1. Primal Origin of the Freshwater Invertebrates Jerry 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

2. 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?

3. PFP t = ((MP t + FP t )  2)  MSP PFP t  1 = ((MP t  1 + PFP t )  2)  MSP PFP t  2 = ((MP t  2 + PFP t  1 )  2)  MSP PFP t  3 = … Where: PFP t = Predicted freshwater probability MP t = Extant marine taxon probability FP t = Extant freshwater taxon probability MP t-n = Fossil marine taxon probability (mainly Raup 1976) t = Faunal geological period, where 1 = Cenozoic; 2 = Mesozoic; 3 = Palaeozoic; 4 = Precambrian MSP = 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).

11. Paleozoic Fauna 600 - 230 Mesozoic Fauna 230 - 63 Ordovician 22% Devonian 21% Permian 95% Triassic 20% Cretaceous 75% TIME

12. Are there too many species clustered in too few Phyla?

13. PROBABILITYPROBABILITY Precambrian Fauna Paleozoic Fauna Mesozoic Fauna Cenozoic Fauna Extant Fauna P m =0.53 P m =0.51 P m =0.61 P m =0.72 P m =0.81 Idealized Probabilistic Signature of the Freshwater Invertebrate Fauna

16. 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).

17. 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?

18. 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 Routes Route associated competitive strategies

19. Polar Equatorial Continent BROODINGFAUNABROODINGFAUNA SHEDDINGFAUNASHEDDINGFAUNA 85% 15% Lake

20. Polar Equatorial Continent BROODINGFAUNABROODINGFAUNA SHEDDINGFAUNASHEDDINGFAUNA 85 % 15% “Regression Period” Lake K Increased Habitat Decreased Habitat r

21. Polar Equatorial Continent BROODINGFAUNABROODINGFAUNA SHEDDINGFAUNASHEDDINGFAUNA 85 % 15% “Transgression Period” Lake K Decreased Habitat Increased Habitat r

22. 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

23. Most cations and anions are regenerated in the epilimnion, while K + shunts to the benthos. K+K+ Ca 2+ Mg 2+ Na + HCO 3 CO 3 2- SO 4 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)

24. 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 early larval stage (must shift to high [K + ] particle feeding).

25. 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 suggested as a critical factor that regulates freshwater colonization success.