Reproductive strategies, larval dispersal and biogeography

How do salps and doliolids reproduce?

asexually

What is asexual reproduction in polychaete and echinoderms called?

fission

what is asexual reproduction in corals?

fragmentation

what is asexual reproduction in colonial invertebrates (corals and ascidians) and solitary cnidarians?

budding

what is asexual reproduction in scyphozoans?

strobilation

what is the benefit of asexual reproduction?

requires less energy investment, beneficial under favourable conditions - where mates are hard to find or size is an advantage (strong currents)

What is simultaneous hermaphroditism (e.g. barnacles)?

When an organism has both male and female sex organs

Sequential hermaphrodites (e.g. slipper limpets)

start as one sex and change to another

protandrous

male to female

protogynous

female to male

Synchronous meaning

tied to tidal or lunar cycles - e.g. broadcast spawning

brooding

fertilisation from copulation or inhalation of sperm

eggs and sometimes larvae retained

3 larval strategies

1. direct release

2. dispersal over short distance (lecithotrophic larvae)

3. dispersal over long distance (planktonic larvae)

Lecithotrophic larvae

larvae that depend upon a yolk for nutrition (large egg)

plankton larvae advantages

species have larger geographical ranges

avoid over-crowding

new habitats

larval spill over from protected habitats

what is the fundamental limit of species’ distribution?

physiology but also continental shelf, evolutionary history, currents, land masses