Sperm production in an extremophile fish, the cave molly (Poecilia mexicana, Poeciliidae, Teleostei)
- 124 Downloads
A prominent trade-off in life history theory and evolution balances the costs of reproduction with those of basic somatic needs. Hence, reproductive efforts may be reduced in environments where additional energy is required for somatic maintenance. Here, we investigated male sperm stores in Atlantic mollies (Poecilia mexicana) from a sulfidic cave and several sulfidic and non-sulfidic surface habitats. We found significant differences among populations in the number of sperm stripped per male, which was also correlated with differences in gonad weights. The largest sperm stores were detected in males from non-sulfidic surface creeks, while males from a partially sulfidic surface system had lower sperm counts, and males from completely sulfidic systems, surface as well as subterranean, had even fewer available sperm. We conclude that the extreme environmental conditions in sulfidic habitats appear to constrain male sperm production, since hydrogen sulfide as a naturally occurring toxin requires energy-demanding adaptations. Furthermore, we examined sperm counts of lab-reared cave and surface mollies in response to energy limitation. Males from stock populations were placed under high and low food treatments for a 2-week period and then stripped of sperm. Sperm counts of surface mollies tended to be reduced by low food availability, whereas sperm counts of cave mollies did not significantly vary between food treatments, which likely points towards a higher starvation resistance in cave mollies.
KeywordsCave fish Energy limitation Hydrogen sulfide Spermatogenesis Testes weight
N. Franssen and L. Fromhage kindly provided valuable comments on the manuscript. We thank the Mexican Government for issuing research permits (Permiso de pesca de fomento numbers: 291002-613-1577, DGOPA/5864/260704/-2408, and DGOPA/16988/191205/-8101). Financial support came from the University of Oklahoma, the DFG (SCHL 344/15-1; PL 470/1-1), the German Ichthyological Association (M.T. and M.P.), the American Livebearer Association, the Basler Foundation for Biological Research, the Janggen-Poehn-Foundation, the Roche Research Foundation, and the Wolfermann-Nägeli-Foundation (M.T.).
- Bell G, Koufopanou V (1986) The cost of reproduction. In: Dawkins R, Ridley M (eds) Oxford surveys in evolutionary biology, vol 3. Oxford University Press, Oxford, pp 83–131Google Scholar
- Birkhead TR, Møller AP (1998) Sperm competition and sexual selection. Academic Press, LondonGoogle Scholar
- Hüppop K (2000) How do cave animals cope with the food scarcity in caves? In: Wilkens H, Culver DC, Humphries WF (eds) Ecosystems of the world, vol 30: subterranean ecosystems. Elsevier, Amsterdam, pp 159–188Google Scholar
- Langecker TG, Wilkens H, Parzefall J (1996) Studies on the trophic structure of an energy rich Mexican cave (Cueva de las Sardinas) containing sulfurous water. Mem Biospeol 23:121–125Google Scholar
- McMullin E, Bergquist D, Fisher C (2000) Metazoans in extreme environments: adaptations of hydrothermal vent and hydrocarbon fauna. Grav Space Biol Bull 13:13–23Google Scholar
- Plath M, Tobler M, Riesch R, García de León FJ, Giere O, Schlupp I (in press) Survival in an extreme habitat: the role of behaviour and energy limitation. NaturwissenschaftenGoogle Scholar
- Stallones RA et al (1979) Hydrogen sulfide. University Park Press, BaltimoreGoogle Scholar
- Theede H (1973) Comparative studies on the influence of oxygen deficiency and hydrogen sulphide on marine bottom invertebrates. Neth J Sea Res 7:245–252Google Scholar
- Townsend CR, Begon ME, Harper JL (2003) Essentials of ecology, 2nd edn. Blackwell Publishing, OxfordGoogle Scholar
- Trivers RL (1972) Parental investment and sexual selection. In: Campbell B (ed) Sexual selection and the descent of man. Aldine Publishing Company, Chicago, USA, pp 136–179Google Scholar
- Weber JM, Kramer DL (1983) Effects of hypoxia and surface access on growth, mortality and behavior of juvenile guppies Poecilia reticulata. Can J Fish Aqua Sci 40:1583–1588Google Scholar