332 research outputs found
Estimates of growth and comparisons of growth rates determined from length- and age-based models for populations of purple wrasse (Notolabrus fucicola)
Growth of a temperate reefa-ssociated fish, the purple wrasse (Notolabrus fucicola), was examined from two sites on the east coast of Tasmania by using age- and length-based
models. Models based on the von Bertalanffy growth function, in the standard and a reparameterized form, were constructed by using otolith-derived age estimates. Growth
trajectories from tag-recaptures were used to construct length-based growth models derived from the GROTAG model, in turn a reparameterization of the Fabens model. Likelihood
ratio tests (LRTs) determined the optimal parameterization of the GROTAG model, including estimators of individual growth variability, seasonal growth, measurement error,
and outliers for each data set. Growth models and parameter estimates were compared by bootstrap confidence intervals, LRTs, and randomization tests and plots of bootstrap parameter estimates. The relative merit of these methods for comparing models and parameters was evaluated; LRTs combined with bootstrapping and randomization tests provided
the most insight into the relationships between parameter estimates. Significant differences in growth of purple wrasse were found between sites in both length- and age-based models. A significant difference in the peak growth season was found between sites, and a large difference
in growth rate between sexes was found at one site with the use of length-based models
Evolution of wind pollination in Leucadendron (Proteaceae) : experimental evidence and floral trait shifts.
M. Sc. University of KwaZulu-Natal, Pietermaritzburg 2014.Evolutionary transitions from insect to wind pollination are thought to have occurred many
times during the angiosperm radiation. This transition is commonly associated with a suite
of distinctive floral traits such as reduction of flower size and a transition to dry pollen. In
the dioecious genus, Leucadendron (Proteaceae), evolutionary shifts from insect to wind
pollination have been postulated based on floral morphology features. In this study, I
aimed to experimentally test the potential for wind versus insect pollination in several
Leucadendron species and document a variety of floral traits (pollen size, inflorescence
size, scent, colour, etc.) in order to determine their functional significance whilst utilizing
phylogenetic comparative methods to test the statistical significance of evolutionary
associations between particular floral traits and pollination systems.
Fifteen representative Leucadendron species were investigated to verify insect and
wind pollination in as many clades as possible. Insect exclusion experiments confirmed
that five Leucadendron species, L. rubrum, L. salicifolium, L. dubium, L. coniferum and L.
teretifolium are indeed wind-pollinated. Pria cinerascens (Nititulidae) was found to be the
main pollinator of the insect-pollinated Leucadendron species due to their abundance, high
stigmatic contact and relatively pure Leucadendron pollen loads. Overall, however, the
abundance of insects visiting inflorescences was not significantly different between insectand
wind-pollinated species, which highlights the importance of conducting insect
exclusion experiments to evaluate whether a species is wind- or insect-pollinated.
From the previously determined pollination systems of 17 Leucadendron species,
floral traits associated with the shift to wind pollination were investigated to determine
whether transitions from insect to wind pollination were accompanied by modifications of
pollination-relevant floral traits. In a wind tunnel, pollen grains of wind-pollinated species
were found to be more motile than those of insect-pollinated species. Phylogenetic
analyses suggest that transitions from insect to wind pollination occurred at least four times
during the diversification of Leucadendron and that, compared to insect-pollinated
cogeners, wind-pollinated Leucadendron species are characterized by increased production
of smaller pollen grains, higher inflorescence density, less attractive visual and olfactory
cues, and a greater degree of sexual dimorphism for these visual and olfactory cues.
In conclusion, this study experimentally confirms that there were several shifts
from insect to wind pollination in Leucadendron and identifies floral traits that were
evolutionarily modified during these shifts
Proposed allocation of research catches in Divisions 58.4.1 and
At WG-SAM-15, it was noted that 5 members, Australia, France, Japan, Korea and Spain had
notified to conduct research in the exploratory toothfish fisheries off East Antarctica, covered
by CCAMLR Divisions 58.4.1 and 58.4.2. This proposal seeks to establish an arrangement
whereby all notified members have a catch allocation to undertake research, thereby avoiding
Olympic fishing
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