title: How do climate-linked sex ratios and dispersal limit range boundaries?
abstract: BACKGROUND
  Geographic ranges of ectotherms such as reptiles may be determined strongly by abiotic factors owing to causal links between ambient temperature, juvenile survival and individual sex (male or female). Unfortunately, we know little of how these factors interact with dispersal among populations across a species range. We used a simulation model to examine the effects of dispersal, temperature-dependent juvenile survival and sex determining mechanism (temperature-dependent sex determination (TSD) and genotypic sex determination (GSD)) and their interactions, on range limits in populations extending across a continuous range of air temperatures. In particular, we examined the relative importance of these parameters for population persistence to recommend targets for future empirical research.
  
  
  RESULTS
  Dispersal influenced the range limits of species with TSD to a greater extent than in GSD species. Whereas male dispersal led to expanded species ranges across warm (female-producing) climates, female dispersal led to expanded ranges across cool (male-producing) climates. Two-sex dispersal eliminated the influence of biased sex ratios on ranges.
  
  
  CONCLUSIONS
  The results highlight the importance of the demographic parameter of sex ratio in determining population persistence and species range limits.
authors.affiliation: Institute for Applied Ecology, University of Canberra, Canberra ACT 2601, Australia. Maria.Boyle@canberra.edu.au.
authors.forename: Maria
authors.initials: M
authors.lastname: Boyle
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Schwanz
authors.forename: Jim
authors.initials: J
authors.lastname: Hone
authors.forename: Arthur
authors.initials: A
authors.lastname: Georges
mesh_terms: D063147:Animal Distribution; D000818:Animals; D002980:Climate; D003198:Computer Simulation; D005260:Female; D005298:Fertility; D008297:Male; D012744:Sex Ratio; D013696:Temperature