The interaction of season length and development time alters size at maturity |
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Authors: | L Higgins |
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Institution: | (1) Centro de Ecología, Universidad Nacional Autonoma de México, Apartado Postal 70-275, Ciudad Universitaria, C.P. 04510, Mexico e-mail: linden@ent.umass.edu Fax: +1-413-5452115, MX |
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Abstract: | An end-of-season penalty, with late-maturing individuals being smaller than early-maturing individuals, has been observed
in a variety of univoltine terrestrial arthropods. The current study extends these observations, utilizing multiple populations
of a single sexually dimorphic species to examine the ecological correlates and fitness consequences of late maturation at
a small size. The orb-weaving spider, Nephila clavipes, inhabits a broad range of habitats that vary from mild to strong seasonality. Because males mature several instars earlier
than females, they can reach maturity much earlier in the growing season. Within a cohort, I found that female size at maturity
was negatively correlated with timing of maturation in strongly seasonal sites. At a less seasonal site, there was no correlation
between female size and timing of maturation within a cohort. In most populations studied, male size was not correlated with
the timing of maturation within a cohort. Within populations in strongly seasonal sites, late-maturing females had reduced
fecundity. The probability of copulation, survivorship from maturity to first clutch, clutch size relative to female size,
and the number of possible clutches were all reduced with delayed maturation. The probability of pre-reproductive death for
late-maturing females was strongly affected by stochasticity in the timing of the end of the growing season.
Received: 30 December 1998 / Accepted: 1 September 1999 |
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Keywords: | Life-history Phenology Sexual dimorphism Fitness Nephila clavipes |
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