LIFE HISTORY PATTERNS

LIFE HISTORY PATTERNS: is a genetically inherited pattern of resource allocation (= investment) to that optimizes the passing of genes to the next generation Different investment patterns

FOR REST OF TERM – LIFE HISTORY PATTERNS: EGG AND SPERM PRODUCTION SPERM COMPETITION FERTILIZATION PATTERNS TYPES OF DEVELOPMENT LARVAL DISPERSAL STRATEGIES SETTLEMENT PATTERNS is a genetically inherited pattern of resource allocation to that optimizes the passing of genes to the next generation

Spawing and Fertilization

Evolution of Anisogamy Imagine some Precambrian creature Produces undifferentiated gametes Fertilization G. Parker

Gametes produced come in a variety of sizes LargeMediumSmall Number produced Mitotic competence

Gamete size Number produced Size distribution of gametes produced

External fertilization Which ones are the most likely to produce offspring?

Combinations Competence Frequency of contact Very high Moderate Low Very low Moderate Very high Low High Very high

Gamete size Number produced After several generations Selected against

Anisogamy

Spermiogenesis is the final stage of spermatogenesis in which spermatids add tails and become motile Spermatogenesis is the process by which spearmtids are produced from male germ cells via mitosis and meiosis

FERTILIZATION TYPES OF SPERM AND EGG RELEASE AND FERTILIZATION 1. Broadcast spawners (= free spawners) -eggs and sperm are released into the water column - fertilization is external 2. Spermcast spawners -sperm are released into the water column and taken in by the female -fertilization is internal 3. Copulators -sperm placed in the body of the female usually with some intromittent orgtan -fertilization is internal

SPAWNING 1. BROADCAST SPAWNING

SPAWNING 1. BROADCAST SPAWNING Problems for broadcast spawners How does an animal ensure fertilization by dumping eggs and sperm in the open ocean? 1. Proximity 2. Timing 3. Currents 4. Sperm/egg contact

Boradcast spawners suffer a dilution effect Quinn and Ackerman Limnol Oceanogr. 2011: 176

Boradcast spawners suffer a dilution effect

1. Proximity How to get around this problem mussels oysters

2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al Mar.Ecol.Prog.Ser.213:193

2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al Mar.Ecol.Prog.Ser.213:193

2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al Mar.Ecol.Prog.Ser.213:193

2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al Mar.Ecol.Prog.Ser.213:193

2. Timing and synchrony How to get around this problem Haliotis asinina Counihan et al Mar.Ecol.Prog.Ser.213:193 Conclusions (Counihan et al. 2001) 1. Spawning season is determined by water temperature 2. Precise time of spawning is influenced by tidal regime 3. Both sexes spawn in response to an evening high tide 4. Males spawn 19 mins before high tide: females 11 mins after 5. More animals spawn in presence of opposite sex.

3. Currents

Patterns of flow – move gametes unpredictably Advection – mean direction and velocity of a gamete cloud Diffusion –rate of gamete spreading Main problem – production of eddies (vortices) – unpredictable and ephemeral

3. Currents

4. Sperm-egg contact a. Dilution -is it sperm concentration or egg:sperm ratio? If sperm and egg are at similar concentrations -sperm :egg ratio is important Sperm:egg ratio important Sperm concentration is imporant

Sperm concentration and fertilization 1) Fertilization success more sensitive to sperm concentration Reduction in egg concentration Reduction in sperm concentration Same reduction in fertilization success Reduction in egg concentration Reduction in sperm concentration

Final problem Egg and sperm longevity Sperm live less than a few hours Horseshoe crabs Sea urchins Sea stars Ascidians hydroids Eggs live about 3x longer than sperm Sea urchins Sea stars Ascidians

How can sperm and egg increase the chances of contact? a) Chemical attractants

How can sperm and egg increase the chances of contact? a) Chemical attractants L- Tryptophan in abalone Tryptophan cloud

How can sperm and egg increase the chances of contact? b) Jelly coat Jelly coat increases the size of the egg and acts as a spermtrap

Fertilization Spermcast spawning -mating by releasing unpackaged spermatozoa to be dispersed to conspecifics where they fertilize eggs that have been retained by their originator. Bishop and Pemberton Integr.Comp.Biol. 46:398

Fertilization Spermcast spawning most sponges many hydroids some corals (Cnidaria) some polychaetes (Annelida), some bivalve Mollusca, Entoprocta, some articulate Brachiopoda, all Ectoprocta, most or all pterobranchs(Hemichordata), most ascidians (Chordata: Tunicata)

Fertilization Spermcast spawning In most spermcasters - Sperm release Intake by female Storage of sperm Fertilization and brooding Release of competent larvae

Fertilization Spermcast spawning Factors influencing spermcasters 1. Longevity of sperm SpeciesTemperatureHalf life (h) Tunicate A16.58 Ectoproct12, 16, Tunicate B Retain ability to fertilize longer than free spawners

Fertilization Spermcast spawning Factors influencing spermcasters 2. Conservation of energy Sperm release Sperm are inactive or periodically active Intake by female Sperm consistently active Consequence: Fertilization can happen with fewer sperm at greater distance

Fertilization Spermcast spawning Factors influencing spermcasters 3. Sperm storage -allows accumulation of a number of allosperm Celleporella hyalina - Several weeks Diplosoma listerianum - 7 weeks

Fertilization Spermcast spawning Factors influencing spermcasters 4. Egg development Celleporella hyalina Diplosoma listerianum Sperm release Intake by female Triggering of vitellogenesis Consequence: Investment in eggs is not wasted.