Primal Origin of the Freshwater InvertebratesJerry L. Kaster
What is the Geologic Time-Scale History of Freshwater Invertebrates?
What are the Colonization Routes of the Freshwater Invertebrates?
Habitat Corridors
Continental Corridors
What was the Role of K+ Scavenging in Establishing a Brooding Fauna?
Regression-Transgression
Bryant 1775
Route associated competitive strategies
First, the contemporary marine and freshwater faunas are more ecesis compatible than are faunas not contemporary.
Second, marine taxa with a high survival rate (implying gene pool breadth) on a geological time scale are more likely to colonize new habitats, both marine and freshwater, than taxa with a low survival rate.
By example, the extinct trilobites would have a zero probability for a modern colonization of freshwaters; whereas extant marine forms without a contemporary freshwater counterpart, such as branchiopods or echinoderms would score a probability for a modern occurrence in freshwaters. The fact that the latter two forms do not now exist in freshwater does not rule out the possibility that they may colonize in the future.
Assumptions
Third, the predicted probability of occurrence for a ancestral freshwater fauna is a recapitulation of its descendant freshwater fauna.
What is the Geologic Time-Scale History of Freshwater Invertebrates?
PFPt = ((MPt + FPt) 2) MSP
PFPt 1 = ((MPt 1 + PFPt) 2) MSP
PFPt 2 = ((MPt 2 + PFPt 1) 2) MSP
PFPt 3 = …
Where: PFPt = Predicted freshwater probability
MPt = Extant marine taxon probability
FPt = Extant freshwater taxon probability
MPt-n = Fossil marine taxon probability (mainly Raup 1976)
t = Faunal geological period, where 1 = Cenozoic; 2 = Mesozoic; 3 = Palaeozoic; 4 = PrecambrianMSP = Marine taxon survival probability (Easton 1960): Crustacea (0.930),
Gastropoda (0.821), Annelida (0.973), Pelecypoda (0.423), Porifera (0.560), Ectoprocta (0.504), Echindermata (0.270), and Brachiopoda (0.015).
Extant FW Invertebrate Probability Signature
(Kaster, various data)
0
0.1
0.2
0.3
0.4
0.5
0.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
ba
bili
ty Known FWProbability
Extant FW Invertebrate Probability Signature
(Kaster, various data)
y = 5E-05x4.4233
R2 = 0.9302
0
0.1
0.2
0.3
0.4
0.5
0.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
ba
bili
ty
Extant FW Invertebrate Probability Signature
(Kaster, various data)
y = 5E-05x4.4233
R2 = 0.9302
0
0.1
0.2
0.3
0.4
0.5
0.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
ba
bili
ty
Extant
Predicted
Pow er Function
Cenozoic FW Invertebrate Probability Signature
(Raup, 1900 -1970 data)
y = 0.0004e0.9056x
R2 = 0.7886
0
0.1
0.2
0.3
0.4
0.5
0.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ility
Mesozoic FW Invertebrate Probability Signature
(Raup, 1900-1970 data)
y = 0.0008e0.7131x
R2 = 0.6345
0
0.1
0.2
0.3
0.4
0.5
0.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ilit
y
Paleozoic FW Invertebrate Probability Signature
(Raup, 1900-1970 data)
y = 0.0028e0.5252x
R2 = 0.8103
00.10.20.30.40.50.6
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ilit
y
Precambrain FW Invertebrate Probability Signature
(Raup, 1900-1970 data)
y = 8E-05e0.927x
R2 = 0.7311
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Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ilit
y
Paleozoic Fauna 600 - 230
Mesozoic Fauna 230 - 63
Ordovician22%
Devonian21%
Permian95%
Triassic20%
Cretaceous75%
TIME
2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
Sh
an
no
n D
ive
rsit
y
Are there too many species clustered in too few Phyla?
PROBABILITY
Precambrian Fauna
Paleozoic Fauna
Mesozoic Fauna
Cenozoic Fauna
Extant Fauna
Pm=0.53Pm=0.51
Pm=0.61
Pm=0.72
Pm=0.81
Idealized Probabilistic Signature of the Freshwater Invertebrate Fauna
Permian Extinction FW Probability Signature
(Raup, 1900-1970 data)
0
0.1
0.2
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ilit
y
Pre-extinction
Post-extinction
K-T Extinction FW Probability Signature
(Raup, 1900-1970 data)
0
0.1
0.2
Br Ec Bz Po Pe An Ga Cr
Taxon
Pro
bab
ilit
y
Pre-extinction
Post-extinction
A shift along the time series is characterized by an overall rise in dominance of fewer taxa with high probable occurrence.
Communities of greater horizontal energy-material exchange have more rare species and should be distinguished by greater evolutionary innovation.
Catastrophic Permian community disruption reduced rare taxa, with common taxa gained dominance (reduced diversity). The K-T disruption increased rare taxa relative to common taxa (increased diversity).
Immigration Routes Habitat Corridors
Sea Land Freshwater (pulmonate snails, insects, mites)
Sea Estuary Freshwater (zebra mussels)
Sea Psammolittoral Phreatic Freshwater
(protozoa; micrometazoans)
Sea Marsh Freshwater(amphipods)
What were the Colonization Routes of the Freshwater Invertebrates?
Equatorial Continental Von Martens, 1857
Shotgun approach:
Typical r-strategists. Large pool of tropical species with pelagic larvae.
Polar Continental de Guerne & Richard, 1892
Finesse approach:
Typical K-strategists. Small pool of polar species with brood representing a pre-adapted life cycle to freshwater.
Continental Corridors
Immigration RoutesRoute associated competitive strategies
Polar
Equatorial
Continent
BROODING
FAUNA
SHEDDING
FAUNA
85%
85%
15%
15%
Lake
Lake
Polar
Equatorial
Continent
BROODING
FAUNA
SHEDDING
FAUNA
85%
85%15%
15%
“Regression Period”
Lake
Lake
K
IncreasedHabitat
DecreasedHabitat
r
Polar
Equatorial
Continent
BROODINGFAUNA
SHEDDING
FAUNA
85%
85%15%
15%
“Transgression Period”
Lake
Lake
K
DecreasedHabitat
IncreasedHabitat
r
Why do freshwater forms lack pelagic larvae?
Broad statements (e.g., Neeham 1930; Pennak 1953, 1963, 1985) of ion/osmoregulation provided the framework for its general acceptance of the marine to freshwater transition.
Abundant suggestions:
Ionic - Osmotic gradiant imbalance
Energy expenditure to stay afloat
Poor pelagic nutrient resources
Brooding K-strategist Fauna
Keen competitors “fill the barrel”; Shedding r-strategist fauna poorly colonize a “full barrel”
Others
Most cations and anions are regenerated in the epilimnion, while K+ shunts to the benthos.
K+Ca2+ Mg2+
Na+ HCO3
CO32- SO4
2-
Cl-
K+ is preferentially incorporated into the crystaline lattice of minerals
What was the role of K+ scavenging in establishing a brooding fauna?
Ionic K+ Bottleneck
Earth leaches K+ : Na+ = 1
K+ is readily absorbed to soil particulates and thus there is less K+than Na+ in sea water (K+ : Na+ = 0.021)and freshwater (K+ : Na+ = 0.028)
Marine invertebrate K+ levels are similar to sea water medium:
Sea water K+ = 9.96 mM/l vs. inverts = 11.56 mM/l (ratio = 0.86)
Freshwater invertebrate K+ levels are much higher than the freshwater
medium:Freshwater = 0.03 mM/l vs. inverts = 4.75 mM/l (ratio = 0.0063)
Benthic sediment K+ = 13.8 mM/l vs. 4.75mM/l (ratio = 2.9)
K+ is necessary for membrane function, especially in excitatory tissue such as muscle and nervous tissue.
Bottleneck is at the late embryo (yolk K+ cache depleted) or at the earlylarval stage (must shift to high [K+] particle feeding).
Immigration of K-strategist, marine brooding invertebrates to freshwater largely followed a polar corridor.
The de novo evolution of muscle and nervous systems of the primal metazoans (protozoan-metazoan megaleap) required high benthic K+.
Metazoan de novo “K+ scavenging” may have lead to herbivory and “K+ predation” to predation.
A “K+ bottleneck” during early life history stages is suggestedas a critical factor that regulates freshwater colonization success.