11th ICRS Abstract book - Nova Southeastern University

14.511
Interspecific And Intraspecific Genetic Variation in Deep-Sea Octocorals
Amy BACO-TAYLOR* 1 , Juan ARMANDO SÁNCHEZ 2 , Stephen CAIRNS 3
1 Associated Scientists at Woods Hole, Woods Hole, MA, 2 Universidad de los Andes,
Bogota, Colombia, 3 Smithsonian Institution, Washington, DC
Corals are a key component of the fauna of deep-sea hard substrate habitats and are of
interest as habitat-forming organisms for invertebrates and fishes. They are the dominant
taxon and the most diverse invertebrate group on seamounts. Deep-sea corals are
generally long-lived and slow growing with potentially limited recruitment, making them
particularly unlikely to recover from anthropogenic impacts. The threats to seamounts
make their study time-critical, with corals making an ideal model organism for research
into the biology, ecology and vulnerability of seamount fauna. However, a global
deficiency of scientific expertise in morphological taxonomy has been cited as a
significant impediment to our understanding of deep-sea coral diversity, coral
biogeography, and seamount ecology. Molecular genetic methods can be used to
overcome this impediment and more rapidly assess species diversity in archived
specimen collections. However, these methods have not yet been widely applied to deepsea
corals. Here we compare levels of interspecific and intraspecific genetic variation
for six genes in two octocoral taxa, the Family Paragorgiidae and the primnoid genus
Narella. All specimens were concurrently examined morphologically for species
identifications. Phylogeographic patterns of both taxa on North Pacific seamounts will
also be presented.
14.512
Sewal Wright’s F-statistics are the most common measures of genetic differentiation, are
commonly used to delineate population boundaries, and figure prominently in the design
of Marine Protected Area networks. AMOVA estimates of ΦST and its analogues are
known to be biased by factors such as sample size and levels of heterozygosity.
Consequently, ΦST values do not typically range from zero (complete connectivity) to one
(complete isolation), making comparisons of genetic differentiation among populations
tenuous. This is especially critical for highly variable markers such as microsatellites
where the magnitude of heterozygosity is typically great. To correct this bias, it has been
recommended that F-statistics be standardized relative to their maximum possible value.
We demonstrate that both the minimum and maximum possible values of ΦST are
affected by sample properties other than genetic differentiation. Consequently, ΦST must
be standardized relative to its minimum and maximum possible values for each
population comparison. This also applies to the permutation test, which is used to assign
statistical significance to ΦST values. The maximum and minimum possible ΦST values
change in each iteration of the permutation test, and the P-value obtained from an
unstandardized permutation test is occasionally incorrect. This study highlights the
limitations of comparing and drawing conclusions based on unstandardized F-statistics
and validates the use of F-statistics that are standardized by the minimum and maximum
possible values in comparative population genetic and phylogeographic studies.
Poster Mini-Symposium 14: Reef Connectivity
14.513
Range Expansion Of An Introduced Coral: Investigating The Source And Ecological
Impact Of The Invasion
Tonya SHEARER* 1
1 School of Biology, Georgia Institute of Technology, Atlanta, GA
The introduction of non-native species can have devastating impacts on natural ecosystems and
can result in severe economic costs. A population genetics approach to studying marine
invasions is emerging as a valuable tool to address risk management, identify source
populations, determine the means of introduction and predict persistence and ecological
impacts. Such an approach is being used to evaluate the dynamics and impact of the humanmediated
introduction of the orange cup coral, Tubastraea coccinea, introduced into the
Caribbean and subsequently into Florida, including the Florida Keys National Marine
Sanctuary. As observed with many introduced species, T. coccinea can proliferate rapidly, due
to production of asexual larvae, and appears to exclude native organisms on particular
substrates likely causing a loss of biodiversity. Genetic analyses are being utilized to identify
the potential source populations and evaluate levels of genetic diversity and clonal structure.
Ultimately, the genetic analysis of the introduction and range expansion of this coral will be
used to model biological connectivity throughout the Caribbean and Gulf of Mexico.
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