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UBC Theses and Dissertations
The effects of sperm competition on testes size and intromittent organ morphology in waterfowl Coker, Chris R.
Abstract
Waterfowl are one of very few avian taxa that possesses an intromittent organ (10). This thesis examines the adaptive significance of the 10 in waterfowl by determining the relationships between 10 morphology and the intensity of sperm competition (as reflected by frequency of extra-pair copulations (EPCs)). Intromittent organ morphological characteristics, including length and circumference (adjusted for body size), number of ridges and/or knobs (per unit area), ridge/knob height, ridge/knob length, and % area covered by ridges/knobs were measured from scaled museum drawings of freshly killed, sexually mature, specimens of 57 waterfowl species (across 33 genera). Thirty of which were ranked by frequency of EPC (1= monogamous, 2= rare EPC, 3= frequent EPC, 4= promiscuous). Testes sizes were also investigated in relation to EPCs, where testes masses (adjusted for body size) from 47 species (across 24 genera) were obtained (32 species with mating strategies). The size of the testes, the size (length) of the 10, the size (height) of the 10 ridges/knobs and the % area covered by ridges/knobs increased significantly with the frequency of EPC. These relationships exist even after the removal of phylogenetic constraints. These results are consistent with the hypothesis that waterfowl 10s are involved in sperm competition. Further research into the actual mechanism by which the 10 is involved with sperm competition would be worthwile.
Item Metadata
Title |
The effects of sperm competition on testes size and intromittent organ morphology in waterfowl
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1998
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Description |
Waterfowl are one of very few avian taxa that possesses an intromittent organ (10).
This thesis examines the adaptive significance of the 10 in waterfowl by determining
the relationships between 10 morphology and the intensity of sperm competition (as
reflected by frequency of extra-pair copulations (EPCs)). Intromittent organ
morphological characteristics, including length and circumference (adjusted for body
size), number of ridges and/or knobs (per unit area), ridge/knob height, ridge/knob
length, and % area covered by ridges/knobs were measured from scaled museum
drawings of freshly killed, sexually mature, specimens of 57 waterfowl species (across
33 genera). Thirty of which were ranked by frequency of EPC (1= monogamous, 2=
rare EPC, 3= frequent EPC, 4= promiscuous). Testes sizes were also investigated in
relation to EPCs, where testes masses (adjusted for body size) from 47 species (across
24 genera) were obtained (32 species with mating strategies). The size of the testes,
the size (length) of the 10, the size (height) of the 10 ridges/knobs and the % area
covered by ridges/knobs increased significantly with the frequency of EPC. These
relationships exist even after the removal of phylogenetic constraints. These results
are consistent with the hypothesis that waterfowl 10s are involved in sperm competition.
Further research into the actual mechanism by which the 10 is involved with sperm
competition would be worthwile.
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Extent |
5075981 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-05-04
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0088514
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1998-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.