Mammal Research Institute (MRI), Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa Timing is everything: Seasonal.

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Presentation transcript:

Mammal Research Institute (MRI), Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa Timing is everything: Seasonal reproduction in the spiny mouse, Acomys spinosissimus Katarina Medger Supervisors: Prof. N. C. Bennett & Prof. C. T. Chimimba

Bronson 1985 Introduction

 Distribution  south of the equator  Habits:  nocturnal, rocky habitats  solitary, groups and family parties  Reproduction:  seasonal as well as aseasonal breeding Acomys species  indications for seasonality in A. spinosissimus (Pienaar et al. 1980, South Africa; Smithers 1971, Botswana) (reviewed in Skinner & Chimimba 2005) Spiny mouse – Acomys spinosissimus

Does Acomys spinosissimus reproduce seasonally or aseasonally? Does A. spinosissimus show reproductive photoresponsiveness? Objectives

1. Seasonality Trapping 10 ♀ & 10♂ monthly 1 year Dissection & Blood samples Endocrinology centrifuge blood analyzing plasma for hormones Histology ♀ reprod. organs testes weighed, length & width Skull & DNA sequencing heart, liver, kidney Materials & Methods

2. Photoperiod 14 ♂ 8L:16D 7 ♂ 16L:8D 40 days 30 days Materials & Methods

Climate data Goro Game Reserve – Soutpansberg – 22°S

Testes volume and mass Mean ± SD; p<0.001 (Generalized linear model) p<0.001 (Generalized linear model) Testosterone Results

Ovarian volume Mean ± SD; p<0.001 (ANOVA) p<0.001 (Generalized linear model) Progesterone

Pregnant and lactating females Results

Results - Photoperiod Mean ± SE; p<0.001 (t-test) SD – short day (8L:16D) LD – long day (16L:8D) Testes volumeTestes mass

Results - Photoperiod Testosterone Mean ± SE; p<0.001 (t-test) SD – short day (8L:16D) LD – long day (16L:8D)

Discussion  Seasonal reproduction  main breeding season from September – January  reproductively inactive from February – August But significant increase of testes size from June rain (September – April) and warmest months (>20°C; September – May) females lactating until April but last pregnancy January  Reproductive photoresponsiveness (long days) increase of testes size and testosterone concentration after 30 days under 16L:8D 

Acknowledgments  National Research Foundation  Dave Dewsnap and the staff of the Goro Game Reserve  Field assistants: Jacklyn Chan, Amélie Broucke, Edith Mertz, Luisa Riato, Khomotso Ntuli, Mathews Sebonego, Andr é Prins, Warren Matten, Adrian Harwood, Angela Köhler, Darren Pietersen  Dissection & histology: Marietjie Oosthuizen, Hermien Viljoen, Caroline Yetman  iButtons: Fred Dalerum  others: Babsie Potgieter, Marna Ferreira, Martin Haupt  Nigel Bennett & Chris Chimimba