Dispersal and Speciation Flashcards
How is allopatric speciation different to sympatric speciation? Give an example of each would occur in marine invertebrates
Allopatric Speciation:
Definition: Speciation occurs when populations are geographically isolated from each other.
Barrier forms and evolution of reproductive isolation occurs and species remain distinct when reintroduced. Example would be a seal level change with species on either side so there is a barrier like an island in the way.
Sympatric Speciation:
Original population then genetic difference then reproductive isolation occurs, it can result from behaviour/life history.
An example would be if sea urchins binding proteins changed on their eggs.
What is prezygotic mechanisms and what are examples?
Prezygotic mechanisms are reproductive isolating barriers that prevent the formation of a zygote (fertilized egg) between members of different species. These mechanisms act before fertilization occurs.
Examples:
Geographic isolation, mate choice, gamete incompatibility ( time of gamete release, or gamete recognition )
Whare are post zygotic mechanisms and what are examples?
Postzygotic mechanisms are reproductive isolating barriers that occur after fertilization has taken place, preventing hybrids from producing viable offspring.
Examples:
Hybrid inviability, hybrid sterility
What are the benefits for dispersal?
Gene flow and diversity - allows for mixing of genetic material, which can enhance the adaptability of populations to changing environments.
Reproductive success - can lead to increased reproductive opportunities by allowing organisms to find mates in other locations
Resilience to environmental changes - can help populations survive environmental changes by moving to more favourable conditions with more resources.
What are the costs and problems associated with dispersal?
it is very energetically costly. It is also risky with a high chance of mortality because where they go might not be the right environment for them or there might not be room for new individuals.
Environmental barriers - physical barriers such as currents, temperature gradients and salinity changes may hinder successful dispersal
Predators - there may be more or different predators they aren’t used to
Reproductive isolation - can lead to speciation but can also reduce genetic diversity
What are examples of dispersal mechanisms used by marine invertebrates?
swimming, buoyant structures (bluebottle jellyfish - bubble and sails twist seperate ways so that some of them reach a good destination), gamete production (release eggs and sperm and larvae), in buoyant structure like rafting in kelp holdfasts
