Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises
Birth and pupping season records of Pacific harbor seals (Phoca vitulina richardsi) were used in an analysis of photoperiod effect on the timing of birth in this species. Dates and latitudes of births were converted into photoperiods using a photoperiod equation. Sequential dates from parturition we...
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ftoregonstate:ir.library.oregonstate.edu:td96k4846 2024-09-15T18:10:38+00:00 Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises Temte, Jonathan L. Mate, Bruce R. College of Oceanography Oregon State University. Graduate School https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/td96k4846 English [eng] eng unknown Oregon State University https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/td96k4846 Copyright Not Evaluated Harbor seal -- Reproduction -- Climatic factors Masters Thesis ftoregonstate 2024-07-22T18:06:03Z Birth and pupping season records of Pacific harbor seals (Phoca vitulina richardsi) were used in an analysis of photoperiod effect on the timing of birth in this species. Dates and latitudes of births were converted into photoperiods using a photoperiod equation. Sequential dates from parturition were converted into photoperiods and plotted as a function of latitude. The resulting functions of latitude vs. photoperiod were regressed to determine the point during the reproductive cycle at which latitude did not have an effect on photoperiod. The Pacific harbor seal can be divided into two geographic subgroups by their respective pupping seasons. Seals inhabiting the Puget Sound / Strait of Georgia (PS/SG) System give birth to pups an average of 88 days (P < 0.01) later than do seals of the North American west coast. The dine in the pupping season of coastal harbor seals can be defined by a 13.8 h/day photoperiod occurring at 68 days post partum. PS/SG harbor seals experience a significantly different photoperiod (P <0.001) of 10.8 h/day at 68 days post partum. Progesterone and testosterone levels support an hypothesis that these two populations may be reproductively isolated, as coastal male seals show low testosterone levels during the breeding season for PS/Sc seals. A proposed photoresponse at 68 days post partum occurs at the midpoint between estrus and implantation. This period is characterized by secondary follicular activity in the ipsilateral ovary and other changes occurring in the uterus and corpus luteum. A response to a specific photoperiod terminating the follicular activity and leading to a specific implantation date is suggested. Master Thesis harbor seal Phoca vitulina ScholarsArchive@OSU (Oregon State University) |
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Open Polar |
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ScholarsArchive@OSU (Oregon State University) |
op_collection_id |
ftoregonstate |
language |
English unknown |
topic |
Harbor seal -- Reproduction -- Climatic factors |
spellingShingle |
Harbor seal -- Reproduction -- Climatic factors Temte, Jonathan L. Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
topic_facet |
Harbor seal -- Reproduction -- Climatic factors |
description |
Birth and pupping season records of Pacific harbor seals (Phoca vitulina richardsi) were used in an analysis of photoperiod effect on the timing of birth in this species. Dates and latitudes of births were converted into photoperiods using a photoperiod equation. Sequential dates from parturition were converted into photoperiods and plotted as a function of latitude. The resulting functions of latitude vs. photoperiod were regressed to determine the point during the reproductive cycle at which latitude did not have an effect on photoperiod. The Pacific harbor seal can be divided into two geographic subgroups by their respective pupping seasons. Seals inhabiting the Puget Sound / Strait of Georgia (PS/SG) System give birth to pups an average of 88 days (P < 0.01) later than do seals of the North American west coast. The dine in the pupping season of coastal harbor seals can be defined by a 13.8 h/day photoperiod occurring at 68 days post partum. PS/SG harbor seals experience a significantly different photoperiod (P <0.001) of 10.8 h/day at 68 days post partum. Progesterone and testosterone levels support an hypothesis that these two populations may be reproductively isolated, as coastal male seals show low testosterone levels during the breeding season for PS/Sc seals. A proposed photoresponse at 68 days post partum occurs at the midpoint between estrus and implantation. This period is characterized by secondary follicular activity in the ipsilateral ovary and other changes occurring in the uterus and corpus luteum. A response to a specific photoperiod terminating the follicular activity and leading to a specific implantation date is suggested. |
author2 |
Mate, Bruce R. College of Oceanography Oregon State University. Graduate School |
format |
Master Thesis |
author |
Temte, Jonathan L. |
author_facet |
Temte, Jonathan L. |
author_sort |
Temte, Jonathan L. |
title |
Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
title_short |
Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
title_full |
Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
title_fullStr |
Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
title_full_unstemmed |
Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with notes on reproduction in northern fur seals and Dall porpoises |
title_sort |
photoperiod and the timing of pupping in the pacific harbor seal (phoca vitulina richardsi) with notes on reproduction in northern fur seals and dall porpoises |
publisher |
Oregon State University |
url |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/td96k4846 |
genre |
harbor seal Phoca vitulina |
genre_facet |
harbor seal Phoca vitulina |
op_relation |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/td96k4846 |
op_rights |
Copyright Not Evaluated |
_version_ |
1810448237099745280 |