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Fragmentation & Reproductive Output Slide 2 Altered landscapes Less habitat Smaller patches Various shapes Smaller populations Fewer mates Fewer resources for pollinators Increased isolation between patches Limits exchange of genes (pollen and seed) Changes to habitat health Above and below ground (resources) Slide 3 Pre-European Vegetation Source: National Land & Water Resources Audit Slide 4 Current Vegetation Patterns (2001) Source: National Land & Water Resources Audit >5% natural vegetation Slide 5 Reproduction Many species rely on pollen movement to generated seed Successful sexual reproduction Ensures the next generation Seed is a dispersal mechanism Maintains heterozygosity and fitness Generates new genetic combinations Seed can be an important food source for associated animals and insects some of which will also be pollinators Fragmentation is altering important relationships within communities Slide 6 Fragmented Landscapes Slide 7 Less long distance gene flow Slide 8 Fragmented Landscapes Increased within-patch matings Slide 9 Reproductive Consequences of Fragmentation Case studies Slide 10 Genetic erosion in Rutidosis leptorrhyncoides Herbaceous perennial Self-incompatible S-alleles Insect pollinated Once widespread, now extremely rare Subject to severe habitat loss Small populations ( Polymorphic loci - Western Australia Eucalyptus wandoo Tree Wind/gravity dispersal >40 yrs Insect/bird pollinated Mixed-mating Smaller populations have lower P (p100 yrs Bird/mammal pollinated Mixed-mating Smaller populations have lower P (p Polymorphic loci - Eastern Australia Acacia dealbata Tree Bird/insect/gravity dispersal >20 yrs Insect pollinated Self-incompatible Smaller populations have lower P (p Seed set- Western Australia Eucalyptus wandoo Tree Wind/gravity dispersal >40 yrs Insect/bird pollinated Mixed-mating Smaller populations set less seed (p100 yrs Bird/mammal pollinated Mixed-mating Smaller populations set less seed (p Seed set- Eastern Australia Acacia dealbata Tree Bird/insect/gravity dispersal >20 yrs Insect pollinated Self-incompatible No effect for population size Slide 37 Fitness - Western Australia Eucalyptus wandoo Tree Wind/gravity dispersal >40 yrs Insect/bird pollinated Mixed-mating No effect for population size Calothamnus quadrifidus Shrub Gravity dispersal >100 yrs Bird/mammal pollinated Mixed-mating No effect for population size Young et al. 2005 Slide 38 Fitness - Eastern Australia Acacia dealbata Tree Bird/insect/gravity dispersal >20 yrs Insect pollinated Self-incompatible No effect for population size Slide 39 Outcomes Common species are negatively responding to fragmentation Responses are species-specific need to study more species Population size in an important component of this response Reduced pollination service Increased levels of inbreeding Lower seed set Suggests that perhaps we should now be concentrating on ensuring the long-term population persistence of common species Common species underpin community structure Slide 40 Questions???