Title

Population genetic structure and male reproductive success of a Blanding's turtle (Emydoidea blandingii) population in southeastern Michigan

Date of Award

2001

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Ken Spitze, Committee Chair

Abstract

Both microsatellite analyses and capture histories were used to examine patterns of population differentiation, multiple paternity and male reproductive success in a population of Blanding's turtles. A battery of 8 polymorphic microsatellite loci were used to genotype 222 turtles and 266 hatchlings captured on the University of Michigan's E. S. George Reserve (ESGR), Livingston County, Michigan, USA. This genotype data was complemented by over 6,000 individual capture records collected on the ESGR over the past 26 years.Comparison of independent estimates of population structure derived from capture (coancestry) and microsatellite data (F-statistics) indicated no significant microgeographic genetic structure within the ESGR. Separate Fst analysis restricted to females who annually nest in the same geographic area did not reveal a level of genetic differentiation sufficient to support a hypothesis of natal homing. It appeared that effective movement by both male and female Blanding's turtles was sufficient to ameliorate any microgeographic genetic structure that might have accrued due to behavioral patterns.Blanding's turtles exhibited one of the highest levels of multiple paternity documented in turtles. Examination of 42 nests indicated the minimum number of fathers averaged 1.7 per nest. The majority of ESGR nests (78%) showed evidence of fertilization by multiple males. It is unclear why females exhibit polyandry, yet the frequency of infertile eggs in Emydoidea suggests a hypothesis of fertility assurance. Additional work is required to examine this and other non-mutually exclusive hypotheses.The reproductive success of 54 male turtles captured on the ESGR was determined by assigning paternity to 266 ESGR hatchlings. Likelihood analysis could not establish paternity for all hatchlings, but the pattern appeared related to non-resident females nesting within the ESGR. The pattern of observed success among males was not related to residence area, residual body mass, or ESGR residency, but was significantly correlated with male size and age. When both size and age were considered in a multivariate analysis, only age remained significantly correlated with male success. Similarities to the closely related wood turtle (Clemmys inscuplta) suggest a mate-searching strategy that improves with age (e.g. navigation, experience mating).

Keywords

Biology, Ecology; Biology, Genetics; Biology, Zoology

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3032366