Species (Glynn, 1996). These changes in climate during the

Species at the forefront concern
due to changes in environmental conditions in the anthropocene are coral reefs,
whose keystone species are sensitive to environmental perturbations at a local
and global scale (Putnam et al., 2017). Particularly, the intricate and
delicate mutualistic relationship between the cnidarian host, with focus on scleractinian
corals, and its single cell endosymbiont dinoflagellate resident, Symbiodinium sp., is responsible for
reef accretion of over 10,000 g CaCO3 m-2 a year (Cohen
et al., 2009). The Symbiodinium sp. provides the coral with its
pigmentation and organic compounds necessary for survival such as glucose,
glycerol, and amino acids as products of photosynthesis, serving as the main
driver for coral growth. In exchange, the coral provides the symbiont with a
nutrient rich environment from organic waste products necessary for
photosynthesis.

 The recent increase in ocean sea surface
temperature (SST) threatens to permanently disrupt this relationship (Glynn, 1996).
These changes in climate during the anthropocene have already been observed as
there has been a rapid decrease of coral cover due mass mortality and
bleaching, the physical manifestation of the end of the mutualistic
relationship between the coral host and its symbiont (Ainsworth et al., 2016). The
current status of coral reefs is of primary concern, as they support ecosystems
valued at over 100’s of billions of dollars (Costanza et al., 2014) and provide
protection from high-energy waves to islands and shorelines, preventing erosion
(Carpenter et al., 2008). Therefore, the identification of a mechanism through
which the coral holobiont, the assemblage of the coral host and its symbiont,
may be capable of rapid acclimatization to these changes in both local and
global conditions is of primary concern in order to implement measures that may
prevent the collapse of the marine ecosystems and include climate change models
to predict the future of marine populations.

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Research that concerns coral
reproduction, fecundity and recruitment is of great importance, as it sheds
light on the relationship between species and local climate, and species
persistence in future generations in an area undergoing rapid changes in biotic
and abiotic factors. Porites astreoides is
a well-know, stony, reef building coral common in the Caribbean Sea and
Atlantic Ocean.  As a brooder, Porites astreoides relies on internal
fertilization to achieve reproduction. Around the new moon, the internally
brooded larvae are released as planulae larvae which then drift in the water
column until they settle onto the seabed and each metamorphose into a
flower-like shape, known as a primary polyp. Each planula grows into a colony
by initiating the production of a CO3 skeleton and budding, a type
of asexual reproduction in which a new bulb-like organism is developed through
cell division.

Previously in Bermuda, research on
this coral has shown that differences in fitness, i.e. survival and
reproduction, may be attributed to differences in reef zones, e.g. patch and
rim. Corals located in patch reef areas exist in water conditions that are not
buffered by the cold deep ocean waters and are therefore exposed to more
extreme changes in temperature while corals located in rim areas are more
sheltered to these extreme conditions due to the incoming currents carrying the
cold, deep waters which allow for a stabilization in temperature. A
reproductive time shift table describing differences in spawning of Porites astreoides has shown that these
differences in abiotic factors between the patch and the rim reefs may be the
underlying cues responsible for spawning (de Putron et al. 2014). These abiotic
factors may also lead to larval phenotypic differences which can lead to
differences in settlement success and changes in population dynamics (de Putron
et al. 2017).

Variation in fitness among
conspecifics that exist under different abiotic factors may be explained
through differences at the molecular level. Specifically, a comparison of epigenetic
patterns due to mechanisms such as DNA methylation may provide insight as to
what creates these differences among conspecifics (Feil and Fraga 2012). DNA
methylation is an epigenetic mechanism that is capable of providing multiple
outcomes out of the same genetic material by regulating gene expression through
the addition of a methyl group (CH3) to DNA nucleotides (reviewed in
Verhoeven et al. 2016). These changes through DNA methylation are
environmentally induced and may have potential transgenerational inheritance.
Through this mechanism, organisms are shaped by the environment in which they
currently exist allowing for phenotypic plasticity.

The ability of corals to rapidly
acclimatize to local changes in their environment through epigenetic mechanisms
is a new area. Previous research on Pocillopora
damicornis is the first one to show rapid environmentally-induced changes
in total percent of DNA methylation with possible implication of changes in the
performance of the organism both in metabolism functions and growth (Putnam et
al., 2016). Furthermore, these changes in gene expression of the parental
genome through methylation due to environmental stress can be inherited by the
offspring (Bonduriansky and Day, 2009). Transgenerational epigenetic changes
can either promote an adaptive response, allowing for rapid acclimatization
within a single generation or exacerbate the negative response to the present
stressor (Putnam et al., 2015). Acclimatization, through phenotypic variation,
therefore may provide a compensatory response for these rapid anthropogenic
environmental changes which can alleviate the severity of the abiotic stressors
on coral population survival.

In order to address these
questions, the study of the coral Porites
astreoides in conjunction to an area such as Bermuda provides the ideal
platform for such an experiment. Geographically, Bermuda provides multiple
types of reef zones within close proximity of one another. This allows for an
environment of high genetic connectivity among conspecifics separated by areas
of different abiotic factors and thus phenotypic differences across reef-zones
(de Putron et al., 2017). Furthermore, as an internal brooder, Porites astreoides provides to be an
ideal model organism to study transgenerational acclimatization responses as
the environment may alter larval development during the internal brooding
process of the parent (Bonduriansky and Day 2009). The goal of this study is to
investigate the mechanisms underlying phenotypic variance, thus differences in
reproductive output between conspecifics, and how this may affect the
survivorship of their offspring.