To explore the origins and possible behavioral consequences of structural plasticity in an insect brain, we have taken advantage of the following: (1) the highly compartmentalized nature of the primary antenno-sensory centers (antennal lobes) of the brain, (2) the ease with which individual compartments, or glomeruli, within the antennal-lobe neuropil can be identified, and (3) the predictability of changes to readily identifiable glomeruli in the antennal lobes of the adult worker honey bee. Treatment with the juvenile hormone analog methoprene and hive manipulation techniques are used to induce precocious foraging behavior in young worker honey bees. The impact of these treatments on the ontogeny of olfactory learning performance and on the volumes of readily identifiable glomeruli in the antennal lobes of the bee brain are examined in parallel. The study reveals that (1) significant changes in glomerular volume are activity dependent and (2) associative learning of floral odors improves with experience. Improvements in associative learning performance coincide temporally with increases in glomerular volume. This raises an important question: are changes in glomerular volume that result from shifts in behavior simply a consequence of changes in the use of peripheral sensory pathways, or are they associated with events that underlie learning and the formation of long-term memories?

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Aim Resolving the origin of invasive plant species is important for understanding the introduction histories of successful invaders and aiding strategies aimed at their management. This study aimed to infer the number and origin(s) of introduction for the globally invasive species, Macfadyena unguis-cati and Jatropha gossypiifolia using molecular data. Location Native range: Neotropics; Invaded range: North America, Africa, Europe, Asia, Pacific Islands and Australia.Methods We used chloroplast microsatellites (cpSSRs) to elucidate the origin(s) of introduced populations and calculated the genetic diversity in native and introduced regions.Results Strong genetic structure was found within the native range of M. unguiscati, but no genetic structuring was evident in the native range of J. gossypiifolia. Overall, 27 haplotypes were found in the native range of M. unguis-cati. Only four haplotypes were found in the introduced range, with more than 96% of introduced specimens matching a haplotype from Paraguay. In contrast, 15 haplotypes were found in the introduced range of J. gossypiifolia, with all invasive populations, except New Caledonia, comprising multiple haplotypes.Main conclusions These data show that two invasive plant species from the same native range have had vastly different introduction histories in their non-native ranges. Invasive populations of M. unguis-cati probably came from a single or few independent introductions, whereas most invasive J. gossypiifolia populations arose from multiple introductions or alternatively from a representative sample of genetic diversity from a panmictic native range. As introduced M. unguis-cati populations are dominated by a single haplotype, locally adapted natural enemies should make the best control agents. However, invasive populations of J. gossypiifolia are genetically diverse and the selection of bio-control agents will be considerably more complex.

Loss of genetic diversity and increased population differentiation from source populations are common problems associated with translocation programmes established from captive-bred stock or a small number of founders. The bridled nailtail wallaby is one of the most endangered macropods in Australia, having been reduced to a single remnant population in the last 100 years. A translocated population of bridled nailtail wallabies was established using animals sourced directly from the remnant population (wild-released) as well as the progeny of animals collected for a captive breeding programme (captive-bred). The aims of this study were to compare genetic diversity among released animals and their wild-born progeny to genetic diversity observed in the remnant population, and to monitor changes in genetic diversity over time as more animals were released into the population. Heterozygosity did not differ between the translocated and remnant population; however, allelic diversity was significantly reduced across all released animals and their wild-born progeny. Animals bred in captivity and their wild-born progeny were also significantly differentiated from the source population after just four generations. Wild-released animals, however, were representative of the source population and several alleles were unique to this group. Both heterozygosity and allelic diversity among translocated animals decreased over time with the additional release of captivebred animals, as no new genetic stock was added to the population. Captive breeding programmes can provide large numbers of animals for release, but this study highlights the importance of sourcing animals directly from remnant populations in order to maintain genetic diversity and minimise genetic drift.

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