Ecological Archives E090-119-D1

Lisa E. Schwanz, Rachel M. Bowden, Ricky-John Spencer, and Fredric J. Janzen. 2009. Nesting ecology and offspring recruitment in a long-lived turtle. Ecology 90:1709.


INTRODUCTION

For long-lived animals, early-life stages are often considered to be minor components of population demography, with the assumption that the performance of advanced juveniles and reproductive-aged individuals contributes more to population structure (e.g., Crouse et al 1987; Heppell et al 1996; Heppell 1998). Despite this assumption, few long-term data are available to test whether variation and temporal fluctuations in the vital rates of early life stages play a substantive role in population dynamics (Dutton et al 2005; Spencer and Thompson 2005; Wisdom et al 2000). In addition, if the recruitment of early life stages is affected by maternal reproductive behavior, natural selection on the reproductive success of individuals could alter reproductive behavior and, thereby, population dynamics. Maternal reproductive behavior influences offspring phenotype in many animals, which may have fitness consequences for both mothers and offspring (Deeming and Ferguson 1991; Bernardo 1996; Gagliano and McCormick 2006; Marshall and Uller 2007; Mousseau and Fox 1998a,b; Räsänen and Kruuk 2007). For animals that terminate maternal care at egg deposition, maternal provisioning of eggs and nest characteristics such as temperature, moisture, and pH, can influence embryonic growth, morphology and viability (Deeming and Ferguson 1991). In addition, incubation temperature determines embryonic sex in many long-lived reptiles (temperature-dependent sex determination, TSD; Bull 1980, Janzen and Paukstis 1991). Furthermore, the timing of nesting and nest-site selection may influence depredation and parasitism rates. Thus, maternal nesting ecology and hatchling recruitment may be more influential in population dynamics than previously thought. Little is known about long-term patterns in the nesting ecology of populations of long-lived vertebrates, and as a consequence, we have a limited understanding of natural fluctuations in population demography and the consequences of such fluctuations.

We have been monitoring a population of painted turtles (Chrysemys picta) in Illinois, USA, for 18 years in an effort to better understand the ecology, evolution and demographic consequences of maternal nesting behavior (i.e., timing of nesting and nest-site selection) and temperature-dependent sex determination on offspring phenotype. The population of painted turtles used for this ongoing long-term project was studied at one major nesting beach (41°57' N, 90°07' W) along the backwaters of the Mississippi River near Thomson, Illinois, USA. Painted turtles are an aquatic species that nests in large numbers on nesting beaches at our study site. They dig shallow nests that contain 3–21 eggs per clutch (mean = 10.5, mode = 10), and females may deposit up to three separate nests during a single nesting season in this area. Hatchling painted turtles remain in the nest for winter hibernation and emerge the following spring (Weisrock and Janzen 1999).

Data were collected to examine the role of nesting phenology, nest-site selection, depredation rates, and clutch success on hatchling recruitment. The site was monitored daily for the duration of the nesting season between 1989 and 2006. We excavated nests in the fall of each year to determine nest survivorship. These efforts provided data for each nest describing date of laying, vegetation cover, depredation, and hatchling survival. For a subset of the nests, clutch size was also known.

Portions of these data have been used to address numerous ecological and evolutionary questions. Data for onset and duration of the nesting season have provided the starting point for computer simulations and empirical assessments of the biotic impact of climate warming on populations of turtles with temperature-dependent sex determination (TSD; Janzen 1994a; Morjan 2003a, b; Schwanz and Janzen 2008). Female turtles have been shown to demonstrate repeatability in selection of nest vegetation cover (Janzen and Morjan 2001). In addition, nest vegetation cover has been shown to be spatially autocorrelated and to influence nest temperature and sex ratio (Janzen 1994b; Valenzuela and Janzen 2001). Portions of the data set have also been used to show that depredation is a strong component of nest survival (up to 95.8% nest depredation in a year), and is nonrandom with respect to nest location (Kolbe and Janzen 2002). Moreover, the probability of nest depredation is influenced by the nature of precipitation events, with heavy rain on the day of nest construction reducing the frequency with which nests are destroyed by predators (Bowen and Janzen 2005). These studies have made valuable contributions to our understanding of the ecology and evolution of nest-site selection, yet many questions remain. We intend for the data provided here to be used by researchers to explore such issues in greater detail and by teachers to illustrate the linkage between maternal behavior, offspring recruitment, and population dynamics of a globally imperiled taxon.

METADATA

CLASS I. DATA SET DESCRIPTORS

A. Data set identity: Nesting attributes of Painted turtles (Chrysemys picta) on Thomson Causeway, IL: timing, vegetation cover, clutch size, depredation, and hatchling survival.

B. Data set identification code: Chrysemys_picta_1989-2006.txt

C. Data set description

Principal Investigator: Fredric J. Janzen, Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011 USA

Abstract: The role of early life stages (eggs, neonates, and juveniles) for population persistence in long-lived organisms is thought to be minor. However, few long-term data sets are available to test this assumption. Variation in vital rates over space and time and the potential for the success of early life stages to shape adult reproductive behavior evolutionarily suggest that more thorough consideration of these life stages is necessary. In particular, the impact of climatic variation on early life-stage recruitment is not well understood. Furthermore, predation occupies a significant role in theoretical models of population dynamics, but its impact on populations through variable vital rates of early life stages is unknown. Maternal nest site selection, an important component of nesting ecology, may influence many offspring traits and respond to selection to optimize offspring success. Overall, we have limited information regarding the long-term patterns of natural fluctuations in the nesting ecology and hatchling recruitment of populations of long-lived organisms.

The research site for this ongoing long-term project is on an island (41°57' N, 90°07' W) in the Mississippi River near Thomson, Illinois, USA. Painted turtles (Chrysemys picta) have been studied extensively at this location since 1989 to examine the ecology and potential demographic consequences of nest-site selection and depredation, with the aim of understanding the evolution of maternal nesting behavior and its effects on offspring phenotype. We monitored the site every day of the nesting season each year to record nesting and depredation events. The data presented here include nesting phenology, nest vegetation cover, total number of nesting events, clutch size, depredation, and hatchling survival.

Portions of this data set have been used to address related questions in ecology and evolutionary biology. In particular, climatic variation influences the probability of nest depredation events. Such events are typically nonrandom, primarily occurring adjacent to habitat edges. Because habitat edges may have atypical vegetation composition and vegetation influences nest temperature, such nonrandom depredation could influence offspring recruitment and, hence, population structure. Given the unique scope and accessibility of this data set, researchers and teachers should find it to be a valuable empirical resource for exploring important facets of nesting ecology and hatchling recruitment in a wild population of a long-lived species.

D. Key words: climate change; maternal effects; nesting behavior; predation; temperature-dependent sex determination; turtles.

CLASS II. RESEARCH ORIGIN DESCRIPTORS

A. Overall project description

Identity: Nesting behavior, nest depredation, and offspring recruitment of Painted turtles (Chrysemys picta) in Illinois.

Originator: Fredric J. Janzen, Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011 USA

Period of Study: 1989 – 2006 (ongoing)

Objectives: To use data on nesting behavior of painted turtles, nest depredation, and hatchling recruitment to test hypotheses concerning the evolutionary consequences of maternal reproductive behavior and nesting ecology on population structure.

Abstract: Same as above.

Sources of funding: All data collection has been supported by the NSF (DDIG BSR-8914686, DEB-9629529, UMEB IBN-0080194, LTREB DEB-0089680, IBN-0212935), as well as the ASIH Gaige Fund, Sigma Xi, and the Department of Zoology and Genetics at Iowa State University.

B. Specific subproject description

1. Site description: We monitored nesting events of painted turtles at one nesting beach (South Potter's Marsh) on the Thomson Causeway, near Thomson, Illinois, USA. The Thomson Causeway is an island of Illinois in the Mississippi River near the Illinois shore. The island consists of mixed forest interspersed with cleared, open woodland. The majority of the island is roughly 1.0 m above river-water level (583 ft msl). The nesting beach consists of a grassy area, approximately 250 × 75 m (~1.5 ha), on the eastern edge of the island (facing Illinois). The west and south sides of the nesting beach are bordered by woodland. The east side borders the backwaters of the Mississippi River. The area is largely flat, with the exception of the short slope to the edge of the water.

Geography: Thomson Causeway is located at 41°57' N, 90°07' W in the Mississippi River, USA. The island is approximately 450 × 900 m in area and approximately 200 m from Illinois.

Habitat: The nesting beach is a grassy area, with varying cover from cottonwood, maple, oak, and juniper trees (Janzen and Morjan 2001). The nesting locations are between 0.01 and 1.0 m above river water level.

Geology: The nesting beach consists of moist loam soil. The shoreline of the site on the backwaters of the Mississippi River has an east aspect. With the exception of the immediate shoreline, the nesting beach is level.

Watersheds/hydrology: The site is adjacent to the backwaters of the Mississippi River.

Site history: The Thomson Causeway was formed in the 1930s when development of Lock and Dam 13 at Fulton, Illinois (approximately 6 km south of Thomson) elevated the Mississippi River, isolating the site from mainland Illinois. In the early 1960s, the field site was partially cleared to develop a recreation area. Portions of the nesting beach were covered with blacktop and developed with underground piping and electricity to designated campsites in 1983.

Climate: The site experiences typical climate for the midwest USA. January air temperatures average -2.0/-11.9°C and July air temperatures average 29.7/15.6°C. Annual precipitation averages (960 mm). Data are from Mount Carroll, Illinois weather station (1901–2006 averages, Illinois State Water Survey).

2. Sampling design

Design characteristics: The sampling regime was designed to record the majority of painted turtle nesting events at South Potter’s Marsh. Annual sampling periods encompassed the nesting season (late May to early July), providing data on nesting phenology. Hourly monitoring between sunrise and sunset was adequate to detect the majority of nesting events, while not producing excessive disturbance to nesting females. Females often produce two clutches in a year.

Data collection period: We monitored the nesting beach annually between 1989 and 2006 from mid-May until early July (spring sampling period). Most turtles nest in June, so this period encompasses the annual nesting season of painted turtles at this site. During this sampling period, the site was monitored hourly from sunrise to sunset every day for the presence of nesting female turtles (except for 1990, 1991, and 1994, which had more sporadic checks for visually-recognizable nests). Nests were checked every three days during the spring-summer sampling period for depredation events. Eggs hatch roughly 2–3 months after they are laid and the hatchlings remain in the nests for winter hibernation. The fall sampling period consisted of the third weekend in September every year. During this period, all nests that were not known to be depredated (active nests) were relocated and excavated.
3. Research methods: Every day during the spring-summer sampling period, the site was monitored hourly between sunrise and sunset for nesting painted turtles. All observed nests were recorded. Once a female completed her nest, the nest location was mapped by triangulating (nearest cm) with respect to permanent local landmarks. In addition, numbered markers were placed above the nest neck. Vegetation cover above each nest was recorded using a spherical densiometer for each of the four cardinal directions (Janzen 1994b, Weisrock and Janzen 1999). A subset of nests was excavated to count eggs. This monitoring provided data on the total number of nests completed, the seasonal phenology of nesting activity, nest-site characteristics (i.e. vegetation cover and location), and clutch size. Nests were subsequently monitored during the spring-summer sampling period for depredation events. Nest depredation on the Thomson Causeway was largely attributed to raccoons and was easily detected as there was an empty hole in the ground where the nest was located. Numbered markers were frequently recovered from the predation hole. In the absence of this direct evidence of the nest identity, the predated nest was distinguished from any nearby intact nests by confirming that nearby nests retained their markers above undisturbed soil or by using our nest measurements to confirm nest locations. Nest monitoring provided data on the depredation of each nest.

During the fall sampling period, we relocated and excavated all active nests. The live hatchlings from each nest (0–16 hatchlings per nest; mean = 2.9, mode = 0) were counted and placed together in a plastic container and transported to Iowa State University. A subset of the hatchlings was sacrificed for the determination of sex. The remaining hatchlings were maintained in the laboratory over the winter under naturalistic conditions and released at the Thomson Causeway the following May. This sampling provided data on final nest depredation, nest survival and hatchling survival.

Taxonomy and systematics: Painted turtles (Chrysemys picta) are in the Family Emydidae (Starkey et al. 2003).

Permit history: Research on the Thomson Causeway was performed with the permission of the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, and the Illinois Department of Natural Resources.

Legal/organizational requirements: Animal care permits have been held continuously during the study from the University of Chicago, the University of California-Davis, and Iowa State University.

4. Project personnel: Fredric Janzen, Ricky Spencer, Rachel Bowden, Lindsay Kasuga, Ryan Paitz, Heidi Harms, Lori Neuman-Lee, Yadira Ortiz, Jason Kolbe, James Krenz, Yewah Lau, David Weisrock, Paul Colbert, Carrie Morjan, Dan Warner, Luke Harmon, Jada Rohloff, Molly Reida, Lydia Neilsen, Amelia Gauger, Michael Mullins, and Curtis Eckerman all spent at least two full field seasons at the Thomson Causeway working on this long-term project.

CLASS III. DATA SET STATUS AND ACCESSIBILITY

A. Status

Latest update: The data set was last modified 12 May 2008. Data collection is ongoing.

Latest Archive date: 12 May 2008

Metadata status: The metadata are complete.

Data verification: The data in the data set were verified by confirming the accuracy of the original digital data entries of individual nests. This was done in the following manner. Nests were counted in a year if the original data sheets confirmed that the nest was real and unique. Nesting dates were confirmed randomly for each year (3–5% of nests checked). For nests that lacked nesting dates in the digital data files, the original data sheets were consulted and these data were entered into the data file when available. All original data entries of depredation events, nest survival, and number of live hatchlings were confirmed by comparing entered data with hand-written data on the original data sheets. Nests were counted as depredated if the data sheet indicated a depredation event, if the nest was empty during the fall sampling period, or if the data sheet did not indicate a fate, but no hatchlings or eggs were recovered from the nest. In some years, a portion of the nests was protected against depredation with subsurface metal grates. These nests were counted as depredated if digging marks of predators were present at the nest. These events were counted as depredation because, under normal situations, those nests would have been consumed. Any hatchlings produced by these nests were not included in the data set. Nests were counted as surviving if at least one live hatchling was recovered from the nest. Counts of live hatchlings in a nest excluded dead eggs and late-stage embryos. The original nest data have also been checked multiple times previously during the course of preparing publications using nest data (see below).

B. Accessibility

Storage location and medium: (Ecological Society of America data archives [Ecological Archives link], URL published in each issue of its journals). Original data in digital format and original data sheets are located at Iowa State University, Ames, IA, USA, in the Janzen Lab and in the office of Fredric Janzen.

Contact person: Fredric Janzen, email: fjanzen@iastate.edu, Tel. 515.294.4230, Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011, USA

Copyright restrictions: None.

Proprietary restrictions: NSF grants DEB-9629529 and DEB-0089680 should be acknowledged for providing the primary funding necessary to collect the data contained herein.

Costs: None.

CLASS IV. DATA STRUCTURAL DESCRIPTORS

A. Data Set File

Identity:Chrysemys_picta_1989-2006.txt

Size: 3083 records, not including header row.

Format and storage mode: ASCII text, tab delimited

Header information: See variable names in Section B.

Alphanumeric attributes: Mixed

Special characters/fields: Missing data denoted as -999.9

Authentication procedures: The sums of selected columns are: Nest_Date=432858, S+W_Vegetation=140792.7, Live_Hatchlings=7898.1.

B. Variable definitions

Year: Year of data collection.

Nest: Unique nest identification number.

Nest_Date: Date nest was laid if known. Window of dates in which nest must have been laid, or date before (“<”) or after (“>”) which nest must have been laid if the nest was discovered later (Julian days).

S+W_Vegetation: South + West vegetation cover (%) over a nest.

Clutch_Size: The number of eggs in the nest, if recorded.

Nest_Predation: Indicates whether a nest was depredated before the fall excavation period (third weekend in September); 1 = depredated, 0 = not depredated.

Nest_Survival: Indicates whether a nest produced any live hatchlings at the fall excavation period (third weekend in September); 1 = the nest produced at least one live hatchling; 0 = the nest produced no live hatchlings (due to depredation or clutch mortality from unknown causes).

Live_Hatchlings: The number of live hatchlings excavated from the nest in the fall sampling period.

Variable name

Variable definition

Units

Storage type

Range numeric values

Missing value codes

Year

Year

N/A

Integer

1989-2006

N/A

Nest

Nest number

N/A

Integer

1989001-2006268

N/A

Nest_Date

Date of nesting event or nesting window

Julian

Integer, range of integers, “<” or “>” integer

variable

-999.9

S+W_Vegetation

Percent vegetation cover in south and west directions

Percent

Integer

0 - 200

-999.9

Clutch_Size

Clutch size laid in nest

N/A

Integer

3 - 21

-999.9

Nest_Predation

Depredation of nest

N/A

Integer

0 - 1

-999.9

Nest_Survival

Survival of nest

N/A

Integer

0 - 1

-999.9

Live_Hatchlings

Number of live hatchlings in the nest in the fall

N/A

Integer

0 - 16

-999.9

C. Data anomalies: In 1993, the entire research site was flooded prior to depredation counts. For this reason, no data are available for 1993 on nest depredation. No nests survived in 1993 (all excavated nests had dead eggs). In all years, nests outside of South Potter’s Marsh were also recorded and numbered, but are not included in this data set. For a few nests, a greater number of live hatchlings were excavated in the fall than the number of eggs that had previously been recorded during spring-summer excavation. We assume, in these cases, that some eggs were overlooked during initial nest excavation in the spring-summer.

CLASS V. SUPPLEMENTAL DESCRIPTORS

A. Data acquisition

Data forms: Customized data sheets with records of individual nesting events.

Location of completed data forms: Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011 USA

Data entry/verification procedures: Field personnel were supplied with data sheets to record nesting data in the field. Data were entered from field and other data sheets into a computer in the lab and double-checked. Files are stored on Janzen Lab computers at Iowa State University, Ames, IA, USA, and on CD as Microsoft Excel files.

B. Quality assurance/quality control procedures: See descriptions of data verification (Class III, Section A), data entry/verification procedures (Class V, Section A), and computer programs and data processing algorithms (Class V, Section D).

C. Related material: Data on individual nests, including: female ID, first or second nesting event for the female, female size, spatial relatedness of nests, nest temperature profiles (for a subset of nests from 1995–2005), and clutch sex ratio.

D. Computer programs and data processing algorithms: Nests located outside of South Potter’s marsh were removed from the dataset. Nesting date in Julian days was calculated from the record of the calendar date of nesting (or nesting window), taking into account leap years. Vegetation cover data were processed from raw densiometer readings into percentage cover. Previous analyses have indicated that vegetation cover in the southern and western directions are most important in determining nest temperature and clutch sex ratio (Janzen 1994b, Morjan and Janzen 2003, Weisrock and Janzen 1999). South and west vegetation cover readings from the densiometer were multiplied by 1.04 to calculate percentage vegetation cover in those directions. These values were summed using the “sum” function of excel to calculate S+W Vegetation cover. In 2004 and 2005, vegetation cover was measured using a spherical lens on a digital camera. These digital images provide measures of transmitted solar radiation, which can be converted back to S+W Vegetation cover by a simple linear equation (verified from data of digital images and densiometer readings collected in 2003; Kasuga et al unpubl.)

E. Archiving: n/a

F. Publications using portions of the data set:

Bowen, K. D., and F. J. Janzen. 2005. Rainfall and depredation of nests of the Painted turtle, Chrysemys picta. Journal of Herpetology 39:649–652.

Colbert, P. L., R.-J. Spencer, and F. J. Janzen. 2009. Does the risk of predation drive incubation times in turtles? Functional Ecology 23:accepted pending revision.

Janzen, F. J. 1994a. Climate change and temperature-dependent sex determination in reptiles. Proceedings of the National Academy of Sciences, USA 91:7487–7490.

Janzen, F. J. 1994b. Vegetational cover predicts the sex ratio of hatchling turtles in natural nests. Ecology 75:1593–1599.

Janzen, F. J., and C. L. Morjan. 2001. Repeatability of microenvironment-specific nesting behaviour in a turtle with environmental sex determination. Animal Behaviour 62:73–82.

Kolbe, J. J., and F. J. Janzen. 2002. Spatial and temporal dynamics of turtle nest predation: edge effects. Oikos 99:538–544.

Morjan, C. L. 2003a. Variation in nesting patterns affecting nest temperatures in two populations of painted turtles (Chrysemys picta) with temperature-dependent sex determination. Behavioral Ecology and Sociobiology 53:254–261.

Morjan, C. L. 2003b. How rapidly can maternal behavior affecting primary sex ratio evolve in a reptile with environmental sex determination? American Naturalist 162:205–219.

Morjan, C. L., and F. J. Janzen. 2003. Nest temperature is not related to egg size in a turtle with temperature-dependent sex determination. Copeia 2003:366–372.

Schwanz, L. E., and F. J. Janzen. 2008. Climate change and temperature-dependent sex determination: can individual plasticity in nesting phenology prevent extreme sex ratios? Physiological and Biochemical Zoology 81:826–834.

Valenzuela, N., and F. J. Janzen. 2001. Nest-site philopatry and the evolution of temperature-dependent sex determination. Evolutionary Ecology Research 3:779–794.

Weisrock, D. W., and F. J. Janzen. 1999. Thermal and fitness-related consequences of nest location in painted turtles (Chrysemys picta). Functional Ecology 13:94–101.

G. Publications using the same sites:

Paitz, R. T., H. K. Harms, R. M. Bowden, and F. J. Janzen. 2007. Experience pays: offspring survival increases with female age. Biology Letters 3:44–46.

Valenzuela, N., and T. Shikano. 2006. Embryological ontogeny of Aromatase gene expression in Chrysemys picta and Apalone mutica turtles: comparative patterns within and across temperature-dependent and genotypic sex-determining mechanisms. Development, Genes and Evolution 217:55–62.

Valenzuela, N., A. LeClere, and T. Shikano. 2006. Comparative expression of steroidogenic factor 1 in Chrysemys picta and Apalone mutica turtles with environmental and genotypic sex determination. Evolution and Development 8:424–432.

Bowen, K. D., and F. J. Janzen. 2005. Rainfall and depredation of nests of the painted turtle, Chrysemys picta. Journal of Herpetology 39:649–652.

Bowen, K. D., R.-J. Spencer, and F. J. Janzen. 2005. A comparative study of environmental factors that affect nesting in Australian and North American freshwater turtles. Journal of Zoology 267:397–404.

Harms, H. K., R. T. Paitz, R. M. Bowden, and F. J. Janzen. 2005. Age and season impact resource allocation to eggs and nesting behavior in the painted turtle. Physiological and Biochemical Zoology 78:996–1004.

Bowden, R. M., H. K. Harms, R. T. Paitz, and F. J. Janzen. 2004. Does optimal egg size vary with demographic stage because of a physiological constraint? Functional Ecology 18:522–529.

Valenzuela, N., D. C. Adams, R. M. Bowden, and A. C. Gauger. 2004. Geometric morphometric sex estimation for hatchling turtles: a powerful alternative for detecting subtle sexual shape dimorphism. Copeia 2004:735–742.

Morjan, C. L. 2003a. Variation in nesting patterns affecting nest temperatures in two populations of painted turtles (Chrysemys picta) with temperature-dependent sex determination. Behavioral Ecology and Sociobiology 53:254–261.

Morjan, C. L. 2003b. How rapidly can maternal behavior affecting primary sex ratio evolve in a reptile with environmental sex determination? American Naturalist 162:205–219.

Morjan, C. L., and F. J. Janzen. 2003. Nest temperature is not related to egg size in a turtle with temperature-dependent sex determination. Copeia 2003:366–372.

Starkey, D. E., H. B. Shaffer, R. L. Burke, M. R. J. Forstner, J. B. Iverson, F. J. Janzen, A. G. J. Rhodin, and G. R. Ultsch. 2003. Molecular systematics, phylogeography, and the effects of Pleistocene glaciation in the painted turtle (Chrysemys picta) complex. Evolution 57:119–128.

Janzen, F. J., and C. L. Morjan. 2002. Egg size, incubation temperature, and posthatching growth in painted turtles (Chrysemys picta). Journal of Herpetology 36:308–311.

Kolbe, J. J., and F. J. Janzen. 2002. Spatial and temporal dynamics of turtle nest predation: edge effects. Oikos 99:538–544.

Pearse, D. E., F. J. Janzen, and J. C. Avise. 2002. Multiple paternity, sperm storage, and reproductive success of female and male painted turtles (Chrysemys picta) in nature. Behavioral Ecology and Sociobiology 51:164–171.

Janzen, F. J., and C. L. Morjan. 2001. Repeatability of microenvironment-specific nesting behaviour in a turtle with environmental sex determination. Animal Behaviour 62:73–82.

Morjan, C. L., and N. Valenzuela. 2001. Is ground-nuzzling by female turtles associated with soil surface temperatures? Journal of Herpetology 35:668–672.

Pearse, D. E., C. M. Eckerman, F. J. Janzen, and J. C. Avise. 2001. A genetic analogue of mark-recapture methods for estimating local population size: an approach based on molecular parentage assessments. Molecular Ecology 10:2711–2718.

Pearse, D. E., F. J. Janzen, and J. C. Avise. 2001. Genetic markers substantiate long-term storage and utilization of sperm by female painted turtles. Heredity 86:378–384.

Valenzuela, N., and F. J. Janzen. 2001. Nest-site philopatry and the evolution of temperature-dependent sex determination. Evolutionary Ecology Research 3:779–794.

Weisrock, D. W., and F. J. Janzen. 1999. Thermal and fitness-related consequences of nest location in painted turtles (Chrysemys picta). Functional Ecology 13:94-101.

Janzen, F. J., M. E. Wilson, J. K. Tucker, and S. P. Ford. 1998. Endogenous yolk steroid hormones in turtles with different sex-determining mechanisms. General and Comparative Endocrinology 111:306–317.

Brodie, E. D., III, and F. J. Janzen. 1996. On the assignment of fitness values in statistical analyses of selection. Evolution 50:437–442.

Packard, G. C., and F. J. Janzen. 1996. Interpopulational variation in the cold-tolerance of hatchling painted turtles. Journal of Thermal Biology 21:183–190.

Janzen, F. J. 1994a. Climate change and temperature-dependent sex determination in reptiles. Proceedings of the National Academy of Sciences USA 91:7487–7490.

Janzen, F. J. 1994b. Vegetational cover predicts the sex ratio of hatchling turtles in natural nests. Ecology 75:1593–1599.

H. History of data set usage

Data request history: N/A

Data set update history: N/A

Review history: N/A

Questions and comments from secondary users: N/A


ACKNOWLEDGMENTS

We thank the U.S. Army Corps of Engineers for access to the Thomson Causeway and the U.S. Fish and Wildlife Service and the Illinois Department of Natural Resources for collecting permits. Research was supported by National Science Foundation grants (DDIG BSR-8914686, DEB-9629529, UMEB IBN-0080194, LTREB DEB-0089680, IBN-0212935), as well as the ASIH Gaige Fund, Sigma Xi, and the Department of Zoology and Genetics at Iowa State University. While preparing the database, LES was supported by an NSF Postdoctoral Fellowship in Biological Informatics.

LITERATURE CITED

Bernardo, J. 1996. Maternal effects in animal ecology. American Zoologist 36:83–105.

Bowen, K. D., and F. J. Janzen. 2005. Rainfall and depredation of nests of the Painted turtle, Chrysemys picta. Journal of Herpetology 39:649–652.

Bull, J. J. 1980. Sex determination in reptiles. Quarterly Review of Biology 55:3–21.

Crouse, D. T ., L. B. Crowder, and H. Caswell. 1987. A stage-based population model for Loggerhead sea turtles and implications for conservation. Ecology 68:1412–1423.

Deeming, D. C., and M. W. J. Ferguson. 1991. Egg incubation: its effects on embryonic development in birds and reptiles. Cambridge University Press, Cambridge.

Dutton, D. L., P. H. Dutton, M. Chaloupka, and R. H. Boulon. 2005. Increase of a Caribbean leatherback turtle Dermochelys coriacea nesting population linked to long-term nest protection. Biological Conservation 126:186–194.

Gagliano, M., and M. I. McCormick. 2006. Maternal condition influences phenotypic selection on offspring. Journal of Animal Ecology 76:174–182.

Heppell, S. S., L. B. Crowder, and D. T. Crouse. 1996. Models to evaluate headstarting as a management tool for long-lived turtles. Ecological Applications 6:556–565.

Heppell, S. S. 1998. Application of life-history theory and population model analysis to turtle conservation. Copeia 1998:367–375.

Janzen, F. J. 1994a. Climate change and temperature-dependent sex determination in reptiles. Proceedings of the National Academy of Sciences, USA 91:7487–7490.

Janzen, F. J. 1994b. Vegetational cover predicts the sex ratio of hatchling turtles in natural nests. Ecology 75:1593–1599.

Janzen, F. J., and C. L. Morjan. 2001. Repeatability of microenvironment-specific nesting behaviour in a turtle with environmental sex determination. Animal Behaviour 62:73–82.

Janzen, F. J., and G. L. Paukstis. 1991. Environmental sex determination in reptiles: ecology, evolution, and experimental design. Quarterly Review of Biology 66:149–179.

Kolbe, J. J., and F. J. Janzen. 2002. Spatial and temporal dynamics of turtle nest predation: edge effects. Oikos 99:538–544.

Marshall, D. J., and T. Uller. 2007. When is a maternal effect adaptive? Oikos 116:1957–1963.

Morjan, C. L. 2003a. Variation in nesting patterns affecting nest temperatures in two populations of painted turtles (Chrysemys picta) with temperature-dependent sex determination. Behavioral Ecology and Sociobiology 53:254–261.

Morjan, C. L. 2003b. How rapidly can maternal behavior affecting primary sex ratio evolve in a reptile with environmental sex determination? American Naturalist 162:205–219.

Morjan, C. L., and F. J. Janzen. 2003. Nest temperature is not related to egg size in a turtle with temperature-dependent sex determination. Copeia 2003:366–372.

Mousseau, T. A., and C. W. Fox. 1998a. Maternal Effects as Adaptations. Oxford University Press, Oxford, UK.

Mousseau, T. A., and C. W. Fox. 1998b. The adaptive significance of maternal effects. Trends in Ecology and Evolution 13:403–407.

Räsänen, K., and L. E. B. Kruuk. 2007. Maternal effects and evolution at ecological time-scales. Functional Ecology 21:408–421.

Rhodin, A. G. J., and G. R. Ultsch. 2003. Molecular systematics, phylogeography, and the effects of Pleistocene glaciation in the painted turtle (Chrysemys picta) complex. Evolution 57:119–128.

Schwanz, L. E., and F. J. Janzen. 2008. Climate change and temperature-dependent sex determination: can individual plasticity in nesting phenology prevent extreme sex ratios? Physiological and Biochemical Zoology 81:826–834.

Spencer, R.-J., and M. B. Thompson. 2005. Experimental analysis of the impact of foxes on freshwater turtle populations. Conservation Biology 19:845–854.

Starkey, D. E., H. B. Shaffer, R. L. Burke, M. R. J. Forstner, J. B. Iverson, F. J. Janzen, A. G. J. Rhodin, and G. R. Ultsch. 2003. Molecular systematics, phylogeography, and the effects of Pleistocene glaciation in the painted turtle (Chrysemys picta) complex. Evolution 57:119–128.

Valenzuela, N., and F. J. Janzen. 2001. Nest-site philopatry and the evolution of temperature-dependent sex determination. Evolutionary Ecology Research 3:779–794.

Weisrock, D. W., and F. J. Janzen. 1999. Thermal and fitness-related consequences of nest location in painted turtles (Chrysemys picta). Functional Ecology 13:94–101.

Wisdom, M.J., L.S. Mills, and D. F. Doak. 2000. Life stage simulation analysis: estimating vital-rate effects on population growth for conservation. Ecology 81:628–641.


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