Comas M, Reguera S, Zamora-Camacho FJ, Moreno-Rueda G. Age structure of a lizard along an elevational gradient reveals nonlinear lifespan patterns with altitude.
Curr Zool 2019;
66:373-382. [PMID:
32939218 PMCID:
PMC7485750 DOI:
10.1093/cz/zoz063]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 12/23/2019] [Indexed: 11/14/2022] Open
Abstract
Lifespan is one of the main components of life history. Shorter lifespans can be expected
in marginal habitats. However, in the case of ectotherms, lifespan typically increases
with altitude, even though temperature—one of the main factors to determine ectotherms’
life history—declines with elevation. This pattern can be explained by the fact that a
shorter activity time favors survival. In this study, we analyzed how lifespan and other
life-history traits of the lizard Psammodromus algirus vary along a
2,200 m elevational gradient in Sierra Nevada (SE Spain). Populations at intermediate
altitudes (1,200–1,700 m), corresponding to the optimal habitat for this species, had the
shortest lifespans, whereas populations inhabiting marginal habitats (at both low and at
high altitudes) lived longest. Therefore, this lizard did not follow the typical pattern
of ectotherms, as it also lived longer at the lower limit of its distribution, nor did it
show a longer lifespan in areas with optimal habitats. These results might be explained by
a complex combination of different gradients along the mountain, namely that activity time
decreases with altitude whereas food availability increases. This could explain why
lifespan was maximum at both high (limited activity time) and low (limited food
availability) altitudes, resulting in similar lifespans in areas with contrasting
environmental conditions. Our findings also indicated that reproductive investment and
body condition increase with elevation, suggesting that alpine populations are locally
adapted.
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