3.6 Speciation Flashcards
Understand and be able to summarize information from lesson (19 cards)
Speciation
the formation of new species from existing species (macro-evolution)
What are the 2 ways populations may become isolated?
Pre-zygotic or Post-zygotic isolation
What does pre-zygotic isolation mean?
it is usually a barrier that impered mating between species or prevents fertilization of the eggs of individuals from another species attempt to mate sometimes called a pre-fertilization barrier
Basically all the reasons that prevents mating, or prevents fertilization
What are the pre-zygotic isolating mehcanisms?
Behavioural, Habitat, Temporal, Mechanical, Gametic isolating mechanisms.
Behavioural isolating mechanisms
species specific behaviour that prevents inbreeding of closely related species (ex. songs of birds, chemical signals (pheromones) or courtship rituals.
Habitual Isolating Mechanisms
some live in the same region but differ by habitat therefore rarely encounter
Temporal Isolating Mehcanisms
timing mehcanisms
the species live together but mate at different times
Mechanical Isolating mehcanisms
Incompatible anatomy for mating therefore can’t fertilize.
Gametic Isolating mechanisms
are able to mate but gametes will not fuse to form a zygote
What does post-zygotic mechanisms mean?
barrier that prevents zygotes from developing into viable or fertile individuals
this is why it’s also called post-fertilization barrier
what are the post-zygotic mechanisms?
Hybrid inviability, Hybrid sterility, Hybrid breakdown.
Hybrid Inviability
genetic incompatibility of interbreed species that stops development of a zygote
Hybrid Sterility
species will mate and their hybrid offspring are sterile or unable to reproduce
Hybrid Breakdown
offspring are viable but future generations lose fertility and die out before they can be classified as a new species.
What are the types of speciation?
Sympatric and Allopatric speciation
Sympatric Speciation
populations that live in the same region diverge and become reproductively isolated
often due to errors in meiosis that change the number of chromosomes
This is more common in plants
Allopatric Speciation
a population splits into two plus groups geographically isolated
Ecological Niche
A role or position a species is in which decides it’s habitat, food sources and interactions with other species
Adaptive Radiation
the diversification of a common ancestral species into a variety of differently adapted species.
