Abstract

Introduction

Occupancy Models which begin with Levins (1965) function with respect to colonization and extinction.Here a model of ostracod evolution that yokes these two processes by an hypothesis that uses the suggestion that there is a relation between plate tectonic movement and magnetic pole reversals is presented. These kinematics cause induced electric currents in conductive (salt) water that fluctuate thus with the motion of the plates, the magnetic pole reversals and wanderings and ostracods are claimed to locomote along these path directions.

Ostracods are known to possess galvanic kinesis moving in the cathodic direction. Here this movement is claimed to underlay colonization activities while plate tectonic movement both creates the locations that can moved to (between plate areas and new water ways opened in the process) and where increased extinctions happen (plate collisions). Thus both the colonization and extinction effects on occupancy are related in this system and the occupancy modeling framework appears to apply in this case. Mass colonization effects also occur in this model when the galvanic kinesis is combined with passive dispersal within oceanic currents and flowing /flooding rivers. As a result complex source-sinke patterns due to purely physical drivers force ostracods to remain parthenogenic , preventing them from evolving new sexual species, explains brooding as an adaptation to remain in historically canalized e-m field paths created by the Earth’s core, and predicts locations where ostracod terrestrialization is more probable. Since ostracods yoke extinction to colonization in this way they do not necessarily fill up all of occupiable niche space geographically and thus can persist in metacommuities of other species (predators and prey) while still remaining as parthenogens.

The Model

A literature review??? reveals either that the statement of 2000 (Evolutionary Biology of the Ostracods) that little attention has been given beyond Batralins 98 an dMartens 97 on using gthe effective shifting balance theory or metapopulations to ostracods.

Sexual and Asexual clones are modeled as inbreeders with dispersion/colonization where sexual clones are considered to be superior competitors but that asexual clones can disperse better. Colonization contains two components , that caused by adults moving in the e-m field and that by the eggs (carried by wind,birds, insects) where the dessication resistant eggs need only one to establish occupancy in an empty patch but the sexual need two and need to find each other thus the egg part sexual = (egg part motion asexual/2)^2

The Equations

dS/dt = (1-Ps)msPs –ePs –x PaPs

dA/dt = (1-Ps-Pa)maPa – ePa – PsmsPs

Colonization due to Motion of Egg CE and Motion of Adult CA

ms(Sexual) = f(CEsCAs);

ma (asexual) =f(CEa,Caa) ;

CEs ~=~ (CEa/2)^2

Equilibrium

(1-Ps)ms –e –xPa =0 : line

(1-Ps-Pa)ma –e-Psms =0 :line

Stability- Stable when (ms-e)ma<x(e-1)

Conditions-

Butterfly Effect (sensitivity to initial conditions)-

A small change in motion, extinction can cause a complete flip in whether asexual or sexual are favored. The addition of the decrease in sexual change due to time spent finding each other rarther than tracking the field makes flip a function of increased sexual efficiency which permanently favors asexual clones once the sexual clones ability to find each other reaches a threshold. Thus if indeed ostracods are colonizing empty patches by tracking the em field then that is why they do not evolve sex.

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The model shows that if ostracods do indeed use the em field to track colonizations and if these trackings are in some synchrony with the disturbances that open up new patches and cause extinctions then by having sexual lineges the flipping point where asexuals benefits becomes dependent on being a better sexual speciator and so lineage occupancy is more likely to persist by not speciating and remaining on the tracks laid down by the em field. This idea can then be applied to brooding which could be an adaptation for those lineages to remain thus on those paths that were already yielding more asexuals even if the brooding is done by sexual.

Consequence –The meaning of Brooding

On this model brooding (female carrying young that are prevented from dispersing) is an adapation to keep to the past trajectories rather than disperse to try to find new empty patches. It is an adaptation to increase the proportion of empty patches available for colonization.

A Prediction – Locations where Terrestrialization is more probable

A Conclusion

Pulliam in commenting beyond Holt tended to think that the idea shows that Hutchinson was mistaken when asserting that the realized niche is smaller than the fundamental niche when competition is involved. Nonetheless, this early work on metacommunites showed that sink populations with lambda <1 could exist provided there was some BIDE dispersal from sources with lambda >1.

This vindicates Croizat’s use of dispersal from what dispersal and thus metacommunty ideas (as here discussed) do not alter the Hutchinsonian niche but rather the importance of Darwin’s centered

dispersal. Vicariance is thus speculated with the genetic bases of em splitting genes in ostracods and their specially adapted predators as they search for prey with varing rs.

Changing the Model

This is a metapopulation model but a metacommunity model would be preferable. Inclusion of ostracod prey and predators should also be included. Tests of relation to geographic parthenogenesis should be conducted but a metacommunity model would be preferable. Inclusion of ostracod prey and predators should also be included. Tests of relation to geographic parthenogenesis should be conducted

Verifications Needed

Model design

Strength of the field

Ability of Ostracods to orient and move with field variations

Number of Ostracod species with galvanism

Individual variability in motions towards or away from fields and when

Movement in Fresh water?

References

Baltanas A. (1998) Ostracod Populations as Metapopulations In Sex and Parthenogensis ed. Martens Backhuys Publishers, Leiden

Holt, R.D. (1985). Population dynamics in two-patch environments: some anomalous consequences of an optimal habitat distribution. Theor. Popul. Biol., 28, 181–208.

Pulliam, H.R. (1988). Sources, sinks, and population regulation. Am. Nat., 132, 652–661.

https://etd.ohiolink.edu/ap:0:0:APPLICATION_PROCESS=DOWNLOAD_...OSTRACODE METACOMMUNITY. A Dissertation. Presented to. The Graduate Faculty of The University of Akron

Metacommunities: Spatial Dynamics and Ecological Communities edited by Marcel Holyoak, Mathew A. Leibold, Robert D. Holt.

Reevaluating the assumptions of organism-based ...www.museum-joanneum.at/.../Geo11_51_Michelson%20&%20Park_Re...

Plate tectonics may control reversals in the Earth's magnetic field - 16 October 2011 in Geophysical Research Letters. http://www2.cnrs.fr/en/1923.htm

THE STORY