after the eyes have opened and the olfactory system is functional.
Families represented within top phyla. In Fig. 1b, families representing the top 20 most abundant... more Families represented within top phyla. In Fig. 1b, families representing the top 20 most abundant species are shown. The remaining families within each phylum are shown in Fig. 1 are listed in this table. (DOCX 121 kb)
Comparison of burrow soil distance matrices with geographical distance. Weighted and unweighted U... more Comparison of burrow soil distance matrices with geographical distance. Weighted and unweighted UniFrac discance matrices were compared to geographical burrow distance. At all burrow soil depths, community presence/absence significantly correlated with geographical burrow distance and bacterial community structure from mid and surface burrow soil significantly correlated with geographical burrow distance. (DOCX 17Â kb)
Summary of statistical analyses. Statistical analyses were performed using R, and each command an... more Summary of statistical analyses. Statistical analyses were performed using R, and each command and R package used is specified for each analysis. (DOCX 106Â kb)
Sampling summary. Two swab samples (uropygial gland and brood patch) were collected from each of ... more Sampling summary. Two swab samples (uropygial gland and brood patch) were collected from each of 22 birds. Genotyping determined that 14 birds were female and 8 were male, and 5 male/female dyads were mated pairs. Burrow soil was sampled at 3 depths per burrow. (DOCX 20Â kb)
Diagram of bird body sampling locations and burrow soil sampling depths. (DOCX 136Â kb)
Map of sampling locations on Bon Portage Island, Nova Scotia, Canada. Study samples were collecte... more Map of sampling locations on Bon Portage Island, Nova Scotia, Canada. Study samples were collected from an area of the colony (approximately 4Â m2) where petrel burrows are located among dense balsam fir, red pine, and spruce forest. (DOCX 217Â kb)
Vetted hatch dates for chicks 2011-2015, within +- 3 days
Year, mass, tarsus length, wing chord, for adults used in morphometrics*genotype analyse
Number of amino acid substitutions between Ocle-DAB2 allele pairings
File contains genotypes for DAB1 and DAB2 MHC alleles, for all established breeding pairs identif... more File contains genotypes for DAB1 and DAB2 MHC alleles, for all established breeding pairs identified between 2010-2015. Female allele IDs are listed in columns FDAB1.1 : FDAB2.2; males in MDAB1.1 : MDAB2.2
Molecular ecology, Jan 16, 2018
Studies of MHC-based mate choice in wild populations often test hypotheses on species exhibiting ... more Studies of MHC-based mate choice in wild populations often test hypotheses on species exhibiting female choice and male-male competition, which reflects the general prevalence of females as the choosy sex in natural systems. Here, we examined mutual mate-choice patterns in a small burrow-nesting seabird, the Leach's storm-petrel (Oceanodroma leucorhoa), using the major histocompatibility complex (MHC). The life history and ecology of this species are extreme: both partners work together to fledge a single chick during the breeding season, a task that requires regularly travelling hundreds of kilometres to and from foraging grounds over a 6- to 8-week provisioning period. Using a 5-year data set unprecedented for this species (n = 1078 adults and 925 chicks), we found a positive relationship between variation in the likelihood of female reproductive success and heterozygosity at Ocle-DAB2, a MHC class IIB locus. Contrary to previous reports rejecting disassortative mating as a me...
Journal of Experimental Biology, 2016
Procellariiform or ‘tubenosed’ seabirds are challenged to find prey and orient over the seemingly... more Procellariiform or ‘tubenosed’ seabirds are challenged to find prey and orient over the seemingly featureless oceans. Previous studies have found that life history strategy (burrow vs. surface nesting) was correlated to foraging strategy. Burrow nesters tended to track prey using dimethyl sulphide (DMS), a compound associated with phytoplankton, whereas surface-nesting species did not. Burrow nesters also tended to be smaller and more cryptic, whereas surface nesters were larger with contrasting plumage coloration. Together these results suggested that differences in life history strategy might also be linked to differences in visual adaptations. Here, we used Leach's storm-petrel, a DMS-responder, and Northern fulmar, a non-responder, as model species to test this hypothesis on their sensory ecology. From the retinal ganglion cell density and photoreceptor dimensions, we determined that Leach's storm-petrels have six times lower spatial resolution than the Northern fulmars....
Journal of Experimental Biology, 1995
The western Atlantic spiny lobster Panulirus argus undergoes an annual migration and is also capa... more The western Atlantic spiny lobster Panulirus argus undergoes an annual migration and is also capable of homing to specific dens in its coral reef environment. Relatively little is known, however, about the orientation cues that lobsters use to guide their movements. To determine whether lobsters can orient to the earth’s magnetic field, divers monitored the orientation of lobsters tethered inside magnetic coil systems submerged offshore in the Florida Keys, USA. Each coil could be used to reverse either the horizontal or vertical component of the earth’s field. Tethered lobsters walking inside the coils often established and maintained consistent courses towards specific directions. After a lobster had established a course, it was exposed to one of three conditions: (1) a reversal of the horizontal component of the earth’s field; (2) a reversal of the vertical component of the earth’s field; or (3) no change in the ambient field (controls). Lobsters subjected to the horizontal field...
The Senses of Fish, 2004
Olfactory imprinting is a specialized form of unconditioned learning in which olfactory informati... more Olfactory imprinting is a specialized form of unconditioned learning in which olfactory information is acquired and then used in some specific behavioral context later in life. A key characteristics of an imprinted memory is that it is formed during a sensitive period of development. This prerequisite thus distinguishes olfactory imprinting from other types of odor learning in which only conditioned exposure to an odor stimulus is required for learning to occur. Most investigations designed to explore the mechanisms underlying olfactory imprinting have focused on mammalian species, concentrating on synaptic events at the level of the main and accessory olfactory bulbs (Hudson 1993). Recent integrative studies with salmon (Dittman et al. 1997; Nevitt et al. 1994) and rabbits (Semke et al. 1995), however, provide compelling evidence that highly specific imprinted odor memories may also be retained in the periphery, i.e., at the level of the olfactory epithelium proper. These results suggest that populations of olfactory receptor neurons may be selectively tuned to respond to odor molecules present during a hormonally linked sensitive period. A potential key to the mechanism of how these peripheral odor memories become established draws on the unique ability of olfactory receptor neurons to turn over throughout an organism’s life span (Farbman 1994). How hormonal and environmental factors work together to influence olfactory neurogenesis is not yet been rigorously addressed in the literature (Shepherd 1994), but ultimately may provide important new insights not only for basic science but for salmon conservation as well.
Canadian Journal of Fisheries and Aquatic Sciences, 1996
... Andrew H. Dittman, Thomas P. Quinn, and Gabrielle A. Nevitt ... que cette imprégnation olfact... more ... Andrew H. Dittman, Thomas P. Quinn, and Gabrielle A. Nevitt ... que cette imprégnation olfactive survient au cours d'une période sensible associée à des hausses momentanées des teneurs en thyroxine plasmique au cours de leur transformation de tacon en smolt. ...
Procellariiform seabirds are known for their well-developed olfactory capabilities, reflected by ... more Procellariiform seabirds are known for their well-developed olfactory capabilities, reflected by their large olfactory bulb to brain ratio and olfactory-mediated behaviors. Many species in this clade use olfactory cues for foraging and navigation, and some species can recognize individual-specific odors. Their genomes and transcriptomes may yield important clues about how the olfactory receptor (OR) subgenome was shaped by natural and sexual selection. In this study, we assembled a high-quality Leach's storm petrel (Oceanodroma leucorhoa) genome to facilitate characterization of the OR repertoire. We also surveyed expressed OR genes through transcriptome analysis of the olfactory epithelium - to our knowledge, the first avian study to interrogate OR diversity in this way. We detected a large number (~61) of intact OR genes, and identified OR genes under positive selection. In addition, we estimated that this species has the lowest proportion (~60%) of pseudogenes compared to oth...
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Papers by Gabrielle Nevitt