Article

Evolutionary Ecology

, Volume 17, Issue 3, pp 277-292

Are seed set and speciation rates always low among species that resprout after fire, and why?

  • Byron B. LamontAffiliated withEnvironmental Biology, Curtin University Email author 
  • , Delbert WiensAffiliated withRancho Santa Ana Botanic Garden

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Abstract

A general dichotomy in response to catching alight during fire is for perennial plants to die (nonsprouters, N) or to regrow via dormant buds (resprouters, R). Contrasting effects on other life-history traits, especially those relating to sexual reproduction, can be expected. We hypothesized that fecundity should be lower in R. Our meta-analysis of 33 case studies of co-occurring generic pairs of N and R showed that viable seed and fruit set relative to inflorescence, flower and ovule production were lower for R than N in 30 cases. Three mechanisms have been invoked to explain these trends: resource competition between vegetative and reproductive growth, an outbreeding (R)/inbreeding (N) dichotomy, and higher genetic load among R due to their accumulation of deleterious somatic mutations over many fire cycles. Though poorly researched, we conclude that the high genetic load of R in association with strong self-incompatibility (xenogamy) can best explain the dichotomy in lifeform-fecundity as well as the exceptions. Over the long-term, we suggest that marked xenogamy-longevity in association with frequent axillary branching (induced by recurrent fire, herbivory and drought) via copious stored buds within R might favour expression among their genets and ramets of beneficial somatic mutations present in their meristematic tissues. These conditions would favour ecotypic differentiation and speciation among R that has contributed, along with N, to the exceptional species richness of several fire-prone mediterranean regions.

breeding system disturbance fire response genetic load resource allocation speciation