Phenotypic plasticity in the timing of reproduction in Andean bears. (22nd April 2018)

• Record Type: Journal Article
• Authors: Appleton, R. D.; Van Horn, R. C.; Noyce, K. V.; Spady, T. J.; Swaisgood, R. R.; Arcese, P.
• Is Part Of: Journal of zoology. Volume 305:Number 3(2018)
• Page Start: 196
• Page End: 202
• Publication Date: 2018-04-22
• Subjects: facultative seasonality -- reproduction -- photoperiod -- phenotypic plasticity -- Andean bear -- Tremarctos ornatus -- mating behavior -- latitude; Zoology -- Periodicals; Zoologie -- Périodiques; 590.5
• DOI: 10.1111/jzo.12553
• Languages: English
• ISSNs: 0952-8369

Abstract

Abstract: Many factors influence whether mammals reproduce seasonally or continuously but disentangling them can be challenging in free‐living species that are hard to observe. We described the seasonality of reproduction in Andean bears ( Tremarctos ornatus ) in NW Peru (6°26′S, 79°33′W) to test for phenotypic plasticity in response to extrinsic cues. To do so, we compared the mating behavior and birthdates of free‐living bears to the birthdates of captive bears housed over a broad range of latitudes. Free‐living bears were observed on 302 occasions over 6 years (967 field‐days), and mating behaviors recorded 61 times from late Dec to Jan. The mean birthdate of 12 wild‐born litters was 17 August (range = 23 Jun – 15 Oct), 57 ± 10 (SD) days after the winter solstice. Birthdates for 367 captive litters varied widely by comparison (range = 1 Jan – 31 Dec; mean = 14 ± 49 days after the winter solstice). However, captive bears in the tropics had fewer births in autumn and winter (71.4% of births) than captive bears at higher latitudes (96.8% of births; P < 0.001). Differences in seasonal reproduction among captive bears at high and low latitudes and captive and a free‐living at tropical latitudes suggest that Andean bears display phenotypic plasticity in reproductive timing but influenced by photoperiod at high latitudes. Because photoperiodic effects were less evident at tropic latitudes, we suggest that seasonality in the timing of reproduction in the free‐living bears we observed was influenced by seasonal variation in food abundance. The observed effect of photoperiod on reproduction in captive Andean bears at high latitudes may also imply that free‐living bears at the southern edge of the range may be constrained in their ability to adjust reproductive timing to resource availability as environments change. Abstract : We described the seasonality of reproduction in Andean bears ( Tremarctos ornatus ) to test for phenotypic plasticity in response to extrinsic cues. We compared the mating behavior and birthdates of free‐living bears to the birthdates of captive bears. Differences in seasonal reproduction among captive bears at high and low latitudes and captive and a free‐living at tropical latitudes suggest that Andean bears display phenotypic plasticity in reproductive timing but influenced by photoperiod at high latitudes. This may imply that free‐living bears at the southern edge of the range may be constrained in their ability to adjust reproductive timing to resource availability as environments change.