Biological Rhythms in Polychaeta II, The Earth Moon system and Evolution of biological time

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Biological Rhythms in Polychaeta II, The Earth
Moon system and Evolution of biological time

• PJW Olive1, KS Last1, P Edwards1, CP Kyriacou2, E
  Rosato3 C Kramer2 and T Bailhache3
• 1 Newcastle University School of Marine Science
  and Technology
• 2 Leicester University Dept of Genetics, 3
  Department of Biology
• NERC ENVIRONMENTAL GENOMICS PROGRAMME

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Clocks work in worms

• many clocks appear to function in marine worms
• Nereis virens (previous presentation
• Complex biorhythmical behaviour
• circadian period 24 hours
• circatidal period 12.4 hours
• circalunidian period 24.8 hours
• photoperiodic response to annual LD cycle
• Long term quasi circannual
• Life cycle semelparous modular annual
• Platynereis dumerilli
• lunar rhythms of epitoky (cf eclosion)
• Life cycle semelparous modular lunar
• Palola viridis
• Synchronised spawning with lunar, tidal, diel and
  annual components

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Canonical clock genes in Nereis virens

• Clock
• Bmal 1
• Kaseine Kinase 1, 2? and ?
• Micro array (see Rosato this conference to
  search for the entire gene network involved in
  the tidal and circadian clocks

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In situ hybridisation for clock gene expression
in larval brains

• An ongoing component of the study is the
  localisation of clock gene expression in larval
  brains
• Here expression of Bmal in Platynereis

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What are the Polychaetes, when did they arise?
VIII International Polychaete Conference Madrid
2004

• Traditional morphological cladistic studies Rouse
  and Fauchald 1997, Zoo Scripta 26139-204
• WormNET compiling data from large and small
  nuclear ribosomal subunits, nuclear protein
  coding genes EF1?, EF2, RNApol II and MyoII and
  complete mitochondrial genomes
• Emerging concensus for the Polychaeta
• Clitellata (Earth worms and leeches) lie within
  the Polychaete clade as do Echiura and Sipuncula
• Robust sub-clades include PHYLLODOCIDA and
  EUNICIDA,
• Both are well represented in the early palaeozoic
  (fossil jaws (scolecodonts) from around 480MA
• likely rapid radiation around 600MA (D. McHugh

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A recent concensus
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Scolecodonts
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Reproductive strategies in Cambrian Ordovician
Polychaetes

• Scolecodonts suggest a radiation of Eunicida and
  Phyllodocida by 500Ma
• Many of these animals were large bodied worms
  (judging by jaw size) living in intertidal and
  shallow habitats (Eriksson, 2004)
• Synchronised epidemic spawning, external
  fertilisation and planctonic development is
  typical of such animals now (Olive, 1984)
• Why not then? Rouse
• This requires a functional clock to synchronise
  reproductive activity (Lewis and Watson - this
  conference)

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Core Hypothesis

• We propose that
• the original metazoan clock had the capacity to
  predict lunar/tidal time as well as the solar
  day
• that this clock had emerged at least in the
  Polychaete clade by the early to mid Cambrian
  i.e. around 600 Ma.
• What were the periodicities of the Earth Moon
  system at that time?

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The earth moon sun time system
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The earth moon sun time system
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The present day periods

• Rotational period of the Earth, P1
• 0.9973 days
• Orbital period of the Moon, P2
• 27.3127 days
• The orbital period of the Earth, P3
• 365.2422 days

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Changes in periods

• The period of the Earths rotation is declining
• The angular momentum of the Moon is declining
• The Moon is retreating from the Earth.

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Historical astronomical evidence for changing
periods

• By the 17th Century it had become impossible to
  reconcile contemporary observations with biblical
  and babylonian records
• Halley 1677 used the transit of the Sun by
  Mercury as a measure of absolute time that can be
  compared with time based on the rotation of the
  earth - Universal time.

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Universal Time and
Transit of Mercury across the Sun
Time point
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Universal Time and Dynamical Time (from Morrison
1978)

• Positions of Moon measured against instants of
  time based on star fixes
• Star fix based on Universal Time (UT) derived
  from Earth Rotation
• Predicted positions calculated from integration
  of orbit equations Dynamical Time (TD)
• 14 times a century mercury transits the sun
  instants in TD
• Differences between instants in UT and TD
  deceleration of Earth
• Average deceleration
• -262 secs/century2

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Historical astronomical evidence for changing
periods

• Kant 1754 formulated the concept of tidal
  friction
• The difference between Universal and Dynamical
  Time is due to the frictional resistance of the
  Earth to the lunar and solar induced tides

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Lunar retreat

• Laser measurements following the Apollo mission
  provide confirmatory data - the Moon decelerates
  at a rate of 25.9 seconds per century per
  century
• The Moon retreats from the Earth at a rate of
  about 4 cm per year
• Thus billions of years ago the Moon was much
  closer to the Earth than now

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Tidal Friction (Simplified)
The Earth rotation pulls the tidal bulge ahead
in relation to the Moon/earth line
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Palaentological and Geological Confirmation

• Palaentology - fossil growth lines
• During the 1970s there was a great interest in
  fossils showing growth lines (see Scrutton,
  1978)
• Growth lines suggest there were 410 days per year
  in the Silurian - equivalent to a day length of
  around 20 hours
• Rhythmites deposits
• Tidal deposits back to 600 - 900 million years
  ago (see Williams, 2000)

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How has length of day LOD changed since origin of
life?

• Origin of Life 4Ga
• First fossils (Cyanobacteria) 2Ga
• Linear extrapolations (Lathe 2003) suggests LOD
  4 hours 4Ga
• Equations describing the Moons Orbital motion
  and the Earths rotation suggest a critical
  period around 1.8 billion years ago
• Actually this is very complicated BUT...

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Krasinskys solutions Krasinsky, 2002 ..
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Length of day and number of (then) days per lunar
month

• Non-linear change in day length down to around 4
  hours at tcrit around -1.8 Ga
• the number of running days per month increased
  rapidly to around 29 after tcrit but then
  declined only slowly

Epoch (ma) LoD Days per month Now 24
hr 27.3 -1200 17.5 29.5 -1843(tcrit) 5.95 9.6
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Past earth moon system and the protoclock

• In the past the rotational velocity of the Earth
  was greater and length of day less
• LOD c18 hours in the Early Cambrian but possibly
  very dynamic increase from around 4 hours at
  -2Ga
• The Moon was closer - bigger tidal forces
• There was a single land mass Pangaea and an
  ocean, it probably had two tides per then day.

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Implications of Krasinsky calculations IIPangaea

• The Moon was closer - bigger tidal forces
• There was a single land mass Pangaea and an ocean
  until recent
• Palaeotides? If semi-diurnal - period around 2
  hours until 2Ga
• Without continents high latitudes have diurnal
  tide and low latitudes semi-diurnal
• But what do we know about the ocean and land
  masses 4Ga? - next to nothing

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Lets take an imaginary journey back in time
using as a model our Nereis data

• Tidal biorhythmicity in Nereis

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Period of rhythm at different epochs
Worms much like modern worms present at this time
Rhythms in the earliest organisms may have been
like this
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Conclusions

• The tidal period c 2 hours? may have been every
  bit as important as the length of day for
  proto-organisms
• circa-tidal and circadian clocks must have
  increased their period since the origin of the
  protoclock
• Models for the origin of the clock must take into
  account the changes in period that have occurred
  over biological time.

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Platynereis dumerilli first demonstration of
lunar periodicity

• Epitoky in Platynereis cf eclosion biorhythnms of
  Drosophila
• Life cycle periodicity modular lunar not modular
  annual
• clear response to lunar signals.

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Spawning of Platynereis has constant phase delay
? in relation to the end of the full moon phase
light at night)
Number
?
?
Lunar days
Lunar days
Data from Hauenschild (1960) Cold Spring Harbor
Symposia in Quantitative Biology 25 491-257
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Palola viridis time keeper par excellence

• Pictures or data on spawning of palola