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Females first? Past, present and future variability in offspring sex ratio at a temperate sea turtle breeding area
Author(s) -
Katselidis K. A.,
Schofield G.,
Stamou G.,
Dimopoulos P.,
Pantis J. D.
Publication year - 2012
Publication title -
animal conservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.111
H-Index - 85
eISSN - 1469-1795
pISSN - 1367-9430
DOI - 10.1111/j.1469-1795.2012.00543.x
Subject(s) - hatchling , sex ratio , temperate climate , biology , incubation , turtle (robot) , range (aeronautics) , seasonal breeder , ecology , sea turtle , offspring , demography , population , hatching , pregnancy , biochemistry , materials science , sociology , composite material , genetics
The long‐term survival of species with temperature‐dependant sex determination requires a sufficient range of incubation temperatures to ensure that both males and females are produced. The primary sex ratio of sea turtles is determined by the temperature experienced by eggs during the middle third of incubation. Here, we investigated the variability in the production of male and female offspring by loggerhead sea turtles C aretta caretta at six nesting beaches in the temperate breeding area of Z akynthos, G reece. Hatchling sex ratios were estimated using incubation durations and sand temperatures for 2007–2009, while the empirical relationship between air and sand temperature was used to infer historical (1875–2010) and future (2011–2100) hatchling sex ratios. First, all six beaches produced males; 55% of production was across five beaches, while 45% was focused on one beach (primarily in J uly). Second, male production varied across the season in different years; there was an initial peak in J une, with production (rising, declining or plateauing) later in the season being regulated by A ugust air temperatures. Interestingly, the annual male production rate estimated from the 3‐year dataset (23%) was half that estimated from the 135‐year reconstruction (50%), with the latter showing broad interannual variation. Finally, modelled predictions of future sex ratios ranged from a conservative 7.6% decline in male production by 2100 versus no production by 2038. This study provides a baseline from which predicted trends in hatchling sex ratio, in parallel to regular field assessments, could be used to provide guidelines for the selection of appropriate nest protection management protocols, to maintain required sex ratios that safeguard the future of this population.