Movements Related to Differential Reproductive Strategies in Male and

Female Sonoran Mud Turtles (Kinosternon sonoriense)

Kenneth J. Locey, Paul A. Stone, Marie E. Stone, Brian D. Stanila

Department of Biology, University of Central Oklahoma, Edmond, OK 73034

Introduction

Reproductive Effort– Energy expended towards finding and competing for

mates, and towards provisioning offspring

Female-biased Parental Effort:– Anisogamy requires females to allocate energy to egg

productionMale-biased Mating Effort:– Anisogamy allows males to allocate energy to finding

and / or competing for mates

Differential reproductive strategies of males and females

“Ecological constraints impose limits on the degree to which sexual selection can operate”– (Emlen and Oring, 1977)

Introduction

Sonoran Mud Turtle - Kinosternon sonoriense

Adults: 168 mm carapace length, maximum1-2 clutches of eggs per year, 6-7 eggs per clutchMax life-span: 20+ ?

Introduction

These environmental conditions impose ecological constraints on the reproductive efforts of K. sonoriense

Contexts for differential reproductive strategies in Kinosternids

Male biased vagility as a result of mate searching has been previously reported in K. baurii (Tuberville, Gibbons, and Greene (1996) Asynchronous Aquatic Activity in K. sonoriense (Peterson and Stone, 2000)Female S. odoratus have the ability to store sperm (Gist and Congdon, 1998)Forced Aestivation - Turtles survive complete drying of habitats by burying themselves on land (Peterson and Stone, 2000)

IntroductionSpatiotemporal distribution of resources affects the success of female K. sonoriense– selection for females that seek resources and

copulate enough to maintain stores of sperm

Spatiotemporal distribution of females affects success of male K. sonoriense– Selection for males that seek females and will attempt

long distance movements to find females that have not been copulated with

Introduction

Hypothesis: The movements of male and female Sonoran Mud Turtles support the predictions of sexual selection theoryTwo main predictions:– Males make longer movements within canyons than

females– Males make more frequent movements between

canyons than females

Main Vegetation: Oak / Juniper forest, scrubland, abundant wildflowers during rainy seasons

Blackwater Canyon -July 2006

Canyons and Stock tanks are prone to rapid and extreme changes in water availability

Blackwater Hole

Data CollectionMark-recapture efforts in the Peloncillo Mountains since 1994.Hoop nets placed in stock tanks and baited with sardinesHand-captures from canyon pools and streams

Blackwater Canyon mapped in ’94 with compass and tape, and again in ’07 with GPS.Spatial environment created in ArcMap 9.2Georeference locations and waypoints in ArcMapMeasure Maximum Recorded Distance Moved for Individuals captured 5 or more times. One-tailed t-test.Examine frequency and demography of inter-canyon migrations with one-tailed binomial test.

Data Collection

ResultsMales Females

Intra-canyonMean ± SE

Max Recorded Distance (m),

753 ± 141.29 (N = 40)

184 ± 35.15(N = 48)

Inter-canyon Movements

22 5

Results

Males moved farther than females, t86 = 4.235, P = 2.85E-5

Males made inter-canyon movements more often than females Cα(1),27 = 8, P = 6.015E-4

#1104, Male, 453 day between captures, 2.4 km

#244, Male, 8 years and 9 days, 6.3 km

Discussion

Differences in movement of male and female K. sonoriense support the predictions of sexual selection theory

Males compete indirectly for mates

Future Analyses

Sexual selection hypotheses of differential reproductive strategies as responses to ephemeral resources– Scramble competition

Hydrological study– Quantify water availability

Estimates of recapture and survival with respect to sex and water availability– Program MARK

Acknowledgments

We thank everyone involved with data collection efforts for their assistance, and the Joe Jackson College of Graduate Studies and Research at UCO for support