Alteration of testicular response to long photoperiod by transient exposure to short photoperiod in collared lemmings (Dicrostonyx groenlandicus)

Gower, Barbara A.; Nagy, Tim R.; Stetson, Milton H.

doi:10.1530/jrf.0.1090257

Cited by 6 publications

(10 citation statements)

References 3 publications

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“…In Truelove Lowland, Canada (75°33′ N), the proportion of mature males with functional testes dropped from 92% in June to only 34% in August (Fuller et al 1977). This physiological response, possibly reflecting evolution in the Arctic where reproduction is not necessarily advantageous in summer (Gower et al 1997), might also partly explain the infrequent breeding events in my high Arctic study area (72°30′ N) compared with more southern areas (e.g. Pearce Point: 69°48′ N) with a different photoperiod regime.…”

Section: Discussionmentioning

confidence: 92%

“…Finally, mature collared lemming males are known to influence maturation of females (Hasler and Banks 1975), but they have a unique reproductive response to photoperiod. Long photoperiod causes testicular regression and if males are born and live under long photoperiod, their maturation is delayed (Nagy 1993, Gower et al 1997Gower et al 1998). In Truelove Lowland, Canada (75°33′ N), the proportion of mature males with functional testes dropped from 92% in June to only 34% in August (Fuller et al 1977).…”

Section: Discussionmentioning

confidence: 99%

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The summer decline of the collared lemming,Dicrostonyx groenlandicus,in high arctic Greenland

Gilg¹

2002

Oikos

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

The summer decline of the collared lemming,Dicrostonyx groenlandicus,in high arctic Greenland

Gilg¹

2002

Oikos

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“…A degree of control by photoperiod has been seen in some species (e.g. Gower et al 1997) but experimental evidence strongly suggests that food availability and the temperature-insulating effect of deep snow are the major factors allowing them to do this. While the ability of such small animals to reproduce in such energetically challenging conditions has been called a 'physiological miracle' (Krebs 1993), it may be even more widespread than thought and, as will be noted shortly, it may involve individual variation in reproductive photoresponsiveness.…”

Section: Seasonal Reproduction F H Bronson 3333mentioning

confidence: 99%

Climate change and seasonal reproduction in mammals

Bronson

2009

Phil. Trans. R. Soc. B

320

278

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Seasonal reproduction is common among mammals at all latitudes, even in the deep tropics. This paper (i) discusses the neuroendocrine pathways via which foraging conditions and predictive cues such as photoperiod enforce seasonality, (ii) considers the kinds of seasonal challenges mammals actually face in natural habitats, and (iii) uses the information thus generated to suggest how seasonal reproduction might be influenced by global climate change. Food availability and ambient temperature determine energy balance, and variation in energy balance is the ultimate cause of seasonal breeding in all mammals and the proximate cause in many. Photoperiodic cueing is common among long-lived mammals from the highest latitudes down to the mid-tropics. It is much less common in shorter lived mammals at all latitudes. An unknown predictive cue triggers reproduction in some desert and dry grassland species when it rains. The available information suggests that as our climate changes the small rodents of the world may adapt rather easily but the longer lived mammals whose reproduction is regulated by photoperiod may not do so well. A major gap in our knowledge concerns the tropics; that is where most species live and where we have the least understanding of how reproduction is regulated by environmental factors.Keywords: seasonality; gonadotropin-releasing hormone; foraging conditions; energy balance; photoperiod; the tropics The world's climate has changed radically from hot to cold and wet to dry and back again throughout its 4.5 billion-year history. When mammals first appeared 250 million years ago, the world was warming and drying out and there was only one landmass in existence, the supercontinent of Pangea. Some parts of Pangea experienced extreme seasonal cycles of climate and food availability, while others did not (Crowley 1994). Thus, some of the first mammals probably reproduced only seasonally, while others reproduced throughout the year. As Pangea broke up and the new continents spread around the world, the Earth's climate continued to shift from one extreme to the other and the expanding numbers of mammals continued to adapt reproductively. The Cretaceous mass extinction of 65 Ma opened the door to massive adaptive radiation and today more than 4000 species of mammals can be found surviving and reproducing in a huge diversity of habitats, most characterized by some degree of seasonal variation. The world's climate is changing rapidly now and there is a concern that many species may face extinction if they cannot evolve new seasonal strategies (Bradshaw & Holzapfel 2006). The objectives of this paper are threefold: first, to consider what laboratory experimentation has taught us about the neuroendocrine pathways that link seasonal factors to the reproduction of mammals; second, to relate the knowledge gained in the laboratory to the kinds of challenges mammals actually face in natural habitats; third, to use the information generated by the first two objectives to consider how mammals might or might not adapt s...

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“…However, other environmental cues also may be important for fine-tuning when breeding occurs. Experimental evidence suggests a strong influence of both food availability and winter snow-insulation, for example, on reproductive timing in photoperiodic collared-lemmings [45]. Alternatively, other species use an endogenous circannual clock to regulate annual cycles [44].…”

Section: (B) Ecological and Environmental Cuesmentioning

confidence: 99%

Changing seasonality and phenological responses of free-living male arctic ground squirrels: the importance of sex

Sheriff

Richter

Buck

et al. 2013

Phil. Trans. R. Soc. B

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Many studies have addressed the effects of climate change on species as a whole; however, few have examined the possibility of sex-specific differences. To understand better the impact that changing patterns of snow-cover have on an important resident Arctic mammal, we investigated the long-term (13 years) phenology of hibernating male arctic ground squirrels living at two nearby sites in northern Alaska that experience significantly different snow-cover regimes. Previously, we demonstrated that snow-cover influences the timing of phenological events in females. Our results here suggest that the end of heterothermy in males is influenced by soil temperature and an endogenous circannual clock, but timing of male emergence from hibernation is influenced by the timing of female emergence. Males at both sites, Atigun and Toolik, end heterothermy on the same date in spring, but remain in their burrows while undergoing reproductive maturation. However, at Atigun, where snowmelt and female emergence occur relatively early, males emerge 8 days earlier than those at Toolik, maintaining a 12-day period between male and female emergence found at each site, but reducing the pre-emergence euthermic period that is critical for reproductive maturation. This sensitivity in timing of male emergence to female emergence will need to be matched by phase shifts in the circannual clock and responsiveness to environmental factors that time the end of heterothermy, if synchrony in reproductive readiness between the sexes is to be preserved in a rapidly changing climate.

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Alteration of testicular response to long photoperiod by transient exposure to short photoperiod in collared lemmings (Dicrostonyx groenlandicus)

Abstract: The reproductive response of collared lemmings (Dicrostonyx groenlandicus)

Cited by 6 publications

References 3 publications

The summer decline of the collared lemming,Dicrostonyx groenlandicus,in high arctic Greenland

The summer decline of the collared lemming,Dicrostonyx groenlandicus,in high arctic Greenland

Climate change and seasonal reproduction in mammals

Changing seasonality and phenological responses of free-living male arctic ground squirrels: the importance of sex

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