Sperm competition in three species of ground-dwelling squirrels: intraspecific and interspecific differences
| dc.contributor.author | Carvalho dos Anjos, Elaine Aparecida | |
| dc.contributor.examiningcommittee | Anderson, Judith (Biological Sciences) Suh, Miyoung (Human Nutritional Sciences) | en_US |
| dc.contributor.examiningcommittee | Montegomerie, Robert (Evolutionary Biology Queen’s University) | en_US |
| dc.contributor.supervisor | Waterman, Jane (Biological Sciences) | en_US |
| dc.date.accessioned | 2020-06-16T16:48:43Z | |
| dc.date.available | 2020-06-16T16:48:43Z | |
| dc.date.copyright | 2020-06-08 | |
| dc.date.issued | 2020-06 | en_US |
| dc.date.submitted | 2020-06-08T17:33:58Z | en_US |
| dc.degree.discipline | Biological Sciences | en_US |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | en_US |
| dc.description.abstract | Sperm competition is a post-copulatory evolutionary process that can affect sperm production, and consequently reproductive success. Successful males may not necessarily be the males with the highest number of sperm. Other traits such as sperm motility or abnormality may also be factors that impact fertilization success, when there is selection for traits that improve the ability of the sperm to reach the egg. Ground squirrels are an ideal group of organisms to address questions of reproduction and fertility because of the large species diversity in the group, a well-documented phylogeny, a high variety of mating systems and their diversity of life history traits. The main objective of my thesis was to investigate sperm competition in ground squirrels, since it is biologically, ecologically, and evolutionary important to recognize what traits influence the fertilizing efficiency of males and how different species maximize their reproductive success through post-copulatory sexual selection. I sampled free-ranging adult male Cape ground squirrels in the Northern Cape and SA Lombard Nature Reserve, Bloemhof, South Africa, Richardson’s ground squirrels in Assiniboine Park Zoo, Winnipeg, Canada, and Barbary ground squirrels of an invasive population on Fuerteventura Island (Canarian archipelago), Spain. Key findings demonstrated: 1. A positive relationship (interspecifically) between operational sex ratio (OSR) and relative testes size (RTS); 2. A negative relationship (intraspecifically) between RTS and sperm concentration in Cape and Richardson’s ground squirrels; 3. Cape ground squirrel males in better body condition produced more sperm and had larger Cowper glands; 4. Sperm length and speed were related in Cape and Richardson’s ground squirrels; 5. Selective pressures may act to decrease sperm head variability among males, or possibly favor different sizes and morphologies of sperm within an ejaculate; 6. Barbary ground squirrels had higher sperm concentration, lower sperm abnormality and larger RTS compared to many other species, suggesting there is no evidence of inbreeding depression on sperm traits in this highly inbred population. This research contributes to advance our understanding of post-copulatory sperm competition in mammals as viewed from an ecological and evolutionary perspective. | en_US |
| dc.description.note | October 2020 | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/34714 | |
| dc.language.iso | eng | en_US |
| dc.rights | open access | en_US |
| dc.subject | Ground squirrels | en_US |
| dc.subject | Sexual selection | en_US |
| dc.subject | Relative testis size | en_US |
| dc.subject | Sperm concentration | en_US |
| dc.subject | Sperm quality | en_US |
| dc.subject | Sperm speed | en_US |
| dc.subject | Sperm size | en_US |
| dc.subject | Accessory glands | en_US |
| dc.subject | CASA | en_US |
| dc.subject | Male condition | en_US |
| dc.title | Sperm competition in three species of ground-dwelling squirrels: intraspecific and interspecific differences | en_US |
| dc.type | doctoral thesis | en_US |
| local.subject.manitoba | yes | en_US |